Invest 94L—70% 2 day and 90% seven day odds of development

[WxWatcher007]

This is a pretty wild setup. Everything is on the table. I can't recall two invests being this close to one another. 

 

[GaWx]

12Z UK 94L: TD just NE of C Bahamas moving ESE

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 108 HOURS
FORECAST POSITION AT T+108 : 24.5N 77.2W

LEAD CENTRAL MAXIMUM WIND
VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS)
-------------- ---- -------- ------------- -------------
0000UTC 29.09.2025 108 24.5N 77.2W 1008 28
1200UTC 29.09.2025 120 25.0N 77.0W 1008 27
0000UTC 30.09.2025 132 25.0N 77.1W 1007 27
1200UTC 30.09.2025 144 24.4N 76.6W 1006 24
0000UTC 01.10.2025 156 23.9N 75.0W 1005 25
1200UTC 01.10.2025 168 CEASED TRACKING

[WxWatcher007]

Although there’s not much in the way of low level center, there’s a pretty robust mid level reflection as evidenced by visible satellite and  TJUA radar. Not sure I buy the 12z GFS evolution. 

[WxWatcher007]

I may be wrong, but I don’t recall the NHC delivering key messages for an undesignated or non-PTC system.

 

[GaWx]

 The 12Z EPS, like 0Z and 12Z of yesterday, actually has an uncomfortably high # of members (10+/20%+) hitting the SE US 9/28-10/4, which is earlier than the 10/5-7 12Z Euro freakish US hit.

 One thing that’s a bit concerning is the forecasted MJO phase 2 by both GEFS and EPS for 9/27-10/3. As I posted about last month, phase 2 has had (whether inside or outside the circle) by a wide margin the highest % (after taking into account % of days in each phase) of Conus Jul-Sept MH hits and along with phase 8 the highest % of H hits since 1975.

GEFS

 

EPS

[GaWx]

Followup: 

 Upon closer inspection, 40% (20) of 12Z EPS members affect a portion of the SE with either a TC direct landfall, a skirting of the coast, or a weak remnant. Also, a clear majority of members that weren’t steered by a Fujiwhara from Humberto were in that 40%. So, whether or not Humberto pulls 94L into it might turn out to be the crucial factor for whether or not the SE US is threatened.

[GaWx]

23 minutes ago, GaWx said:

Followup: 

 Upon closer inspection, 40% (20) of 12Z EPS members affect a portion of the SE with either a TC direct landfall, a skirting of the coast, or a weak remnant. Also, a clear majority of members that weren’t steered by a Fujiwhara from Humberto were in that 40%. So, whether or not Humberto pulls 94L into it might turn out to be the crucial factor for whether or not the SE US is threatened.

Example:

18Z Icon: no Fujiwhara and 94L gets stuck under the strengthening US Great Lakes ridge and subsequently turns NW toward C FL:

 

Edit: And the GEFS/EPS are forecasting this to be during the potentially dangerous phase 2.

[MJO812]

Closer view of the Icon

[MJO812]

[Floydbuster]

This is a very interesting setup. Here is an evening video update.
 

 

[GaWx]

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 PM EDT Wed Sep 24 2025

For the North Atlantic...Caribbean Sea and the Gulf of America:

 Eastern Caribbean Sea (AL94):
Showers and thunderstorms have become better organized since 
yesterday in association with a tropical wave centered near Puerto 
Rico.  This 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 early tomorrow.  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, the 
Turks and Caicos Islands, and the Bahamas should monitor the 
progress of this system. 
* Formation chance through 48 hours...medium...40 percent.
* Formation chance through 7 days...high...80 percent.




Public Advisories on Humberto are issued under WMO header
WTNT33 KNHC and under AWIPS header MIATCPAT3.
Forecast/Advisories on Humberto are issued under WMO header
WTNT23 KNHC and under AWIPS header MIATCMAT3.


Forecaster Blake

[MJO812]

Euro AI

[Eskimo Joe]

5 hours ago, WxWatcher007 said:

I may be wrong, but I don’t recall the NHC delivering key messages for an undesignated or non-PTC system.

It's the anniversary of Helene, people in the southeast are justifiably on edge.

[Eskimo Joe]

Uh, is that the HWRF trying to put 94L to near Cat 3 strength by HR 120?

[Eskimo Joe]

FYSA, starting tonight several east coast WFOs will being launching 06z and 18z soundings until further notice. 

[MJO812]

[WxWatcher007]

1 minute ago, MJO812 said:

What was 12z and 18z?

[GaWx]

0Z Icon: Humberto pulls 94L ESE to keep it safely away:

[GaWx]

0Z UKMET: TD forms Mon night NW Bahamas, initially then drifts slowly NW followed by a stall and dissipation as the much stronger Humberto only ~500 miles east takes over:

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 102 HOURS
FORECAST POSITION AT T+102 : 25.0N 77.5W

LEAD CENTRAL MAXIMUM WIND
VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS)
-------------- ---- -------- ------------- -------------
1200UTC 29.09.2025 108 25.9N 78.2W 1008 27
0000UTC 30.09.2025 120 26.1N 78.3W 1007 23
1200UTC 30.09.2025 132 26.1N 78.1W 1007 20
0000UTC 01.10.2025 144 CEASED TRACKING

[GaWx]

1. 0Z CMC Georgetown, SC hit with 975 mb H as not as strong Humberto (983 mb) doesn’t dominate:
 

 

2. 0Z GFS is safely OTS with Fujiwara from Humberto.

[GaWx]

0Z GEFS: the most threatening run yet to the SE US (even more than 18Z):
 

[Floydbuster]

I am skeptical of the GFS showing a strengthening dangerous hurricane over the Bahamas suddenly being sucked into Humberto. If it were just a wave, sure...but if 94L is a well established hurricane by that time, I highly doubt that it just gets sucked away.

[GaWx]

26 minutes ago, Floydbuster said:

I am skeptical of the GFS showing a strengthening dangerous hurricane over the Bahamas suddenly being sucked into Humberto. If it were just a wave, sure...but if 94L is a well established hurricane by that time, I highly doubt that it just gets sucked away.

But the 0Z GFS has 94L no stronger than the high 980s while it has Humberto ~25 mb stronger (~963 mb). Were you aware of that? So, considering that, wouldn’t it make sense for Humberto to dominate?

[Floydbuster]

36 minutes ago, GaWx said:

But the 0Z GFS has 94L no stronger than the high 980s while it has Humberto ~25 mb stronger (~963 mb). Were you aware of that? So, considering that, wouldn’t it make sense for Humberto to dominate?

I still think 980 mb is pretty strong, and the outflow of 94L would be dominating against Humberto. 

[GaWx]

0Z Euro, just like the 0Z CMC, hits Georgetown, SC, on Monday evening (probably because it was further N than Humberto) though it isn’t as strong as the CMC (989 mb per WxBell):

 

So, of major 0Z ops, Euro and CMC hit Georgetown while UKMET, GFS, and Icon stay well offshore.

[GaWx]

 The 0Z EPS is by far the most ominous for the SE US (including some that get into the Gulf) with a whopping ~75% of the members hitting or skimming. Some of these are very weak (not full TCs) while ~1/3 of the hits are strong.

[GaWx]

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.

Forecaster Bucci

[NorthHillsWx]

I said this yesterday and it holds just as true today but what a crazy TC setup. Some of these model solutions don’t even seem possible with twin strong hurricanes dancing around each other. EPS is concerning as are hurricane models but that being said given the proximity to Humberto, j wouldn’t put stock in ANYTHING until we have a coc and even then the evolution of Humberto will be critical 

[NorthHillsWx]

If you’re on the coast from Florida to NC I would be following this closely and make sure you have the ability to prepare if needed. This forecast is as uncertain as it gets relating to a tropical cyclone 

[TriPol]

I don;t understand the physics of how Humberto kicks the other system into the east coast.