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9th warmest February on record; La Niña conditions continue but weaken

By: Dr. Jeff Masters, 12:35 PM GMT on March 20, 2009

Global temperatures in February remained about where they've been the past year, with Earth recording its 9th warmest February on record, according to statistics released by the National Climatic Data Center. This past winter was the eighth warmest winter on record (December-February), and the January-February year-to-date period was also the eighth warmest. The most notable extreme February heat occurred February 7 in southern Australia. Many locations set new all-time hottest temperature records, including an all-time state record for Victoria when temperatures reached 48.8°C (119.8°F) in Hopetoun, shattering the previous record of 47.2°C (117.0°F) set in January 1939. The extreme heat was accompanied by very dry conditions that contributed to the development of deadly wildfires that killed 210 people. The most notable cold conditions for the winter of 2008/2009 occurred in the United Kingdom, which had its coldest winter since 1995/1996.

Figure 1. Departure of temperature from average for the month of February 2009. Image credit: NOAA's National Climatic Data Center.

A dry and warm February for the U.S.
For the contiguous U.S., February temperatures were the 27th warmest in the 114-year record, according to the National Climatic Data Center. The month was very dry, ranking as the 8th driest February. New Jersey and Delaware had their driest February ever recorded. The winter of 2008/2009 (December - February) ranked as the 5th driest winter on record, and the year-to-date January - February period was the driest ever such period. Texas recorded its driest winter. Thanks to all the dry weather, the U.S. has only seen about 50% of normal tornado activity in 2009, according to NOAA's Storm Prediction Center. On March 19, 2009, 21% of the contiguous United States was in moderate-to-exceptional drought. This is unchanged from January.

La Niña conditions continue
La Niña conditions continued in the Eastern Pacific Ocean in February, and NOAA's Climate Prediction Center is continuing their La Niña Advisory. They define La Niña conditions as occurring when the 1-month mean temperature anomaly in the equatorial Eastern Pacific (the area 5°N - 5°S, 120°W - 170°W, also called the "Niña 3.4 region") cools below -0.5°C and is expected to persist for three consecutive months. In addition, the atmospheric response typically associated with a La Niña must be observed over the equatorial Pacific Ocean. Sea surface temperatures anomalies peaked at -1.1°C below average in the Niña 3.4 region during early January. It appears that La Niña has peaked, as ocean temperatures in the Niña 3.4 region have warmed to -0.4°C below average as of March 15. Nearly all the model forecasts for the Niño 3.4 region show that La Niña will dissipate between May - July 2009, and neutral conditions are expected for the August - October peak of hurricane season. Only three out of 16 El Niño models are predicting an El Niño event for hurricane season. The number of Atlantic hurricanes is typically reduced in an El Niño year, due to increased wind shear from strong high-level winds, but that doesn't look like it will happen this year.

Expected impacts of the current La Niña conditions during during March - May 2009 inlude above-average precipitation over Indonesia, and below-average precipitation over the central equatorial Pacific. Compared to the Northern Hemisphere winter, La Niña impacts over the United States are typically less pronounced. For the contiguous United States, potential impacts include below-average precipitation across the southern states. Other potential impacts include below-average temperatures in the Pacific Northwest and above-average temperatures across much of the southwestern and south-central United States.

Sea ice extent
February 2009 Northern Hemisphere sea ice extent was the 4th lowest on record, according to the National Snow and Ice Data Center, and is currently near its annual maximum. The record February low was set in 2005. Since today is the Spring Equinox, the sun will rise at the North Pole, bringing 24-hour daylight and warming conditions that will begin melting Arctic sea ice.

Portlight Relief Walk this weekend
Saturday March 21 in New Orleans marks the inaugural event in a series of 18 fundraising Relief Walks sponsored by Portlight.org. A hearty thanks go to all the organizers and participants in this effort!

Jeff Masters

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The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.