Potential Tropical Cyclone Nine

[GaWx]

12Z Euro H5 114 hits CHS:

[WxWatcher007]

Closer to the coast than 00z, but a departure from the clear landfall at 06z. Humberto is pulling away as the ridge rolls over the top so the escape route probably closes. Still a lot to figure out with not a lot of time. 

[GaWx]

1 minute ago, WxWatcher007 said:

Closer to the coast than 00z, but a departure from the clear landfall at 06z. Humberto is pulling away as the ridge rolls over the top so the escape route probably closes. Still a lot to figure out with not a lot of time. 

Then per other sources it stalls just offshore for 24+ hours

[WxWatcher007]

2 minutes ago, GaWx said:

Then per other sources it stalls just offshore for 24+ hours

[GaWx]

“Hilton Head landfall Thursday morning on euro” way out at hour 144 or so with devastating amounts of rainfall in SC. Then drifts S to near SAV.

 

[WxWatcher007]

Note how the ridge above slams the door shut for an escape, even though Humberto is able to initially exert some influence. It leads to a prolific rain event...

[Eskimo Joe]

22 minutes ago, GaWx said:

“Hilton Head landfall Thursday morning on euro” way out at hour 144 or so with devastating amounts of rainfall in SC. Then drifts S to near SAV.

The sound you just heard was every emergency manager in South and North Carolina furiously trying to order extra water rescue teams.

[WxWatcher007]

Don’t look at the specifics. I’m just highlighting the threat of widespread high end rainfall. That signal has been there consistently, even though the axis of heaviest rain has bounced around. 

 

[olafminesaw]

21 minutes ago, WxWatcher007 said:

Note how the ridge above slams the door shut for an escape, even though Humberto is able to initially exert some influence. It leads to a prolific rain event...

I could see in a setup like this a primary flood zone near/North of where the center stalls, as well as a secondary flood zone where banding sets up away from the core of the system. With onshore flow and moisture being wrung out between the storm and the HP it the secondary banding could overperform

[olafminesaw]

Pretty grim for a mean

[WxWatcher007]

13 minutes ago, olafminesaw said:

Pretty grim for a mean

It looks like the ensemble members on balance don’t have that coastal stall. The slower members stay OTS

 

[NorthHillsWx]

The high end rain potential here is very scary in the Carolina’s especially with what happened last year. That needs to be the messaging right now no one needs to focus on intensity yet

[Eskimo Joe]

12z Euro is a Matthew redux for a large portion of the Carolinas.

[wthrmn654]

Funny no one's talking about the 12z euro ai run......

 

Doesn't come to shore anywhere it lingers south until the high to north weakens and comes to the north east around 983 mb close to long island...

[Kraychav]

1 hour ago, Eskimo Joe said:

12z Euro is a Matthew redux for a large portion of the Carolinas.

Total noob here. I follow this board pretty closely for weather info, and I understand about 10% of what I read. However, I'm learning. This comment really caught my eye.

I was at Ground Zero for Matthew (and Florence) here in southeastern NC. I mean, we had Jim Cantore in our town and everything. One if the biggest issues with Matthew was that we'd had a lot of rain prior to that storm. Right now, however, it is extremely dry in most of our part of the state. I assume that would make a huge difference when comparing potential outcomes of this storm to Matthew, or am I totally off base?

[wthrmn654]

1 minute ago, Kraychav said:

Total noob here. I follow this board pretty closely for weather info, and I understand about 10% of what I read. However, I'm learning. This comment really caught my eye.

I was at Ground Zero for Matthew (and Florence) here in southeastern NC. I mean, we had Jim Cantore in our town and everything. One if the biggest issues with Matthew was that we'd had a lot of rain prior to that storm. Right now, however, it is extremely dry in most of our part of the state. I assume that would make a huge difference when comparing potential outcomes of this storm to Matthew, or am I totally off base?

Extremely dry can lead to extreme run off until the ground gets moist enough to absorb rain.  

[wthrmn654]

Google models look to mainly stay offshore then go up coast in various ways to. 

https://www.weathernerds.org/models/genc.html?&inittype=zoom&initfield=SST_Anomaly_Surface&initcycle=determine&initfhour=120&initimdimx=1050&initimdimy=630&initrange=55.000000000000:230.000000000000:20.000000000000:300.000000000000&initcx1=NaN&initcy1=NaN&initcx2=NaN&initcy2=NaN&initcross=False&initsound=False&initsoundx=429&initsoundy=291&initloop=True&initoverlay=False&initlstart=000&initlend=360&initlint=6&initol1=SST_Anomaly_Surface&initol2=null&initol3=null&initol4=null&initol5=null&initcities=Off&inithgwys=Off&inittracks=On&initlows=On&initlatlon=Off

[wthrmn654]

Going be interesting to see if the AI models can be good like what they did for Erin, again. 

[Newman]

Should have PTC 9 at the 5pm or 8pm advisory at the latest, it's coming up on Tomer Burg's site as a PTC now. By the way, some really nice value added products on his tropics site:

polarwx.com/tropical

[jlauderdal]

Extremely dry can lead to extreme run off until the ground gets moist enough to absorb rain.  

Also can take more precip, refer to Flash Flood Guidance. The terrain causes extra problems..8 inches of rain in NC is very different than Sofla.

[marsman]

Schools closed Monday in Brunswick County NC (most southern county)

[NVAwx]

NHC will initiate advisories on Potential Tropical Cyclone Nine (formerly AL94), located near eastern Cuba, at 500 PM EDT (2100 UTC).

[NVAwx]

Humberto is now a Cat 3.

 

SUMMARY OF 500 PM AST...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...22.3N 58.1W
ABOUT 430 MI...690 KM NE OF THE NORTHERN LEEWARD ISLANDS
MAXIMUM SUSTAINED WINDS...115 MPH...185 KM/H
PRESENT MOVEMENT...WNW OR 295 DEGREES AT 5 MPH...7 KM/H
MINIMUM CENTRAL PRESSURE...962 MB...28.41 INCHES
 

[WxWatcher007]

Taking a look at our coming PTC. Thanks to @Nibor for showing me how to post larger gif animations. 

You can clearly see both the gradual organization and headwinds for the coming PTC 9. To the north, you can see arc clouds still radiating out of the area, indicating the presence of some dry air. You can also see some of the thunderstorm tops being sheared, although it does look like in recent frames that things may have slackened some.  

It's easier to see the larger scale spin, and recon is on the way to examine how well defined a low level center there is. For a relatively short term forecast, there is still a lot to be figured out. 

[NVAwx]

BULLETIN
Potential Tropical Cyclone Nine Advisory Number   1
NWS National Hurricane Center Miami FL       AL092025
500 PM EDT Fri Sep 26 2025
 
...TROPICAL STORM WATCHES AND WARNINGS ISSUED FOR PORTIONS OF THE
BAHAMAS...
 
 
SUMMARY OF 500 PM EDT...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...20.9N 74.6W
ABOUT 55 MI...90 KM NNW OF THE EASTERN TIP OF CUBA
ABOUT 200 MI...325 KM SSE OF THE CENTRAL BAHAMAS
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...NW OR 305 DEGREES AT 9 MPH...15 KM/H
MINIMUM CENTRAL PRESSURE...1008 MB...29.77 INCHES
 
 
WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY:
 
The government of the Bahamas has issued a Tropical Storm Warning
for the central Bahamas and a Tropical Storm Watch for portions 
of the northwestern Bahamas.
 
SUMMARY OF WATCHES AND WARNINGS IN EFFECT:
 
A Tropical Storm Warning is in effect for...
* Central Bahamas, including Cat Island, the Exumas, Long Island, 
Rum Cay, and San Salvador.
 
A Tropical Storm Watch is in effect for...
* Portions of the northwestern Bahamas, including Eleuthera, New 
Providence, the Abacos, Berry Islands, and Grand Bahama Island.
 
A Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning area, within 36 hours.
 
A Tropical Storm Watch means that tropical storm conditions are
possible within the watch area, generally within 48 hours.

For storm information specific to your area, please monitor
products issued by your national meteorological service.

Interests in eastern Cuba, the southeast Bahamas, the Turks and 
Caicos Islands, and the southeastern U.S. should monitor the 
progress of this system.
 
 
DISCUSSION AND OUTLOOK
----------------------
At 500 PM EDT (2100 UTC), the disturbance was centered near latitude
20.9 North, longitude 74.6 West. The system is moving toward the
northwest near 9 mph (15 km/h). A north-northwestward motion is 
expected during the next few days.  On the forecast track, the 
center of the system is expected to track across the central and 
northwestern Bahamas this weekend and approach the southeast U.S. 
coast early next week. 
 
Maximum sustained winds are near 35 mph (55 km/h) with higher gusts.
Gradual strengthening is forecast, and the system is expected to 
become a tropical depression on Saturday and a tropical storm 
Saturday night or early Sunday.
* Formation chance through 48 hours...high...90 percent.
* Formation chance through 7 days...high...90 percent.
 
The estimated minimum central pressure based on surface 
observations is 1008 mb (29.77 inches).
 
 
HAZARDS AFFECTING LAND
----------------------
Key messages for Potential Tropical Cyclone Nine can be found in 
the Tropical Cyclone Discussion under AWIPS header MIATCDAT4 and 
WMO header WTNT44 KNHC.

WIND:  Tropical storm conditions are expected in the tropical
storm warning area beginning Saturday night and are possible in the
watch area on Sunday.
 
RAINFALL: The disturbance is expected to produce the following 
storm total rainfall amounts through Monday morning.

Eastern Cuba: 8 to 12 inches, with isolated maximum totals of 16 
inches possible. 

Bahamas: 4 to 8 inches of rain are expected. 

Hispaniola, Jamaica, and portions of central and southern Cuba: 2 to 
4 inches of additional rainfall are expected. 

This rainfall will likely produce flash and urban flooding. 
Mudslides are also possible in areas of higher terrain across 
eastern Cuba, Hispaniola, and Jamaica. 

An increasing threat of heavy rainfall from this system is forecast 
over the southern Mid-Atlantic through coastal Georgia which could 
cause flash, urban, and river flooding into next week. 

For a complete depiction of forecast rainfall and flash flooding 
associated with Potential Tropical Cyclone Nine, please see the 
National Weather Service Storm Total Rainfall Graphic, available at 
hurricanes.gov/graphics_at4.shtml?rainqpf.
 
STORM SURGE: A storm surge will raise water levels by as much as 1 
to 3 feet above ground level along the immediate coast in areas of 
onshore winds in the northwestern Bahamas. Near the coast, the 
surge will be accompanied by large waves.

SURF:  Swells generated by both this system and Hurricane Humberto 
will affect portions of the Bahamas this weekend, and spread to 
portions of the southeast U.S. coast early next week.  These swells 
are likely to cause life-threatening surf and rip current 
conditions.  Please consult products from your local weather office.

A depiction of rip current risk for the United States can be found 
at:
hurricanes.gov/graphics_at4.shtml?ripCurrents
 
 
NEXT ADVISORY
-------------
Next intermediate advisory at 800 PM EDT.
Next complete advisory at 1100 PM EDT.
 
$$
Forecaster Cangialosi

[Wannabehippie]

6 minutes ago, WxWatcher007 said:

Taking a look at our coming PTC. Thanks to @Nibor for showing me how to post larger gif animations. 

You can clearly see both the gradual organization and headwinds for the coming PTC 9. To the north, you can see arc clouds still radiating out of the area, indicating the presence of some dry air. You can also see some of the thunderstorm tops being sheared, although it does look like in recent frames that things may have slackened some.  

It's easier to see the larger scale spin, and recon is on the way to examine how well defined a low level center there is. For a relatively short term forecast, there is still a lot to be figured out. 

Still looks like a mess on recent still color enhanced satellite photos. No closed center that I see.

[yoda]

Potential Tropical Cyclone Nine Discussion Number   1
NWS National Hurricane Center Miami FL       AL092025
500 PM EDT Fri Sep 26 2025

Visible satellite images and surface observations suggest that 
Invest 94L is gradually organizing and beginning to develop a 
low-level circulation near eastern Cuba with estimated maximum winds 
of about 30 kt.  Although the system does not meet the criteria of a 
tropical cyclone currently, it is expected to become one during the 
next day or so.  In addition, the system is likely to bring tropical 
storm conditions to portions of the central and northwestern Bahamas 
this weekend and potential impacts to portions of the southeast U.S. 
early next week.  Therefore, NHC is now initiating Potential 
Tropical Cyclone advisories for this disturbance. 

The system has been moving west-northwestward at about 8 kt during 
the past 12 to 24 hours.  However, this motion is expected to change 
as the disturbance is forecast to turn northward in southerly flow 
between a large-scale trough over the eastern U.S. and a subtropical 
ridge over the central-western Atlantic.  This track should take the 
system across the central and northwestern Bahamas over the weekend. 
The models are in good agreement through that time period, but they 
diverge significantly early next week when the synoptic pattern 
becomes complicated.  If the system moves on the fast side of the 
guidance, it will likely be more influenced by the U.S. trough that 
is expected to cut off.  In that scenario, the disturbance would 
move inland over the southeast U.S. early next week.  Conversely, if 
the system moves on the slow side of the guidance, Humberto's 
circulation will cause the steering currents to collapse, resulting 
in this system stalling near the southeast coast or drifting 
eastward.  The NHC track forecast lies roughly between these 
scenarios, in best agreement with EMXI, but confidence is very 
low in the days 4 and 5 positions.

Strengthening is likely to be slow in the short term due to the 
current land interaction and some southerly shear.  However, gradual 
intensification seems like a good bet this weekend and on Monday 
while the system tracks over the Gulf Stream and within a diffluent 
upper-level wind pattern.  The NHC intensity forecast lies close to 
the hurricane regional and consensus models and shows the system 
reaching hurricane strength early next week.  It should be 
emphasized that the long-range intensity forecast depends largely on 
where the system is and the degree of land interaction at those 
periods, and therefore, is of low confidence. Given the 
higher-than-usual uncertainty in the forecast track and intensity of 
the system, NOAA Hurricane Hunter aircraft have been collecting data 
over the western Atlantic since yesterday, and additional upper-air 
launches are occurring.  This data collection will continue through 
the weekend to help improve the model guidance for this system.

KEY MESSAGES:

1. The disturbance is forecast to become a tropical storm this 
weekend and bring tropical storm conditions to portions of the 
central and northwestern Bahamas, where Tropical Storm Warnings and 
Watches, respectively, have been issued. Rainfall associated with 
this system will impact eastern Cuba, Hispaniola, Jamaica, and the 
Bahamas through the weekend.  

2.  There is an increasing threat of heavy rainfall early next 
week from coastal Georgia through the Carolinas and into the 
southern Mid-Atlantic states, which could cause flash, urban, and 
river flooding. 

3. The system is expected to be at or near hurricane intensity 
when it approaches the southeast U.S. coast early next week, where 
there is a risk of storm surge and wind impacts. Residents in that 
area should monitor updates to the forecast and ensure they have 
their hurricane plan in place.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  26/2100Z 20.9N  74.6W   30 KT  35 MPH...POTENTIAL TROP CYCLONE
 12H  27/0600Z 21.7N  75.3W   30 KT  35 MPH...POTENTIAL TROP CYCLONE
 24H  27/1800Z 22.7N  75.8W   30 KT  35 MPH...TROPICAL CYCLONE
 36H  28/0600Z 24.1N  76.4W   35 KT  40 MPH
 48H  28/1800Z 25.6N  76.9W   45 KT  50 MPH
 60H  29/0600Z 27.4N  77.3W   55 KT  65 MPH
 72H  29/1800Z 29.7N  78.0W   65 KT  75 MPH
 96H  30/1800Z 31.8N  78.9W   65 KT  75 MPH
120H  01/1800Z 32.3N  79.3W   60 KT  70 MPH
 
$$
Forecaster Cangialosi
  

[olafminesaw]

7 minutes ago, Wannabehippie said:

Still looks like a mess on recent still color enhanced satellite photos. No closed center that I see.

Models haven't really been showing meaningful organization for another 24 hours or so, so we appear to be on track

[yoda]

 

[Wannabehippie]

So far wind shear still an issue.