Miami Florida: Coldest December on Record

January 1, 2011 12:24


How’s that global warming thing workin’ out for ya’? From the NOAA National Weather Service Office in Miami: A cool and wet January through March was followed by the hottest summer on record, and then concluded with the coldest December on record for the main climate sites in South Florida.

by Anthony Watts at Watts Up with That?

From the NOAA National Weather Service Office in Miami comes this year end report:

2010 South Florida Weather Year in Review
Coldest December on Record Concludes Year of Extremes
December 30th, 2010: Temperature and precipitation extremes marked the weather of 2010 across South Florida. A cool and wet January through March was followed by the hottest summer on record, and then concluded with the coldest December on record for the main climate sites in South Florida (details on the above mentioned periods will be included below).

Here are December 2010 temperature averages for select sites (through 7 AM Dec 30th):

* Location of observations for each location have moved since the first year of record, but are representative of the city for record keeping purposes.
** Present Miami Beach and Moore Haven temperature data may not be totally comparable to historical data due to difference in time of daily reports which causes double-reporting of low temperatures.
Complete statistics of the record cold December for all sites above (except Moore Haven) will be provided in Record Reports which will be issued early on Jan 1, 2011.

The main culprit behind the cold temperatures in December 2010 was the same one which caused the cold winter of 2009-2010; a strongly negative North Atlantic Oscillation (NAO) and Arctic Oscillation (AO). When these atmospheric oscillations are in the strong negative phase, they essentially “flip” the weather pattern across North America, with upper-level high pressure and relative warmth over Greenland and Northeastern Canada and upper-level low pressure and cold over the eastern Continental United States, including Florida (Figure 1). This pattern forces the jet stream to plunge south from northern Canada into the southeastern U.S., transporting Arctic air masses into Florida.

A pronounced shift in the ENSO (El Niño Southern Oscillation) phase was noted in 2010, from a strong El Niño, or warm, phase to a borderline strong La Niña, or cold, phase. While this may appear at first glance to be a key contributor to the temperature extremes noted across South Florida during 2010, it is believed that it was the strongly negative NAO and AO, not the ENSO phase, which contributed to the cold temperatures in early and late 2010. A strongly phased NAO/AO operating on shorter time scales can override the longer-term ENSO phase.

As mentioned above, South Florida experienced its hottest summer on record in 2010 (with the exception of Naples which recorded its second hottest recorded summer). Despite the record hot summer, average yearly temperatures at the main climate sites will end up around 1 degree below normal, which will be the coolest calendar year since the early and mid 1980s, and among the top 10 on record (except for Miami). At secondary sites Miami Beach and Moore Haven, it was the coolest year on record (please note caveat below table).

Here are the 2010 temperature averages for the year for the primary climate sites through December 29:

** Present Miami Beach and Moore Haven temperature data may not be totally comparable to historical data due to difference in time of daily reports which causes double-reporting of low temperatures.

Some other interesting 2010 temperature statistics:
– Miami International Airport (MIA) observed 103 days of temperatures at or above 90 degrees, the 4th most on record. The average number of 90+ degree days per year is 51. MIA also had a record 45 days of low temperatures of 80 degrees or higher, besting the previous record of 39 set in 2009. The average number of 80+ degree low temperature days per year is 13. On the other end of the thermometer, MIA had 6 mornings with low temperatures below 40 degrees. This ties the 5th most number of sub-40 degree days on record. The average yearly number of sub-40 degree days is 2.
– Fort Lauderdale/Hollywood International Airport (FLL) observed 9 days of low temperatures below 40 degrees. This ties the 4th most number of sub-40 degree days on record. The average yearly number of sub-40 degree days is 3.
– Palm Beach International Airport (PBI) observed 106 days of temperatures at or above 90 degrees, the 8th most on record. The average number of 90+ degree days per year is 56. PBI also had a record 34 days of low temperatures of 80 degrees or higher, crushing the previous record of 17 set in 1900 and 2002. The average number of 80+ degree low temperature days per year is 6. On the other end of the thermometer, PBI had 18 mornings with low temperatures below 40 degrees. This easily breaks the previous record of 10 days set in 1920 and 1981. The average yearly number of sub-40 lows at PBI is 3. Six of the 18 days occurred in December, which breaks the previous monthly record for December of 5 set in 1962.
– Naples Regional Airport (APF) observed 125 days of temperatures at or above 90 degrees, the 12th most on record. The average number of 90+ degree days per year is 109. Naples also observed 13 days of low temperatures below 40 degrees. This ties the 5th most number of sub-40 degree days on record. The average yearly number of sub-40 degree days is 3. Eight of the 13 days occurred in December, which breaks the previous monthly record for December of 7 set in 1981.

Full report at NOAA/NWS here:

http://www.srh.noaa.gov/images/mfl/news/2010WxSummary.pdf

h/t to Joe D’Aleo



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