2021 Global Model Runs Discussion (Out thru day 16)

[SFLcane]

A little more Caribbean long range support. Well see what it looks like in a week.

[AutoPenalti]

I remember last year we had the same thing happen where models began to pinpoint something developing heading towards SFL only for it to move towards the Gulf again.

[aspen]

I remember last year we had the same thing happen where models began to pinpoint something developing heading towards SFL only for it to move towards the Gulf again.

That would probably be Gamma and/or Delta.

If this Caribbean storm forms but the possible MDR system behind 98L forms first, this will get the name Victor. That sounds more fitting for a possible late-season Caribbean major than Teresa.

[LarryWx]

Latest GEFS is wild; has many members have 98L develop into a potent hurricane that may miss the islands by a very small margin, has a signature for a Charley-tracked WCAR storm, and has another MDR signature for an early October system after 98L passes. Perhaps this is the "true" peak season for this year? At the end of September?

The 6Z GEFS WCAR signal is still pretty weak. But that’s the area most of us will be looking at for the most likely next genesis area for the next potential CONUS threat based on climo. Climo doesn’t say there will be a threat from there but rather that becomes the area most likely to spawn a CONUS threat in early to mid October if there is going to be one. And of course the Gulf as a secondary area. In addition, the area from just E of the Lesser Antilles to north of the Greater Antilles can’t be ignored. But of course, hopefully there will be no more hits this season although I wouldn’t bet on that.

[wxman57]

The MDR has been quite hostile all season, particularly the western part east of the Caribbean. Like 2020, the eastern MDR has allowed for some significant development (Larry). Models indicate the first real cold front of the season arriving this week, after which time the Gulf may be dominated by strong westerly wind shear for quite a while. This is quite different from last season. The Gulf may be closing for business soon, with the exception of the SE Gulf & Florida late season.

High shear from later this week through Oct. 5th in the latest GFS:
https://www.tropicaltidbits.com/analysis/models/gfs/2021091906/gfs_shear_atl_65.png

Indeed a very strong front for this time of year which should really put a dent into the warmer SSTs across the northern Gulf:

https://i.postimg.cc/YCtc9ptg/gfs-T2m-seus-fh0-162.gif

It's not the small dent in the SSTs that matters, it's a signal that the jet stream is digging southward into the Gulf, bring lots of westerly shear.

[emeraldislenc]

I agree one cold fronts start appearing in the southern states on a regular basis it signals to me that things are changing. I agree with the weather expert on that!

[otowntiger]

A little more Caribbean long range support. Well see what it looks like in a week.

https://i.postimg.cc/RZgnqXDg/2-FFB5568-5-AD3-4-C64-AB81-54-B035-D2289-E.png

Probabably waaay different.

[gatorcane]

What I find remarkable this season is the compete lack of model canes plowing through Florida particularly in the peak ASO (August/September/October) months so far. In a typical season, you get a handful of runs which level Florida making great fodder and endless speculation for this thread and the model invest threads. This year nothing, even the GFS (Giving Florida Storms) has been crickets. I am certainly not complaining but I think it is surprising some others as well. We will see if it will give us some of that in October, with the so-called “trick or treat” GFS runs.

[ElectricStorm]

If the GFS is right, we may have to watch a wave behind 98L for development. It's been on the last few runs, but this is the first one to really develop it.

[Stormybajan]

Definitely not a fan of that 0z cmc run tonight. Misses Barbuda by like an inch to prevent a direct hit. Also has a low rider system developing at 240 hours. Hopefully this trend doesnt continue

[Shell Mound]

The MDR has been quite hostile all season, particularly the western part east of the Caribbean. Like 2020, the eastern MDR has allowed for some significant development (Larry). Models indicate the first real cold front of the season arriving this week, after which time the Gulf may be dominated by strong westerly wind shear for quite a while. This is quite different from last season. The Gulf may be closing for business soon, with the exception of the SE Gulf & Florida late season.

High shear from later this week through Oct. 5th in the latest GFS:
https://www.tropicaltidbits.com/analysis/models/gfs/2021091906/gfs_shear_atl_65.png

Interestingly enough, the GFS also shows below average shear in the equatorial EPAC. During a La Nina? I find that very strange personally.

EPAC warm pool at work? N of the Equator SST have been AN in the EPAC.

[aspen]

There’s a single 06z GEFS ensemble member that is essentially a Maria repeat, and it comes from the wave behind 98L. Hopefully 98L is the end of MDR threats.

[Category5Kaiju]

There’s a single 06z GEFS ensemble member that is essentially a Maria repeat, and it comes from the wave behind 98L. Hopefully 98L is the end of MDR threats.

Yeah no thanks, I really hope that does not happen at all. Having another Cat 4 hit Puerto Rico would lead to ungodly horrific ramifications that I choose to not think of.

[storminabox]

Imagine if the peak of MDR season is in late September (what most models showing with the potential for two strong systems)?! Would be pretty wild!

[aspen]

That second MDR system appears on the 12z ICON. If it forms, it’ll be named Teresa.

[LarryWx]

Significant increase in W Caribbean on 12Z GEFS for 9/28+ fwiw.

[LARanger]

https://i.postimg.cc/5t2tR1xC/59314731-5-E18-45-A8-96-D6-CDCAC45-B7915.gif

Definitely keeping an eye on that. Looks like late September/early October is going to be quite threatening should that actually happen.

Looks like the tropics fire a shotgun, to my untrained eye . . . I assume all those red dots are not, in fact, rotating on the inside?

Also, a generic question about models and verification . . . I know there's an overall assessment of accuracy by the NHC regarding their forecasts at large, but has anyone ever done such a thing regarding model forecasts for hurricanes in the GoM, specifically? I mean, overall accuracy regarding storms that inconvenience the fish in the mid-Atlantic is important, too, but if a model was notably better at Gulf storms, that tidbit would be of interest.

[IcyTundra]

https://i.postimg.cc/5t2tR1xC/59314731-5-E18-45-A8-96-D6-CDCAC45-B7915.gif

Definitely keeping an eye on that. Looks like late September/early October is going to be quite threatening should that actually happen.

Looks like the tropics fire a shotgun, to my untrained eye . . . I assume all those red dots are not, in fact, rotating on the inside?

Also, a generic question about models and verification . . . I know there's an overall assessment of accuracy by the NHC regarding their forecasts at large, but has anyone ever done such a thing regarding model forecasts for hurricanes in the GoM, specifically? I mean, overall accuracy regarding storms that inconvenience the fish in the mid-Atlantic is important, too, but if a model was notably better at Gulf storms, that tidbit would be of interest.

Less observations out in the MDR which leads to more guess work the models have to do.

[Teban54]

I know all eyes are on 98L for good reasons, but regarding the wave behind it, seems like recent GFS runs finally agreed with the other models in not immediately sending it straight north on a Rose-like track. Instead, now all models agree on the wave moving west at a rather low latitude, either as a TC or some vorticity. Could be something to watch down the road.

[aspen]

The second wave very quickly develops into Tropical Storm Teresa after moving off the coast of Africa next week on the 12z ICON. Other models are not as consistent or strong, however.