Globe has 1st or 2nd warmest March on record; El Niño fades to weak category

The globe recorded its warmest March since record keeping began in 1880, according to the National Oceanic and Atmospheric Administration's (NOAA's) National Climatic Data Center. The March temperature anomaly of 0.77°C (1.39°F) beat the previous record set in 2002 by 0.03°C. The last time the globe had a record warmest month was in January 2007 (according to NOAA) or in November 2009 (according to NASA). NASA's Goddard Institute for Space Studies rated March 2010 the second warmest March on record, 0.01°C behind the record set in 2002. The year-to-date period, January - March, is the 4th warmest such period on record, according to NOAA, and the warmest on record, according to NASA. March 2010 global ocean temperatures were the warmest on record, while land temperatures were the 4th warmest. Global satellite-measured temperatures for the lowest 8 km of the atmosphere were the warmest on record in March, according to both the University of Alabama Huntsville (UAH) and Remote Sensing Systems (RSS) groups. The March temperature anomaly of 0.66°C was the third highest monthly anomaly on record, behind the 0.76°C anomalies measured in February and April of 1998.

For those interested, NCDC has a page of notable weather highlights from March 2010.


Figure 1. Departure of temperature from average for March 2010. Image credit: NOAA National Climatic Data Center.

A warm March for the U.S.
For the contiguous U.S., it was the 32nd warmest March in the 116-year record, according to the National Climatic Data Center. For the third month in a row, Florida was the coldest state, relative to average. It was Florida's 4th coldest March. No other state had a top-ten coldest March. Rhode Island had its warmest March on record, and thirteen other states had a top-ten warmest March, including all of New England, plus Michigan, Wisconsin, Minnesota, and Montana.

U.S. precipitation and drought
For the contiguous U.S., March 2010 ranked as the 35th driest in the 116-year record. Michigan, Wisconsin, and Montana recorded a top-ten driest March. However, all-time March precipitation records were set in Massachusetts, New Jersey, and Rhode Island. New Hampshire and Connecticut each had a top-five wettest March. At the end of March, 2.0% of the contiguous United States was in severe-to-exceptional drought. This is the lowest March drought footprint in the U.S. in the past ten years.


Figure 2. Computer model forecasts of El Niño/La Niña made in April. The forecasts that go above the red line at +0.5°C denote El Niño conditions; -0.5°C to +0.5°C denote neutral conditions, and below -0.5°C denote La Niña conditions. No computer models predict El Niño conditions and six predict La Niña for the upcoming hurricane season (ASO, August-September-October). The rest of the models predict neutral conditions. Image credit: Columbia University's IRI.

El Niño fades from moderate to weak
El Niño slowly weakened during late March and early April, and El Niño conditions crossed the threshold from moderate to weak during the past two weeks. Sea surface temperatures over the tropical Eastern Pacific in the area 5°N - 5°S, 120°W - 170°W, also called the "Niña 3.4 region", were at 0.83°C above average on April 11, which is just below the 1.0°C threshold to be considered a moderate El Niño, according to the Australian Bureau of Meteorology. Anomalously strong westerly winds along the Equator that had helped maintain the current El Niño slackened in late March, and winds are now near average over the Equatorial Pacific. It now appears very likely that El Niño will be gone by hurricane season. None of the sixteen El Niño models (updated as of April 15) are predicting El Niño will be around during the height of hurricane season (August-September-October); six are predicting La Niña conditions for hurricane season. The expected demise of El Niño, coupled with sea surface temperatures in the tropical Atlantic that are currently at record levels, have prompted two major hurricane forecasting groups (tropicalstormrisk.com and Colorado State University) to predict a well-above average 2010 Atlantic hurricane season.

March sea ice extent in the Arctic 5th lowest on record
March 2010 Northern Hemisphere sea ice extent was the 5th lowest since satellite measurements began in 1979. Ice extent was lower than in 2009 and 2008, but greater than in 2004, 2005, 2006, and 2007, according to the National Snow and Ice Data Center (NSIDC). The weather pattern over the Arctic during much of March 2010 featured a strongly negative Arctic Oscillation (AO). This pattern tends to slow the winds that typically flush large amounts of sea ice out of the Arctic between Greenland and Iceland, and the Arctic lost less ice this winter compared to the previous few years. The larger amount of multi-year ice could help more ice to survive the summer melt season. However, this replenishment consists primarily of younger, two- to three-year-old multi-year ice; the thickest ice more than three years old has continued to decline.

Iceland's Eyjafjallajökull volcano continues to disrupt European air travel
The Eyjafjallajökull volcano on Iceland erupted Wednesday, sending a towering cloud of volcanic ash 6 - 11 km (20,000 - 36,000') high in the air from its 1666 meter (5500') high peak. The ash cloud continues to cause a dramatic interruption of air traffic over much of northern Europe today, and this disruption will spread southwards and eastwards as the ash cloud gradually spreads and disperses. For the latest forecasts of where the ash cloud is expected to go, consult the UKMET Office. The Norwegian Institute for Air Research runs a computer trajectory model called FLEXPART that has longer, 3-day forecasts. The FLEXPART model shows that ash will continue to be a problem for much of Europe through Tuesday. Spain and Portugal look like the best bet to have airports that will stay open. An excellent source of links of information on the eruption is available at http://islande2010.mbnet.fr/2010/04/eyjafjallajok ul-links-liens-a-propos-de-leyjafjallajokul/. My post on Thursday discusses the likely non-impact of this eruption on Earth's climate.


Figure 3. Forecast extent of the plume from the Iceland volcano with the unpronounceable name. Forecast was made at 17 UTC Saturday, April 17, 2010, and is valid for 12 UTC Tuesday, April 20, 2010. Image credit: Norwegian Institute for Air Research.

Jeff Masters