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 , 1:24 PM GMT on June 17, 2010
The globe recorded its warmest May since record keeping began in 1880, according to the National Oceanic and Atmospheric Administration's (NOAA's) National Climatic Data Center (NCDC). The May temperature anomaly of 0.69°C (1.24°F) beat the previous record set in 1998 by 0.06°C. We've now had three consecutive warmest months on record, the first time that has happened since 1998. NASA's Goddard Institute for Space Studies also rated May 2010 as the warmest May on record, tied with May 1998. Both NOAA and NASA rated the year-to-date period, January - May, as the warmest such period on record, and the last 12-month period (June 2009 - May 2010) as the warmest 12-month period on record. May 2010 global ocean temperatures were the second warmest on record, while land temperatures were the warmest on record. Global satellite-measured temperatures for the lowest 8 km of the atmosphere were the 2nd warmest on record in May, according to both the University of Alabama Huntsville (UAH) and Remote Sensing Systems (RSS) groups.
For those interested, NCDC has a page of notable weather highlights from May 2010.
Figure 1. Departure of temperature from average for May 2010. Image credit: NOAA National Climatic Data Center (NCDC).
Asia and Southeast Asia record their hottest temperatures in history
The mercury hit an astonishing 53.5°C (128.3°F) at MohenjuDaro, Pakistan, on May 26. Not only is the 128.3°F reading the hottest temperature ever recorded in Pakistan, it is the hottest reliably measured temperature ever recorded on the continent of Asia. The evidence for this record is detailed in a post I made earlier this month. The Pakistan heat wave killed at least 18 Pakistanis, and temperatures in excess of 50°C (122°F) were recorded at nine Pakistani cities on May 26, including 53°C (127.4°F) at Sibi. Record heat also hit Southeast Asia in May. According to the Myanmar Department of Meteorology and Hydrology, Myanmar (Burma) had its hottest temperature in its recorded history on May 12, when the mercury hit 47°C (116.6°F) in Myinmu. Myanmar's previous hottest temperature was 45.8°C (114.4°F) at Minbu, Magwe division on May 9, 1998. According to Chris Burt, author of Extreme Weather, the 47°C (116.6°F) measured on May 12 this year is the hottest temperature measured in Southeast Asia in recorded history.
An average May for the U.S.
For the contiguous U.S., it was the 50th coldest (66th warmest) May in the 116-year record, according to the National Climatic Data Center. Idaho had its second coolest May on record, while it was Montana's fourth coolest, Wyoming's and Oregon's seventh coolest, Utah's eighth, California's ninth, and Nevada's tenth coolest such period. Rhode Island observed its second warmest May on record and Florida tied for its second warmest. Other states much warmer than normal during May included: Louisiana (4th warmest), Massachusetts (5th warmest), Connecticut (6th warmest), New Hampshire (7th warmest), Mississippi and New York (each 8th warmest), and New Jersey (9th warmest).
NCDC's Climate Extremes Index (CEI) for spring (March-May) was about 5 percent higher than average. The CEI measures the prevalence of several types of climate extremes (like record or near-record warmth, dry spells, or rainy periods). Factors contributing to spring's elevated values: widespread (2-3 times larger than average) coverage of anomalously warm daily max and min temperatures, and above-average extent of extreme one-day precipitation events. According to NOAA's Storm Prediction Center, tornadic activity in May was near normal with 290 preliminary tornado reports.
U.S. precipitation and drought
For the contiguous U.S., May 2010 ranked as the 35th wettest May in the 116-year record. The state of Washington had its third wettest May on record and extreme precipitation events in Tennessee and Kentucky contributed to their sixth and seventh wettest such period, respectively. It was the tenth wettest May in North Dakota. At the end of May, approximately 3% of the contiguous United States was in severe-to-exceptional drought. This is a very low amount of drought for the U.S.
La Niña likely by July
El Niño rapidly dissipated in May, with sea surface temperatures (SSTs) over the tropical Eastern Pacific in the area 5°N - 5°S, 120°W - 170°W, also called the "Niña 3.4 region", falling to 0.50°C below average by June 14, according to NOAA.. The Australian Bureau of Meteorology is reporting that this number was 0.31°C below average (as of June 13.) Since La Niña conditions are defined as occurring when this number reaches 0.50°C below average, we are right at the threshold of a La Niña. NOAA's Climate Prediction Center has issued a La Niña watch, and it is likely that a full-fledged La Niña will emerge by July. Ten of the 23 El Niño models (updated as of May 19) are predicting La Niña conditions for hurricane season. However, as NOAA's Climate Prediction Center commented in their June 3 advisory, a number of the more reliable models are now calling for La Niña to develop this summer. They comment, "there is an increasing confidence in these colder model forecasts, which is supported by recent observations that show cooling trends in the Pacific Ocean and signs of coupling with the atmospheric circulation."
It is interesting to note that the last time we had a strong El Niño event, in 1998, El Niño collapsed dramatically in May, and a strong La Niña event developed by hurricane season. History appears to be repeating itself, and the emergence of La Niña will likely occur by July. The demise of El Niño, coupled with sea surface temperatures in the tropical Atlantic that are currently at record levels, suggest that a much more active Atlantic hurricane season that usual likely in 2010. The 1998 Atlantic hurricane season was about 40% above average in activity, with 14 named storms, 10 hurricanes, and 3 intense hurricanes. The season was relatively late-starting, with only one named storm occurring before August 20.
Figure 2. Ice extent through June 15, 2010 in the Arctic, compared to the record low years of 2006 and 2007. Record low Arctic ice extent began about June 1, and has remained at record low extent for the first half of June. Image credit: National Snow and Ice Data Center.
Arctic sea ice extent reaches a record low at end of May
Northern Hemisphere sea ice extent in May 2010 was the 9th lowest since satellite records began in 1979, according to the National Snow and Ice Data Center. Ice extent was near average at the beginning of May, but thanks to the fastest rate of decline ever observed during the month of May (50% faster than average), ice extent reached a record low by the end of May. Ice extent has remained at record low levels throughout the first half of June, as well. Ice volume was also at a record low at the end of May, according to University of Washington Polar Ice Center, due to the fact the Arctic is now dominated by thin first and second-year ice.
Record low Northern Hemisphere snow extent in May
For the second consecutive month, the Rutgers Snow Lab reported that the snow cover footprint over North America was the smallest on record for the month. A record-small snow footprint was also observed over Eurasia and the Northern Hemisphere as a whole.
The Atlantic is quiet
The 92L low pressure system, now located about 300 miles east of the northern Lesser Antilles Islands, has been completely disrupted by wind shear and dry air, and is no longer a threat to develop. The remnants of 92L, which are currently kicking up some strong thunderstorms due to interaction with an upper-level trough of low pressure, will bring heavy rain showers and wind gusts up to 35 mph to the northern Lesser Antilles Islands tonight through Friday, and into Puerto Rico Friday night through Saturday. On Sunday, the disturbance could bring heavy rains to northern Haiti. The earthquake zone in southern Haiti may also receive heavy enough rains to be of concern for the 1.5 million people living in tents and under tarps.
None of the reliable computer models is predicting formation of a tropical cyclone in the Atlantic over the next seven days, though the GFS model was suggesting a weak development moving through the southern Lesser Antilles Islands seven days from now.
Oil spill wind and ocean current forecast
Light and variable winds less than 10 knots will blow in the northern Gulf of Mexico for the next five days, according to the latest marine forecast from NOAA. The winds will tend to have a westerly component through Sunday, which will maintain a slow (1/4 mph) eastward-moving surface ocean current that will transport oil eastwards along the Florida Panhandle coast, according to the latest ocean current forecast from NOAA's HYCOM model. These winds and currents may be capable of transporting oil east to Panama City, Florida, and oil will continue to threaten the coasts of Louisiana, Alabama, and Mississippi for the remainder of the week as well, according to the latest trajectory forecasts from NOAA and the State of Louisiana. Ocean current forecasts for early next week show a weakening of the eastward-flowing currents along the Florida Panhandle, which would limit the eastward movement of oil so that it would not move past Panama City. The long range 8 - 16 day forecast from the GFS model indicates a typical summertime light wind regime, with winds mostly blowing out of the south or southeast. This wind regime will likely keep oil close to the coastal areas that have already seen oil impacts over the past two weeks.
NOAA has launched a great new interactive mapping tool that allows one to overlay wind forecasts, ocean current forecasts, oil location, etc.
Oil spill resources
My post, What a hurricane would do the Deepwater Horizon oil spill
My post on the Southwest Florida "Forbidden Zone" where surface oil will rarely go
My post on what oil might do to a hurricane
NOAA great new interactive mapping tool that allows one to overlay wind forecasts, ocean current forecasts, oil location, etc.
Gulf Oil Blog from the UGA Department of Marine Sciences
Oil Spill Academic Task Force
University of South Florida Ocean Circulation Group oil spill forecasts
ROFFS Deepwater Horizon page
Synthetic Aperture Radar (SAR) imagery from the University of Miami
I'll have an update on Friday.
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