2017 Global Model Runs Discussion (Out to day 16)

[Shell Mound]

A large system could slowly emerge over the southern Caribbean during the first week of October as a monsoonal trough combines with enhanced low-level convergence northwest of Colombia. The ECMWF solution seems most likely, with low-level ridging inducing southeasterly flow in the wake of Maria. This combines with cyclonic vorticity emerging eastward from the Pacific as an enhanced low-level westerly jet is juxtaposed with upper-level +VVP. This should help generate enhanced convection and the potential for a low-level circulation to gradually consolidate over the southern Caribbean, with an upper-level anticyclone forming. A weakening baroclinic (shear) zone to the north of the potential system will provide a focal point for lowering pressures and ascent over the southern Caribbean. The baroclinic zone will lose definition over Florida, the Bahamas, and the eastern Gulf of Mexico while supporting development over the southern Caribbean. In short, all the ingredients should come together in classic October fashion for a late-season, slowly brewing tropical cyclone in the southern Caribbean. The Greater Antilles, Central America, and the Gulf Coast, including the Florida peninsula, should keep watch, as anything that develops (or doesn’t) will likely generate impacts to land somewhere, whether heavy rainfall, strong winds, or, worse, storm surge.

[DESTRUCTION5]

12z GFS looks like the GEM today making 4 storms in and around the western Atlantic. Looks like a game of dodgeball.

[Frank2]

What Frank may have meant is that high pressure won't allow a TC to move toward Florida we all know that high pressure can aid in TC development.

Thanks, perk, that's exactly what I meant...

[jlauderdal]

12Z GFS develops a weak tropical storm in the Bahamas this weekend, looks to be heading toward Florida

BOTH THE GFS AND ECMWF ARE
SHOWING THE POTENTIAL FOR WEAK SURFACE LOW DEVELOPMENT OFF TO OUR
NORTHEAST ALONG THE MOISTURE BOUNDARY AS THE UPPER LEVEL LOW LIFTS
OUT THIS WEEKEND.

[Alyono]

GFS goes for a short track version of Matthew now in the long range...

[LarryWx]

The 12Z Euro says to the GFS/CMC: what retrograding surface low off of the east coast of FL at hour 144? It has nothing of the sort.

[LarryWx]

But at hour 216, the 12Z Euro develops a NW Caribbean surface low that moves NNW to just south of west central Cuba at hour 240.

[SFLcane]

12z GFS is absolutely the most ridiculous thing i've ever seem lol. What a joke

[WeatherEmperor]

Here is a good look at the 12z ECMWF at 240hrs. Looks like there are competing areas of low pressure on the EPAC side and the Caribbean side?


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[coreyl]

Feels like there's been hints of this for a week or two so I'm starting to become skeptical, every day it says 240 hours or am I missing something??

[LarryWx]

Feels like there's been hints of this for a week or two so I'm starting to become skeptical, every day it says 240 hours or am I missing something??

In reality, this 1002 mb low on today's 240 hour Euro is easily the strongest W. Caribbean low for early October on any Euro run. Also, keep in mind that even the 216 hour's 1004 mb low is stronger than any other low showing for early Oct. on any past Euro run.
It's possible that you've been deceived by the 18Z GEFS runs, which shouldn't count due to bias, and which today will likely over do it yet again. Please ignore the deceptive extra high levels of development that constantly show up on the 18Z GEFS, folks! If other GEFS runs or EPS runs show high levels of actrivity, that's totally different.

[otowntiger]

GFS goes for a short track version of Matthew now in the long range...

could you elaborate? Short track meaning: it ends in sooner than Mathew or starts later?? Thanks.

[Alyono]

GFS goes for a short track version of Matthew now in the long range...

could you elaborate? Short track meaning: it ends in sooner than Mathew or starts later?? Thanks.

hurricane forms in Bahamas, goes up the East coast of Florida and into Georgia

[LarryWx]

GFS goes for a short track version of Matthew now in the long range...

could you elaborate? Short track meaning: it ends in sooner than Mathew or starts later?? Thanks.

It starts much later. But it is a low that suddenly forms at hour 300 on an operational GFS. I wouldn't pay much attention to it. I'd pay more attention to the EPS and the non 18Z GEFS right now for the 11-15.

[LarryWx]

The 11-15 day 12Z EPS is quite active and more active than the 0Z EPS in the western Caribbean/Gulf! More details to come once I've had time to examine the individual members. I can already tell you that the 240 hour 12Z EPS has many members with a low between 1004 and 1000 mb in the W Caribbean similar to the 12Z Euro op.

[TheStormExpert]

12z EPS (Euro) Ensembles through 10 days are definitely more bullish with one or two members showing Cat.1 intensity now.

[TheStormExpert]

12z GFS is absolutely the most ridiculous thing i've ever seem lol. What a joke

GFS clearly doesn't have a handle on things to say the least!

[LarryWx]

I used to think that the "We toss" reference to the 18Z was just to be silly. Not anymore! Speaking of which, it wouldn't be Happy Hour without the presentation of the 18Z GEFS. It is no surprise that it is the most active GEFS in the W Caribbean/Gulf since the prior 18Z though it doesn't get really active til days 13-16. I counted about 40% of the members with a hurricane and the vast majority of members with at least a TS. Oh, 18Z GEFS, you really must love the attention!

[Steve]

GFS Ensembles going Deep Phase 8 over the next 2 weeks. That should indicate favorable conditions on our side of the world.

http://www.cpc.ncep.noaa.gov/products/p ... r_wh.shtml

[Emmett_Brown]

I've noticed on recent runs that the GFS spins up a short lived low off of SE FL this weekend, and brings it onshore. Perhaps something to watch.