Windspeed

A convergent boundary has setup in place north of the Yucatán that is associated with 91L's northern axis. Low level flow is southerly but with an absence of any notable cyclonic rotation. However, if this boundary can persist with strong convection and increase the gradient, an MCS may develop, which could increase potential of development as the feature drifts north into the central GOM. Shear appears too strong over the BOC for anything to get going for the original low pressure. If something is to organize, it's going to be out of that region of strong low level convergence.

Larry has a huge circulation. But its new massive eyewall might be moving just fast enough with respect to oceanic heat content to do something special over night, perhaps not seen in the Atlantic since Isabel: A giant annular intensifying major hurricane. Category four intensity seems in reach as the presentation continues to improve. Could it make a run at Isabel's lofty status as the most powerful annular 'cane? If it can maintain forward motion enough to avoid its own upwelling we could definitely see some significant intensification here. But Isabel is the rarest of the rare, so probably no...

Larry appears to be going through another EWRC. It looks like the inner eyewall, which isn't exactly small, is not convectively bursting as much and may be breaking down. The new eye may end up being quite large.

Agree. Doesn't matter if the WATL is suppressed if you already had genesis in the MDR from the convectively active phase over the WAM. Just means it's less likely to be homegrown genesis.

Well now quasi-annular is a thing. Probably should have had an official designated title when 'canes are showing annular characteristics but are not fully annular. Kind of like quasi-linear super cells. Linear cells that have super cell characteristics.

Guidance is allowing greater confident this remains east of Bermuda and keeps them out of the core. The remaining threats would be large swells for the ECONUS seaboard and problems for maritime shipping interests. But direct landfall is becoming unlikely, which is good news. Hopefully no wild swings back west until the track is locked in..

The sudden warming interval began around 14,700 years ago. The cold reversal didn't occur until around 12,800 years ago. That's almost 2000 years of warming that led into the potential salinity driven cold spike. But it was rapid back to cold, yes. But even at that, the rapid cold swing can be explained by several hypothesized natural phenomenon. Where as right now at present, the warm spike in ~200 years is pretty astonishing.

It's the TC the GFS evolves out of 91L.

There are several natural catalysts that can explain the Younger Dryas though. We do not have a natural catalyst for the ongoing rapid changes we are seeing at present. I am impressed that you referenced it. I love reading about all the potential hypothesis and some which have been presented in journals as corresponding theory. Was it an impact event? Rapid glacial rebound due to a swift decrease in salinity? Volcanic fallout? Aliens? (joking).. At any rate, current changes are none of these. Well maybe it's aliens. Edit: I might also add that the Younger Dryas still took several thousand years to unfold, not ~200. What occurred then is still noteworthy compared to gradual change, but compared to the recent history is still a much longer drawn out period of change. We are seeing unprecedented changes unfolding at present, compared even to interglacial spikes and glacial spikes. Also, rapid changes are cold spikes after a long duration warming trend due to a natural catalyst. We are swinging warm rapidly at present without a natural catalyst. This may be jumping way off topic even for a banter thread about anything/everything, but it was referenced above for the tropical landfall event. I digress...

Oh man, Larry is checking all my boxes here: • Cape Verde Hurricane [emoji736] • Minimal land threat [emoji736] • Major Hurricane Status [emoji736] • Rapid Intensification [emoji736] • Large eye [emoji736] • Annular characteristics [emoji736] • Daylight hours (visible satellite presentation) [emoji736] Yes, I am a weenie. [emoji894]

Note that I stated "anthropogenic"; that was for a reason. Clearly climates change over time, but very slowly and on the geological scale of ages such a glacial and interglacial periods. These are also forced by introductions of gases or particulates into the atmosphere via a natural process (volcanic activity or rising/sinking crust), continental movements via plate tectonics and changes in shallow marine environments, or a slight change in a solar output via our closest star. These are gradual and we have geologic ages built around some of the major ones. That being said, macroclimates should not be rapidly changing within a few hundred years like a microclimate without some large scale global catalyst. There are no natural processes that can explain what we are measuring. Oh, except that pesky fact that human beings are wreaking havoc on the planet by both altering the surface and pumping 40 billion metric tons of carbon into the atmosphere per year; and that figure is still unfortunately rising each year that passes.

Recent satellite estimates support an upgrade to Category 3. The NHC's 00z best track analysis now shows 100 kts. Since we do not have recon data to overrule estimates, this is most likely the upgrade intensity on the next advisory package, 11PM AST. AL, 12, 2021090400, , BEST, 0, 152N, 427W, 100, 964, HU

Sunset over what is likely to be a major hurricane by morning. A large eye is clearing out as the Sun slips over the horizon.

That's the GFS developing the invest 91L in the SW GOM next week. It's certainly possible. Although I hope it doesn't resolve anything close to LA. They certainly don't need any kind of TC right now, even the weak TS variety.

Ida, though not as intense a hurricane, reminded me a lot of Camille in both track and extreme inland flooding far away from landfall. Sometimes these TC setups over the ECONUS can lead to much greater loss of life than the initial impact at landfall.

After Larry, long range EPS guidance is suggestive of a pattern more susceptible to AEWs or resultant TCs being steered further into the WATL and Caribbean. If this pattern evolves, mid-Sept into October might not only be active with a favorable MJO, but with increased probabilities of land interaction. Something to watch.

Larry looks healthy today. Good convective bursting and a cirrus covered eye that is notably larger than yesterday (Thursday) at this time. Should be a major hurricane over night or on Saturday. Time to pump up the ACE. I still feel a bit uneasy about Bermuda. This may still be a strong hurricane that just misses to the east. But a little stronger Azores ridging could get the island into the core. We've still got the weekend to iron out modeling and any potential downstream impacts there. Edit: I originally typed Friday above but in my head I was thinking Saturday for major hurricane status, if not over night, though certainly that wouldn't be impossible by the 11 AST package if Larry continues to improve structurally over the next six hours. I digress, I originally meant Saturday.

Climate change is real. Too much scientific evidence to support that anthropogenic influences are leading to events being amplified. I was a skeptic for a while. However, let me stress that simply picking a single event on the whim and blaming climate change is unwise and not very scientific. Plenty of bad tropical cyclones made impacts prior to the onset of anthropogenic influence upon the atmosphere. If anything, blatant blaming this or that without regard dilutes the message without evidence to support claims. You cannot merely state that Ida would not have occurred without climate change and not be undermined by historical TC landfalls. It is possible or at least more believing that climate extremes may lead to more frequency or stronger systems now, but it's why scientists do research. But you cannot just wave a magic wand however and erase the similar events that occurred 100 years ago.

Yes. The cyclonic low is post-tropical, but still the same system. See: Sandy, Agnes, Hazel, etc.

Ida's remnant low is wreaking havoc on the Northeast this evening. The total of this event from LA to Maine is going to punch the top five costliest in US history.

Holy!!!! [emoji102]

Larry is far enough south in track right now on a westward heading that it doesn't appear thermodynamics are going to be much of an issue at its given rate of motion. It is currently moving over 27-28°C SSTs, and will be crossing over a region of 28°C SSTs soon. It has a fairly moist envelope. It also looks like the vigorous mid-level circulation is wrapping convection up pretty fast here. Larry looks to be steadily strengthening and may be a hurricane sooner than forecast. It might even pull off a large eye right out the gate. The last CV hurricanes I can remember forming a large stable eye early into hurricane intensity were Isabel and Igor.

Even though the cyclone is in its infancy, the circulation is quite large. I'd imagine Larry is going to be a large hurricane as has been hinted by modeling. A core has not developed yet but there are good banding features already in progress. Probably won't take long to form a core once deep convection becomes centralized.