WxWatcher007

@weatherwiz Maybe a partial explanation for the quiet in the western portion of the basin too. Too much subsidence in the Gulf/western Atlantic…too much rising air over the African continent, particularly over the Sahara. This kind of early peak bust requires all the dominoes to fall too. Take a look at the thread as it has other years included.

This is a worthwhile read. That massive area of subsidence over the Gulf and western Atlantic may also be why the western half of the basin has been bereft of activity despite several opportunities—as we’re even seeing now with the Gulf disturbance we’ve been casually watching.

People are trying to do them now with 65-70% of the season to go so yes Don’t get me wrong it looks bad—historically bad—but it’s like canceling winter on December 31, which people do every year as we know lol.

I think that’s one of the reasons—seedlings that would otherwise mature are getting smothered by a combination of stable air profiles and cool SSTs to the north of the CV islands before getting anywhere. That said, even stuff that’s come off south and plodded along into the tropical Atlantic east of the Lesser Antilles has struggled mightily. So I don’t think that’s the only explanation. The ITCZ dropping south may be late for tropical Atlantic genesis which should suppress the NS number, but if an active WAM is going to allow the train of vigorous waves to continue into October, once they get to the Caribbean and western Atlantic where TC genesis is climatologically favored things may open up. We’re just so far into uncharted territory (no NS during this period since 1968) that idk if anyone knows what’ll happen. It’s incredibly fascinating to watch.

I’m not sure if it’s just a delayed signal that’ll get washed out on the EPS, but 12z was quite robust in the Gulf with the current Caribbean disturbance. Seems to pull it north or NE eventually too with the eastern U.S. trough next week.

Right. SSTs/OHC can tell you which side of the AN/BN coin to lean, but that only takes you so far. It’s shocking that with shear being low so often across the basin we’re as low as we are. I’ve been factoring in stability/SAL for a few years now and it just seems like every year it gets worse. It’s far from apples to apples but it reminds me of the great setups we get in winter and confluence to the north just grinds up what’d be a KU 95 times out of 100. Everything else is good as it gets from a broader seasonal perspective—but you can’t factor in this one persistent feature that kills potential in the cradle. It’s both maddening and fascinating. Pouring in the Sahara and puffy sand laden clouds in the tropical Atlantic.

Thanks. I’m dumbing down why it’s been historically quiet, but there are likely a series of factors that has made the season an increasingly epic dud thus far. The real interesting part is whether this continues into later September when we usually see climo shift west and warmth aloft diminish. I’m not ready to totally pull the plug. The late season storms we get in the western Atlantic could be absolute nukes with enough runway.

Agree—we’ve seen anomalously low shear in the basin all season. Cool neutral hasn’t hurt. It’s far more complicated than anyone can fully grasp I think. Quietest since 1968 when a few months ago a top 5 season looked like a lock? That doesn’t happen easily.

Tropical Update--September 3, 2024 Yikes Now that we're actually moving through the upswing of the climatological peak of the season, we're entering epic bust territory. Since Hurricane Ernesto early in August, there has been an intractable lid on the Atlantic. Not just the MDR, but the entire basin. We have held at 5/3/1, and while our ACE number is still above normal for this time of year due to the fast start and high end systems relative to the early part of the season, we've gone from historically active to historically...inactive. According to Dr. Phil Klotzbach, this is the first time since 1968 that we haven't had a named storm between August 13 and September 3. That's extraordinary. There is a lot of conversation happening in the tropical wx space about reasons for this. I'd argue that despite historically warm SST/OHC and anomalously low wind shear across the MDR most of the season, that a combination of stability, SAL, and in the last month or so, a much further north ITCZ leading to waves leaving Africa too far north to survive getting to even the central Atlantic has been the main culprit. It's possible that too wet a West African Monsoon is bad for TC genesis. Stability issues further west into the tropical Atlantic (the area between Africa and the Antilles) has stifled everything that has tried to develop there in essentially the last month. Even now, it's not a good look in the tropical Atlantic. For my peak season forecast of 15/10/5, we need to get on the board soon. The reason to not completely pull the plug on higher end activity in terms of H and MH is two fold. 1) Despite the iron lid being over the basin, the underlying factors for a quality over quantity season still remain Simply put, the lack of instability in the eastern MDR to this extreme once again makes me believe that truly significant activity here is a lost cause. However, just west, with a combination of lower shear (especially as the trade wind impact diminishes with climo) and historically high OHC and much more normal instability, I do think that a lot can happen through later September and October. 2) Even though it's September 3, approximately 65-70% of historical activity in a given season still remains. The favorable conditions above should be able to take center stage as climatology abandons the tropical Atlantic and the focus for TC genesis becomes the western Atlantic and Caribbean. We'll see if they do. Areas of Interest The basin is still hostile, but the chance of development is there for any one of these. The NHC notes three areas and I add a fourth. 1. Caribbean Disturbance--60% This is the one we've been following for a while, and the signal has continued to waffle on the models. Unlike in the tropical Atlantic, this one has been firing more convection in the Caribbean (speaking to greater instability) but ran into the problem of shear and becoming more strung out as it quickly moved west. It's just south of the island of Hispaniola right now, and while it barely has visible signs of life I would not count this one out yet. The ensemble signal is still modest, and with a more favorable environment likely as it gets into the western Caribbean or potentially Bay of Campeche, it's worth watching. 2. Eastern Atlantic Wave--40% All the way near the Cabo Verde Islands we have a strong wave that's a bit tied up in the currently further south ITCZ/monsoon trough. The model signal is modest but I need to see that something can develop this far east to believe it given the profound stability issues. 3. Central Atlantic Wave--30% The third area on my list has only really started grabbing attention in the last 24 hours, in large part because it has for now been able to maintain persistent convection. If you refer back to the SAL/water vapor image at the beginning of this post, you'll see that there's a lot of dry air lurking. I'm less bullish on this one as well because there's no evidence yet of robust low level vorticity. Yet at least. This wave only has a few days before conditions become even more hostile, but if it can keep convection firing that may be enough time for a quick spin up before getting ripped apart. Low odds at this time. 4. East Coast Hybrid--10% Finally, the lowest odds of development come from something not even tagged by the NHC. The signal for some type of low pressure to form off of an offshore boundary has been persistent for a week now, and the guidance continues to try to spin something up along the boundary in the coming days. If you look at the vorticity image above, it's easy to see why. The question however, is how far south does something develop, and can it attain tropical characteristics. Most indications are that it's more baroclinic than tropical or subtropical, which makes sense given the trough and fact that anything tropical trying to develop would get blasted by shear, but something hybrid may be worth keeping a casual eye on.

Low of 46.5°

892mb at landfall too, and it was a slow mover. Just insane.

Not related to New England, but this one is one of the all time greats. Going 1 to 5 that close to FL is incredible.

I don’t think that’ll be the case. Everyone not a hypster acknowledges that there was a major miss analyzing the sub-seasonal stability in the basin. If we ended up 13/9/3 that’s an epic failure of the consensus seasonal forecast. That said—I still caution against calling bust on big H and MH numbers. The NS forecast is gone, but when climo shifts the primary development region to the Caribbean there will be much more instability, and lack of shear, and historically warm SST/OHC. Even before all that we could see some activity.

I noticed that earlier too. UW-CIMSS has modest 700mb vorticity south of Louisiana. Less so at 850/925mb. The most robust low level circulation continues to be closest to the TX coast. That said, this is one of those deals where persistent convection could spin up a solid vortex. 700mb 850mb 925mb You can also see the elongated vorticity just east of the Antilles. Seems like that area has taken a step back from earlier genesis this evening but that’s still a fluid situation.

Beat me to it

Same at my house actually, but a few miles south was much wetter.

When will they post the JJA stats?

So much for dry lol

Going to need to be a lot of study on how pervasive stability and a further north ITCZ stifled the highest end potential. I don’t recall the ITCZ issue in the past, but stability has been a major issue the last decade.

I still think it’s too early to pull the plug completely. We could easily have a big peak between September 15 and October 30 and that’s probably impactful for the US given climo, but for now…the lid is still on even though it’s showing signs of trying to come off.

Perhaps if it can stay offshore for another day or so it could get the requisite convection to fire over the center. There’s deeper convection around but not where it needs to be for TC genesis. I guess we’ll see if some of the shallow stuff around the center can take off over time. Environment seems conducive especially if it drifts south.

It’s not great lol. My own peak season forecast aside, I think the high NS seasonal forecasts are likely cooked, with the H forecasts now in legitimate danger. MH still squarely on the table because I think the environment outside of the eastern MDR is ripe for nukes, but we can’t get anything developed enough to take advantage of historic SST/OHC and anomalously low shear. Just throwing a number out but something like a 14/8/4 seasonal total instead of a 25/15/6 seems more likely especially if we can’t get this central Atlantic wave to pop in the next 5-7 days. I think that one is a true toss up. Edit: and to be clear since I was defending the forecasts/activity two weeks ago lol, 14/8/4 would be a seasonal bust of EPIC proportions.

It’s having a hell of a time trying to generate convection so far today. Anemic may be generous. If it can’t get the engine started in the next 24h imo those less bullish model depictions through the Caribbean become much more likely.