Overall, in terms of impacts, the main question here is how much rain South Florida and the low crosses of the Keys will get. Ryan Truchelut/WeatherTiger


As the newly discovered season of “hotumn” comes to its long-belated close and crisp breezes spread across the land, the Tropics are probably continuing to fall further off your proverbial radar. By this point, potential hurricane threats are receiving far fewer thoughts than pumpkins and their affiliated spices.

And it is certainly true that the hurricane season is heading towards garbage time, with barely 3 percent of U.S. landfalls occurring after Oct. 25. However, as I’ve been warning for a couple of weeks, the Caribbean is heating up as Halloween nears, which could spoil South Florida’s candy haul with the meteorological equivalent of a box of raisins this weekend.

Today’s tropical disturbance of note is Invest 93L, located in the western Caribbean. Showers and storms have gotten a little more consolidated around a potential weak low a couple hundred miles east of Nicaragua in the past 24 hours and satellite scatterometer data is indicating an elongated surface circulation could be forming.

In a modestly supportive environment, this slow trend toward increased organization means the odds of a tropical depression developing over the northwest Caribbean or Southeastern Gulf on Friday or Saturday are slightly better than even. If this system becomes a subtropical or tropical storm, it would be named Phillipe.

Invest 93L is part of a broader area of rotation over Central America, which is a similar pattern to the one that spawned Hurricane Nate at the beginning of the month. However, a key difference between early and late October is the strength and frequency of cold fronts.

Not only did a doozy just clear Florida, but there’s another unseasonable Arctic blast on the way. So, whereas Nate had more time to organize and move north, 93L will be quickly turned northeast and merge with the front late this weekend. All models and ensembles bring the system northeast across either South Florida or the Bahamas overnight Saturday into Sunday, at intensities ranging from moderate tropical storm on the perma-bullish Canadian to hot mess on the GFS.

Overall, in terms of impacts, the main question here is whether South Florida picks up around 1” of frontal rain this weekend should the system pass to the south and east, or if the low crosses the Keys or Southwest Florida and bumps totals into the 2-4” range. Winds are not a major threat in either case. As 93L is getting organized a little faster than expected, I’d lean towards the wetter scenario in which moisture is drawn further north as part of a loosely organized depression or storm.  It’s also worth noting that 93L’s energy and moisture is likely to contribute to the development of a strong non-tropical storm for the Northeast U.S. on Sunday and Monday.

Otherwise, there are no other threats this week, and I also don’t see anything likely to fire up in the next seven days if 93L fails to ignite. The upper-level pulse supporting increased convection in the Atlantic this week will move away from the U.S. in 8-10 days, so there’s no particular indication of late-season danger as typically (but not always) calm November arrives. Let’s hope the fearful specter of an undead Tropics is put away with the Halloween decorations this year.

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