ATL: IAN - Post-Tropical - Discussion

[Hammy]

https://twitter.com/DerekOrtt/status/1572428762461118464?s=20&t=MBtHmFapFexRHhco9TA3cQ

That answers the question I'd been wondering where it seems the further south and west/faster it goes, the further east and north it seems to go later

[Teban54]

1. Western Tropical Atlantic:
A tropical wave is producing shower and thunderstorm activity a few
hundred miles east of the southern Windward Islands. The system
continues to show signs of organization and it will likely become a
tropical depression within the next two or three days. The
disturbance is forecast to move west-northwestward across the
southern Windward Islands by late today and then move toward the
central Caribbean Sea later this week. Interests in the Windward
Islands should closely monitor the progress of this system as heavy
rainfall and gusty winds could affect these islands beginning later
today.
* Formation chance through 48 hours...high...70 percent.
* Formation chance through 5 days...high...90 percent.

Technically meets the criteria for PTC advisories now.

[Hammy]

1. Western Tropical Atlantic:
A tropical wave is producing shower and thunderstorm activity a few
hundred miles east of the southern Windward Islands. The system
continues to show signs of organization and it will likely become a
tropical depression within the next two or three days. The
disturbance is forecast to move west-northwestward across the
southern Windward Islands by late today and then move toward the
central Caribbean Sea later this week. Interests in the Windward
Islands should closely monitor the progress of this system as heavy
rainfall and gusty winds could affect these islands beginning later
today.
* Formation chance through 48 hours...high...70 percent.
* Formation chance through 5 days...high...90 percent.

Technically meets the criteria for PTC advisories now.

It all depends on when it's expected to bring tropical storm winds. For example it's increasingly likely it wouldn't to the Lesser Antilles, so watches may not be necessary there.

[Hurricane Mike]

It definitely has a spin. Notice the northerly shear from Hurricane Fiona's outflow has let up ever-so-slightly the further north Fiona moves.

[otowntiger]

https://twitter.com/DerekOrtt/status/1572428762461118464?s=20&t=MBtHmFapFexRHhco9TA3cQ

Interesting. So the opposite of what we usually hear. This time the stronger earlier the further west it goes.

[cycloneye]

 https://twitter.com/dmorris9661/status/1572515681278791682

[jlauderdal]

Already seeing the doomsday facebook posts of a Cat 4 hitting the FL panhandle

They have PTSD for a good reason, been hit/under attack the last few years.

[Blown Away]

Clearly see the beginnings of 98L @10.2N/57.8W.

[Blown Away]

National Weather Service Miami FL
Issued by National Weather Service Key West FL
346 AM EDT Wed Sep 21 2022

For the early portion of next week, uncertainty remains higher than
normal for this portion of the forecast period as attention shifts to
the tropics where a tropical disturbance currently is pushing westward
through the Caribbean Sea. While it remains too early to speculate the
exact details regarding this disturbance, winds across the area will
veer more to the southeast and draw in deep tropical moisture to
the region during this time frame. This will continue to increase
the chances of showers and thunderstorms across South Florida for
early next week regardless of potential development of the tropical
disturbance. This will continue to be monitored as the week progresses.

Excerpt from NWS Miami.

National Weather Service Melbourne FL
429 AM EDT Wed Sep 21 2022

Fri-Wed...The aforementioned upper high gets battered by continual
shortwave energy and slowly slips southeastward to the Gulf Coast
States while on a weakening trend. The 500 mb flow remains northerly
into late Sat across Florida. Fairly strong upper troughing moves
into the Great Lakes Region and the northeast CONUS late this
weekend and early next week, only departing these areas into mid-
week as upper ridging tries to re-establish itself across the
southeast U.S. and Gulf Coast States. As we venture into early/mid-
week, ALL attention will turn towards the yet "un-named" Tropical
Cyclone (Hermine) moving from the Caribbean and into the southern
GoMEX.

Excerpt from NWS Melbourne Fl.

[Lightning48]

Good morning to the West coasters of Fl. ( actually to everyone)For reference I’m in South Tampa.
This one’s going to be a nailbiter. Look forward to seeing all your thoughts and analysis

[Poonwalker]

One of the things that bothers me .. and this is I admit terribly unscientific … is the wave being so far south and traversing the Caribbean on that heading. I have always “felt” the one that hooks us here would have that path setup. Most have gotten eaten in the past by shear or had a high blocking them but this one could strengthen rapidly and go poleward in response to the low as indicated in the models. The southern setup is worrisome with low shear projected.

[HurricaneBelle]

National Weather Service Miami FL
Issued by National Weather Service Key West FL
346 AM EDT Wed Sep 21 2022

For the early portion of next week, uncertainty remains higher than
normal for this portion of the forecast period as attention shifts to
the tropics where a tropical disturbance currently is pushing westward
through the Caribbean Sea. While it remains too early to speculate the
exact details regarding this disturbance, winds across the area will
veer more to the southeast and draw in deep tropical moisture to
the region during this time frame. This will continue to increase
the chances of showers and thunderstorms across South Florida for
early next week regardless of potential development of the tropical
disturbance. This will continue to be monitored as the week progresses.

Excerpt from NWS Miami.

National Weather Service Melbourne FL
429 AM EDT Wed Sep 21 2022

Fri-Wed...The aforementioned upper high gets battered by continual
shortwave energy and slowly slips southeastward to the Gulf Coast
States while on a weakening trend. The 500 mb flow remains northerly
into late Sat across Florida. Fairly strong upper troughing moves
into the Great Lakes Region and the northeast CONUS late this
weekend and early next week, only departing these areas into mid-
week as upper ridging tries to re-establish itself across the
southeast U.S. and Gulf Coast States. As we venture into early/mid-
week, ALL attention will turn towards the yet "un-named" Tropical
Cyclone (Hermine) moving from the Caribbean and into the southern
GoMEX.

Excerpt from NWS Melbourne Fl.

NWS Tampa is also taking note:

HIGH PRESSURE WILL THEN TRY TO BUILD IN FROM THE EAST EARLY
NEXT WEEK AS A POTENTIAL TROPICAL CYCLONE MOVES NORTH INTO
THE GULF OF MEXICO. THE EXACT LOCATION AND STRENGTH OF THIS
SYSTEM REMAIN UNKNOWN, SO CONTINUE TO MONITOR THE SITUATION
AND KEEP UP WITH THE LATEST NHC FORECASTS.

[cycloneye]

Western Tropical Atlantic:
A tropical wave is producing shower and thunderstorm activity a
couple hundred miles east of the southern Windward Islands. The
system continues to show signs of organization, and it will likely
become a tropical depression within the next couple of days. The
disturbance is forecast to move west-northwestward across the
southern Windward Islands today and then move toward the central
Caribbean Sea later this week. Interests in the Windward Islands
should closely monitor the progress of this system as heavy rainfall
and gusty winds are affecting these islands. Regardless of
development, heavy rainfall is forecast to affect northwestern
Venezuela, northeastern Colombia, and the ABC island chain later
this week.
* Formation chance through 48 hours...high...70 percent.
* Formation chance through 5 days...high...90 percent.

[Jelmergraaff]

Although a potential US-landfall is still far out (7+ days), I do think there is a decent amount of consensus between the models. Of course, the exact location/path is not known yet, but all models are showing the tropical wave to move WNW during the next couple of days (probably developing into a depression/storm), but intensity-wise not too special. But looking at the models available, they almost all show (rapid) intensification in the NW-Carribean on it's way to the GOM. Most of the models now show a landfall in Flordia, although this varies from the very south (Florida Keys) to the far NW (around Mobile). Of course, there are also other probabilities but I feel like there is a general consensus that Flordia has by-far the highest chance of seeing a potential US-landfall from this system.

[cycloneye]

AL, 98, 2022092112, , BEST, 0, 102N, 590W, 30, 1009, DB

https://ftp.nhc.noaa.gov/atcf/btk/bal982022.dat

[cycloneye]

Ok folks, let's turn back to discuss about invest 98L.

[Iceresistance]

This was from yesterday, but no LLC from both ASCATs

 https://twitter.com/AndyHazelton/status/1572427620746416128

[MGC]

98L looks a bit disheveled this morning. Doubt a TD forms till 98L reaches the central Caribbean......MGC

[aspen]

Here's a MPI pressure map from CIMSS, with 98L's location from 96-168hrs marked in white. The waters in the WCar are easily able to support a sub-900mb Cat 5, and with such an excellent UL environment during this time frame, I won't be surprised if it makes a run for Cat 5 intensity. If it does go bonkers, then hopefully we'll have perfectly timed and working recon for its peak, unlike Eta (didn't stay long enough to get its lowest pressure) and Sam. I don't see any solution where this can avoid clobbering someone, unfortunately.

[Poonwalker]

98L looks a bit disheveled this morning. Doubt a TD forms till 98L reaches the central Caribbean......MGC

Agree. It needs to gain latitude and seems to be battling outflow shear from Fiona. Being so far south there is less Coriolis effect to help it organize.