Windspeed

94L has been a pestering nuisance. I kept waving it off. But it kept pulsing convection just enough. Glad it's finally squashed. Gordon is an excellent example of the continued unusual stable state of the MDR during peak ASO. Typically, by mid-September, we see higher latitude CV systems that go through TCG eventually go on to thrive in the central Atlantic to reach hurricane intensity. But Gordon isn't impressing me much. Interesting comments/thread by Webb on reinforced stability across the MDR by a strengthening Summer +NAO here:

Hrmm... 94L is looking quite interesting this morning. Against low odds, the previous light convective bursting has finally given way to deeper persistent convection overnight. This invest already had a small vortex. The disturbance had just failed to maintain any prolonged convection with a notable west wind at the surface on ASCAT. That may be changing, however. Could this be a real player now? Modeling support has remained abysmal.

Surge is starting to move into Dulac per chaser Aaron Jayjack. Hope he didn't make a bad decision by going too far south. He's normally pretty savvy. But if he gets cutoff south of Dulac, he'll have to ride out the surge in place as it continues to rise.

I should have prefaced that it's also a bit early. Let the eyewall come ashore and give the datasets time to update. Hope that the surge is mitigated, but these are unknowns. We'll just have to hope for the best and wait and see.

[mention=2227]wthrmn654[/mention] The onshore flow is going to be a problem for areas east of the eye. Those places you posted are experiencing offshore flow. I'd focus on eastern Terrebonne Parish, Montegut, Chauvin, especially Coco Marina at the end of Little Caillou Rd, and points further east, for worst surge presently based on current motion.

Eye clearing out a bit right at landfall. Nice convective burst going up over the NE quadrant. Probably too late to correspond to much of a pressure fall, but the deepening convection moving over land may translate to wind gusts mixing down with more force for places like Houma, Amelia and Morgan City as the eyewall passes over.

I am not trying to be argumentative in my response here, but I am lost on any correlation, much less causation with respect to sunspot activity and solar influences as inhibiting factors for cyclogenesis. During the same long-duration interseasonal quiet stretch in the Atlantic basin, we saw active stretches in the western and eastern Pacific basins. Solar influences should not discriminate between bodies of water. We have plenty of evidence of phenomenon contained within the troposphere to hypothesize why the Atlantic has struggled versus the WPAC and EPAC. Greater stability across the MDR due to +2-3°C warmer tropopause is among the evidence. But attributing that to sunspot activity seems more of a stretch than SPH placement, MJO, and meridional SSTs negative feedback to counter atmospheric lift versus subsidence.

At present, the eye is easily discerned on visible satellite. The structure represents what we are seeing on radar. The more intense echoes of the north and western eyewall is where the deepest convection persists on satellite.

94L grabs the eye due to a vigorous exposed mesoconvective vortex (MCV) left spinning in the mid levels. That feature is exposed, and though easy to see on visible, associated convection is waning. I'm more interested in 92L. Persistent convection may eventually allow its mid level circulation to drill down. There is notable westerly flow to the low-level cloud motion south of the wave axis. In short, I'm not really impressed by either, and both systems lack model support. We'll see if 92L can get its act together. It could still be a threat to the NE Antilles if it does develop.

NHC will initiate advisories on AL072024 or TD07 at 11AM AST. This was formerly Invest 93L near the Cabo Verdes. I don't think it warrants a new thread as it is too far into the eastern MDR and shouldn't be any near-term threat to land. Any light discussion will be fine here in the main thread. Modeling consense is for the TC to move into the central Atlantic into the midrange.

Francine is following the script here. I do not expect any surprises. As has been much discussed, with mid-level flow tilting the vortex and advecting in pockets of dry continental airmass into the circulation, any further strengthening should be held in check. Pressure falls have leveled off and might even be rising some now. I wouldn't be surprised if the core weakens slightly prior to landfall. Obviously, flash flooding and surge are the prominent dangers here. I don't think sustained winds or gusts will be more than what seasoned Louisianans are able to handle. Not downplaying, it's still a hurricane. But this region has seen much worse in previous years.

The potential for arid stable airmass due to flow off the Mexican landmass is going to be something that Francine (or any TC regardless of year in this location) has to deal with. The steering layer is no longer easterly but from an arid source. That being said, Francine does presently have a nice structure with a healthy spiral band. If a core does complete into an eyewall tonight, more significant intensification can ensue. That would allow Francine to better shield itself off from the arid southwesterly steering flow as the TC turns NE within it.

They're not going to forecast a strong hurricane with several key variables being uncertain. Genesis has yet to occur. The phasing of the frontal low and the tropical surface low is still evolving, and a broader circulation could prolong development prior to any potential period of RI. Even if the upper-level flow looks favorable, mid-level flow could advect an arid airmass into the circulation out of Mexico/Texas prior to the core becoming dominant to shield itself. I do think this becomes a hurricane as it has enough time over high heat content. But I would be reluctant to forecast a major. Of course, now that I have said that, it will go full Opal thanks to Murphy's Law.

While much of the focus is on 91L/GOM system potential, as it should be, it may be time to start looking out into the MDR again. A disturbance has been designated 92L and is forecast to develop with good modeling support. As such, no surprise that the environmental state in the central MDR where this invest is located has improved significantly since the abnormally long interseasonal quiet period. 500 mb ridging across the north Atlantic is forecast to strengthen into the midrange, which should turn a hypothetical TC into an easterly steering layer. Can't rule out the NE Leewards, so we'll need to keep tabs on this system. Later into the long-range, there are too many unknowns for CONUS consideration. However, in the least, chances favor the development of a long-tracking MDR TC here and a potential ACE machine.

Considering the numerous videos floating around on SM showing direct hits or close calls by flying debris unleashed by extreme winds on pedestrians, motorists and especially motorcyclists, I am left to wonder at how little these populaces disregard official warnings (or the lack thereof) to protect life and property. For all of the flak Americans get for riding out TCs, at least most of us heed warnings and stay sheltered. Another thought that crosses my mind is even more sobering. The struggle to keep a job for basic survival forces folks to risk life and limb. People can bitch and moan at the disruption a TC will bring to a region, but I am very relieved and proud that we have the societal structure and system of government in place to not only protect our citizens, but help them manage the survival part so they aren't forced by some shitty corporation to either bleed or starve.

Yagi continues to re-intensify and is now a Category 4 equivalent as explosive convection with HTs wrap the eye. Dire situation unfolding. Densely populated region at or below 2.5 meters (8 feet) -- essentially infrastructure built upon a river delta. The shallow gulf combined with shape of the coastline within the northern half of the circulation may funnel surge into these low-lying urban areas.

Yagi may be the big bad TC of 2024. That's not to downplay Shanshan's flooding impacts to Japan. Yagi has already caused severe flooding in the Philippines, smacked a densely populated city (Haikou) at Category 3+ intensity, and appears to have reintensified now prior to densely populated port cities in northern Vietnam. I can not recall a typhoon ever this strong impacting the Haiphong and Ha Long metropolitan regions in the satellite era. I am worried about potential storm surge up the estuaries there. Yagi may have been moving just slow enough to regain fetch in the Gulf of Tonkin.

Klotzbach weighs in again.

Fair enough. I think we're all just a bit stressed trying to resolve what is going on versus the 20-25% failure mode. What factors are essentially countering other overwhelming favorable data points. Additionally, all hell could break loose in two weeks. We get complacency. Peak merely got delayed until mid-to-late September this year when all these countering factors subside.

If I put you on the spot, well, you just made a post inquiring pros and cons about stepping away from the pack. So without empirical datum, you just played devils advocate and went with average numbers knowing if a 20-25% failure rate of climate precursors resolves, you are sailing to victory and looking quite brilliant and bold. lol... I appreciate the honesty versus jumping on the WAM strength/OS Index/Tonga (*barf*)/+NAO etc., etc... things we are trying to resolve in situ. I should also point out that you can still have a hyperactive season and only have 13 named storms based on metrics being ACE. Granted, that means the insanity of nearly all TCs being long-lived hurricanes or powerful majors. At any rate, I digress. I am pretty sure we know what you meant by hyperactive.

Better yet, what was your reasoning in only going with 13 named storms in the face of overwhelming model and climate parameter support for a hyperactive season? I mean, you're sharing your numbers while knowing full well the majority of the best TC climatologists on the planet are scrambling for answers. 13 named storms is barely average.

Welp...

The MDR wave from last week's big AEW is gaining a robust convective envelope tonight. It's worth watching just to see if it pulls off some quick development through late week. There is an upper trough that is modeled to amplify north of the Lesser Antilles in 3-4 days that will likely impede the system with strong shear regardless. But in the meantime, perhaps it can grab a name and end the drought.

Yeah, if deeper convection remains absent, dominant vorticity or an amplified wave remains nothing more than a feature of interest until environmental conditions improve.

Despite the anemic appearance, the MDR disturbance east of the Lesser Antilles actually looks better organized this Sunday morning. The axis of the resultant wave that's developed out of the ITCZ breakdown is quickly folding around dominate 850-700 hPa vorticity. Shallow convection has aided this process. Granted, we need deep convection to take over now to allow this vorticity to ramp up at the surface to spawn TCG. But the stage has now been set. We do not have competing vorticies along the boundary of the old MT but more of a stand-alone easterly wave structure. If deeper convection begins to fire and wrap into fold, the wave will likely get labeled an official invest. Without competing centers of vorticity, it may not take long for development to initiate TCG in the ECARIB. We may even see this all go down on radar out of Barbados.