Windspeed

GFS OP could just as easily swing back to a weak system on the 06z, and I will beat a dead horse and reiterate that we may see big swings between mere 6 hour runs due to the tightrope in which this system will have to walk to become a strong hurricane. That being said, it is a bit ridiculous that a global operational run intensifies a system to the brink of major hurricane strength within 72 hrs from TCG. I really hope that's just a random crap OP run.

Hrmm...

Looks like Leslie will be upgraded to a hurricane on the next advisory. AL132024 - Hurricane LESLIE per TAFB best track.

Notice how a few of the most northern EPS track simulate RI to a powerful major, then suddenly weakens the TC down to TS status prior to landfall. That's most likely due to the blasting mid-to-upper ST jet. An earlier developed TC gets ventilation and divergence aloft until the TC's core drifts too far north and gets decapitated. Interestingly, many of the middle tracks support a hurricane all the way into landfall (though granted not nearly as intense), which again likely has a lot to do with the core remaining just enough south of the shear axis to not get sheared off prior to landfall. Many possibilities on the table from this one, including the very small chance we see that first option: We get a huge scare from a rapidly intensifying hurricane that gets ripped completely apart prior to landfall. Much more likely scenario is a strong TS to minimal hurricane that makes it into landfall prior to significant weakening, but huge question marks on placement of TCG location, eventual track and proximity to shear axis values above 50 kts across the northern GOM. With the PRE and main system landfall, heavy rain and flash flooding is a higher risk, but attention has to be there for the wind and surge risk in case we get a stronger hurricane.

There's actually not much of a precedence in either the GOM or Caribbean, for that matter. Only a few TCs that come to mind that had an E to ENE track into landfall from the GOM or Caribbean that became strong. I recall Category 4 Lenny in November of 1999. Obviously, Wilma hooked ENE across the southern Florida Peninsula that originated out of the NW Caribbean. Opal developed out of the BOC and became a hurricane on Oct. 2nd, taking a NE track into the Panhandle. But overall, these types of tracks into the Peninsula are very rare. You would think it would happen more often, but the most likely reason I can think of why it doesn't is due to how tropical jet interaction works with these systems. Most often, if a TC or invest gains too much latitude, they get sheared off versus enhanced. Obviously, we do see a lot more frequent E to ENE tracks in the central ATL that become strong hurricanes.

Ongoing issues with commercial trucks trying to navigate alternative routes and mountain roads, which end up not being able to handle the hairpin turns and steep inclines. GSNPS is closing 441 temporarily to alleviate the problem.

Ongoing issues with commercial trucks trying to navigate alternative routes and mountain roads, which end up not being able to handle the hairpin turns and steep inclines. GSNPS is closing 441 temporarily to alleviate the problem.

Damascus, VA, US-58 between there and Johnson Co., TN, completely gone.

Damascus, VA, US58 between there and Johnson Co., TN, completely gone.

Looks like there will be an associated PRE with this setup as well before the potential TC reaches the peninsula:

RE: BOC system. The 12z ECMWF resolves a somewhat more concerning scenario for higher intensity because it keeps the core just far enough south of the shear axis as the system moves E to ENE. It does seem there will be a very fine line on how far north the system tracks versus intensity potential because shear will be very high (30-50+kt 850 to 250 hPa values) over the northern half of the GOM. It's difficult to know how exactly this plays out because even minute changes in proximity of flow above 500 hPa versus TC position will give large outcomes on strength. However, there is obviously increasing potential for a TC impact on the Florida Peninsula, even if it's still far more likely to be a heavy rain event. Should have an invest soon. This is one of those situations when we get an invest labeled, we see large swings in maximum TC intensity output for each 6-hr TC model run as tiny changes in TCG location, track and shear axis resolve huge differences in guidance.

Helene's vortex was closed. The western eyewall was clearly weaker with broken convection and rapid rate of forward motion; however, Helene's eye was clear and warm. I do not doubt the in situ recon data that supported Category 4 intensity. The issues here are 1) A lopsided major hurricane at landfall; 2) The peak winds were localized to the eastern and southeastern quadrants based on storm motion and recon; 3) The storm chasers settled on Perry based on best guess to sample the center of eye. I believe Josh was just west of Perry. But this location would have been missed by Helene's worst winds that were off to the east and southeast. There's not much else to do here but speculate since the location was within a marshland reserve and forested area.

I expected MDR SSTs to produce a Cat 4/5 CV hurricane this season, just not in October. Crazy what Atlantic TCs can do when atmospheric conditions switch to favorable. I mean, obviously, we've seen numerous powerful CV majors over the years during peak September. It's just been a weird season. Beryl rolls off and explodes in late June, followed by three months of late intensfiers near land; then Atlantic environmental conditions finally improve, and the MDR looks like September 3rd, not October 3rd.

Rainy and windy. Gale warnings and definitely TS force gusts, perhaps some hurricane force gusts, but Helene would be far enough along in its post transition to have a spread out gradient by that point. Still, it is a hefty low pressure and windy for certain, but those folks aren't strangers to strong mid-latitudinal cyclones.

Major Hurricane Kirk will be moving over increasingly warm SSTs. It should cross over 29+ SSTs for several days, though, as the forecast calls for increasing shear by the weekend, its MPI should come down. Regardless, this is a powerful hurricane and should pack on the ACE while being fun to track without all the prior drama we've had to deal with this season. Barring some sharp hook into the Azores, Kirk should remain no threat to land.

If Kirk just follows the forecast intensity guidance for the remainder of its life cycle, it should get the Atlantic back to average seasonal ACE numbers, if not put it above. If Leslie can follow its intensity guidance, we should be above average by a good amount; however, unless the rest of October goes crazy, it would be quite a long shot to reach the lofty hyperactive seasonal forecasts from earlier in the year. That's the good news. There is, unfortunately, plenty of season left for something in the Caribbean to form, which obviously would increase a land threat, but hopefully, we can avoid any more devestating landfalls to close out what has been a bad season regardless.

Yeah, I just noticed that and made the correction. lol... I've no doubt Kirk is going to reach Category 4 now.

Multiple VHTs rotating around the eyewall. I'd imagine Kirk will continue intensifying. Category four definitely looks attainable before in moves into cooler SSTs. Should be a big ACE producer.

Helene broke many September pressure records for the SE region: https://twitter.com/DRmetwatch/status/1840475902737846729?t=x0t-G1ommyEyZ4OwvoAw3w&s=19

Would have been the SE quadrant based on storm motion, most likely the ESE inner edge of eyewall band, when it had its most intense echoes while intersecting the shoreline. This flow coming off the north side of Deadman Bay. This would have been just NW of Steinhatchee within the Big Bend Wildlife Management Area. Nobody was there to record or document it, of course, unless they were recording on the back end route, Beach Road. At least that we yet know about.

Helene broke September pressure records for the region: https://twitter.com/DRmetwatch/status/1840475902737846729?t=x0t-G1ommyEyZ4OwvoAw3w&s=19

I am so sorry. Heartbreaking. Please let us know if you hear anything.

RE: Big ACE producers, wiith background mean SSTs still quite above normal across the MDR, we could see some late records fall. I believe Lorenzo holds the record for furthest east Category 4 or greater after September 28th. But you would think it would be very rare for an MDR system to reach the CONUS with ridging giving way to a more typical Fall pattern / October troughs over the central Atlantic. The only one I can think of in recent decades is Matthew.

Perhaps we should make a Helene thread after all with everything unfolding. Pretty much everything here back to post #266 has been about Helene. How difficult would it be for @Mr Bob or one of the mods to mass move all posts after Carver's first post about it into that thread for posterity? If it's too much of a pain, never mind.