Talking the Tropics With Mike: Long term development *possible* over W. Caribbean/S. Gulf of Mexico

Jacksonville, Fl. — The “Buresh Bottom Line”: Always be prepared!.....First Alert Hurricane Preparation Guide... City of Jacksonville Preparedness Guide... Georgia Hurricane Guide.

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Tropics threats for Jacksonville/NE Florida/SE Georgia: No direct impacts from tropical systems this week but minor to moderate tidal flooding will continue along the St. Johns River & its tributaries as well as the intracoastal & beaches this week into the weekend due to the full moon, all the recent rainfall & a good deal of onshore flow.

“Buresh Bottom Line”:

* “Gordon” is over the Eastern Atlantic & will stay far to the east over the open Atlantic struggling against shear & dry air before potentially strengthening late in the week/this weekend.

* The Caribbean &/or Southern Gulf of Mexico may be an area to carefully monitor next week for tropical development. This is a favored area for genesis later in Sept. & virtually all forecast models indicate low pressure “of some sort” gradually developing.

The Atlantic Basin Overview:

(1) ‘93-L’ was upgraded last Wed. morning to tropical depression seven & Fri. morning to tropical storm Gordon then back down to a depression late Sunday & then degenerated into an open tropical wave Tue. afternoon. The Bermuda high remains displaced to the east & northeast over the Atlantic & such a position favors an alleyway for systems to turn north over the Central Atlantic... at least over the next 10 days or so. “Gordy” has been struggling against mid & upper level wind shear, overall subsidence & dry air. But Gordon has a shot at restrengthening later this week into the weekend while staying far out to sea.

(2) Experimental ‘horizon’ forecast model by Climavision’s HorizonAI Global Model (this model uses its own data & analysis for initialization of each model run + some AI input) is showing longer range tropical development over the Caribbean - forecast map below is for early Monday, Sept. 23. The model has trended slower on development & more west. Many other global models are indicating development as well - anywhere from the Southern Gulf to the Caribbean. Any potential tropical system in this area would probably have at least some semblance of a northward movement. This is a climatologically favored area for tropical development later in Sept. & such systems are often steered northward by an ever more active, more meridional jet stream as we start to see the impacts of autumn weather patterns. The water, of course, is very warm & deep oceanic heat content is just about at its annual peak.

Any tropical development in this area will likely be gradual (festering) at first. Then once/if the energy can be “bundled”, the disturbance may increase in intensity quickly. So the Caribbean & Gulf will be an area to carefully monitor through the next week to 10 days.

Fitting the pattern for the increased tropical activity overall - as well as the wet/cloudy spell the first 2 weeks of September for Florida - is persistent & seasonally strong surface high pressure at northern latitudes from the Central U.S. to the Northwest Atlantic. This high pressure will bring has brought an early taste of fall across the Northern U.S. & generally encourages low pressure to the south - a pattern that often favors tropical development at southern latitudes. It’s Mother Nature’s constant balancing/compensating act. And it’s likely why we’ve seen forecast models struggle with the overall pattern developing sometimes spurious & frequent low pressure areas near & south of about 35 degrees N. It may also be why low pressure areas have a hard time “bundling” their energy - there’s just so much low pressure.

Climavision’s HorizonAI Global Model:

‘Velocity potential anomalies’ below still shows “sinking” air (brown lines) across the Atlantic Basin. In such a state, tropical development can occur but overall conditions are not as conducive as when there is overall rising (green lines) air such as much of the Pacific Basin where convection is active. This “pulse” of upward motion is moving eastward toward the Atlantic Basin & may help to be a cause for an uptick in Atlantic activity late this month into October.

REMEMBER WHEN A TROPICAL STORM OR HURRICANE IS APPROACHING: Taping windows is *not* recommended & will not keep glass from breaking. Instead close curtains & blinds.

Realize the forecast cone (”cone of uncertainty”) is the average forecast error over a given time - out to 5 days - & *does not* indicate the width of the storm &/or where damage might occur.

The upper oceanic heat content (UOHC) [tropical cyclone heat potential/TCHP] across the SW Atlantic, Gulf & Caribbean is very high:

Water vapor loop (dark blue/yellow is dry mid & upper level air):

September tropical cyclone origins (early season breeding grounds are the Gulf &/or Western Caribbean:

Averages below based on climatology for the Atlantic Basin for September (2 hurricane so far, 3 tropical storms):

Wind shear (red - strong shear; green - low shear):

Saharan dust spreads west each year from Africa driven by the prevailing winds (from east to west over the Atlantic). Dry air = yellow/orange/red/pink. Widespread dust is indicative of dry air that *can* interfere with the development of tropical cyclones. However, sometimes “wanna’ be” waves will just wait until they get to the other side of - or away from - the dust plume then try to develop if other conditions are favorable (we’ve already seen this with Beryl & Debby this year). In my personal opinion, there is way too much “hoopla” about the presence of Saharan dust & how it relates to tropical cyclones. In any case, the peak of Saharan dust typically is in June & July.

2024 names..... “Helene” is the next name on the Atlantic list (names are picked at random by the World Meteorological Organization... repeat every 6 years). Historic storms are retired [Florence & Michael in ’18 (the last time this year’s list was used)... Dorian in ’19 & Laura, Eta & Iota in ‘20, Ida in ‘21 & Fiona & Ian in ‘22]). In fact, this year’s list of names is rather infamous because of the ‘04 season when Charley, Frances, Jeanne & Ivan - all retired names - hit Florida within a matter of about 6 weeks. The WMO decided - beginning in 2021 - that the Greek alphabet will be no longer used & instead there will be a supplemental list of names if the first list is exhausted (has only happened three times - 2005, 2020 & 2021). The naming of tropical cyclones began on a consistent basis in 1953. More on the history of naming tropical cyclones * here *.

Peak of the hurricane season Sept. 10th:

East Atlantic:

Mid & upper level wind shear (enemy of tropical cyclones) analysis (CIMMS). The red lines indicate strong shear:

Water vapor imagery (dark blue indicates dry air):

Deep oceanic heat content over the Gulf, Caribbean & deep tropical Atlantic. The colors will brighten greatly as the water warms to greater depths deeper into the season: