Jacksonville Winter Weather Summary 2010-2011

            For the second consecutive winter, long-lasting cold temperatures and multiple hard-freeze events headlined the weather across all of Southeast Georgia and Northeast Florida.  Climate locations averaged twice as many the normal number of freeze events from December to February.  Winter began with strong negative phases of both the Arctic Oscillation (AO) and North Atlantic Oscillation (NAO). These phases help funnel cold-air outbreaks down through the Eastern United States where they settle over the Deep South for long periods of time.

The strong La Nina event ongoing over the Pacific Ocean did help continue below normal precipitation amounts from the autumn of 2010, especially in December and the latter half of February.  The first 6 weeks of 2011 were quite cool and wet across portions of northeast Florida where total winter precipitation amounts averaged close to normal.  Areas across southeast Georgia averaged closer to 5 inches below normal for the winter months

Freezes
The total number of freeze events between December 2010 to February 2011 set all-time records at local climate sites (Table 1). Alma, Georgia dropped at or below freezing for an all-time record 43 times this past winter, which broke the old record of 42 times set during the winter of 1963-64.  Across northeast Florida, Jacksonville recorded a total of 30 freeze events this winter season while Gainesville recorded 27. These totals rank the winter of 2010-2011 as having the 2^nd most freeze events for both Jacksonville and Gainesville.  In fact, the month of December was the coldest on record at Alma, Jacksonville and Gainesville.  December 2010 ranked as the third coldest for St. Simons Island.

Climate Site	Winter 2010-11 Total Number of Freezes	Normal Winter Number of Freezes (Dec-Feb)	Current and Old Record Number of Freezes
Jacksonville, FL	30 (Rank 2nd all-time)	16	31 in 1976/77

Temperatures

Temperatures finally started to moderate during the last half of February which was the only month this past winter to have above normal temperatures.  Even with the mild February, all of the climate sites registered one of the coldest winters on record, with average winter temperatures ranging from 2 to 6 degrees below normal.  In fact, all of the climate sites reported one of the coldest winters on record.  Jacksonville, Florida had back-to-back record setting cold winters during 2009-2010 and 2010-2011 which both ranked in the Top 5 all-time coldest winters.  The winter of 2010-2011 ranked just slightly colder than last winter.

Climate Site		December 2010 (All-time Coldest Rank)	January 2011      (All-time Coldest Rank)	February 2011    (All-time Warmest Rank)	Winter2010/11 Total (All-time Coldest Rank)
Jacksonville, FL	Normal Temp Actual Temp Departure	55.0F 46.1F -8.9F (1st)	53.1F 49.0F -4.1F (13th)	55.8F 58.5F +2.7F (47th)	54.6F 51.0F -3.6F (4th)

Precipitation

December of 2010 was not only one of the coldest on record, but it was also a very dry one which felt drought conditions that escalated last autumn.  Most climate sites received less than an inch of precipitation and ranked as one of the Top 10 driest Decembers on record.  At the beginning of 2011, the storm pattern shifted which brought a series of low pressure systems from the Gulf of Mexico across the Florida Peninsula.  These storms yielded much needed rainfall, and those across northeast Florida received normal to above normal rainfall totals.  Southeast Georgia, which was on the weaker side of these precipitation-producing systems, received less rainfall.  This continued severe drought conditions as precipitation values remained below normal

Climate Site	Precipitation        in Inches	December 2010 (All-time Driest Rank)	January 2011	February 2011	Winter2010/11 Total (All-time Driest Rank)
Jacksonville, FL	Normal Pcpn Actual Pcpn Departure	2.64” 0.34” -2.30” (9th)	3.69” 5.75” +2.06”	3.15” 4.06” +0.91”	9.48” 10.15” +0.67

Freezing Precipitation Events
As a low center tracked across the Florida peninsula on January 10^th, cold air combined with enough moisture to produce light freezing rain along the Altamaha River Basin.  The freezing rain coated some of the trees in the region but did not cause any transportation problems. Some light snow flurries were also reported in the wake of a cold low pressure system on December 26^th, 2010, across southeast Georgia and portions of northeast Florida along the I-10 corridor.  The Jacksonville metro area even experienced a brief period of snow flurries that morning.