Friday 3 February 2017

Record warm winter in south Florida

Winter Abandons South Florida: A Record-Warm Two-Month Stretch

By: Bob Henson 

1 February, 2017

Millions of people head to Florida to soak up the state’s famed winter mildness—but this year’s snowbirds may feel more like they flew into a summer sauna. The winter of 2015-16 featured periods of exceptional warmth in South Florida, yet even that high bar is being eclipsed by the persistent simmering that’s gone on for most of the last two months. In Miami, the average temperature of 74.65°F for the two-month period of Dec. 2016 - Jan. 2017 is a full degree above the 73.6°F record from 1971-72 in NOAA/NCEI data going back to 1948, and it also tops any two-month Dec-Jan interval in NWS/Miami data going back to 1895. Likewise, Key West averaged 75.25°F for the two-month Dec-Jan period, besting the record of 74.8°F (1990-91) in NCEI records going back to 1901.

The two cities also racked up an impressive pile of daily records along the way. Between Dec. 1, 2016, and Jan. 31, 2017, a total of 11 warmest highs for the date and 6 warmest lows for the date were tied or broken in Miami, where record-keeping began in 1895. In Key West, 5 daily record highs and 6 daily warmest-low records were set. Another sign of this winter’s persistent warmth: Miami has yet to dip below 50°F. It’s 
only the third time in Miami history that a winter has gone this late without reaching the 40s at least once. Hand in hand with the extremely warm air, sea-surface temperatures (SSTs) in the adjacent Gulf of Mexico and northwest Atlantic have also been unusually high. As reported by Brian McNoldy, on January 27, the water temperature in Miami's Biscayne Bay was 80.2°. The average for the date: 70.8°.
The potential role of the now-fading La Niña

La Niña may have played a part in South Florida’s summerlike winter. The last several months of 2016 featured weak La Niña conditions in the Pacific, and temperatures across the United States were very consistent with that: generally cooler than average toward the northwest and milder than average toward the southeast, including Florida. However, the current La Niña event appears be on its last legs: the cooling of the tropical equatorial Pacific has weakened and retreated to the central Pacific, while unusually warm SSTs and sultry air invade the coast of Peru and Ecuador, producing conditions more akin to El Niño than La Niña. Daily low temperatures over the weekend of around 77°F were among the warmest on record in Lima, Peru. The latest roundup of international climate models 
posted on Monday by the Australian Bureau of Meteorology shows that full-fledged El Niño could be in place as soon as this summer, even by the more strict Australian definition (SSTs in the Niño3.4 region of at least 0.8°C above average, vs. the 0.5°C required by NOAA).

Cooler air finally moved into the state over the weekend, producing a chilly, rainy Sunday. Fort Lauderdale tied its record lowest high for the date (62°F), as did West Palm Beach (59°F). South Florida then saw the lowest temperatures of the winter thus far, including 51°F in Miami (Mon), 51°F at Fort Lauderdale (Mon & Tues) and 43°F in West Palm Beach (Tue). The cooldown will be short-lived, though, as upper-level ridging will help build the warmth back into the state over the next week.

Bob Henson

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