Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.
By: Dr. Jeff Masters , 16. kesäkuuta 2011 klo 14:27 (GMT)
May 2011 was the globe's 10th warmest May on record, according to the National Oceanic and Atmospheric Administration (NOAA) National Climatic Data Center (NCDC). May 2011 global ocean temperatures were the 11th warmest on record, and land temperatures were the 6th warmest on record. Sea surface temperatures (SSTs) in the Atlantic Main Development Region (MDR) for hurricanes from the Caribbean to the coast of Africa between 10°N and 20°N were 0.6°C above average, the 7th highest SSTs of the past 100 years. Global satellite-measured temperatures for the lowest 8 km of the atmosphere were above average, the 8th or 12th warmest in the 34-year record, according to Remote Sensing Systems and the University of Alabama Huntsville (UAH).
Figure 1. Departure of temperature from average for May 2011. Image credit: National Climatic Data Center (NCDC).
Unusual global extremes in May and spring 2011
As I discussed in yesterday's post, during the spring period of March, April, and May 2011, 46% of the U.S. had abnormally (top 10%) wet or dry conditions--the greatest such area during the 102-year period of record. On average, just 21% of the country has exceptionally wet conditions or exceptionally dry conditions during spring. In addition, heavy 1-day precipitation events--the kind that cause the worst flooding--were also at an all-time high in the spring of 2011.
A highly extreme precipitation pattern was also observed over the British Isles during spring 2011. England suffered its driest spring in over a century during May, with late May soils the driest on record over large parts of eastern and central England. In contrast, Scotland had its wettest spring on record.
New Zealand had its warmest May since records began there in 1909, whereas Australia saw its coolest March-May since their records began in 1950.
Our weather historian, Christopher C. Burt, has a detailed summary of May 2011 global weather extremes.
La Niña is gone; conditions are neutral
Although sea surface temperatures increased in the equatorial Pacific overall, El Niño/La Niña conditions remained neutral in the month of May, according to NOAA's Climate Prediction Center. Sea surface temperatures were near-average across the central Pacific Ocean, and were 0.5°C or more above average in the far western and eastern Pacific Ocean. Neutral conditions are expected to continue through the summer.
May Arctic sea ice 3rd lowest extent on record
Arctic sea ice in May 2011 was much-below average according to data from the National Snow and Ice Data Center, and ranked 3rd lowest on record for the Northern Hemisphere. Sea ice loss has accelerated during the first half of June, and as of June 16 was the lowest for the date since satellite measurements began in 1979. Snow cover extent in the Northern Hemisphere was also below average, making May 2011 the 7th consecutive May with below-average snow cover extent in the Northern Hemisphere.
Five-day period of critical fire conditions expected in the Southwest
The powerful winds that helped fan Arizona's massive Wallow fire into the state's largest fire on record will return in force today, after a two-day quiet period that allowed firefighter to achieve 29% containment of the fire by Wednesday evening. The forecast for Eastern Arizona calls for afternoon winds of 20 - 30 mph with gusts to 45 mph today and Friday. NOAA's Storm Prediction Center forecasts that even stronger winds will blow Saturday and Sunday. With hot conditions and humidity values below 10%, these are likely to be among the worst fire conditions the region has seen this year.
Figure 2. Smoke from Arizona's Wallow fire (top area with red squares denoting active fires) drifts northeastward over New Mexico in this image taken by NASA's Terra satellite at 20:30 UTC on June 15, 2011. Arizona's Horseshoe Two fire is also visible, as well as fires burning in New Mexico and Mexico.
The Atlantic is quiet, with no tropical cyclones predicted over the next seven days by the reliable computer models.
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