Talking the Tropics w/ Mike: WARNINGS for parts of Florida as Helene develops & starts to organize

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Tropics threats for Jacksonville/NE Florida/SE Georgia: Given *current forecasts*, heavy rain, isolated tornadoes/waterspouts, gusty winds & rip currents at area 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 in N. Central Florida.

All areas from Mississippi 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. The peak time for impacts will be Thu.-Thu. night for Florida... Friday for Georgia & parts of the Carolina’s... even as far north as Tennessee.

“Buresh Bottom Line”:

* As expected... “Helene” has formed over the Northwest Caribbean. While consistency amongst the models has been lacking during the past week, agreement has increased markedly during the past couple days, but major differences remain 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 near the 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 & perhaps parts of the Western Carolina’s & as far north as Tennessee.

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

IMPACTS FOR JACKSONVILLE/NE FLORIDA & SE GA.:

* Primarily Thu. afternoon through Thu. night into early Fri. Expect rapidly improving weather conditions - but still breezy - through the day Friday.

* WINDS - near/west of I-75 including Lake City, Fl. - sustained winds 50 up to 60 mph, gusts 70-80 mph

I-75 to Highway 301: sustained winds 40 up to 50 mph, gusts 55-65 mph

I-95 corridor: sustained winds 25-35 mph, gusts 45-55 mph

Beaches, coast, intracoastal: sustained winds up to 50 mph, gusts 55-65 mph

* STORM SURGE - SE Duval/St. Johns Co.: 1-3 feet...

NE Duval, Nassau, FL... Camden, Glynn, Ga: 2 - 4 feet.

St. Johns River: 1 -3 feet but higher values - up to 4 feet for downtown Jacksonville due to a period of strong winds from the south pushing water up & out of the riverbank.

* TORNADOES & WATERSPOUTS - isolated Thu. afternoon & night.

* RAINFALL: 3 - 6+ inches from Lake City, Fl. to Waycross, Ga.... 2-5 inches east of I-75 to Highway 301... 1-3 inches east of Highway 301 to the coast including most of Jacksonville/Duval Co.

The Atlantic Basin Overview:

(1) A Storm Surge WATCH: Indian Pass southward to Flamingo ... Tampa Bay ... Charlotte Harbor

A Hurricane WATCH: Cabo Catoche to Tulum, Mexico ... Cuban province of Pinar del Rio .. Englewood to Indian Pass ... Tampa Bay.

A Tropical Storm WARNING: Dry Tortugas ... Lower Florida Keys west of the Seven Mile Bridge ... Grand Cayman ... Rio Lagartos to Tulum, Mexico ... Cuban provinces of Artemisa, Pinar del Rio, and the Isle of Youth

A Tropical Storm WATCH: Middle Florida Keys from the Seven Mile Bridge to the Channel 5 Bridge ... Flamingo to south of Englewood * West of Indian Pass to Walton Bay County line.

All systems are “go” for low pressure - ‘97-L’ - “Potential Tropical Cyclone Nine” - upgraded to tropical storm Helene late Tue. morning - to move over the Northwest Caribbean & Southern then Eastern Gulf of Mexico through Thursday. I’ve been hitting on this for more than a week but models have been all over the place on both location & intensity though are finally have been coming into much better agreement recently. Landfall is Thursday, Sept. 26th in the evening.

Anyone with travel plans to - or who lives along - the Eastern Gulf Coast & west coast of Florida needs to pay attention to the latest forecast & would be wise to complete preparations for a hurricane by sunset Wed. night, certainly no later than sunrise Thursday.

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 - 10 & 11th image below is for 2pm & 8pm Thu., Sept. 26. The model is pointing to a track into the Big Bend or even upper west coast of Florida with a landfalling hurricane that is moving quickly to the northeast. 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 & was significantly more west but steadily trending east & a little stronger though still not as intense as the GFS or ‘Horizon’. The Canadian model is generally similar to the European though a bit more east & in line with the UKMET model. Overall there is at least agreement on a timing for landfall of Thursday in the afternoon/evening.

Any potential tropical system over the Gulf will continue northward thanks to general troughing aloft over the Lower 48 that gets reinforced through the week. The depth & exact position of this trough is key to how sharp the northward movement of Helene will be vs. a track more to the east.

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.

The low pressure/tropical development in this area has been gradual (festering) as expected. Now that the center is becoming better organized, the disturbance may significantly increase in intensity ... & perhaps quickly. 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 to the north over the Lower 48 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 which may occur right up to landfall barring eyewall replacement cycles. The underside of Helene should quickly dry out at & beyond landfall leaving a heavily weighted north side storm as Helene moves swiftly inland & gradually decays while rotating dry continental air into its counterclockwise circulation.

The National Weather Service began extra 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) hurricane landfall in the last 13 months - a very rare feat.

Anyone living along - or traveling to - the area from Alabama to Florida northward to the Tennessee Valley & Western Carolina’s needs to stay up to date on the latest forecasts & folks in the Fl. Panhandle & west coast of Florida in particular should be moving along with hurricane preparedness measures completing the tasks & any evacuations by Wed. evening.

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 Helene 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.

It’s also interesting to note the rapid strengthening of hurricane “John” over the far East Pacific that moved inland on the west (Pacific side) coast of Mexico Mon. night/early Tue. There may be some symmetry with the Gulf system as upward vertical velocities that aided John spread eastward to the Atlantic Basin.

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. Remember that a more narrow cone simply means a higher confidence forecast:

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

Climavision’s HorizonAI Global Model for late Thu., 09/26 for 2pm & 8pm EDT respectively (pretty steady trend & track - near 960mb/28.35″ 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 Wed. & Thu. 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. The 2nd image is deep oceanic heat content (OHC) + shear.

Radar imagery from South Fl. Water Management District (solid line is ‘Helene’ forecast track previous advisory vs. latest NHC advisory:

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.:

(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.

‘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..... “Isaac” 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:

Sea surface temp. anomalies:

SE U.S. surface map:

Surface analysis centered on the tropical Atlantic:

Surface analysis of the Gulf:

Caribbean:

Atlantic Basin wave period forecast for 24, 48, 72 & 96 hours respectively:

East & Central Pacific:

John has rapidly strengthened & moved into Mexico Southern Pacific side Mon. night - early Tue. & will now weaken inland:

Central Pacific:

Hawaii satellite imagery:

West Pacific:

Global tropical activity: