NATL: IMELDA - Post-Tropical - Discussion

[Sciencerocks]

[LarryWx]

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 AM EDT Thu Sep 25 2025

Eastern Caribbean Sea (AL94):
A tropical wave centered near the Dominican Republic continues to
produces widespread disorganized showers and thunderstorms. The
wave is expected to move west-northwestward around 10 to 15 mph,
spreading heavy rainfall and gusty winds across Puerto Rico and the
Dominican Republic through today. The system is then expected to
slow down and turn northwestward when it reaches the southwestern
Atlantic. A tropical depression is likely to form when the
disturbance is in the vicinity of the Bahamas late this week.
Interests in Puerto Rico, the Dominican Republic, Haiti, the Turks
and Caicos Islands, and the Bahamas should monitor the progress of
this system.
* Formation chance through 48 hours...medium...50 percent.
* Formation chance through 7 days...high...80 percent.

[Hammy]

Looks like maximum vorticity is about here, and the loop shows a lot of strong, southerly inflow on the eastern side

Things are starting to come together, though the shear will likely slow it down

[edit: not sure how a picture of Humberto ended up in here, fixed to put the right image]

[chaser1]

https://olorin.tropicaltidbits.com/satimages/goes19_vis-swir_08L_202509230725_lat14.2-lon-47.6.jpg

Looks like maximum vorticity is about here, and the loop shows a lot of strong, southerly inflow on the eastern side

Things are starting to come together, though the shear will likely slow it down

I'm thinking the same, Hammy. It's looking like a weak LLC might be trying to establish itself on the Northern coastline of D.R. Visible satellite will offer a better view in a few hours

[SouthFLTropics]

I could be wrong, but it would appear that the outflow from 94L is causing some shear to Humberto. I’d be curious to see what 94L does if Humberto ends up being weaker than forecasted.

[cycloneye]

[TomballEd]

I don't think Hispaniola is doing 94L any favors. It looks a mess.

[GCANE]

According to CIMSS, LL Vort is on the SE end of Hispaniola.
Convection is pretty much all shear driven at this time.

Satellites are currently tagging the LLC at 17.9N 70.4W
https://rammb-data.cira.colostate.edu/t ... 0_swhr.gif

[cycloneye]

If it develops quick enough,it could erode the trough and have a favorable jet interaction and if that occurs, is going to be scary stuff, but hopefully it does not happen.

[skillz305]

Very tricky indeed. Still keeping an eye out here in EC Central FL.

[GCANE]

Looks like shear is mainly driven by an Upper-Level Low NE of Hispaniola.
This actually is in a good location for 94L to intensify later since outflow will be enhanced.
I expect later today for large convection to develop over Hispaniola which will help to reduce shear.
Low level vort will likely move thru the Windward passage into the Bahamas.
Looks like 355K PV will be in the clear then.
Models are converging on a Charleston area landfall.

[ronjon]

Jim Cantore from TWC said this morning that a NOAA jet is sampling the upper air environment over the SW Atlantic this morning which will be fed into the forecast models later today. Hopefully over the next few days we get some consistent guidance on 94l track.

[cycloneye]

Once again the letter I is cursed. The name will be Imelda, but hopefully this I turns out to sea.

[Hypercane_Kyle]

Land interaction, a storm that hasn't formed yet, with a probable Humberto interaction. That's just way too many variables right now.

Yeah, the models won't have a clue until maybe 72 hours before landfall.

[GCANE]

Humberto is pulling high TPW air out of the Amazon.
Helping to fuel 94L.

https://rammb-data.cira.colostate.edu/t ... 250900.png

[GCANE]

GFS forecasts the track to go thru maximum relative humidity and total-precipitable water
Sea-surface temps around 29 to 30C
Will hit the Gulf Stream before landfall.

https://rammb-data.cira.colostate.edu/t ... 0_f000.png

[GCANE]

Already seeing 3000 CAPE in the Windward Passage.
CAPE should increase significantly over Haiti and Cuba this afternoon.
Expecting to see a massive blow up in convection this afternoon.

[GCANE]

Ouch.
GFS is forecasting 355K PV to become very favorable for intensification in the Bahamas.

https://www.tropicaltidbits.com/analysi ... atl_14.png


Not looking too good.
Kermit and Miss Piggy already doing high-altitude recon.
Let's see how the models process their data.

[GCANE]

Core structure looks pretty good at this point.
Slightly off center but good lapse-rate from the surface.

https://rammb-data.cira.colostate.edu/t ... 6_tano.gif

[cycloneye]

Central Caribbean Sea and Southwestern Atlantic (AL94):
A tropical wave is producing a large area of disorganized showers,
thunderstorms, and gusty winds across portions of the Dominican
Republic, and the Turks and Caicos Islands. An area of low pressure
is expected to form along the wave tonight or early Friday when it
moves near the southeast Bahamas. This low is expected to become
a tropical depression when it is in the vicinity of the central and
northwest Bahamas in a couple of days. Interests in the Dominican
Republic, Haiti, the Turks and Caicos Islands, and the Bahamas
should monitor the progress of this system as heavy rains and gusty
winds are likely across that region regardless of development.
Interests along the coast of the southeastern United States should
also monitor the progress of this system.
* Formation chance through 48 hours...high...70 percent.
* Formation chance through 7 days...high...90 percent.