Talking the Tropics w/ Mike: Watches for parts of Florida... disturbance destined to be Helene

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: None through Tue. into Wed. Given *current forecasts*, heavy rain, isolated tornadoes/waterspouts & rip currents at beaches will be a growing threat for NE Fl./SE Ga. Wed. night through Thu. into early Fri. due to landfalling Helene a couple hundred miles west of Jacksonville. How significant these impacts are will depend on the exact track & strength of Helene. Right now - the I-75 corridor will have the highest winds.

All areas from Louisiana to Florida need to stay up to date on the latest forecasts for mid to late parts of the upcoming week. Those in the Fl. Panhandle & west coast of Florida should be well underway with hurricane preps.

“Buresh Bottom Line”:

* The Northwest Caribbean & especially Gulf of Mexico remain the area where tropical development will occur through Wed. This is a favored area for genesis later in Sept. & all forecast models are now onboard & indicate low pressure developing. While consistency amongst the models has been lacking during the past week, agreement has increased rather markedly during the past couple days, but there are still major differences on exact track & intensity. Don’t get caught up with unreliable sources & crazy postings on social media & elsewhere. Landfall looks to be this Thu. afternoon/evening on the upper Florida west coast/Big Bend/Eastern Panhandle as a ‘major’ Cat. 3+ hurricane. Due to its swift movement inland, wind damage will occur well inland into at least Georgia.

*** Do not get caught off guard & stay up to date on the latest forecasts. Everyone from Texas to Florida - but especially Mississippi to the Fl. Panhandle to the Florida west coast should prepare for impacts from what is likely to be “Helene”. ***

The Atlantic Basin Overview:

(1) A Hurricane WATCH: Cabo Catoche to Tulum, Mexico ... Cuban province of Pinar del Rio.

A Tropical Storm WARNING: Grand Cayman ... Rio Lagartos to Tulum, Mexico ... Cuban provinces of Artemisa, and Pinar del Rio, and the Isle of Youth.

A Tropical Storm WATCH: Dry Tortugas ... Lower Keys south of the Seven Mile Bridge

All systems are “go” for low pressure - ‘97-L’ - “Potential Tropical Cyclone Nine” - to develop over the Northwest Caribbean & Southern Gulf of Mexico over the next couple days. I’ve been hitting on this for more than a week but models have been all over the place on both location & intensity though finally coming into some semblance of agreement now. Given what looks like a more east development, the trek to land will be a shorter distance & therefore the timing has sped up with landfall Thursday, Sept. 26th anywhere from midday into the evening.

Anyone with travel plans to - or who lives along - the Gulf Coast & west coast of Florida needs to pay attention to the latest forecast & would be wise now to begin preparations for a tropical cyclone.

The 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) has at least been consistent in indicating tropical development - 4th image below is for early midday Thu., Sept. 26. The model has trended stronger & more east (central pressure sub 950mb/27.00″) & is pointing to a track into the Big Bend or even upper west coast of Florida. Virtually all other global models are indicating development as well with relatively small - now - deviations in timing (centered on Thu.) but still a large range in intensity & exact location. The GFS has been & still is generally the most aggressive/strongest & farthest to the east - ‘Horizon’ model is similar - while the European operational model is not as strong & significantly more west - Central Panhandle. The Euro has been a west outlier & quite weak for most of the past week... the Canadian model is generally similar to the European though not as far west & is more west than the GFS & ‘Horizon’ & not as strong. Models have at least converged on a timing for landfall of Thursday ranging from midday to evening. Recently Monday model trends have been slightly west & still strong on the GFS while the European is more to the east than it has been & at least a little stronger though not as strong as GFS & ‘Horizon’. Canadian has trended stronger & is quite of compromise between the GFS & European.

Any potential tropical system over the Gulf will continue northward thanks to general troughing aloft over the Lower 48 that gets reinforced in a few days. The Caribbean & Gulf are 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.

I suspect that low pressure/tropical development in this area will likely be gradual (festering) at first. Then once/if the energy can be “bundled”/organized, the disturbance *may* significantly increase in intensity. There has been a good deal of mid & upper level wind shear along with lots of dry air over & near the Gulf, but both factors are becoming less hostile & more conducive for a strengthening tropical system through Thu. night. The nearby upper level trough will aid ventilation over the top of Helene with shear vectors in roughly the same direction as the forward movement - both can aid to intensify tropical cyclones.

The National Weather Service will begin an extra 2 weather balloon launches at 2am (06Z) Tue. The goal is to hopefully have better analysis - input - for the model initialization which in turn could improve output & therefore accuracy:

Alert Administrative Message National Weather Service Southern Region Headquarters 0837 AM CDT Sun Sep 22 2024

TO: EWX FWD OUN BRO CRP LCH SHV LIX LZK JAN OHX BMX FFC TAE JAX TBW MFL KEY FROM: SR ROC

SUBJECT: Special Soundings for NHC NHC is requesting special 06/18Z soundings for the developing tropical system in the Gulf of Mexico and its evolution, starting at 06Z Tuesday 24 September, and continuing through at least 18Z Thursday 26 September.

IF this system does indeed move into or very near the Big Bend, it would be the 3rd (Idalia & Debby) in the last 13 months - a very rare feat.

Anyone living along - or traveling to - the area from Texas to Florida needs to stay up to date on the latest forecasts & folks in the Fl. Panhandle in particular should be moving along with hurricane preparedness measures.

I would be remiss if I did not mention some early striking similarities between the forecast development over the Gulf & hurricane Michael in 2018. I AM NOT SAYING the developing storm will be as intense but the storm during the upcoming week will be developing in a similar area, similar movement with influence from an upper level trough to the north... & forming quickly from next to nothing just a few days prior.

(2) A tropical wave over the Eastern Atlantic has high potential for gradual development but early indications are that the system would stay far out to the east over the open Atlantic. Another tropical wave will then follow that one.

Keep in mind on the map below that the red shading is where a storm has the potential to develop & is not a track forecast:

Keep in mind impacts from the storm will extend well beyond the center AND the cone. Do not fixate on the cone or a perceived center point.

The storm surge forecast map below will expand dramatically up the coast soon:

Climavision’s HorizonAI Global Model for late Thu., 09/26 (trend has been a little east & intense - sub 950mb/28.00″ which is similar to GFS model):

The ultimate track of the *possible* storm will be dictated by an upper level trough that continues to get reinforced over the contiguous U.S. & any potential ridging underneath or on either side of the trough. Essentially - a stronger, deeper (more south) trough would allow for more north or even northeastward movement while a stronger ridge &/or weaker trough would allow the system to stay more west or perhaps even languish over the Gulf for a while.

500mb forecast from the GFS for Thu., 09/26. The upper level trough over the Central U.S. + positioning of a high pressure cell over the Western Atlantic & stronger ridge to the west will be key in where a Gulf tropical cyclone might track. The European has the trough more to the west, therefore, a track of Helene more to the west (Panhandle).

Mid & upper level wind shear is currently strong across the Gulf & Caribbean but is forecast to abate some over the next few days. Dry air over the Gulf is gradually moistening. And convection has increased a great deal over the Western Caribbean.

Jacksonville/NE Fl./SE Ga. rainfall courtesy GFS & European models:

Heavy rain is forecast along much of the Gulf coast. While it’s recently been drier for NE Fl. & SE Ga., a lot of water remains “in the system” so flooding will be a concern by Thu./Fri.:

‘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: