Hot Gulf Summer: The Hurricane Watch for August 24th
The chance of a tropical storm in the Gulf next week starts to come into focus.
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Florida tropical threat synopsis: The Florida Gulf Coast may see an organized tropical system move onshore from the Gulf between Tuesday and Thursday of next week. The forecast remains uncertain, but is worth monitoring closely.
Almanac: It’s Thursday, August 24th… day 85 of the 2023 hurricane season, 98 days to go. By total storm energy, the season is 18.6%, 31.1%, and 21.3% complete for the Atlantic, continental U.S., and Florida, respectively.
Gulf sea surface temperatures don't need a top off ahead of a potential tropical system next week, but they'll get one anyway this weekend. Widespread triple digits are expected across the northern Gulf Coast Saturday and Sunday, with mid and upper 90s pushing daily records in Central Florida as well. Gulf SSTs have “dipped” slightly in spots in Harold’s wake, but this event should return the widespread 87-91F temps seen last week in the eastern Gulf to the fore. Oof on both counts.
Active Storms: Tropical Storm Franklin is adrift north of Hispaniola today with maximum sustained winds of around 60 mph. Franklin is following the NHC forecast scenario closely, sliding northeast today, a motion that will continue into the weekend. On Sunday, Franklin should accelerate north as a hurricane, then pass west of Bermuda by Tuesday. The storm has a decent chance of becoming the first major hurricane of the season next week, and eventually may be a significant storm for Atlantic Canada in 7 days. No U.S. threat from Franklin.
Other Disturbances in NHC outlook, with 2-/7-day NHC development odds:
Central Subtropical Atlantic (ex-Emily): NHC still gives ex-Emily a 70% chance of briefly returning to tropical storm status in the next day or two before departing into the north Atlantic. No change and no consequences here.
Central Tropical Atlantic (Invest 92L): A tropical wave passing 40W is still strung out, with its low-level spin under shear and convection displaced far south. The NHC has bumped 7-day development odds since yesterday a touch to a 40% chance with a little more model support for organization by early next week. This one is destined for the open water of the central Atlantic either way, and is no risk to the U.S. or any landmass.
NW Caribbean/Eastern Gulf: The potential for a broad low to develop near the Yucatan this weekend and move north across the eastern Gulf of Mexico next week is now being highlighted by the NHC at a 10% chance of development over the next two days and 50% chance through day 7. Given strong upper-level troughing over the Great Lakes next week, anything that develops is coming north and northeast in the general direction of Florida, so this is certainly a concern for the state should it form.
The GFS is a better match for the current location of convection and rotation than the Euro. However, let’s not get ahead of ourselves. The thunderstorm complex in question is still in the Pacific Ocean, just west of Nicaragua, embedded in a very broad region of cyclonic turning. How these storms are influenced by crossing mountainous Central America is an open question, and model opinions of how the disturbance will look in the immediate future are mixed. The Euro continues to be most bullish on developing a tropical storm in the Gulf, but also appears unrealistically too far east with the strongest low-level rotation this afternoon, which allows for less land interaction and faster development in the Caribbean. The early hours of the less bullish GFS forecast seem a better match to observations; most GFS Ensemble members bring a disorganized moisture surge or weak tropical storm across Florida next week, not a strong tropical storm or hurricane.
In short, given the significant hurdles in front of this feature in the next few days, I’m a little skeptical of its development potential until I see that a circulation is consolidating over water. This isn’t to say that the Florida Gulf Coast (both Panhandle and peninsula) shouldn’t be on watch for the chance of a tropical storm or even hurricane in 5-7 days; this is a possibility, but we’re still in evaluation mode for another day or two with this system. Stay tuned.
Elsewhere: Nothing of note.
Next report: Daily bulletin out tomorrow afternoon.