ATL: ALBERTO - Post-Tropical

[tailgater]

https://www.tropicaltidbits.com/analysis/models/?model=icon&region=watl&pkg=z500_mslp&runtime=2018052312&fh=165

icon 4 days out, I don't trust anything past 4 days usually really 3 days

NOT liking that solution at all or the euro. I know next to nothing about that models(ICON) accuracy though.

[Steve]

Yeah, it's out to about 120 hours and still goes inland in SW Florida but hooks counterclockwise through the state and is around the FL/GA/AL intersection before possibly lifting out in the next frame. It's taking a longer way to get to the same spot (or a couple hundred miles east of where) most of the other models have it. ;

[gatorcane]

12Z CMC has shifted east:

[cycloneye]

@RyanMaue
GOES-16 visible satellite loop of the Caribbean between Cancun and Jamaica shows some sustained thunderstorm activity or convection.



 https://twitter.com/RyanMaue/status/999318561746284544

[cycloneye]

Landfall of Canadian more east.

[Steve]

The Canadian looks somewhat reasonable for where things stand now.

[Aric Dunn]

The Canadian looks somewhat reasonable for where things stand now.

Except for the secondary vort that develops and they rotate around each other causing wobbles in track. otherwise, the CMC is nearly the same.

[gatorcane]

The Canadian looks somewhat reasonable for where things stand now.

Except for the secondary vort that develops and they rotate around each other causing wobbles in track. otherwise, the CMC is nearly the same.

The CMC shift could be a trend more towards the GFS we'll see. At any rate, the new CMC looks to bring much more rain to the FL peninsula as the simulated IR shows. Then the CMC hits the peninsula with the "tail" of the storm later on with even more rain.

[Stormcenter]

So if something were not to organize out of 90L would it be safe to say that ALL of the models were out to lunch?

I mean that is still a real possibility.

[robbielyn]

I want to thank cycloneye for posting what these tweets say since they have been blocked from my work computer.

[LarryWx]

In partial deference to the models, I'm currently still near a respectable 1 in 3 chance for a TD to form this week though now I'm thinking in the GOM if it occurs, which is quite high in that area for late May based on history, but still only near a 5% chance for a subsequent FL TS hit. So, I'm saying that IF a TD forms this week, there's about a 1 in 6 chance for that TD to hit FL as a TS before the month is out. That's how I get my 5% FL TS hit chance. I'm at a 10% chance for an actual TS hit anywhere along the US Gulf coast by the end of May.

In deference to non-GFS models persisting with genesis of either a TC or a STC after a couple of days (genesis time coming in closer despite it being only late May) and also considering satellite trends, I'm raising the chance for a GOM genesis of either a TD or a STD to 50%. In concert with this, I'm also raising the chance for either a TS or a STS landfall anywhere on the Gulf Coast to a 1 in 3 chance. In other words, I'm now at a 2 out of 3 chance for a TS/STS landfall IF there is a TD/STD genesis. I'm still at only a 10% chance for a TS/STS landfall on FL. This is based on seeing SSTs that are plenty warm enough to sustain a TS/STS all the way to the coast but moreso west of the FL Panhandle. I'm at only a 5% chance that this will ever be a H and am only at a 1% chance for this to landfall as a H somewhere on the Gulf coast.

[PSUHiker31]

Maybe one day we will actually have good funding and good choices to have a decent American model

[NDG]

I agree with the 12z best track approximate position of the broad circulation of low pressure. So far it has been doing what the Euro has been showing.
No signs of a new surface vorticity to the NE of it taking over the next couple of days as the whole circulation starts moving northward.

[MississippiWx]

Do the run to run comparison for the CMC. It literally goes back and forth each run. Just kind of shows the uncertainty.

[chaser1]

I'am with gatorcane and find any well stacked low in the gulf highly suspect. Environment just looks awful. lol GFS 10+ inches across SFL EURO 2-4

It's not hard to believe when models like the CMC and NAM are showing low 200-850mb shear over the system, almost nonexistent actually. Current shear has no bearing on what it will look like in a few days. Not saying CMC/NAM are right but this depiction by the CMC last night showed a nice setup for organization and stacking of the system.

Correct, current shear does not necessarily imply what might verify in 72-96 hours. If during the prime-time of the season and allied by more favorable convergent surface dynamics that would result in far greater convective development, i'd give greater credence to a budding tropical disturbance being able to better evolve it's own upper environment and attempt to better build a somewhat tilted (right sided) anticyclonic outflow channel. I'm not seeing those conditions being nearly as ideal especially given the relative mid to upper level westerlies over much of the gulf and marginal SST's.

Having said all that, I side with Gatorcane's thinking in terms of where development might best occur given the overall environment as we see/anticipate it to be. Based on that, I'm leaning toward a solution that more or less "marry's" the GFS with remaining Global suite models. Essentially I think that the weaker and more "east gulf" GFS has some merit, but just not as far east as recent runs have been indicating. The EURO, CMC, and NAM (did I just actually type NAM and EURO in the same sentence lol?) are implying a better co-location of a stacked COC and mid level circulation as the system nears the coast, but I just can't see that solution occurring west of Mobile. I'm thinking that we'll eventually see NHC tagging Invest Blob 97L , to "Tropical (Comma) Storm Alberto" primarily due to gradient induced winds on its east side over a fairly large swath of real estate. If the system is able to consolidate enough and perhaps become temporarily blocked offshore, that I can possibly see upper level conditions potentially improving just enough just offshore the Florida panhandle between Apalachicola and Pensacola to merit a true sub-tropical storm with 996/998 pressures. Sure, you'll need to be standing with a hand held anemometer on the top floor of an offshore tall building in the N. Gulf (not too many of those ) to measure many quick gusts that exceed 55 mph, but hey.... while not particularly damaging to structures 25-35 knot winds along with high tides over a couple/few days can certainly push a lot of water and cause a whole lot of beach erosion. That would muck-up many small docks, undermine beach restoration projects, flood coastal roads and low bridges during high tide, and cause a bunch of people to consider moving or securing boats. Add potential rainfall dumps to the mix and you have one cruddy Chamber of Commerce weekends for points between Ceder Key and New Orleans. Bottom line, I don't see anything sub 999mb coming out of this blob (probably 1003mb at lowest) but I do anticipate it being named and eventually coming ashore at/near Ft. Walton Beach Fl. I'd take the EURO rain-shield maps and probably shove 'em about 150 miles to the east too. As for you folks in and around Tampa to the north-central Florida panhandle.... this might be a good time to check out craigslist for any cheap used kayaks.

[Frank2]

Early season systems in the GOM are usually sheared and weak, and so far this appears to follow the same pattern. The main issue will be rain, but hoping dry air forecast to wrap around the system will lower PWAT rates.

Frank

[gatorcane]

I agree with the 12z best track approximate position of the broad circulation of low pressure. So far it has been doing what the Euro has been showing.
No signs of a new surface vorticity to the NE of it taking over the next couple of days as the whole circulation starts moving northward.

https://i.imgur.com/1y8gGeC.gif

The GFS doesn't develop the new surface vorticity east of this low until 54 hours from now on the 12Z run. The GFS takes the current best track low and moves it over the Yucatan while dissipating it.

[NDG]

I agree with the 12z best track approximate position of the broad circulation of low pressure. So far it has been doing what the Euro has been showing.
No signs of a new surface vorticity to the NE of it taking over the next couple of days as the whole circulation starts moving northward.

https://i.imgur.com/1y8gGeC.gif

The GFS doesn't develop the new surface vorticity east of this low until 54 hours from now on the 12Z run. The GFS takes the current best track low and moves it over the Yucatan while dissipating it.

That's the difference between the GFS and Euro, that the Euro does not dissipate the current broad circulation over the Yucatan while the GFS does.

[chaser1]

Early season systems in the GOM are usually sheared and weak, and so far this appears to follow the same pattern. The main issue will be rain, but hoping the dry air forecast to wrap around the system will lower PWAT rates.

Frank

Agreed, but in spite of dry air entrainment I'm still thinking that a stout surface high from the east could set up one heck of a fire hose from Tampa north to Gainesville, and points north and west from there. 10" in several locals wouldn't shock me.

[cycloneye]

Jeff Masters discussion of 90L.

@wunderground
The area of disturbed weather in the western Caribbean (dubbed 90L) continues to slowly organize. Models disagree on its timing and strength, but heavy weekend rains from this system are a good bet across Southeast U.S. https://bit.ly/2s1ouOg



 https://twitter.com/wunderground/status/999333918284304384