GaWx

This is unreal and very sad (from PTC 8):

Thanks. Normally I’d treat the Crazy Uncle at 222 with little significance. However, it has had this storm every run since the 12Z of 9/13 with similar timing (all originating in the SW Caribbean ~9/21) and fairly similar tracks. Plus it has good ensemble support along with climo support. Euro Weeklies in a general sense have been calling for something like this for several weeks. 12Z CMC 222:

Note what looks like a circulation near 32N, 70W. This came from that further east convection that was separate from PTC8. It likely will never amount to much, regardless, though it is interesting to see.

The various ensembles overall continue to look fairly active for late Sept. with FL possibly in the crosshairs from a Caribbean originating storm.

Potential Tropical Cyclone Eight Discussion Number 2 NWS National Hurricane Center Miami FL AL082024 1100 PM EDT Sun Sep 15 2024 The Potential Tropical Cyclone (PTC) has become a bit better organized tonight, with deep convection on the northeast side of the circulation. Additionally, the last aircraft pass just north of the estimated center of the system indicated that the temperature gradient from east-to-west had weakened. However, it is still unclear whether a well-defined center exists looking at the latest satellite and radar animations, with the center that the plane found earlier looking somewhat elongated. For now, the system will remain a Potential Tropical Cyclone, and the winds are set to 40 kt. An Air Force Reserve reconnaissance aircraft is scheduled to be in the area overnight for a better look at the system's structure. It appears the system has only drifted northwest since this afternoon. The PTC should move a bit faster to the northwest on Monday and Tuesday due to flow from a ridge over the northeastern United States. There is general agreement on this track in the models, though they differ on the speed. The new forecast is trended a bit slower than the last one, but not as slow as the ECMWF model. The system has a high chance of being a tropical cyclone early tomorrow, and some strengthening is possible before landfall as it moves over warm waters with a conducive upper-level trough interaction. The official forecast is similar to the latest decay-SHIPS model guidance and the prior forecast. FORECAST POSITIONS AND MAX WINDS INIT 16/0300Z 32.2N 77.9W 40 KT 45 MPH...POTENTIAL TROP CYCLONE 12H 16/1200Z 32.8N 78.5W 45 KT 50 MPH...TROPICAL CYCLONE 24H 17/0000Z 33.6N 79.3W 35 KT 40 MPH...INLAND 36H 17/1200Z 34.5N 80.0W 25 KT 30 MPH...POST-TROPICAL 48H 18/0000Z 35.5N 80.7W 20 KT 25 MPH...POST-TROPICAL 60H 18/1200Z 36.6N 81.0W 20 KT 25 MPH...POST-TROPICAL 72H 19/0000Z 36.5N 80.5W 20 KT 25 MPH...POST-TROPICAL 96H 20/0000Z...DISSIPATED $$ Forecaster Blake

Potential Tropical Cyclone Eight Advisory Number 2 NWS National Hurricane Center Miami FL AL082024 1100 PM EDT Sun Sep 15 2024 ...POTENTIAL TROPICAL CYCLONE MOVING SLOWLY OFF THE COAST OF THE CAROLINAS... ...EXPECTED TO BRING HEAVY RAINS AND COASTAL FLOODING... SUMMARY OF 1100 PM EDT...0300 UTC...INFORMATION ----------------------------------------------- LOCATION...32.2N 77.9W ABOUT 125 MI...200 KM ESE OF CHARLESTON SOUTH CAROLINA ABOUT 180 MI...295 KM SSW OF CAPE LOOKOUT NORTH CAROLINA MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H PRESENT MOVEMENT...NW OR 320 DEGREES AT 5 MPH...7 KM/H MINIMUM CENTRAL PRESSURE...1006 MB...29.71 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: None. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Tropical Storm Warning is in effect for... * Edisto Beach, South Carolina northward to Ocracoke Inlet, North Carolina For storm information specific to your area, including possible inland watches and warnings, please monitor products issued by your local National Weather Service forecast office. DISCUSSION AND OUTLOOK ---------------------- At 1100 PM EDT (0300 UTC), the disturbance was centered near latitude 32.2 North, longitude 77.9 West. The system is moving toward the northwest near 5 mph (7 km/h), and this general motion is expected through Tuesday. On the forecast track, the center of the system should reach the coast within the warning area on Monday. Maximum sustained winds remain near 45 mph (75 km/h) with higher gusts. This system is likely to become a tropical storm overnight or tomorrow morning, and some strengthening is possible before the system makes landfall. * Formation chance through 48 hours...high...80 percent. * Formation chance through 7 days...high...80 percent. Tropical-storm-force winds extend outward up to 175 miles (280 km) from the center. The estimated minimum central pressure is 1006 mb (29.71 inches).

No: https://kamala.cod.edu/nc/latest.wgus62.KRAH.html

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.

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.

W winds to 43 knots? Is that right? Extrap SLP 1010 mb there. 05204730 3148N 07710W 8417 01578 0095 +162 +139 239037 041 033 008 03204800 3147N 07711W 8431 01565 0099 +165 +129 260038 041 029 007 00204830 3146N 07711W 8432 01564 0095 +172 +122 269040 043 029 008 00204900 3144N 07712W 8417 01581 0099 +168 +114 262032 038 029 008 00204930 3143N 07713W 8422 01576 0102 +163 +115 273029 031 026 008 00205000 3142N 07714W 8436 01559 0105 +154 +129 269022 027 022 009 00205030 3140N 07712W 8420 01579 0100 +166 +117 272025 027 022 003 00205100 3139N 07711W 8431 01572 0103 +166 +129 266021 026 020 002 00205130 3138N 07709W 8428 01575 0103 +172 +120 257023 028 020 000 00

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

No upgrade but NHC is initiating advisories on PTC 8 at 5PM EDT: https://x.com/nhc_atlantic/status/1835410217334603844

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.

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?

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.

There’s still plenty of time to drop a good amount per the latest models. CDAS 3.4, TAO buoys, and OHC have all been dropping to their coolest yet. OISST 3.4 has been lagging but I’m looking for it to resume cooling. SOI has been averaging positive overall although it has been negative the last few days. I’m central based weak Niña (ONI based) and moderate Niña (RONI based) based on latest model runs.

The model consensus is suggesting that after the current NE Rex block breaks down and Invest 95L goes inland that there could be a similar 2nd one during the 6-10 blocking things up again. Thereafter, the ensembles suggest a TC moving NE from the W Caribbean (which could be very strong) across or just E of FL is quite possible as the pattern changes to more autumn-like. It wouldn’t be a shocker if that would be the next MH based on its modeled origins. Increased activity then would be consistent with the Euro Weeklies. Based on the Weeklies, more activity originating from the W Caribbean or Gulf would be quite possible the week after that.

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.

I don’t see a clearcut correlation of NAO with Atlantic tropical activity. Look no further than 2018, way more +NAO than 2024 and the most +NAO hurricane season on record. Yet, it had Michael, Florence, and a total of 8H/15NS. 1979 had David and Frederic. Aug/Sep of 2005 were both +NAO. The most +NAO Sep on record (over +2!), 1989, had Hugo. 1995 was dominated by a +NAO. Sep of 2020 had a +NAO and 10 NS, etc. No correlation of +NAO with less activity looking at the hard data. In addition, the US has already had 3 H hits, more than the avg for the entire season!

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

This is now Invest 95L.

The extratropical LLC is near 31.5N, 76.5W. Below is the latest SST map (couldn’t save as high res). The LLC is over 84F water in the Gulf Stream. On the progged path, it will cross water as warm as 85. But then they fall sharply to 77-8 at the coast of the Carolinas thanks to recent BN temps/clouds. I’d think that would help keep the storm from being too strong at landfall should it become tropical:

Thanks. It will be interesting to see if during 2028-31 we see the -NAO/near solar min pattern continuing. The last 4 mins back to the mid 1980s have had 1-2 -NAO winters as per that graph and that’s it. Only 1 in 7 of the last 45. So, if the next one waits til then it wouldn’t surprise me. Or will the pattern finally break and one slip in before the late 2020s? Will be fun to follow.

OHC back down to <-1, near Apr low:

Big disconnect over last 2 weeks between OISST (steady) and CDAS/TAO (sig cooling):