Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather
By: Dr. Jeff Masters , 3:17 PM GMT on January 11, 2010
The Deep South shivered through a ridiculously frigid weekend, with low temperature records crumbling over much of Florida, Texas, and Louisiana. This morning, record lows for the date fell in Miami, West Palm Beach, Tampa, Fort Myers, Lakeland, Tallahassee, and St. Petersburg. The most extreme low temperature record this morning was set in Key West, where the mercury fell to 42°F at 5am--the second coldest temperature ever observed in Key West. This is just 1° warmer than the all-time coldest temperature observed in Key West--41° in January of 1981 and 1873. Widespread reports of sleet and snow flurries accompanied the cold blast across Central Florida on Saturday, the eighth snow event in Florida since 2000, according to Wikipedia. It remains to be seen how much damage the $9.3 billion Florida citrus industry will see because of the cold blast, which is the most severe in Florida since the December 1989 cold wave that devastated the citrus industry. Temperatures below the 28° that causes fruit damage affected some citrus-growing areas again this morning, for the third consecutive morning.
Figure 1. Ice encases citrus in Altoona, Florida. Image taken Sunday, January 10, 2010 by wunderphotographer CAVU.
Intense and long-lasting cold
In Texas, two airports tied all-time January low temperature records on Saturday morning--Hondo, who's 12°F tied the record set January 11, 1982, and Cotulla La Salle, which hit 16°F, tying the record set January 13, 1975. Most of Texas' airports set daily low temperature records on Saturday morning. Saturday's low in Waco of 8°F broke the previous record of 15° for the date, and was the first time Waco has been in the single digits since the -4°F reading on December 23, 1989. Not only has the South's cold been intense, it has been exceptionally long-lasting. Montgomery, Alabama has had a low temperature below 25° nine consecutive days, breaking the old mark of seven straight days set in January 2001. With the cold snap only grudgingly scheduled to release its grip on the South, Montgomery can expect to run their streak of sub-25° lows to at least eleven straight days this week. Mobile, Alabama and Pensacola, Florida now have their second longest streak of days with a minimum temperature below freezing, at nine and eight days, respectively. Pensacola may equal or top their record of eleven straight days (set in January 1940) later this week, but Mobile is unlikely to break their record of fifteen straight days (set in February 1940). Also of note is that Key West has seen five consecutive days with low temperatures below 50 degrees (January 7th - 11th). This is the second longest such streak recorded in Key West, one day short of the record six-day streak on December 1 - 6, 1876. Key West has a decent chance of tying that record on Tuesday morning, when the low should fall to 50 or below.
A nicer beach weekend in Antarctica than Central Florida
Saturday's high and low temperatures in Orlando and Daytona Beach, Florida were 40° and 30°F. Tampa's high and low were 42°F and 29°F. Under sunny skies and light winds less than 10 mph, Saturday's high and low temperature at San Martin Base, Antarctica were 44° and 34°F. Gray, cloudy skies with winds gusting to 16 - 21 mph greeted beach goers at the beaches near Daytona Beach and Tampa, so it was a much nicer day at the beach in the Antarctic Peninsula than in Central Florida on Saturday (the Florida Chamber of Commerce loves stats like that!) Nice beach weather in Antarctica continued through Sunday, with sunny San Martin, Antarctica (high 41°, low 35°) recording an average temperature warmer than most stations in Central Florida. In all fairness, it is summer in Antarctica, and the ocean temperatures in Florida were a bit warmer than in Antarctica.
A major pattern shift coming
As I noted in my previous post, a sharp kink in the jet stream and a strong negative phase of the North Atlantic Oscillation is responsible for this winter's cold blast over eastern North America and Europe. The ridge of high pressure that has been blocking the west-to-east motion of weather systems over the past ten days is weakening, though, and a major shift in the winter weather pattern is in store for the Northern Hemisphere by late this week. A more typical El Niño pattern will set up, with the jet stream diving southward over California, bringing a strong flow of moist, Pacific air to the West Coast. A strong low pressure system will also bring heavy rain to the Gulf Coast on Friday and Saturday. Temperatures will slowly moderate across Europe and the Midwest and Eastern U.S. this week as the pattern gradually shifts, and more ordinary winter weather can be expected in these regions by next weekend.
Figure 2. Departure of the surface temperature from average for the first eight days of 2010 shows much colder than average conditions were present over the Midwest and Southern U.S., much of Europe, and Central Asia. Much warmer than average temperatures were present over the Northwest U.S., Greenland, the Arctic, and Southern Asia. A sharp kink in the jet stream was responsible for the temperature anomaly pattern. Image credit: NOAA/ESRL.
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