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2024 - tracking the tropics


mcglups
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that really is amusingly calm out there in the mdr.    here it is the apex climo or close to it, and huckleberry fin's raft could make it unscathed the entire thousands of miles across the basin

...during a season of predicted epicosity.     never gets old!  hahaha

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Still watching this one. Steering pattern looks to be such that if this ends up east of the forecasts it could be shunted up the Atlantic, potentially close or on NE, like that GFS run a few days ago. Quite unlikely but it’s something, and we’ve had storms arrive in that manner from the West before

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It's not the quantity but the quality of the tropical season.
Only taking one to memorialize and it ain't over.
Was it dust, shear or the latitude of the waves exiting the African coast?  
Thinking is the present threat the whole W. Coast of Florida from Tampa Bay to the Big Bend. Ground Zero.  

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interesting looking over the 97L  ( destined to born 'Helene' ) on high res vis loop this morning.  i'm not sure if it is just an illusion put on by the frame rate of the loop working with cloud morphology, but that circulation in the low levels is already faster than TD strength - it would be despite not yet having been upgraded..etc...    but like i said, it could be a trick of morphology and the fact that the frame rate isn't exactly hd

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my knee jerk impression from blending the models is that 'Helene' may actually get an assist in developing when she ( ...if it identifies Helene as a woman ) starts moving n-nne through the channel and over the eastern gulf.  

storm relative shear drops when that happens, while for a transient time ... the trough in the u/l off to the nw might create an outflow/channeling assist. 

i'm bothering to speculate because the models are dropping the pressure down to 940 mb in some case ( perhaps 948 mean) across these recent runs, and that's powerful hurricane, not more than 4 days from impacting the n or ne gulf. 

the preceding is for tropical enthusiasts in general ... not intended for local dystopian luster audiences

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also, there's growing support ( fwiw ) for a more important mdr system over the next week to 10 ds.  

the status of the hemisphere the baser uvm metric has improved a little - less negative in recent days.  with  the rmm mjo showing at least some modest presentation in phase 8-1-2 in the modeling,  the correlation favors weakening the erstwhile suppression further - that which has helped cap the season to date.  we'll see if we can pop the lid late.

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Tropical Storm Helene Poised Inundate Florida Gulf Coast  as Hurricane Late Thursday Night

Devastating Surge Likely for Florida "Big Bend" Region

The Situation:

As of 11AM EDT, newly formed Tropical Storm Helene is located near latitude 19.5 degrees North and longitude 84.3 degrees West and moving towards the Northwest at 12mph. Maximum sustained winds are near 45mph with the minimum central pressure approximately 1000mb.
 
SAT.jpg

Track Forecast:

Although the track forecast for Helen is fairly fluid and complex, it is relatively high confidence. The system is currently being steered to the northwest between an upper level low to its west-southwest and one to its northeast in the general vicinity of southern Florida.
 
STEERING.png
 
There is fairly strong agreement that once Helene reaches the Yucatan channel and in the general vicinity of the northeast tip to the Yucatan peninsula, it will begin to veer to the north around the western periphery of the upper level Low over Florida. The system will then eventually accelerate to the north northeast or northeast, as it becomes influenced by the southwest flow aloft in advance of an approaching trough over the south central US. Guidance is in remarkably good agreement on the aforementioned scenario relative to this timeframe.
 
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While there maybe come subtle changes that could have drastic impacts for the areas affected between now and landfall,  the larger-scale interaction with the approaching trough from a synoptic track standpoint is fairly easy to diagnose. It is how the interaction with this trough modulates Helene's intensity that is the primary challenge from a meteorological standpoint, but from a societal standpoint, this point is moot.

 

Intensity Forecast:

Currently Tropical Storm Helene is just beginning to become better organized and develop a nascent central core.
 
 
MICRO.png
 
This is likely in response to the system beginning to exit the area of greatest wind shear in association with the upper level low near the Yucatan and convection should begin to slowly encompass more of the center of circulation over the next 24-36 hours.
 
CURRENT%20SHEAR.png
 

This process of steady, albeit deliberately paced organization should continue until the system potentially interacts with the northeast tip of the Yucatan tomorrow night. Limited interaction is anticipated at this time, however, it could be enough to halt or even reverse the current intensification for a period of time. The degree of interaction with and the amount of time spent over the Yucatan is the first crucial variable at play with respect to the intensity forecast because if it were to spend several hours plus over this area, then the core could be severely disrupted, which would result in a dramatically weaker storm. Assuming that is not the case, and folks should be preparing as such, the system then veers to the northeast and accelerates over some of the warmest and deepest waters that the entire Atlantic basin has to offer courtesy of the "loop current".

 
TCHP.png
 

The system's increasing forward speed would act to limit any self destruction by way of the upwelling of cooler waters once it becomes appreciably potent, anyway, however a track over the loop current will. make the next to impossible. Wind shear is rapidly decreasingly over the southern Gulf at this time.

 
SHEAR%20TREND.png
 

In fact,  poleward ventilation of Helene may be enhanced as a result of the approaching trough's initial interaction with the system in addition to what is obviously likely to be a very moist airmass in the mid levels of the atmosphere.

 
7AM%20THURSDAY.png

 

 
 Thus needless to a say conditions may be essentially ideal for a period of rapid intensification over the central Gulf of Mexico during the day on Thursday. 
 
OUTFLOW.png
 
The main limiting factor with respect to maximum sustained wind speed achieved may be the sheer size of Helene, as larger systems tend be more stable and less prone to wild fluctuations in strength. Thus even under very favorable conditions, it may take a considerable amount of time for Helene's circulation to constrict. The system's large size coupled with the notion that there is a finite amount of time before environmental conditions potentially begin to grow more hostile once again by later Thursday warrants the use of caution with respect to maximum intensity. Depending on the precise speed and direction of movement, increasing wind shear in association with the incoming trough that caused the system to turn to the northeast and initially enhance outflow may begin to have a detrimental impact on the overall health of the storm by tilting the system's structure. 
 
SHEAR%20INCREASE.png
 
Helene will also most likely begin to have drier air work into the circulation by Thursday evening, would could also act to weaken the system somewhat on approach to the coast.
 
7PM%20THURSDAY.png
 
Drier air should definitely have began to be entrained into the core prior to landfall late Thursday night of very early in the predawn hours of Friday.
 
10PM%20THURSDAY.png

 

But the final variable with respect to Helen's precise interaction with with the trough that will play a crucial role in the modulation of intensity will be how much diffluence (spreading of wind vectors) remains up until landfall. It is possible that this can offset negative factors, such as wind shear, and to a lesser extent dry air. However, it is much easier to offset wind shear with the evacuation of air aloft then it is dry air being entrained into the core, as that has a highly deleterious impact on tropical cyclones.
 

FIRST CALL:

**Cautionary Note**: It was mentioned that the Helen's ultimate landfall intensity, albeit immensely challenging due to the multitude of factors at play with respect to its interaction with the trough, is a "moot" for those directly impacted. This is because due to the large size, fast movement on final approach landfall and high likelihood of appreciable intensity all but ensuring a devastating storm surge, which will be the primary impact. The difference between a 100 mph and 130 mph landfall will be relatively trivial and primarily a point of contention for those in meteorological circles. Surge on the east side of Apalachee Bay, FL is likely to reach 15', regardless.
FIRST%20CALL.png

Final Call be Issued on Thursday-
 

 

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Good stuff, @40/70 Benchmark. Our thoughts are aligned. If there is a legitimate inner core completed or near completion at the Yucatán Channel, I think it’ll be all systems go for a high end wind and surge system, even if an ERC levels things off later. 

If not, it may just slow walk its way along in terms of intensification until Thursday.

I do think this will end up a large system and will be much more resistant to shear and/or dry air as a result, with the increasing forward speed being a secondary factor in limiting any window for weakening. I think the floor is probably around 100mph and the ceiling is still fairly high, around 140mph.

Right now I think LF is probably around 120 imo. 

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