Contemplating a South Florida fall

Students are heading back to school over the next couple of weeks, and there are already some Halloween displays at stores. The NFL played its first pre-season game on Thursday.

AccuWeather published its fall forecast on Thursday with the word “snow” plastered over the Rocky Mountain States.

In South Florida, fall is more of a concept than an event, but there are some subtle changes that take place.

To wit: The normal high in West Palm Beach, 91 since July 31, edges down to 90 on Tuesday. That doesn’t exactly portend a breath of fresh air, but it’s the first downward adjustment of the normal high temperature since January 18. Florida is surrounded by hot water in the fall, and the high of 89 on August 30 only ticks down to 87 on September 30.

Miami’s high remains at 91 until August 29, and hits 88 on September 30. Fort Lauderdale’s normal high of 91 edges down to 90 on August 17, while Naples’ normal high doesn’t fall to 90 until September 3, and it doesn’t hit 89 until September 25.

Overnight lows along Florida’s East Coast have been in virgin territory over the past two decades, with record warm lows being busted every month of the year. The average low in West Palm Beach in August is 76; 77-78 in Miami; 79 in Fort Lauderdale and 75-76 in Naples. Yet there are many summer nights in which the temperature fails to drop below 80.

Fort Lauderdale’s low on Friday was 84, a new record warm low for the date — and the previous record of 83 was set just eight years ago in 2009. The low was 82 in West Palm Beach, tying the record set in 1993.

By the way, the normal low in West Palm Beach doesn’t sink below 70 until October 27.

As for AccuWeather’s autumn sneak peek, the commercial forecasting company is calling for “a few tropical hits” during the season for the southeastern U.S., with areas along the Gulf Coast and the Carolinas most vulnerable.

Forecasters also warned about flooding rains in the Florida panhandle and states as far north as Kentucky.

Elsewhere, they predicted California and the West Coast would have a warm and dry fall, with chilly temperatures in the Midwest and drought conditions in the Northern Plains. They said New England would have an unusually warm autumn.

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storm_99

Forecast tracks for Invest 99L. (Credit: SFWMD)

TROPICS WATCH: The GFS has been picking on Florida over the past few days with suggestions on Friday that Invest 99L could turn into a major hurricane and threaten the Keys and Florida’s West Coast. Slight adjustments in track make all the difference in the world, and while Friday’s model runs kept the storm off-shore of Puerto Rico, Hispaniola and Cuba — a set-up that primes a system for a potential punch to Florida — Saturday’s runs plowed it into the Greater Antilles.

That can and often does tear up a storm thanks to some mountainous terrain, taking Florida off the hook.

Models are run every six to 12 hours, so we can expect many more flips and flops over the next week as 99L gets closer to the islands.

On the plus side, the European (ECMWF) is not terribly interested in 99L, but spins up the disturbance in the Caribbean (90L) and drives it into Mexico from the Bay of Campeche. The Euro has actually been very consistent with this forecast.

The Canadian has had its own brand of consistency with 99L, depicting a vigorous storm that rolls north well east of the Bahamas and off the U.S. East Coast.

It’s been clear the last few days that the Atlantic is still dominated by lots of dry air, and 99L has been struggling with these conditions. The National Hurricane Center slightly reduced chances of tropical development on Saturday, although forecasters continue to believe that chances are good for a tropical depression to form early next week.

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Author: jnelander

Freelance writer and editor

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