NATL: IMELDA - Post-Tropical - Discussion

[cycloneye]

AL, 94, 2025092306, , BEST, 0, 172N, 607W, 25, 1010, DB, 34, NEQ, 0, 0, 0, 0, 1012, 180, 150, 0, 0, L, 0, , 0, 0, INVEST, S, 0, , 0, 0, 0, 0, genesis-num, 024, SPAWNINVEST, al752025 to al942025,

https://ftp.nhc.noaa.gov/atcf/btk/bal942025.dat

[ScottNAtlanta]

This is the western wave of the two.

[Blown Away]

AL, 94, 2025092306, , BEST, 0, 172N, 607W, 25, 1010, DB, 34, NEQ, 0, 0, 0, 0, 1012, 180, 150, 0, 0, L, 0, , 0, 0, INVEST, S, 0, , 0, 0, 0, 0, genesis-num, 024, SPAWNINVEST, al752025 to al942025,

https://ftp.nhc.noaa.gov/atcf/btk/bal942025.dat

IMO, Not seeing 94L going N of the islands.

[cycloneye]

East of the Leeward Islands (AL94):
A tropical wave is producing a large area of disorganized showers
and thunderstorms, and gusty winds across much of the Windward and
Leeward Islands. This wave is expected to move west-northwestward
at 15 to 20 mph, spreading heavy rainfall and gusty winds into
Puerto Rico and the Virgin Islands tonight and Wednesday. The
system is then expected to slow down and turn northwestward when it
reaches the southwestern Atlantic near the Bahamas late this week,
and a tropical depression could form when the disturbance is in that
region. Interests in the Virgin Islands, Puerto Rico, the Turks and
Caicos Islands, and the Bahamas should monitor the progress of this
system.
* Formation chance through 48 hours...low...20 percent.
* Formation chance through 7 days...medium...60 percent.

[GCANE]

Looks interesting.
An UL Low to the NW of 94L is currently creating shear-induced convection.
Forecast shows that ULL to dissipate in 48 hrs.
93L and 94L, as waves, will likely move in the Bahamas by the weekend where an anticyclone is forecast to form.
An interesting Fuji effect between 93L and 94L may occur over the weekend as they spin up.
A large trough over Canada may sweep this out to sea.
Watching closely how models develop this.

[cycloneye]

12z Best Track:

AL, 94, 2025092312, , BEST, 0, 173N, 620W, 25, 1010, DB

[TampaWxLurker]

This is the western wave of the two.

Unless and until these 2 new Invests get names, its going to be very easy to confuse them for each other.

[Blown Away]

12z 17.3N/62W... IMO I see no signs of 94L going N of PR, I think this energy will continue more W through or just S of PR/Hispaniola. Maybe it will develop once it's past Hispaniola near Cuba/Bahamas. I bet the NHC adjusts the orange more S and W at next advisory.

[Weathertracker96]

https://i.postimg.cc/zB1hhjbK/goes19-vi ... 1035-2.gif

12z 17.3N/62W... IMO I see no signs of 94L going N of PR, I think this energy will continue more W through or just S of PR/Hispaniola. Maybe it will develop once it's past Hispaniola near Cuba/Bahamas. I bet the NHC adjusts the orange more S and W at next advisory.

That could put more islands & even the east coast on guard if that happens? I saw someone post the HAFS-multstorm model online and it showed this system very close to the coast at hour 174

[kevin]

https://i.postimg.cc/zB1hhjbK/goes19-vi ... 1035-2.gif

12z 17.3N/62W... IMO I see no signs of 94L going N of PR, I think this energy will continue more W through or just S of PR/Hispaniola. Maybe it will develop once it's past Hispaniola near Cuba/Bahamas. I bet the NHC adjusts the orange more S and W at next advisory.

Agreed, would have to move N quite quickly to do so. If it enters the Caribbean it would also put more distance between 93L and 94L, removing the negative effect both invests could have on each other.

[AutoPenalti]

It hasn't happened yet, but the close proximity of each invest may cause a fujiwhara effect that could throw a wrench in the forecast.

[cycloneye]

Plenty of rain with some squally weather is expected here in PR and in other islands of the NE Caribbean.

 https://x.com/NWSSanJuan/status/1970510710355739113

[chaser1]

AL, 94, 2025092306, , BEST, 0, 172N, 607W, 25, 1010, DB, 34, NEQ, 0, 0, 0, 0, 1012, 180, 150, 0, 0, L, 0, , 0, 0, INVEST, S, 0, , 0, 0, 0, 0, genesis-num, 024, SPAWNINVEST, al752025 to al942025,

https://ftp.nhc.noaa.gov/atcf/btk/bal942025.dat

IMO, Not seeing 94L going N of the islands.

Agreed; that's what I was thinking as well.

[chaser1]

https://i.postimg.cc/zB1hhjbK/goes19-vis-94-L-202509231035-2.gif

12z 17.3N/62W... IMO I see no signs of 94L going N of PR, I think this energy will continue more W through or just S of PR/Hispaniola. Maybe it will develop once it's past Hispaniola near Cuba/Bahamas. I bet the NHC adjusts the orange more S and W at next advisory.

Agreed, would have to move N quite quickly to do so. If it enters the Caribbean it would also put more distance between 93L and 94L, removing the negative effect both invests could have on each other.

Good point. Furthermore, development further south and west would suggest a somewhat faster solution suggestive of a greater (primarily flooding) threat to E. Cuba, Western Bahamas and potentially S. Florida. I think a slower solution would result in greater interaction with the wave to its east AND would turn more poleward with the projected flow ahead of the trough forecast to dig south from Eastern Canada.

[cycloneye]

2 PM TWO:

East of the Leeward Islands (AL94):
A tropical wave is producing a large area of disorganized showers,
thunderstorms and gusty winds across much of the Windward and
Leeward Islands. This wave is expected to move west-northwestward
at 15 to 20 mph, spreading heavy rainfall and gusty winds into
Puerto Rico and the Virgin Islands tonight and Wednesday. The
system is then expected to slow down and turn northwestward when it
reaches the southwestern Atlantic near the Bahamas late this week,
and a tropical depression could form when the disturbance is in that
region. Interests in the Virgin Islands, Puerto Rico, the Turks and
Caicos Islands, and the Bahamas should monitor the progress of this
system.
* Formation chance through 48 hours...low...20 percent.
* Formation chance through 7 days...medium...60 percent.

[TomballEd]

Hint of a mid level spin near Guadeloupe?

[AutoPenalti]

Hint of a mid level spin near Guadeloupe?

https://i.imgur.com/wyudqv3.gif

If that's the MLC then the ensembles and models will have to adjust to that way further south.

[cycloneye]

18z Best Track a little more south.

AL, 94, 2025092318, , BEST, 0, 168N, 622W, 25, 1010, DB

[Blown Away]

Hint of a mid level spin near Guadeloupe?

https://i.imgur.com/wyudqv3.gif

If that's the MLC then the ensembles and models will have to adjust to that way further south.

AL, 94, 2025092312, , BEST, 0, 170N, 614W, 25, 1010, DB,
AL, 94, 2025092318, , BEST, 0, 168N, 622W, 25, 1010, DB

NHC slowly moving the position S and E towards the mid level swirl...

[BensonTCwatcher]

Looking at the vort center it is right on the NHC position ( over Monserrat) although the LL cloud motions don't show that very well. Also a lot mid level shear over the center of the low pressure now and all the convection to the east is sheared. Moving into an are of much less shear though. The LL circ appears broad on surface obs as well.