Sunday, December 11, 2011

U.S. November 2011 Climate Summary

November 2011 was Warmer than Average for the U.S. (NOAA)

November and the September-November autumn season were warmer than average across the contiguous U.S., according to scientists at NOAA’s National Climatic Data Center (NCDC) in Asheville, N.C. Precipitation totals across the country were also above average during November, but near the long-term average for the autumn season.
The average U.S. temperature in November was 44.3 degrees F, or 1.8 degrees F above the 1901-2000 long term average, while the average autumn temperature was 55.5 degrees F or 1.3 degrees F above average. Precipitation averaged across the nation during November, was 2.33 inches or 0.21 inch above average. The severity of drought conditions lessened across northern Texas, where near-normal precipitation was observed for the month, but in other locations throughout the state, drier-than-normal conditions meant drought conditions remained unchanged.

U.S. Climate Highlights – November 2011
· During November, the eastern half of the country experienced above-average temperatures. The warmest temperature anomalies, which is the actual temperature compared to the 20th century average, occurred across the Midwest, Mid-Atlantic, and Northeast, with13 states across these areas having November temperatures among their 10 warmest on record.
· Cooler-than-average temperatures were present across parts of the West and Northwest, with six states having November temperatures below average.
· Precipitation during November was variable from region to region. Several storm systems brought above-average precipitation to the Ohio Valley and parts of the South, where eight states had precipitation totals ranking among their 10 wettest.
· Below-average precipitation was observed across parts of the West, and parts of the northern and southern United States. Minnesota tied its ninth driest November on record, with only 0.35 inch of precipitation – 0.95 inch below average.
· As of November 29, about six percent of the contiguous United States remained in the worst category of drought, called D4 or exceptional drought, a decrease from the nearly 9 percent at the beginning of the month. Drought conditions lessened across Arkansas, Kansas, and Oklahoma, where there was above-normal precipitation during November.
· The 2011 North Atlantic hurricane season ended on November 30, after an above-average season for the basin. This year’s 19 named storms tied with three other years (2010, 1995, and 1887) as the third busiest season on record. Seven of the named storms became hurricanes, which is near average. Only Tropical Storm Lee and Hurricane Irene made landfall in the United States.
· A large and powerful extratropical cyclone slammed into western Alaska in early November, with extremely high tides, strong winds, heavy rain, and blizzard conditions. Winds gusted to over 80 mph and the storm surge topped eight feet, marking the strongest storm to impact the region in decades.
· A powerful Santa Ana windstorm whipped through mountain passes and canyons across the West and Southwest beginning on November 30 and continuing into December. The near-hurricane force winds were driven by the interaction between a strong high pressure system in the northwest and a low pressure system moving through the southwest. Portland, Ore., recorded its second highest maximum atmospheric pressure reading (30.76”) ever.

This monthly analysis, based on records dating back to 1895, is part of the suite of climate services NOAA provides.

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