Le Brésil confronté à la pire catastrophe naturelle en 40 ans
LEMONDE.FR avec AFP et Reuters | 14.01.11 | 06h42 • Mis à jour le 14.01.11 | 10h52





Vue des dévastations dans le village de Vieira, à 40 kilomètres de Teresopolis.AFP/VANDERLEI ALMEIDA

La région montagneuse près de Rio, dévastée par des pluies qui ont déjà fait plus de 500 morts, attend avec anxiété de fortes précipitations pour vendredi 14 janvier alors qu'elle fait face à la pire catastrophe naturelle de l'histoire du pays.




Selon un décompte fait par le site G1 du groupe de presse Globo, les inondations et éboulements de terrain provoqués par les pluies torrentielles, dans la nuit de mardi à mercredi, ont fait 506 morts. Le site UOL, pour sa part, a cité le chiffre de 501 morts. D'après G1, citant les municipalités concernées, on a dénombré 225 morts à Nova Friburgo, 223 à Teresopolis, 39 à Petropolis et 19 à Sumidouro.

Les médias ont souligné que cette tragédie était "la plus grande catastrophe naturelle de l'histoire du pays". Elle dépasse en effet les glissements de terrain de 1967 à Caraguatatuba, sur le littoral nord de Sao Paulo, donnés jusqu'à maintenant comme la catastrophe la plus meurtrière, avec 436 morts.

La plupart des personnes qui ont trouvé la mort ont été surprises dans leur sommeil par des torrents de boue qui ont tout emporté sur leur passage, arbres, maisons, voitures.





Un homme récupère des affaires dans une maison qui n'a pas été emportée par les flots, dans le village de Vieira.AFP/VANDERLEI ALMEIDA

Confrontée à sa première crise depuis son arrivée à la tête du pays le 1^er janvier, la présidente Dilma Rousseff a survolé la région et s'est rendue à Nova Friburgo. Elle a jugé que la nature n'était pas seule en cause dans cette catastrophe, qui, dans cette ville, a surtout touché des logements de fortune installés au pied des collines. "Se loger dans des zones à risque est la règle plutôt que l'exception au Brésil", a dit Dilma Rousseff. "Quand il n'y a pas de politique du logement, où vont vivre les gens qui ne gagnent pas plus que deux fois le salaire minimum ?" a-t-elle interrogé. Le gouvernement a déjà débloqué 780 millions de reals (350 millions d'euros) pour les sinistrés.





La présidente Dilma Rousseff a survolé la région et s'est rendue dans la ville de Nova Friburgo, où au moins 200 personnes sont mortes.AFP/ROBERTO STUCKERT FILHO

Chaque heure depuis deux jours, des centaines de sauveteurs découvrent de nouvelles victimes sous les torrents de boue qui ont ravagé cette région connue pour la douceur de son climat, refuge préféré des habitants de Rio fuyant la chaleur de l'été austral.

http://www.youtube.com/watch?v=ZaEqA85U7yY...player_embedded

Au milieu des scènes de deuil et de désespoir de familles décimées, quelques "miracles" ont aussi eu lieu, comme pour cette femme de 53 ans, sauvée in extremis des eaux en furie par un mince filin jeté par des voisins, une scène passant en boucle sur les télévisions. Ou comme ce bébé de six mois, sorti indemne par les pompiers après être resté quinze heures enseveli sous la boue, blotti dans les bras de son père.



Les experts expliquent l'ampleur du drame par la conjonction de rares phénomènes naturels et de l'urbanisation sauvage. Résidences secondaires, auberges et hôtels des quartiers aisés ont autant souffert que les habitations précaires des quartiers pauvres occupant illégalement des zones à risque.

Torrential rains inundated a heavily populated, steep-sloped area about 40 miles north of Rio de Janeiro on Tuesday and Wednesday, triggering flash floods and mudslides that have claimed at least 511 lives. Rainfall amounts of approximately 300 mm (12 inches) fell in just a few hours in the hardest-hit regions, Teresopolis and Nova Friburgo. Many more people are missing, and the death toll is expected to go much higher once rescuers reach remote villages that have been cut off from communications. The death toll makes the January 2011 floods Brazil's worst single-day natural disaster in its history. Brazil suffers hundreds of deaths each year due to flooding and mudslides, but the past 12 months have been particularly devastating. Flooding and landslides near Rio in April last year killed 246 people and did about $13 billion in damage, and at least 85 people perished last January during a similar event.


Figure 1. Flooding at Sao Jose do Vale do Vale do Rio Preto in Brazil, photographed on Thursday, January 13, 2011.

Role of near-record sea surface temperatures in Brazil's flood
This week's heavy rains occurred when a storm system crossing from west to east over southern Brazil drew in a moist southerly flow air off the Atlantic Ocean over southern Brazil. Sea surface temperatures along the Brazilian coast are at near-record warm levels, which likely contributed to the heavy rains. Record rains are more likely when sea surface temperatures over the nearby moisture source regions are at record high levels. This occurs because increased amounts of water vapor evaporate into the atmosphere from a warm ocean compared to a cold one, due to the extra motion and energy of the hotter water molecules. According to an analysis I did of the UK Met Office Hadley Centre sea surface temperature data set, December 2010 sea surface temperatures in the 5x5 degree region of Earth's surface along the Brazilian shore nearest the disaster area, 20S to 25S and 45W to 40W, were the second warmest on record since 1900. Temperatures were 1.05°C (1.9°F) above average in this region last month. Only 2007, with a 1.21°C departure from average, had warmer December ocean temperatures.

Meteorologist Eugenio Hackbart, with the Brazilian private weather forecasting company Metsul, wrote in his blog today, "Heavy rains early this year coincide with the strong warming of the Atlantic along the coasts of southern and southeastern Brazil. With waters up to 2°C warmer than average in some places, there is a major release of moisture in the atmosphere essential for the formation of storms."


Figure 2. Newspaper front page story in Brazil after the March 18, 1967 flooding disaster, Brazil's previous deadliest single-day natural disaster. Image credit:Metsul.

Brazil's previous worst natural disaster: the March 18, 1967 flood
The previous worst natural disaster in Brazilian history occurred on March 18, 1967 when a tsunami-like flood of water, mud and rocks swept down a hillside in the coastal city of Caraguatatuba, near Sao Paulo, killing 300 - 500 people. According to meteorologist Eugenio Hackbart with the private Brazilian weather company Metsul, a rainguage at nearby Sao Sebastao measured 115 mm (4.5") on March 17, and 420 mm (17") on March 18. Hackbart puts the death toll from the 1967 disaster at 300 - 500, and refers to it as Brazil's deadliest single-day natural disaster in history. Heavy rains at other locations in Brazil that month caused additional mudslides and flooding deaths, and Wikipedia lists the total death toll for the Brazil March 1967 floods at 785.

I looked at the sea surface temperatures for March 1967 to see if unusually warm ocean waters may have contributed to that year's flooding disaster. Sea surface temperatures in the 5x5 degree region of Earth's surface nearest the disaster site (20S to 25S, 50W to 45W) were 0.24°C (0.4°F) above average, which is not significantly different from normal. So, we can get record rains and flooding when sea surface temperatures are near normal, and it is possible that this week's catastrophe was not significantly impacted by the exceptionally warm water near the coast. However, heating up the oceans loads the dice in favor of extreme rainfall events, and makes it more likely we will have an unprecedented flood. If we look at the departure of temperature from average for the moisture source regions of the globe's four most extreme flooding disasters over the past 12 months, we find that these ocean temperatures ranked 2nd or 3rd warmest, going back through 111 years of history:

January 2011 Brazilian floods: 2nd warmest SSTs on record, +1.05°C (20S to 25S, 45W to 40W)
November 2010 Colombia floods: 3rd warmest SSTs on record, +0.65°C (10N to 0N, 80W to 75W)
December 2010 Australian floods: 3rd warmest SSTs on record, +1.05°C (10S to 25S, 145E to 155E)
July 2010 Pakistani floods: 2nd warmest SSTs on record, +0.95°C (Bay of Bengal, 10N to 20N, 80E to 95E)

The size of the ocean source region appropriate to use for these calculations is uncertain, and these rankings will move up or down by averaging in a larger or smaller region of ocean. For example, if one includes an adjacent 5x5 degree area of ocean next to Brazil's coast that may have also contributed moisture to this week's floods, the SSTs rank as 7th warmest in the past 111 years, instead of 2nd warmest. It would take detailed modeling studies to determine just how much impact these near-record sea surface temperatures had on the heavy rains that occurred, and what portion of the ocean served as the moisture source region.


Figure 3. Predicted total precipitation amounts in South America for the 7-day period ending at 7am EST January 21, 2011, as forecast by the 06Z run of the GFS Ensemble model made January 14, 2011. Image credit: Florida State University.

More rain in the forecast
The coast of Brazil is embedded in a warm, moist tropical airmass that is expected to continue to bring heavy rains over he Rio de Janeiro area for at least the next week. Heavy rains in excess of five inches in the next seven days (Figure 3) are predicted by the GFS Ensemble computer model for the disaster region, just north of Rio de Janeiro. The additional heavy rains are likely to cause more life-threatening mudslides and floods.

Brésil : trois jours de deuil national après les pluies diluviennes
LEMONDE.FR avec AFP | 16.01.11 | 08h13 • Mis à jour le 16.01.11 | 08h13



Selon les derniers bilans les pluis ont fait au moins 610 morts dans la montagne près de Rio où les habitants désespérés font face au chaos et aux pénuries.AFP/MAURICIO LIMA

La présidente du Brésil Dilma Rousseff a décrété samedi un deuil national de trois jours après des pluies diluviennes qui ont fait au moins 610 morts dans la montagne près de Rio où les habitants désespérés font face au chaos et aux pénuries. L'Etat brésilien indique que près de 14 000 personnes sont sans abri dans cette région agricole et de villégiature, à une centaine de kilomètres de Rio où des pics culminent à 2 200 mètres.



Cette tragédie a suscité un élan de solidarité dans tout le pays. Vingt tonnes d'aliments ont été recueillies par la défense civile et à Rio plusieurs centaines de personnes ont donné leur sang.

Un deuil de sept jours a aussi été décrété dans l'Etat de Rio en mémoire des victimes dont la plupart ont été surprises dans leur sommeil par des fleuves de boue qui ont tout emporté sur leur passage.

RISQUES D'ÉPIDÉMIES

La pluie qui avait cessé a repris dans l'après-midi. Le sol reste saturé d'eau et les risques de nouveaux éboulements demeurent élevés. Une dizaine de zones agricoles sont encore isolées et à mesure que les secours les atteindront, le bilan des morts s'alourdira, ont prévenu les pompiers.

La secrétaire à la santé, Solange Sirico, a mis en garde contre "les risques d'épidémies comme la leptospirose et l'hépatite". Elle a également demandé à la population de "ne pas boire l'eau des puits qui est contaminée" et elle a lancé un appel pour recevoir des dons de matériel médical et des médecins volontaires.

Les conséquences économiques s'annoncent importantes : il était déjà très difficile de trouver à Rio des légumes frais, la région serrana (montagneuse) étant la principale zone de production maraîchère de l'Etat de Rio.

Le pape Benoît XVI a envoyé samedi un message de solidarité aux sinistrés et familles des victimes diffusé sur le site de l'archidiocèse de Rio où il se dit "consterné par les tragiques conséquences des fortes pluies" et exprime sa "solidarité spirituelle à la population de Rio".

L'Australie touchée par les pires inondations de son histoire



Depuis fin décembre 2010, la partie nord-est de l'Australie est en proie à des inondations majeures. Cette catastrophe sans précédent touche désormais la troisième ville la plus peuplée du pays.

C'est l'Etat du Queensland, dans le nord-est de l'Australie, qui est littéralement noyé sous de fortes pluies : les plus abondantes depuis que les relevés météorologiques existent. Selon le Bureau Météorologique australien, fin novembre et décembre 2010 ont été extrêmement humides sur une bonne partie de l'Australie orientale. Quatre importantes chutes de pluie ont touché une grande partie des États de l'Est au cours de cette période, entraînant des débordements de nombreuses rivières, en particulier dans le Queensland et la Nouvelle-Galles du Sud. Des pluies torrentielles se sont abattues autour de la période de Noël (jusqu'à 50 litres d'eau par m² et par heure) sur un sol déjà saturé d'eau. Résultat : les cours d'eau ont débordé, ce qui a inondé, outre les habitations, des milliers de km² de terres agricoles et des mines de charbon.

Ces inondations sont les plus graves qu'ait jamais connu l'Australie : plus de 250 000 personnes sont affectées, une quarantaine de villes sont inondées et un territoire grand comme la France et l'Allemagne réunies est touché.
La cause des fortes pluies : un phénomène La Niña marqué

Selon le Bureau Météorologique australien, c'est le célèbre phénomène climatique La Niña, réapparu dès juin dans le Pacifique, qui est à l'origine de ces fortes pluies. Ce phénomène de refroidissement périodique des eaux océaniques dans la zone équatoriale du Pacifique, entraîne généralement un accroissement des précipitations en Indonésie, dans le nord de l'Australie, en Amazonie et dans le sud-est de l'Afrique. La Niña entraîne aussi une diminution des précipitations dans la partie orientale du Pacifique au niveau de l'équateur et dans l'Afrique équatoriale de l'Est.

Or, un important épisode La Niña continue d'affecter le bassin de l'océan Pacifique et risque de perdurer pendant l'automne de l'hémisphère sud. Ainsi, le Pacifique tropical reste beaucoup plus frais que la moyenne pour cette période de l'année, avec des températures de surface 4°C inférieures à la normale dans les régions centrale et orientale (comparable à l'événement La Niña de 1988). De plus, les alizés sont plus forts que la moyenne et la forme des nuages est typique du phénomène.

L'Organisation Météorologique Mondiale avait indiqué en octobre que La Niña était désormais bien installée et devrait perdurer une "bonne partie du premier trimestre de 2011".

Conséquence de cet épisode La Niña : un cyclone a touché le Queensland pendant Noël. Tasha (son nom) a atteint son pic d'intensité le 24 décembre et a déversé pendant plusieurs jours des pluies intenses : jusqu'à 250 litres par m² sur les villes de Rockhampton, Mackay, Bundaberg et Charleville.

Conséquences : des inondations catastrophiques

"De nombreux cours d'eau à travers la région ont atteint des niveaux record. Les dommages aux infrastructures et aux biens ainsi que le coût économique des pertes de récoltes et du retard de production dans les mines, devraient représenter plusieurs milliards de dollars australiens", relève le Bureau Météorologique australien. En effet, certaines rivières sont par endroits montées de huit mètres en une heure, prenant les habitants et les autorités totalement par surprise.

La plupart des maisons touchées sont en bois, beaucoup sont vétustes et il faudra sans doute tout reconstruire.

La ville de Rockhampton - 75 000 habitants, l'une des principales villes de cette région agricole et minière - est touchée par des inondations qualifiées de "bibliques". Toutes les routes qui mènent à la ville sont coupées et la piste de l'aéroport est impraticable. Par conséquent, les produits de première nécessité sont acheminés par bateau et via un pont aérien avec la ville voisine de Mackay.

Autres conséquences de ces inondations : les serpents et crocodiles ont été signalés en ville. Les serpents posent un sérieux problème car ils entrent dans les maisons, à la recherche d'endroits secs. Quant aux crocodiles, il est difficile de les repérer au milieu des débris charriés par les flots. Or les secouristes refusent de s'exposer à ce risque, face à certains habitants qui ne veulent pas évacuer leurs logements. De surcroît, les moustiques pullulent alors que les eaux de pluie se sont mélangées aux fosses septiques, ce qui fait craindre l'apparition d'épidémies.

La capitale de l'Etat, Brisbane, sous les eaux

Mercredi 12 janvier, Brisbane, capitale du Queensland et troisième ville la plus peuplée d'Australie avec 1 600 000 habitants, a été finalement envahie par l'eau : près d'un mètre d'eau noie le centre ville. Des milliers d'habitants ont été contraints d'évacuer leur domicile. La crue de la rivière Brisbane a envahi la capitale : un torrent s'est déversé dans les rues désertes du centre-ville. En effet, des milliers de personnes ont été évacuées, les inondations menaçant 20 000 logements, rapporte ABC News. L'électricité a été coupée en centre-ville par mesure de précaution.

Les lacs de retenue construits pour préserver la ville n'ont pas suffi : ils sont au maximum de leur capacité.

Le port de Brisbane (troisième port à conteneurs du pays) et un important terminal d'exportation du charbon, ont été fermés. Anna Bligh, Premier ministre du Queensland, a évoqué une situation "sombre et désespérante". Elle a dit s'attendre à ce que le niveau des eaux dépasse celui des inondations de 1974 qui avaient fait 14 morts dans la capitale du Queensland. Finalement, ce ne fut pas le cas, le niveau d'eau ayant atteint 4,45 m dans le centre ville de la capitale contre 5,45 m en 1974.

http://www.youtube.com/watch?v=a0Ui9miD0Gg...player_embedded
© Euronews

Bilan des victimes

Le bilan officiel des inondations qui frappent le Queensland depuis trois semaines, est de 25 morts. Toutefois, au moins 80 disparus sont à déplorer après les crues brutales qui ont touché des communes à l'ouest de Brisbane.

De nouvelles pluies sont prévues la semaine prochaine et les autorités ont conseillé aux habitants d'économiser l'eau potable. Les supermarchés ont également été dévalisés de leur produit de base, comme le lait ou le pain.

Des conséquences économiques supérieures à l'ouragan Katrina

Des milliers d'hectares de production agricole : coton, canne à sucre, fruits et légumes, ont été endommagés. Conséquence : la qualité de près de la moitié de la récolte australienne de blé, soit environ 10 millions de tonnes, a été revue à la baisse, ce qui a alimenté la flambée du cours de cette denrée sur les marchés (+45% en 2010).

Toute l'industrie minière est affectée : plus de 75 % des mines ont vu leur activité suspendue. Or, l'état du Queensland est le premier exportateur mondial de coke (plus de la moitié des exportations mondiales), un résidu solide de houille utilisé dans la métallurgie pour l'alimentation des hauts-fourneaux.

Les inondations qui dévastent le nord-est de l'Australie depuis fin 2010 pourraient entamer de 10 milliards de dollars US le produit intérieur brut du pays et peser sur l'économie plus que ne l'avait fait l'ouragan Katrina aux Etats-Unis(1), selon les économistes. "Le coût de tout cela va être bien évidemment important", a déclaré Stephen Walters, chef économiste à la banque d'investissement JP Morgan. Mais l'économie australienne, portée par la demande asiatique en matières premières, devrait récupérer au deuxième semestre 2011, grâce aux travaux de reconstruction des logements, bureaux et infrastructures, selon Stephen Walters.

Pour John Rolfe, économiste à la Queensland Central University, les inondations vont surtout affecter les exportations de charbon et de matières premières, et leur impact se fera sentir pendant plusieurs années. "Sur le plus long terme, l'économie va souffrir à cause des perturbations durables dans la production, et des dépenses supplémentaires, publiques et privées, pour remettre en état les infrastructures", estime-t-il.

Conséquences environnementales

Les inondations mettent également en danger les coraux. Les détritus et pesticides sont charriés par les eaux boueuses et rejetés en mer. Un "cocktail" dangereux pour l'équilibre de cet écosystème. C'est en effet toute la chaîne alimentaire et la vie des coraux qui seront perturbées. Unique au monde, la grande barrière de corail est inscrite au patrimoine mondial de l'Unesco.

Mardi 10 janvier, les Nations unies ont indiqué que le secrétaire général Ban Ki-moon suivait la situation de près, même si l'Australie n'a pas encore lancé d'appel à l'aide internationale.

Dans le même temps, le sud des Philippines connaît depuis la fin décembre des inondations catastrophiques qui ont tué 40 personnes et touchent 144 villes. Près de 340 000 personnes ont été évacuées.

Au Brésil, des pluies diluviennes ont touché la capitale Rio de Janeiro. Des coulées de boues ont fait au moins 370 morts.

Russian heatwave killed 11,000 people

Updated Sat Sep 18, 2010 7:39am AEST
The Kremlin wall in Moscow seen through heavy smog caused by peat fires in nearby forests on August

The Russian authorities have faced searing criticism for downplaying the health risks amid the country's worst ever heatwave (Reuters: Alexander Natruskin)

Moscow registered nearly 11,000 deaths due to an unprecedented heatwave this summer, a city official said, as the mortality rate more than doubled in the Russian capital.

In August alone, 15,016 deaths were registered in the city of more than 10 million people, compared with 8,905 for the same period last year - an increase of 6,111 deaths, city official Evegenya Smirnova said.

A month earlier, Moscow saw 4,824 deaths more compared with the same period in July 2009.

Overall, the city experienced 10,935 deaths linked to the extreme temperatures and stifling smog over the two months from July to August, which represents a 60 per cent rise in the mortality rate.

The Russian authorities have faced searing criticism for downplaying the health risks amid the country's worst ever heatwave when a toxic mix of smog and smoke from nearby bushfires engulfed the city.

The health ministry only acknowledged on August 30 that the country had seen a surge in deaths in the affected regions - up by 50 per cent in Moscow in July - despite media reports this summer describing morgues overflowing.

Federal authorities had earlier refused to give details of the Moscow death toll and there was no public announcement of the figures on Friday.

The authorities have partially attributed the rise in deaths to a spike in the number of drownings as Russians rushed to escape the sweltering temperatures topping 40 degrees Celsius over several weeks.

Officials say it may take months for the government to tally the damage from the disaster that destroyed over a quarter of Russia's grain harvest, but several economists have put the cost to the economy this year at roughly $US7-15 billion.

- AFP

Malgré le temps "doux" qui regne sur la Belgique, le Sud de la France connaît des nuits très fraîches;
Ce matin on relevait
-8,5°C à Chambéry
-5°C à Biarritz
-8°C à Salon-de-Provence
-9°C à Albi,
-7°C à Lyon
...
Localement des températures en-dessous de -10°C furent enregistrées. Mais il n'y a pas eu de record malgré ces température exceptionnelles pour certaines régions. Ces températures très basses sont dues à un ciel dégager durant la nuit.

SHORT RANGE FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
400 PM EST MON JAN 31 2011

VALID 00Z TUE FEB 01 2011 - 00Z THU FEB 03 2011

THE CURRENT NATIONAL WEATHER SERVICE HAZARDS MAP IS FULL OF COLORS
INDICATIVE OF THE UPCOMING WINTER STORM WHICH WILL IMPACT
SIGNIFICANT PORTIONS OF THE CENTRAL AND EASTERN U.S. WINTER
WEATHER RELATED WARNINGS...WATCHES...AND ADVISORIES SPAN FROM THE
HIGH PLAINS THROUGH THE MIDDLE MISSISSIPPI VALLEY...AND INTO THE
OHIO RIVER VALLEY AND NORTHEASTERN U.S. IN ADDITION...BLIZZARD
CONDITIONS ARE A DISTINCT POSSIBILITY GIVEN THE HEAVY SNOW AND
WIND IN THE FORECAST. LURKING BEHIND THIS IMPRESSIVE WINTER STORM
IS A POWERFUL SHOT OF ARCTIC AIR AS A FRIGID SURFACE HIGH DROPS
DOWN FROM CENTRAL CANADA. THIS ARCTIC FRONTAL BOUNDARY WILL EASILY
PUSH ACROSS THE TOPOGRAPHY OVER THE WEST AND EVENTUALLY MAKES IT
WAY INTO THE EASTERN PACIFIC WATERS BY WEDNESDAY MORNING.

THE CATALYST FOR THIS UPCOMING WINTER STORM ARE A PAIR OF FEATURES
CURRENTLY SITUATED ACROSS THE NORTHERN HIGH PLAINS AND EXTREME
WEST TEXAS...RESPECTIVELY. AS THESE TWO SYSTEMS WHICH RESIDE IN
SEPARATE ATMOSPHERIC JET STREAM ADVANCE EASTWARD...INTERACTION IS
EXPECTED TO TAKE PLACE RESULTING IN SIGNIFICANT STRENGTHENING OF
THE SOUTHERN TIER SYSTEM. THIS PARTICULARLY BECOMES NOTABLE BY
TUESDAY EVENING AS THE UPPER TROUGH INTENSIFIES RESULTING IN A
STRENGTHENING SURFACE LOW OVER THE OZARKS. AS THIS MASSIVE
PRECIPITATION PRODUCER MOVES EASTWARD...IT WILL CONTINUE TO FEED
OFF OF AN AMPLE MOISTURE SOURCE IN THE GULF OF MEXICO. THE RESULT
WILL BE MODERATE TO HEAVY SNOW ON THE BACK SIDE OF THE LOW CENTER
WITH NUMEROUS LOCATIONS EXPECTING OVER A FOOT OF SNOW BEFORE IT IS
ALL SAID AND DONE. AN ADDITIONAL THREAT WILL BE SIGNIFICANT
ACCUMULATIONS OF ICE WITH AN AREA STRETCHING FROM THE OZARKS
NORTHEASTWARD THROUGH THE UPPER MIDWEST AND INTO THE OHIO
VALLEY/MID-ATLANTIC REGION. ALL OF THIS UNSETTLED WEATHER WILL
MARCH TOWARD THE NORTH AND EAST IMPACTING NEW ENGLAND BY THE
MIDDLE OF THE WEEK. FOR MORE INFORMATION ON THIS DANGEROUS WINTER
STORM...PLEASE VISIT THE WINTER WEATHER DESK GRAPHICS AT
HTTP://WWW.HPC.NCEP.NOAA.GOV/WWD/WINTER_WX.SHTML.

THE FRIGID AIR INVADING THE CENTRAL U.S. WILL BE EASILY EVIDENT IN
SURFACE TEMPERATURES AS SOME REGIONS WILL STRUGGLE TO EVEN PUSH
ABOVE THE 0 DEGREE MARK FOR A HIGH. MEANWHILE...OVERNIGHT LOWS MAY
EASILY PLUNGE INTO THE -20S WITH EVEN SOME ISOLATED -30S FORECAST.
A PRETTY SIGNIFICANT TEMPERATURE CONTRAST WILL SETUP WITH HIGHS ON
TUESDAY IN THE SINGLE DIGITS ACROSS NORTH TEXAS WHILE 60S AND 70S
RESIDE ACROSS THE WESTERN GULF COAST.


RUBIN-OSTER


GRAPHICS AVAILABLE AT WWW.HPC.NCEP.NOAA.GOV

Dr. Jeff Masters' WunderBlog

Potentially historic winter storm poised to impact 100 million Americans

Posted by: JeffMasters, 15:16 GMT le 31 janvier 2011
A huge and potentially historic winter storm is taking shape over the Southern Plains today. By the time the storm exits New England on Wednesday night, as many as 50 million Americans may see heavy snows of at least 6 inches or dangerous ice accumulations of 1/4" or more from the massive storm, and 100 million will be affected by the storm. A potent jet stream with strong winds will dive southwards over the central U.S. today, allowing a cold Arctic airmass to spill southwards out of Canada. In front of this cold air, a flow of very warm, moist air from the Gulf of Mexico will surge northwards, providing copious moisture to fuel snowfall amounts that will likely approach two feet across portions of Iowa and Illinois on Tuesday. The storm could be Chicago's biggest blizzard since January 1999, when a storm dumped 21.6" of snow. Accompanying the heavy snow on Tuesday will be strong winds gusting to 40 mph in Northern Illinois and Northwest Indiana, and a blizzard watch is posted for Chicago. Strong winds in Chicago are expected to generate 14 - 18 feet waves on Lake Michigan, with occasional waves up to 25 feet. A significant coastal flooding event is possible for Chicago, with beach erosion and flooding along Lake Shore Drive. Many major cities will likely receive over 8 inches of snow from the storm, including Kansas City, St. Louis, and Detroit. Perhaps of greater concern is the potential for a major ice storm along a swath from Northwest Oklahoma to Massachusetts. Widespread freezing rain is expected to bring over 1/4" of ice to many major cities, including St. Louis, Indianapolis, Columbus, Cleveland, and Pittsburgh. Some regions could see up to an inch of ice, and widespread power outages due to toppled power lines are likely for millions of people. Damages exceeding $1 billions are possible from this ice storm. In addition, the storm's powerful cold front will bring the potential for severe thunderstorms to the deep South. The NOAA Storm Prediction Center is giving Louisiana and surrounding states a "slight risk" of severe weather on Tuesday, and severe thunderstorms with damaging winds are likely Tuesday afternoon in this region.


Figure 1. Probability of receiving at least 1/4" of ice for the 24 hours ending at 7am EST on Wed Feb 2, 2011. Image credit: NOAA.

Carte inversée; plus doux dans le nord de la France que dans le sud.

Click to view attachment

Historic 3-day tornado outbreak kills at least 40

Posted by: JeffMasters, 14:45 GMT le 18 avril 2011

In a stunning display of violence, close to 200 tornadoes rampaged across the Midwestern and Southeast U.S. April 14 - 16 in one of the largest tornado outbreaks in history. At least 40 people died in the tornadoes, making it the deadliest tornado outbreak since the Super Tuesday tornado outbreak of February 5 - 6, 2008, which killed 57 people. Severe thunderstorms and flash floods killed at least seven more people in this April's severe weather outbreak. Hardest hit was Bertie Country in northeast North Carolina, where an EF-3 tornado carved a path of destruction 18.8 miles long and 1/2 - 3/4 miles wide, killing 11 people in the town of Colerain. It was the deadliest single tornado in the United States since May 10, 2008 in Picher, Oklahoma and Neosho, Missouri, which killed 21. Also hard-hit Saturday was the Raleigh area, where a 3/10 mile-wide tornado carved a 63-mile long path of destruction through downtown. Damage was rated EF-2 in downtown Raleigh, but was EF-3 along other portions of its path, and the tornado killed five people. The 23 tornado deaths in North Carolina made Saturday's outbreak the deadliest day for tornadoes in the state since 1984, when the infamous March 28 tornado outbreak killed 57 people and injured 1248. The 1984 outbreak had more violent tornadoes--seven F4 twisters in all. None of the tornadoes in this year's outbreak have been rated above EF-3, as of yet.


Figure 1. Viewer-uploaded photo sent to WRAL of damage in Fayetteville, NC on Saturday.


Figure 2. Radar reflectivity image of North Carolina on Saturday during the height of the tornado outbreak, showing four simultaneous hook echoes of tornadoes. The storm at the top of the image is the EF-3 tornado that ripped through Raleigh, killing five people.

One of the largest tornado outbreaks in history
NOAA's Storm Prediction Center logged 120 preliminary tornado reports on Saturday, 120 on Friday, and 27 on Thursday, bringing the 3-day total to 267 twisters. In past years, these preliminary tornado reports typically were an over-count of the actual confirmed tornado totals by about 15%. However, this year the Storm Prediction Center stopped trying to filter out preliminary reports they thought were from the same tornado, so the over-count may be higher. Even so, the 3-day April 14 - 16 2011 tornado outbreak will likely will end up with close to 200 confirmed tornadoes, making it the largest tornado outbreak since the 235 tornadoes recorded in the May 22 - 31, 2008 outbreak. According to a list of tornado outbreaks maintained by Wikipedia, only two other tornado outbreaks have had as many as 150 twisters--the May 2004 outbreak (385), and the May 2003 outbreak (401). An average April typically has 150 - 160 tornadoes across the entire U.S.

Tornadoes, huge hail pound the Midwest, but bring little Texas drought relief

Posted by: JeffMasters, 12:41 GMT le 20 avril 2011

Severe weather blasted the Midwest again yesterday, with NOAA's Storm Prediction Center logging 32 reports of tornadoes, 399 reports of damaging thunderstorm winds, and 325 instances of large hail (including softball-sized hail of 4.25 - 4.5" diameter in Clarkesville, MO and Stringtown, OK.) Fortunately, no deaths or injuries were reported from yesterday's storms. The storm also brought the heaviest snow so late in the season to Green Bay, Wisconsin--9.9 inches. This brought the seasonal total for Green Bay to 92.4", the third most on record.

The storm responsible will trek eastwards today, bringing the threat of severe weather to regions of the Southeast hard-hit by last week's remarkable tornado outbreak. NOAA's Storm Prediction Center has placed a wide swath of the country from Eastern Texas to New Jersey under their "slight risk" for severe weather. According to the latest tornado tallies on the excellent Wikipedia page on the April 14 - 16 tornado outbreak, 128 tornadoes are confirmed to have occurred, with 39 of these strong EF-2 and EF-3 twisters. Remarkably, there have been no violent EF-4 or EF-5 tornadoes reported yet in 2011, despite the fact that the preliminary 2011 tornado count as compiled by SPC is 611, which will likely make 2011 the most active tornado season on record for this point in the year.


Figure 1. Satellite image taken at 8pm EDT on Tuesday, April 19, 2011, of the storm system that brought severe weather to the Midwest. Image credit: NASA/GSFC.


Figure 2. Severe weather outlook for today.

Yesterday's storms bring little drought relief for Texas
Yesterday's severe weather outbreak brought a few thunderstorms to the Dallas/Fort Worth area last night, with up to two inches of welcome rain falling in isolated areas. However, the rains missed the areas of Texas where the worst fires area burning, and strong winds associated with the spring storm helped whip up the fires. Winds will not be as strong today, and the latest 1 - 5 day rainfall forecasts show the possibility of isolated thunderstorms bringing drought relief to the same portions of Texas that benefited from last night's rains. These rains will not be enough to significantly slow down the record fires scorching Texas, though, and the latest 2-week forecast from the GFS model shows little chance of drought-busting rains over Texas into early May.


Figure 2. Total rainfall for North Texas from last night's storms brought only isolated drought relief.

Violent EF-4 tornado causes severe damage at St. Louis' airport

Posted by: JeffMasters, 15:25 GMT le 23 avril 2011

A violent EF-4 tornado ripped through St. Louis near 8pm local time Friday night, severely damaging Lambert International Airport. The airport, the world's 30th busiest, may be closed for several days. The tornado ripped off the roof from Concourse C, blew out more than half of the windows in the main terminal, and moved an aircraft that was parked at a gate twenty feet. So far, only minor injuries due to flying glass have been reported from the tornado. The tornado also passed over nearby residential areas, causing severe damage. The National Weather Service office in St. Louis has rated the damage from the St. Louis tornado EF-4, making the twister the first violent EF-4 tornado of the year. Softball-sized hail also pelted three towns in Missouri--Hermann, Big Spring, and Warrenton--during Friday night's severe weather outbreak. NOAA's Storm Prediction Center logged 24 tornado reports Friday in Oklahoma, Arkansas, Missouri, Illinois, and Kentucky. The cold front responsible for triggering last night's severe weather will remain draped over the nation's mid-section for the next three days, and a slight risk of severe weather is predicted along a swath from Texas to Ohio both Saturday and Sunday. A more substantial risk of severe weather is likely on Tuesday through Wednesday, as a new, more powerful spring storm system gathers strength over the Midwest.


Figure 1. Radar reflectivity image of the EF-4 St. Louis tornado taken near 8pm local time on Friday, April 22, 2010. This image is from the high-resolution Terminal Doppler Radar (TDR) at the St. Louis Airport, and shows very fine details of the tornado, which displays a classic hook echo here.


Figure 2. Radar Doppler velocity image of the St. Louis tornado taken near 8pm local time on Friday, April 22, 2010. This image is from the high-resolution Terminal Doppler Radar (TDR) at the St. Louis Airport, located at the "+" sign on the image. Green colors denote areas where precipitation is moving towards the radar, and red and yellow colors show where precipitation is moving away from the radar. Pink colors are bad data regions. The small couplet of greens right next to reds is where the tornado was, since the tight vortex had winds moving towards the radar and away from the radar. The area marked "RFD" shows where a Rear-Flank Downdraft (RFD) was occurring behind the tornado. The downdraft hit the ground to the west of the radar site and spread out in all directions, creating a diverging area of winds moving both towards and away from the radar. An area of air flowing into the tornado on the SE side is marked "Inflow." Thanks go to Dr. Rob Carver, wunderground's tornado expert, for annotating this image.


Figure 3.
Remarkable video from a security camera at the St. Louis airport showing the roof being torn off Concourse C.

http://www.youtube.com/watch?v=EGtumnBej2Q...player_embedded


Figure 4. Severe damage characteristic of at least a strong EF-2 tornado is apparent from this helicopter view of residential St. Louis neighborhoods taken by KMOV.

Jeff Masters

Tornadoes, floods, and fires continue to pound U.S.
Posted by: JeffMasters, 15:13 GMT le 27 avril 2011

The nation's unprecedented April tornado-fest continued full force last night, with NOAA's Storm Prediction Center logging 57 tornado reports, 295 cases of damaging thunderstorm winds, and 254 reports of large hail. The 2-day tornado count from this latest huge April tornado outbreak is already 102. With another "high risk" forecast for tornadoes today, the tornado total for this week's outbreak may rival the April 14 - 16 tornado outbreak (155 confirmed tornadoes) as the greatest April tornado outbreak in history. It is unprecedented to have two such massive tornado outbreaks occur so close together, and the April preliminary tornado count of 654 is truly stunning. Even adjusting this number downwards 15% (the typical over-count in preliminary tornado reports) yields a probable April tornado total of 550. This easily crushes the previous April tornado record of 267, set in 1974. An average April has "only" 163 tornadoes, so we are already 300% over average for the month, and may approach 400% after today's outbreak. According to a list of tornado outbreaks maintained by Wikipedia, only two other tornado outbreaks have had as many as 150 twisters--the May 2004 outbreak (385), and the May 2003 outbreak (401). One positive note--there has only been one violent EF-4 or stronger tornado this year, despite the fact we've already had about 2/3 of the 1200 tornadoes one typically gets for the entire year. Over the past 20 years, we've averaged 7 violent EF-4 or EF-5 tornadoes per year, so we should have had 4 or 5 of these most dangerous of tornadoes so far this year.


Figure 1. Satellite image of last night's storm at 8pm EDT April 26, 2011. Image credit: NASA/GSFC.

Fortunately, no one was killed in last night's tornado frenzy, but four twisters caused injuries, with 7 injuries in Hesterman, Mississippi, and 3 in Beekman, Louisiana. Over 100 homes were damaged when a tornado struck Edom, Texas, approximately 75 miles East of Dallas. One woman was injured when her mobile home was destroyed. The only killer tornado of the current outbreak occurred on Monday night at 7:30 pm CDT when a 1/2 mile-wide EF-2 tornado struck the small town of Vilonia, Arkansas. Four people died in the town, where 50 - 80 buildings were destroyed. Tornado warnings were issued 30 minutes before the storm hit, contributing to the relatively low loss of life.

http://www.youtube.com/watch?v=3d6j2guPZTw...player_embedded
Figure 2. Storm chaser video of a tornado yesterday in Ben Wheeler, Texas.

Another very dangerous tornado outbreak expected today
The busiest April in history for tornadoes continues full-force today, as NOAA's Storm Prediction Center has issued their highest level of severe weather potential, a "High Risk" forecast, for Northern Alabama, Southern Tennessee, and adjoining portions of Georgia and Mississippi. This is the second day in a row, and third time this year, that SPC has issued a "High Risk" forecast. The devastating North Carolina tornado outbreak of April 16, which generated 52 confirmed tornadoes that killed 24 people in North Carolina and 2 people in Virginia, was the other "high risk" day. Numerous tornado warnings have already been issued in Tennessee, Kentucky, Georgia, Mississippi, Arkansas, Ohio, and Alabama this morning, but today's main action is expected to erupt late this afternoon as the cold front from a low pressure system currently over Arkansas moves eastwards over the "high risk" area. Strong daytime heating in a very moist, unstable airmass will allow a tremendous amount of energy to build up ahead of the front. The arrival of the cold front will force the warm, moist air upwards, allowing the pent-up energy to burst out and fuel supercell thunderstorms.

Related post: Are tornadoes getting stronger and more frequent?


Figure 3. Severe weather threat for Wednesday, April 27, 2011.

Unprecedented flooding predicted on Ohio River
This week's storm system, in combination with heavy rains earlier this month, have pushed the Ohio River and Mississippi River to near-record levels near their confluence. The Ohio River at Cairo, Illinois is expected to crest at 60.5 feet on May 1. This would exceed 100-year flood stage, and be the highest flood in history, besting the 59.5' mark of 1937. Heavy rains of 10 - 15 inches have inundated the region over the past few days, and one levee breach at Black River levee near Poplar Bluff, Missouri, has resulted in the evacuation of over 500 homes. Poplar Bluff has received 15.45" of rain since Friday morning. The greatest rain gauge-measured precipitation from the storm occurred in Springdale, Arkansas, where 19.70" inches has fallen since Friday morning.


Figure 4. The latest River Flood Outlook from NOAA shows major flooding is occurring over many of the nation's major rivers.

Extraordinary intentional levee breach of Mississippi River halted by lawsuit
In a sign of just how extreme this flooding situation is, yesterday the Army Corps of Engineers, which is responsible for flood control efforts on the Mississippi River, announced plans to intentionally destroy a levee protecting the west bank of the Mississippi River in Southwest Missouri. The destruction of the levee is intended to relieve pressure on the levees at Cairo, Illinois, at the confluence of the Mississippi and Ohio Rivers. Cairo is currently under a voluntary evacuation order. The levee to be destroyed, located at Birds Point, is called a "fuse-plug" levee, and was designed to be destroyed in the event of a record flood. The levee protects 132,000 acres of prime farmland along the New Madrid Spillway, which is designed to take 550,000 cubic feet per second of water flow out of the Mississippi and redirect it down a 3 - 10 mile wide, 36 - 56 mile long path along the west side of the Mississippi. An 11-mile long section of the levee upstream at Birds Point, and 5-mile long stretch at the downstream end, are set two feet lower than the surrounding levees and filled with holes to accommodate dynamite. These levees will be destroyed if the Army Corps has its way, but a lawsuit by the state of Missouri is currently blocking the way. The Army Corps has now agreed to wait until Saturday to decide whether or not to blow the levee. The Army Corps' website has an unofficial damage estimate of $100 million for destroying the levees and flooding the New Madrid Spillway. At least 100 people live in the spillway and have been evacuated, and it would likely take many years for the farms to recover after flooding. The levees have been blown and the spillway opened only once before, back during the record flood of 1937.

Midwest deluge enhanced by near-record Gulf of Mexico sea surface temperatures
The deluge of rain that caused this flood found its genesis in a flow of warm, humid air coming from the Gulf of Mexico. Sea surface temperatures (SSTs )in the Gulf of Mexico are currently close to 1 °C above average. Only two Aprils since the 1800s (2002 and 1991) have had April SSTs more than 1 °C above average, so current SSTs are among the highest on record. These warm ocean temperatures helped set record high air temperatures in many locations in Texas yesterday, including Galveston (84°F, a tie with 1898), Del Rio (104°F, old record 103° in 1984), San Angelo (97°F, old record 96° in 1994). Record highs were also set on Monday in Baton Rouge and Shreveport in Louisiana, and in Austin, Mineral Wells, and Cotulla la Salle in Texas. Since this week's storm brought plenty of cloud cover that kept temperatures from setting record highs in many locations, a more telling statistic of how warm this air mass was is the huge number of record high minimum temperature records that were set over the past two days. For example, the minimum temperature reached only 79°F in Brownsville, TX Monday morning, beating the previous record high minimum of 77°F set in 2006. In Texas, Austin, Houston, Port Arthur, Cotulla la Salle, Victoria, College Station, Victoria, Corpus Christi, McAllen, and Brownsville all set record high minimums on Monday, as did New Orleans, Lafayette, Monroe, Shreveport, and Alexandria in Louisiana, as well as Jackson and Tupelo in Mississippi. Since record amounts of water vapor can evaporate into air heated to record warm levels, it is not a surprise that incredible rains and unprecedented floods are resulting from this month's near-record warm SSTs in the Gulf of Mexico.


Figure 5. Departure of sea surface temperature from average for April 25, 2001. Image credit: NOAA/NESDIS.

Fierce winds fan Texas, New Mexico fires
Fierce winds fanned raging fires across eastern New Mexico and Western Texas yesterday, thanks to a powerful flow of air feeding into the Midwestern storm system. Temperatures in the upper 80s and low 90s combined with humidities less than 10% combined to make yesterday a nightmare fire day for firefighters attempting to control the worst springtime fires in the history of the region. At 3:53 pm MDT yesterday in Carlsbad, New Mexico, the temperature was 87°F, winds were 38 mph gusting to 46, and the humidity was 8%--a perfect storm for extreme fire weather. In Fort Stockton, Texas near the huge Rock House fire, the temperature was 91°F, winds were 35 mph gusting to 44, visibility was reduced to 5 miles due to haze and smoke, and the humidity was 5% at 5:53pm CDT. According to the Interagency Fire Center, wildfires in 2011 have already burned nearly 2.3 million acres in the U.S. This is the greatest acreage on record so early in the year, and is more area than burned all of last year. The largest U.S. acreage to burn since 1960 was the 9.9 million acres that burned in 2007, so we area already 25% of the way to the all-time record fire year--with summer still more than a month away. The fire weather forecast for today is better then yesterday, with winds not expected to blow nearly as strong.


Figure 6. Major wildfires and smoke plumes as visualized using our wundermap with the "fire" layer turned on.

For those who want to lend a helping hand to those impacted by the widespread destruction this month's severe weather has brought, stop by the portlight.org blog.

Jeff Masters

Ryan Maue a fait une page avec des images radars de ces multiples tornados outbreak :
http://www.coaps.fsu.edu/~maue/weather/severewx.html
En rouge, ce sont les alertes tornade, et en bleu les alertes orages sévère.

Historic Flooding Unfolding Along Mississippi, Ohio Rivers

By Alex Sosnowski, Expert Senior Meteorologist

Apr 28, 2011; 12:58 PM ET


As if tornadoes and damaging thunderstorms were not enough, historic flooding is also threatening the Mississippi River, below St. Louis, as well as the lower part of the Ohio River.

The rising waters are expected to top levels set during February 1937. This mark is the middle Mississippi Valley's equivalent to the 1993 event farther north along Old Man River.

Even if rain were to fall at a normal rate for the remainder of the spring, the consequences of what has already happened in the Midwest will affect way of life, property, agriculture and travel/shipping/navigation for weeks in the region.

While the amount of evacuees currently numbers in the hundreds, it could soon number in the tens of thousands as levees are topped or breached and rivers expand their girth into more farming communities, towns and cities.



The flooding problem is not only for the major rivers in the long term, but flooding could repeat later this season for the smaller rivers feeding into the Mississippi and Ohio rivers as well as the multitude of small streams that feed into the rivers.

The Black River flooded areas around Poplar Bluff, Mo., while rising waters along a stream overtook the town of Johnson, Ark., early this week.

A several-day stretch of rain-free weather is forecast by AccuWeather.com meteorologists to continue into the first part of the weekend. However, more rain and perhaps severe thunderstorms may return by early next week.

River levels at Cairo, Ill., Tiptonville, Tenn., and several other locations are forecast by National Weather Service hydrologists to set new record highs this weekend.

Cairo, Ill., lies along the banks of where the Mississippi and Ohio rivers meet.


The small colored squares on this map indicate river and stream levels at gauge locations. Purple indicates major flooding, red indicates moderate flooding, orange is indicative of minor flooding and yellow suggests levels near flood stage.

A general 6 to 12 inches of rain have fallen on portions of southeastern Missouri, southern Illinois, western Kentucky, Arkansas, Indiana, Ohio and western Tennessee this month. However, there have been much higher amounts locally.

Cape Girardeau, Mo., has received over 19 inches of rain so far this month, which is over five times that of normal for the entire month of April. 14.50 inches of rain have fallen in five days in the city along the Mississippi River.

Cincinnati, Ohio has received over a foot of rain, which around four times its normal rainfall for the entire month.

Record- or near-record water levels are taxing levees in the region.

The stress on the levees in some locations will not only last days but weeks as the huge rivers such as the Mississippi and Ohio take much longer to fall below flood stage than smaller rivers.

The Army Corps of Engineers was preparing to breach the levee at Birds Point, Mo., in order to possibly prevent a levee breach at Cairo, Ill. It is believed this may take some of the pressure off the levee protecting the city.

The planned breach has prompted a court battle between the Corps and the Missouri attorney general Thursday.

Although not forecast to reach record levels, there are other stretches of the Mississippi River farther north and south, and a large part of the Ohio River farther to the east that have been and will continue to remain well above flood stage.

The high water and saturated ground will delay the planting of crops.

Fortunately, the growing season in this region is long and evaporation rates will continue to increase into the first part of the summer.

The region and the souls that work the land are notorious for bouncing back after spring flooding, provided conditions turn favorable in the month or two ahead.

What's Ahead?

The additional rainfall today in southern and eastern areas will raise stream levels in these areas and may add to already high levels of rivers.

While a break of dry weather is coming later in the week into the weekend, the atmosphere is probably not yet done dishing out heavy rainfall (and severe thunderstorms) for the region.



As a pocket of chilly air develops in the Northeast during the first part of May, the battle zone may still lie over the Midwest, where the warm, moist air continues to charge in from the South and rise violently, forming the relentless downpours and big storms.

While the rainfall forecast during May will probably not sustain the flood levels at present or soon to be experienced, it could continue to produce well above average stream flows and river levels above flood stage through much of the balance of the spring.

In addition the weather pattern will favor, at the very least, episodes of flash and small stream flooding on a local basis in the region through much of May.

With the shift in the cool pocket and further confrontations with warmth and chill, there may be an increase in risk of storms with severe weather and flooding farther north over the Midwest, than what we have seen so far this spring.

The surge of high water will also continue to work downstream in the weeks ahead, reaching areas from Memphis to New Orleans.





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Massive tornado outbreak kills 202; 100-year flood coming on Mississippi River
Posted by: JeffMasters, 13:49 GMT le 28 avril 2011

A stunning tornado outbreak of incredible violence has left at least 202 dead across the Eastern U.S.; injuries probably number over a thousand, with 600 injured in the town of Tuscaloosa alone. The tornadoes carved huge swaths of damage, completely flattening large sections of many towns, and damage from the storms is likely to be the greatest in history for any tornado outbreak. Hardest hit was Alabama, with at least 149 dead; at least 36 were killed in neighboring Mississippi. NOAA's Storm Prediction Center logged 160 preliminary reports of tornadoes between 8am EDT yesterday and 8am EDT today. At least 11 of these tornadoes were killer tornadoes; deaths occurred in six states. Damage from some of these storms appeared to be at least EF-4, and it is likely that there were multiple violent EF-4 or EF-5 tornadoes. The death toll makes the April 27 - 28 outbreak the third deadliest tornado outbreak of the past 50 years, behind the April 3 - 4, 1974 Super Outbreak (315 killed) and the 1965 Palm Sunday tornado outbreak (256 killed.)


Figure 1. Damage in Birmingham, Alabama from last night's tornado. Image posted to twitter.


Figure 2. Damage in Tuscaloosa, Alabama from last night's tornado. Image posted to twitter, photographer unknown.


Figure 3. Radar reflectivity image of the Tuscaloosa, Alabama tornado.

The 3-day total of preliminary tornado reports from this outbreak is 278, close to the 323 preliminary tornado reports logged during the massive April 14 - 16 tornado outbreak. That outbreak has 155 confirmed tornadoes so far, making it the largest April tornado outbreak on record. It is unprecedented to have two such massive tornado outbreaks occur so close together. According to a list of tornado outbreaks maintained by Wikipedia, only two other tornado outbreaks have had as many as 150 twisters--the May 2004 outbreak (385), and the May 2003 outbreak (401).


Figure 4. Satellite image of last night's storm at 8:15pm EDT April 27, 2011. Image credit: NASA/GSFC.

Tornado outbreak winding down today
Tornado warnings continue to be issued this morning along the cold front now pushing towards the Atlantic coast, and a tornado was reported at 7:35am EDT in McBee, South Carolina. NOAA's Storm Prediction Center has placed a large swath of the coast, from Florida to Vermont, in their "Slight Risk" region for severe weather. The high instability and high wind shear that triggered so many killer tornadoes yesterday is gone, and we should see only a few weak tornadoes today. No severe storms are predicted for Friday. Saturday has a slight risk of severe weather over Oklahoma and Texas.


Figure 5. Severe weather threat for Thursday, April 28, 2011.

http://www.youtube.com/watch?v=5ohIVzIZLuQ...player_embedded
Figure 6. Remarkable video of the tornado that hit Tuscaloosa, Alabama yesterday. Fast forward to minute four to see the worst of the storm.

http://www.youtube.com/watch?v=zEr2lCnQcow...player_embedded
Figure 8. Tornado near Empire, Alabama, moving rapidly down a hill.

Unprecedented flooding predicted on Ohio and Mississippi Rivers
This week's storm system, in combination with heavy rains earlier this month, have pushed the Ohio River and Mississippi River to near-record levels near their confluence. The Ohio River at Cairo, Illinois is expected to crest at 60.5 feet on May 1. This would exceed 100-year flood stage, and be the highest flood in history, besting the 59.5' mark of 1937. Heavy rains of 10 - 15 inches have inundated the region over the past few days, and one levee breach at Black River levee near Poplar Bluff, Missouri, has resulted in the evacuation of over 500 homes. Poplar Bluff has received 15.45" of rain since Friday morning. The greatest rain gauge-measured precipitation from the storm occurred in Springdale, Arkansas, where 19.70" inches has fallen since Friday morning.


Figure 9. The latest River Flood Outlook from NOAA shows major flooding is occurring over many of the nation's major rivers.

Record 100+ year flood expected on Mississippi River
Snow melt from this winter's record snow pack across the Upper Mississippi River has formed a pulse of flood waters that is moving downstream on the Mississippi, and is currently located in Iowa. When this floodwater pulse moves south of Cairo, Illinois over the next two weeks, it will join with the record water flow coming out of the Ohio River, and create the highest flood heights ever recorded on the Mississippi, according to the latest forecasts from the National Weather Service. Along a 400-mile stretch of the Mississippi, from Cairo to Natchez, Mississippi the Mississippi is expected to experience the highest flood heights since records began 100 or more years ago, at 5 of the 10 gauges on the river along this stretch. The records are predicted to begin to fall on May 3 at New Madrid, and progress downstream to Natchez by May 20. Areas that are not protected by levees can expect extensive damage from the flooding, and it is possible that the Army Corps of Engineers will have to intentionally dynamite a levee at Birds Point and New Madrid, Missouri to protect the town of Cairo from flooding.

The Mississippi River at New Madrid, MO, about 40 miles downstream of the confluence of the Mississippi and Ohio Rivers, is currently at 44', the 3rd highest flood in history. The river is predicted to crest on Tuesday very near the all-time record height of 48 feet. The NWS warns that at this height, "Large amounts of property damage can be expected. Evacuation of many homes and businesses becomes necessary." Previous record heights at this location:

(1) 48.00 ft on 02/03/1937
(2) 44.60 ft on 04/09/1913
(3) 43.60 ft on 04/04/1975
(4) 43.50 ft on 02/16/1950
(5) 42.94 ft on 03/17/1997

The timing of the floods crests will depend upon a complex mix a factors, including how much rain falls over the next month, the possible influence of southerly winds holding up the floodwater pulses, the potential opening of flood control structures and reduction of flows from flood control reservoirs, and potential levee failures (no levee has failed on the Lower Mississippi south of the Ohio River junction since 1950, however.) The Mississippi River is expected to crest at 17 feet at New Orleans on May 22, three feet below the top of the levees. This would likely require opening of the Bonnet Carre Spillway 28 miles upstream from New Orleans, to relieve pressure on the city's levees. Opening the spillway drains 250,000 cubic feet per second of flow into Lake Pontchartrain.

Helping out tornado victims
For those who want to lend a helping hand to those impacted by the widespread destruction this month's severe weather has brought, stop by the portlight.org blog.

Related post: Are tornadoes getting stronger and more frequent? The answer is--we don't know.

Jeff Masters

Army Corps blows up levee to help fight unprecedented Mississippi River flood

Posted by: JeffMasters, 16:47 GMT le 03 mai 2011

A brilliant string of explosions rippled across a two-mile length of the Mississippi River levee at Birds Point, Missouri at 10pm last night. As the levee disintegrated, a 4-story high cascade of muddy brown water from the Father of Waters gushed into the crevasse, thundering with the flow of eight Niagara Falls. The waters quickly spread out over 133,000 acres of rich farmland, rushing southwards along the 35-mile long Birds Point-New Madrid Spillway. The levee that was destroyed--called a plug fuse levee--was designed to be destroyed in the event of a record flood. In a marathon 20-hour operation, 150 engineers from the Army Corps of Engineers packed 22 wells in the levee with explosives on Sunday and Monday. A raging thunderstorm with dangerous lightning halted the work for a time on Sunday night, as the engineers were pulled off the levee due to concerns about lightning. Final approval for the demolition occurred after a series of failed court challenges, brought by the Attorney General of Missouri, ended at the Supreme Court on Monday. Damage to the farmland and structures along the the Birds Point-New Madrid Spillway is estimated to cost $317 million due to the intentional breach of the levee. The fact that the Army Corps is intentionally causing 1/3 of billion dollars in damage is stark evidence of just how serious this flood is. The Birds Point levee has been demolished only once before, during the historic 1937 flood.


Figure 1. Still frame from an Army Corps of Engineers video of last night's demolition of the Birds Point levee on the Mississippi River.


Figure 2. The gauge on the Ohio River at Cairo was at record highs over the past few days, but the river level is now falling, thanks to the demolition of the Birds Point levee.

Unprecedented flooding on the Ohio and Mississippi Rivers
Snow melt from this winter's record snow pack across the Upper Mississippi River has formed a pulse of flood waters that is moving downstream on the Mississippi. This pulse of flood waters passed St. Louis on Saturday, where the river is now falling. The snow melt pulse arrived on Monday at Thebes, Illinois, about 20 miles upstream from the Mississippi/Ohio River junction at Cairo. The Mississippi River crested yesterday at Thebes at 45.52', which beats 1993 as the 2nd highest Mississippi River flood of all-time at Thebes. This floodwater pulse is headed south to Cairo, Illinois, and will join with the record water flow coming out of the Ohio River to create the highest flood heights ever recorded on a long stretch of the Mississippi, according to the latest forecasts from the National Weather Service. Along a 400-mile stretch of the Mississippi, from Cairo to Natchez, Mississippi the Mississippi is expected to experience the highest flood heights since records began over a century ago at 5 of the 10 gauges on the river. Areas that are not protected by levees can expect extensive damage from the flooding, but the mainline levees on the Lower Mississippi are high enough so that the flood waters are predicted to stay at least 3 feet below the tops of the levees.

The Mississippi River at New Madrid, MO, about 40 miles downstream of the confluence of the Mississippi and Ohio Rivers, crested at 46.54' this morning, the 2nd highest flood in history. The river is now falling, thanks to the blowing of the Birds Point levee. Rains of up to ten inches over the past three days in the region have now ended, but this water will enter the river system over the next few days, increasing heights on the river once again. The Mississippi is predicted to rise to 50 feet late this week, two feet above the all-time record height of 48 feet. The NWS warns that at this height, "Large amounts of property damage can be expected. Evacuation of many homes and businesses becomes necessary." Previous record heights at this location:

(1) 48.00 ft on 02/03/1937
(2) 46+ ft on 05/03/2011
(2) 44.60 ft on 04/09/1913
(3) 43.60 ft on 04/04/1975
(4) 43.50 ft on 02/16/1950
(5) 42.94 ft on 03/17/1997


Figure 3. Radar-estimated rainfall near the confluence of the Ohio and Mississippi Rivers totaled 4 - 10 inches over a wide area during the past three days.


Figure 3. Flooding on the Mississippi in Missouri at the end of April. Image credit: USACE.

The "Project Flood"
The levees on the Lower Mississippi River are meant to withstand a "Project Flood"--the type of flood the Army Corps of Engineers believes is the maximum flood that could occur on the river, equivalent to a 1-in-500 year flood. The Project Flood was conceived in the wake of the greatest natural disaster in American history, the great 1927 Mississippi River flood. Since the great 1927 flood, there has never been a Project Flood on the Lower Mississippi, downstream from the confluence with the Ohio River (there was a 500-year flood on the Upper Mississippi in 1993, though.) On Sunday, Major General Michael Walsh of the Army Corps of Engineers, President of the Mississippi Valley Commission, the organization entrusted to make flood control decisions on the Mississippi, stated: "The Project Flood is upon us. This is the flood that engineers envisioned following the 1927 flood. It is testing the system like never before."

At Cairo, the project flood is estimated at 2.36 million cubic feet per second (cfs). The current prediction for the flow rate at New Madrid, the Mississippi River gauge just downstream from Cairo, is 1.89 million cfs on May 7, so this flood is not expected to be a 1-in-500 year Project Flood. In theory, the levee system is designed to withstand this flood. But the Army Corps is in for the flood fight of its life, and it will be a long a difficult few weeks. Here's how Major General Michael Walsh of the Army Corps of Engineers described his decision yesterday to blow up the Birds Point levee:

"Everyone I have talked with--from boat operators, to labors, scientist and engineers, and truck drivers have all said the same thing--I never thought I would see the day that the river would reach these levels.

We have exceeded the record stage already at Cairo. We are on a course to break records at many points as the crest moves through the system. Sometimes people celebrate with "records"--but not this time. Making this decision is not easy or hard--it's simply grave-- because the decision leads to loss of property and livelihood--either in a floodway--or in an area that was not designed to flood. The state of Missouri has done a superb job of helping people escape the ravages of water in the floodway. But other places--not designed to flood have had no warning if their areas succumb to the pressures of this historic chocolate tide.

I spent last night on the river...lashed to an anchor barge in the current near the top of the floodway. The rains continued to pound the deck of the Motor Vessel. The cold winds moved us around--and the current and water levels kept increasing as the rain storms continue to grow over the Ar/Miss/Ohio/TN Watershed.

So, with the tool that has withstood many tests: the test of operation in 1937; decades of challenges that resulted in the 1986 Operation Plan; reviews and numerous unsuccessful court challenges--I have to use this tool. I have to activate this floodway to help capture a significant percentage of the flow.

I don't have to like it but we must use everything we have in our possession, in the system to prevent a more catastrophic event. So, today, I give the order to operate the Floodway."


Jeff Masters
Wappapello Spillway (KittenGotClaws)
Water going over the emergency spillway. A temp berm was built hoping to hold back the water but the extra rains we got pushed it over the edge.

Army Corps of Engineers Blast Mississippi River Levee

By Alex Sosnowski, Expert Senior Meteorologist

May 3, 2011; 7:05 AM ET



Stan Krushas, left, and Bob Flemming with the Illinois Emergency Management Agency stand atop rock and sandbags around an area of seeping floodwater, known as a sandboil, near a levee, as they monitor seepage Sunday, May 1, 2011, in Cairo, Ill. The mayor of the town at the confluence of the Ohio and Mississippi rivers says that most of the city's remaining residents have heeded a mandatory evacuation order, prompted by river water seeping up through the ground behind a levee. (AP Photo/Jeff Roberson)
As record flooding continues along the Mississippi River, the operation to breach a levee to save an Illinois town was carried out Monday night.

The Army Corps of Engineers exploded the levee in the agricultural community of Birds Point, Mo., Monday night to relieve pressure on the levee at nearby Cairo, Ill.

The blast allowed water from the swollen Mississippi River to flood 130,000 acres of prime agricultural lands in southeastern Missouri. The Associated Press states about 100 homes of farmers are located on that land.

Officials deemed the explosion necessary to prevent severe flooding in Cairo, which sits where the Ohio River runs into the Mississippi River.

The Ohio River at Cairo had surged past its previous record stage of 59.5 feet Saturday night. That record was set in early February 1937.

The river peaked at 61.72 feet Monday night, but dropped a foot in seven hours following the blast.

The flooding along the lower Mississippi River will continue to get worse, and could become yet another natural disaster for the U.S. this year.

The region is about to turn into a vast lake that will linger not only days, but weeks due to the very slow-to-respond, massive rivers in a relatively flat part of the nation.

Impacts will range from large agricultural areas and small farmsteads being swallowed by deep waters to unprotected small towns and portions of large cities being flooded by muddy inundations.

Part of the area where the Mississippi and Ohio rivers meet has received over 2 feet of rain in a little over three weeks.

The latest round of rain that arrived this past weekend is finally pushing eastward and will fully depart the Ohio and Mississippi valleys by tonight.

Before the rain leaves, an additional 1 to 2 inches will come down in the Ohio Valley.



In some cases, prior to this past weekend's rainfall, the rivers were cresting or had crested. However, the additional recent deluge of rain will bring a second crest that could be higher than the first in some cases, and prolong flooding in almost all areas.

At Tiptonville, Tenn., the Mississippi River is forecast to reach at least 51 feet, topping the record set on February 7, 1937 of 47.8 feet.

Farther south, in areas such as those near Memphis, river levels next week and beyond may challenge flooding that occurred during April of 1927.

A breach in the levee has occurred along the Mississippi River near Thebes, Ill. during Monday midday and will contribute to flooding in Olive Branch and Cairo.

Due to the very slow progression of flood waters in the region, levees in many areas will feel the strain of high water for weeks.

Along the Ohio, most problems are occurring from where the Wabash River joins in, onward to the Mississippi and the vicinity around Cairo, Ill.

The Wabash and other rivers that feed into the Ohio and Mississippi are also at moderate to record levels. In some cases, the rivers are backing up as they encounter the high water of the larger waterways.

The surge of water will work its way southward in the weeks ahead. The amount and location of additional rain that falls will determine the severity of the rise and potential flooding along the lowest portion of the Mississippi Valley and the Delta.

A break in the rain is coming tonight into Thursday. However, additional downpours are forecast by AccuWeather.com meteorologists late in the week through the weekend over much of the Ohio and middle and lower Mississippi valleys.



In addition to river flooding in the region, potential for flash and urban flooding will extend well beyond the flood zone of the Ohio and Mississippi rivers and their tributaries for the next couple of days to the next couple of weeks.

Rivers and streams are also running high in the Northeast and the northern Plains. Communities along flood-prone waterways in these regions will need to keep an eye on the weather for at least the next couple of weeks.





Related to the Story:

Flooding Trouble Brewing for Some time

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The White House

Office of the Press Secretary
For Immediate Release
May 04, 2011
President Obama Signs Mississippi Emergency Declaration

The White House

Office of the Press Secretary
For Immediate Release
May 04, 2011
President Obama Signs Tennessee Emergency Declaration

RIVER STAGE FORECASTS (A)BV
STATION FS 7PM 12HR ....F O R E C A S T..... (B)LO
STG CHG 0506 0507 0508 0509 0510 CREST/DATE FS

NEW ORLEANS /17/ 15.0 +0.5 15.0 15.4 15.8 16.2 16.6 19.5 5/24A A.5/11A
/ /LEVEES PROTECT CITY OF NEW ORLEANS TO 20 FT STAGE.

Additionally, wildfires in Texas scorched about 1.5 million acres and destroyed more than 300 homes, businesses and churches. Total insured losses here are expected to be more than $180 million.

1) The April 27, 2011 Neshoba/Kemper/Winston/Noxubee Counties, Mississippi tornado (3 killed, 29 mile path length.)

2) The April 27, 2011 Smithville, Mississippi tornado (22 killed, 15 mile path length.)

3) The April 27, 2011 Hackleburg, Alabama tornado (71 killed, 25 mile path length.)

4) The May 22, 2011 Joplin Missouri tornado (138 killed, 14 mile path length.)

5) The May 24, 2011 Binger-El Reno-Peidmont-Guthrie, Oklahoma tornado. (9 killed, 75 mile path length.)

1) 2011 Groundhog Day's blizzard ($1- $4 billion)
2) April 3 -5 Southeast U.S. severe weather outbreak ($2 billion)
3) April 8 - 11 severe weather outbreak ($2.25 billion)
4) April 25 - 28 super tornado outbreak ($3.5 - $6 billion)
5) Mississippi River flood of 2011 ($9 billion)
6) Texas drought ($1.2 billion)
7) Joplin tornado ($1 - $3 billion)

C'est très impressionnant
A quoi est du la formation de ces éclairs ? C'est bien une éruption volcanique pourtant...

Vu qu'apparemment, aucun sujet volcanique n'est ouvert:

Le volcan islandais Grímsvötn est en éruption depuis hier.
....

A suivre.

L'activité éruptive a débuté suite à une crise sismique qui semble avoir débuté dans la journée du 12 juin,sismicité notamment marquée par 2 secousses importantes de magnitude 5,7. La localisation précise du site de l'éruption pose problème : il pourrait s'agir aussi bien du Dubbi que d'un édifice non recensé comme actif par la Smithsonian, le Nabro, un peu plus au sud. Le site de l'éruption reste donc à déterminer. Source : earthquake-report.com

On en parle souvent mais il en arrive que quelqu'un par ans non ?

Des murs de sable comme ça , ça doit être assez impressionnant ! Imaginez qu'il pleuve après la dessus

On en parle souvent mais il en arrive que quelqu'un par ans non ?

Des murs de sable comme ça , ça doit être assez impressionnant ! Imaginez qu'il pleuve après la dessus

Cela arrive dans les déserts de sable
Un haboob est un type de violente tempête de sable observé dans le désert du Sahara, plus particulièrement au Soudan, dans la péninsule Arabique, au Koweït et dans les régions les plus arides de l'Irak