March is the 13th warmest on record; major tornado outbreak expected

March 2011 was the globe's 13th warmest March on record, according to the National Oceanic and Atmospheric Administration (NOAA) National Climatic Data Center (NCDC). NASA's Goddard Institute for Space Studies rated March the 9th warmest on record. March 2011 global ocean temperatures were the 12th warmest on record, and land temperatures were the 12th warmest on record. Global satellite-measured temperatures for the lowest 8 km of the atmosphere were below average, the 12th or 15th coolest in the 34-year record, according to Remote Sensing Systems and the University of Alabama Huntsville (UAH). The global cool-down from November, which was the warmest November on record for the globe, was due in large part to a La Niña episode in the Eastern Pacific. The large amount of cold water that upwells to the surface during a La Niña typically causes a substantial cool-down in global temperatures. The coldest place on the globe in March, relative to average, was Central and Western Canada. The Asian portion of Russia was exceptionally warm, relative to average.

Our weather historian, Christopher C. Burt, has a nice summary of some of the remarkable weather extremes of March 2011.


Figure 1. Departure of temperature from average for March 2011. Image credit: National Climatic Data Center (NCDC).

Congo sets its all-time heat record
The Democratic Republic of the Congo, the world's 12th largest country, set a new all-time extreme heat record on March 8, 2011, when the temperature hit 39.2°C (102.6°F) at M'Pouya. Congo's previous all-time hottest temperature was 39.0°C (102.2°F) at Impfondo on May 14, 2005. Congo is the first nation to set an all-time extreme heat or cold record in 2011. Last year, a record 19 nations, plus the UK's Ascension Island territory, set all-time extreme heat records. I thank weather records researchers Maximiliano Herrera, Christoper C. Burt, and Howard Rainford for their assistance researching these records.

A moderately warm and wet March for the U.S.
For the contiguous U.S., March temperatures were warmer than average, ranking the 39th warmest in the 117-year record, according to the National Climatic Data Center. Only New Mexico had a top ten warmest March; no states had a top ten coldest March. Precipitation was above average, with the month ranking as the 34th wettest March since 1895. Texas had its driest March on record, and top ten driest Marches were experienced in New Mexico and Oklahoma. Washington, Oregon, California, and Pennsylvania had top ten wettest Marches.

La Niña remains weak
La Niña conditions remain weak over the Eastern Pacific, with sea surface temperatures (SSTs) in the equatorial Eastern Pacific about 0.6°C below average. An animation of SSTs since late December shows the weakening La Niña nicely. Springtime is the most common time for a La Niña event to end; since 1950, half of all La Niñas ended in March, April, or May. The weakness displayed by the current La Niña event has prompted NOAA's Climate Prediction Center to predict that La Niña will be gone by June.

Sea ice extent in the Arctic 2nd lowest on record during March
March 2011 Northern Hemisphere sea ice extent was second lowest on record, according to the National Snow and Ice Data Center. Satellite records extend back to 1979. This breaks a string of three consecutive months of record low Arctic sea ice cover.

Major tornado outbreak expected today through Wednesday
Another huge tornado outbreak is likely this week over the U.S., as a strong storm system that is developing over the Mississippi Valley today moves slowly eastwards during the week. A 3-day tornado total of over 100 twisters is quite possible today through Wednesday. NOAA's Storm Prediction Center has issued its "moderate risk" forecast for severe weather today, centered over Arkansas. This region has a significant risk of tornadoes, some of them strong EF-2 and EF-3 strength. A more serious threat of severe weather exists for Tuesday over Arkansas and surrounding states, with the Storm Prediction Center calling the situation "potentially significant/dangerous." The heightened severe weather risk extends through Wednesday, with a moderate risk of tornadoes and severe weather in Tennessee and surrounding states. Preliminary tornado reports for the year 2011 show that this year is probably already the busiest tornado season on record for this point in the season. This week's action will substantially pad the record.


Figure 2. Severe weather threat for Monday, April 25, 2011.

St. Louis tornado rated an EF-4
A violent EF-4 tornado ripped through St. Louis near 8pm local time Friday night, carving a 22-mile path of destruction up to 0.4 miles wide, and severely damaging Lambert International Airport. The airport, the world's 30th busiest, was closed much of the weekend, but has now re-opened. The tornado, rated an EF-2 when it hit the airport, 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. The tornado also passed over a residential area just west of the airport in the community of Bridgton, causing severe EF-4 damage, according to the National Weather Service office in St. Louis. This was the first violent EF-4 tornado of the year.


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


Figure 4.Before and after damage photo of Beaverton Drive in Bridgeton, Missouri, after the April 22, 2011 tornado. This damage was rated EF3. Image credit: National Weather Service office in St. Louis and Google.

Jeff Masters