Potential Tropical Cyclone Eight—50mph/1006mb

[GaWx]

The LLC is just NE of 31N, 76W, where SST is ~83F:
 

[GaWx]

0Z: all major global models hit NC except GFS, which hits way down at Georgetown, SC. But that run is 200 miles SW of yesterday’s 0Z and is the most SW of any run since 9/10 12Z. So, it’s likely too far SW.

 The strongest is the 1002 of the ICON, which along with the CMC, take a pretty direct track to NC. OTOH, the Euro, UKMET, and JMA first go W through Sun night before turning NNE to NC.

 

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 AM EDT Sun Sep 15 2024

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

Active Systems:
The National Hurricane Center is issuing advisories on Tropical 
Storm Gordon, located over the central tropical Atlantic Ocean.

1. Offshore the Southeastern U.S. Coast:
A non-tropical low pressure area has formed along a frontal boundary 
a couple of hundred miles off the southeastern U.S. coast and is 
producing winds to gale force north of its center.  The low is 
forecast to move northwestward or northward over the warm waters of 
the Gulf Stream toward the coasts of North Carolina and South 
Carolina, and it could become a subtropical or tropical storm during 
the next day or two if the associated front dissipates and showers 
and thunderstorms become sufficiently organized.

Regardless of tropical or subtropical development, the low is 
likely to bring gusty winds, heavy rains with the potential for 
flash flooding, coastal flooding, and dangerous beach conditions to 
portions of the U.S. Southeast and Mid-Atlantic coast during the 
next couple of days, and interests in these areas should monitor 
the system's progress.  Additional information can be found in 
products issued by your local National Weather Service Forecast 
Office and High Seas Forecasts issued by the National Weather 
Service.
* Formation chance through 48 hours...medium...50 percent. 
* Formation chance through 7 days...medium...50 percent.

[Kevin Reilly]

Models are confused of what to do is it 1 or 2 we are tracking???  Which area consolidates and develops?  These are questions I have.  Maybe both just fight and compete and don’t develop at all??

[PackGrad05]

The latest RAH Discussion does a good job of explaining that the certain models (NAM included) are having feedback issues and are not being heavily considered at this time.  

[StantonParkHoya]

6z GEFS looks like between CHS and MYR as maybe a TD 

 

note: RAH believes this will be a subtropical system 

[WxWatcher007]

If it can get a designation at all I think the lack of time makes subtropical the only viable option but we’ll see. No real difference in impacts. 

[wthrmn654]

Recon in 95l now

[GaWx]

There is a pretty tight spin that appears to be just SE of 32N, 78W. Is that at the surface? Is it tropical? Recon will tell us more. Could go straight to STS or TS.

[jbenedet]

Should have a designation based on radar and satellite. TD or weak STC. 
 

 

[GaWx]

It’s tricky because even if there were no LLC the high to the N would on its own be causing brisk winds though likely not the 49 knots that’s apparently been measured.

 Is the clear twist that we’re seeing at the surface? Are there W winds? Are dewpoints much lower to the north?

[Normandy]

Upgrade is imminent 

[GaWx]

Assuming I’m decoding recon data correctly, I’m seeing W winds at 20 knots at 31.6N, 77.7W and extrapolated SLP of 1007.4 mb. Should be enough for an upgrade to T or ST unless I’m misinterpreting the data.

[GaWx]

No upgrade but NHC is initiating advisories on PTC 8 at 5PM EDT:

https://x.com/nhc_atlantic/status/1835410217334603844

[GaWx]

Newest recon data suggests pretty tight LLC near 31.9N, 77.5W. Highest winds nearby at 48 knots? Extrapolated SLP 1006 mb? Is this right?

203200 3158N 07735W 8432 01547 0066 +188 +103 328038 041 041 005 00
203230 3156N 07734W 8426 01552 0063 +191 +097 309039 041 042 005 00
203300 3154N 07733W 8425 01554 0064 +193 +097 294039 040 041 004 00
203330 3153N 07732W 8430 01552 0073 +181 +102 297038 041 035 005 00
203400 3152N 07730W 8418 01564 0076 +174 +106 299038 039 /// /// 03
203430 3153N 07729W 8416 01562 0064 +189 +094 288041 042 022 005 00
203500 3155N 07728W 8435 01537 0066 +176 +104 296048 052 030 014 00
203530 3156N 07727W 8412 01545 0072 +131 //// 320026 051 045 038 04

[StantonParkHoya]

Models tightening up on location now. Georgetown, SC has been the hot spot last few years.

[GaWx]

W winds to 43 knots? Is that right? Extrap SLP 1010 mb there.
 

05
204730 3148N 07710W 8417 01578 0095 +162 +139 239037 041 033 008 03
204800 3147N 07711W 8431 01565 0099 +165 +129 260038 041 029 007 00
204830 3146N 07711W 8432 01564 0095 +172 +122 269040 043 029 008 00
204900 3144N 07712W 8417 01581 0099 +168 +114 262032 038 029 008 00
204930 3143N 07713W 8422 01576 0102 +163 +115 273029 031 026 008 00
205000 3142N 07714W 8436 01559 0105 +154 +129 269022 027 022 009 00
205030 3140N 07712W 8420 01579 0100 +166 +117 272025 027 022 003 00
205100 3139N 07711W 8431 01572 0103 +166 +129 266021 026 020 002 00
205130 3138N 07709W 8428 01575 0103 +172 +120 257023 028 020 000 00

[jbenedet]

I feel like NHC just complicates the warning and watch situation by not upgrading marginal calls like this. I.e. they make their job a lot harder. 
 

 

 

[PackGrad05]

Those models put central NC into the right front quadrant. Heavy rain bands and potential rotating storms.


.

[USCG RS]

This looks like it could cause somewhat substantial impacts in the Carolinas and Mid-Atlantic. This should be watched rather closely for those inland as well. 

[Normandy]

A PTC? Come on NHC be better

[StantonParkHoya]

15 minutes ago, USCG RS said:

This looks like it could cause somewhat substantial impacts in the Carolinas and Mid-Atlantic. This should be watched rather closely for those inland as well. 

If 3 inches of rain is “substantial”, then sure

[eyewall]

This looks to be a nuisance event for most here.

[WxWatcher007]

I haven’t been able to follow much today but recon, radar, and satellite paint an interesting picture. It may not be all the way there given the apparent misalignment of the LLC and MLC, but this is looking more tropical given the MLC potentially becoming the true center and being aligned under deeper convection.

Center reformations here can impact landfall location obviously so I’d say there’s a modest amount of uncertainty still for both track and perhaps intensity to a degree. 

Seems like a classic close-to-the-coast homebrew system. 

[GaWx]

12 minutes ago, eyewall said:

This looks to be a nuisance event for most here.

That’s good for a change. 3 for 3 hurricane hits on the CONUS during just the 1st half of the season was highly unusual. Hopefully I’m not jinxing it.

[WxWatcher007]

1 minute ago, GaWx said:

That’s good for a change. 3 for 3 hurricane hits on the CONUS during just the 1st half of the season was highly unusual.

Especially odd given how quiet the season has been on balance. 

[Windspeed]

This scenario is why the PTC designation is great. Allows advisory packages and watches/warnings while also allowing meteorological transitions to complete. NHC is essentially waiting for the loss of frontal attachment here. It is very close and most likely goes straight to Helene.

[Normandy]

38 minutes ago, Windspeed said:

This scenario is why the PTC designation is great. Allows advisory packages and watches/warnings while also allowing meteorological transitions to complete. NHC is essentially waiting for the loss of frontal attachment here. It is very close and most likely goes straight to Helene.

I hear that. I guess I just figure pull the trigger since it’s obvious it will eventually become a TC (get ahead of warnings since you have to write an advisory anyway)

[WxWatcher007]

That’s quite a robust mid-level feature on radar. Even seeing some lightning in the convection there. 
 

 

It still has some time over the warmest waters off the coast, so we’ll see if that feature is able to become fully tropical. It looks like it’s getting there. I didn’t expect that pocket of low shear. 

[GaWx]

15 minutes ago, WxWatcher007 said:

That’s quite a robust mid-level feature on radar. Even seeing some lightning in the convection there. 
 

 

It still has some time over the warmest waters off the coast, so we’ll see if that feature is able to become fully tropical. It looks like it’s getting there. I didn’t expect that pocket of low shear. 

Thanks. That shows competing convection, which might keep it from strengthening. Note also that SSTs are highest where it is now (~84-5). As it moves toward the Carolinas, SSTs drop to 77-8.

[WxWatcher007]

15 minutes ago, GaWx said:

Thanks. That shows competing convection, which might keep it from strengthening. Note also that SSTs are highest where it is now (~84-5). As it moves toward the Carolinas, SSTs drop to 77-8.

True, but the mid level feature does look dominant right now. Agree on the SST drop limiting whatever potential there is.