WxWatcher007

Now designated as Invest 91L

There’s been a persistent and broad signal for activity for a week or two now for both the Gulf and off the East Coast with all this troughing. They didn’t develop into anything tropical, but the signal eventually produced 99L off the EC (it’s a really nice looking system off the NS coast right now) the newest non-tropical low off the Carolina coast right now, what was 90L in the Gulf and whatever happens in the next few days in the BoC. I think the window is open for more in the next two weeks.

Tropical Weather Outlook NWS National Hurricane Center Miami FL 800 AM EDT Sat Sep 7 2024 For the North Atlantic...Caribbean Sea and the Gulf of Mexico: 1. Southwestern Gulf of Mexico: A tropical wave over the Bay of Campeche is producing disorganized showers and thunderstorms. An area of low pressure is forecast to develop while the wave interacts with a frontal boundary during the next couple of days. Environmental conditions are forecast to be conducive for development, and a tropical depression could form during the early or middle part of next week while the system moves slowly northwestward to northward over the southwestern Gulf of Mexico. * Formation chance through 48 hours...medium...40 percent. * Formation chance through 7 days...medium...60 percent.

Really interesting how that signal evolved. First the models were latched onto the western Caribbean wave (which if you recall came out of that monsoon trough last week) before the wave almost got washed out in the Caribbean. Then the models focused on 90L trying to do something before that got absorbed by a frontal system. Now it looks like the Caribbean wave and residual vorticity from what was 90L coalesce and try to develop as it gets pulled northward. Still not a lock to develop because it could get pushed into Mexico too soon but if it stays offshore it could become something decent. At least break the boredom. SE coast may be ripe for something late next week too.

The 00z op GFS continues the signal that started in large part with the ICON. What was 90L dives down into the Bay of Campeche as our western Caribbean wave (which started as part of the monsoon trough a week ago) reaches the BoC. Vorticity merges and organizes into a weak low. A trough/front pulls the coalesced low NW and then NNE into the northern Gulf next week. This is far from a lock to develop and a higher end system is even less likely at this time, but I think the key at least on recent guidance is that the potential low gets pulled north before running out of time to organize. Anywhere from the Gulf coast of Mexico to Louisiana should watch this one imo.

It couldn’t get there before crossing into cooler waters but this is a pretty nice late summer non-tropical low.

I expect this thread to get more active in a few days. It’ll need a title change though as the NHC will likely designate a new invest (if the merged area becomes invest worthy). Very interesting how the model signal has evolved over the last week—from focusing solely on the western Caribbean wave to focusing solely on 90L to now kind of combining the residual vorticity of the two.

Model signal looking a little more legit at 12z as the energy from 90L merges with the western Caribbean wave we’ve had on our radar forever. The BoC topography may help organize this over the weekend.

A little surprised to see the ensemble signal there but it’s hard to bet against the BoC topography. Hyper inactive…

Pretty wild

Each night the convection has waned significantly but the model signal has increased a touch. Best chance of genesis would be the ICON if this shifted south this weekend before getting pulled north. Clearly it needs space and time.

That’s what I meant by the longer range wave, but it’s hard for me to be bullish on anything in the eastern MDR given the stability issues. The signal for genesis is there though and we’re talking closer to mid month when conditions are progged to be more favorable. https://www.tropicaltidbits.com/analysis/models/gfs/2024090518/gfs_z850_vort_atl_37.png The GFS plays with something spinning out of the MT but very low odds https://www.tropicaltidbits.com/analysis/models/gfs/2024090518/gfs_z850_vort_atl_19.png

Always one model run each season

Up the Bay!

Two invests in one day almost feels historic lol

All good. This place should be fun especially during the “down” times.

12z models so far are a little more robust with the Gulf low by keeping the center offshore. Plenty of rain for parts of the coast though.

Congrats Nova Scotia. Newly designated 99L is trying to develop…while getting blasted by 40kt shear lol. The MDR can’t even generate real convection lol let alone have it attempt to organize.

We have 5 lemons in the basin and a new invest, so let's take a quick morning look at each because any of them could have a chance in the short or long term. I attach my own personal odds of development to each. 1. Invest 99L--40% odds of subtropical development The area off the east coast has continued to be interesting on satellite and the models despite being blasted by exceptionally high shear and as a result, we have our first invest in an eternity. What's most of interest to me this morning is that despite the shear, you can clearly see the low level center try to tuck itself under deeper convection, a key element for TC genesis. The model signals continue to suggest that in the next 48 hours or so this has its best chance to further organize and deepen some. I'd prefer to see a tighter low rather than some of the current model depictions to feel that genesis is more likely, but for now this has held its own in a high shear environment. I think the shear ultimately keeps this from becoming fully tropical, but we'll see. WPC analysis still has this attached to a boundary for now. What to watch for: evidence of convection building over the LLC on IR 2. Area of Interest in northern Gulf of Mexico--30% odds Sometimes the door is open, and something just needs to walk through. I'm not sure if the area of interest that folks have been tracking for days now will step forward, but this morning it looks like it's trying. Shout out to @salbers for sticking with this one. On satellite, we see the sun rise over deep convection just off the Texas coast. Radar suggests that there is some level of a low level rotation, though imo the signal is just modest. This is the strongest iteration of what we've been tracking however, and given the SSTs in the area, present area of deep convection, and apparent pocket of low wind shear, it has a chance to develop. However, the big caveat is that there's not a lot of time to do so. The models bring a boundary through the region as early as tomorrow afternoon, meaning that the upper winds become hostile for any organization. If this one is going to steal a name, it needs to do it fast. With more time, I'd say this one has a fairly good chance of development, but with little time it seems much less likely. This is one that'll be interesting to watch through the day though, especially if deep convection can continue to fire over the apparent center. What to watch for: persistent deep convection over the center on IR, and evidence of a tightening LLC, increase in velocities, and banding on radar. 3. Western Caribbean Wave--30% odds We've been tracking this one seemingly forever, and it's entering the put up or shut up stage. Our wave has a little more spin and convection this morning, but probably not enough time to do anything meaningful before hitting land. Its best shot will be in the Bay of Campeche, where there's still a model signal for development, though it's not as robust as it once was. I'm far less bullish than I was the other day, but anytime a wave gets into the BoC it bears watching. 4. Eastern Atlantic Wave & Monsoon Trough--20% This is meh for now, but guidance has shown that something could pop out of the monsoon trough in the central Atlantic at any point in the next 7-10 days, and there is a longer range signal for an African wave to develop. Wake me up when it actually happens given the massive stability issues in the tropical Atlantic. This area gets a 1/5 shot right now out of respect for climo. 5. Central Atlantic Wave--10% This one may be more interesting 5 days from now, but as it travels WNW into the western Atlantic, there is some signal, most notably on the Euro that it'll try to organize some before getting either obliterated or turned OTS by an east coast trough. Nothing interesting at this time.

lol what a year (so far)

Fantastic

I prefer a January 20 plug pull