Surface Trough East of Florida (Is Invest 90L)

[TropicalAnalystwx13]

Over the past several days, model guidance – the GFS, ECMWF, and CMC – has become increasingly persistent with the potential for subtropical or tropical development off the Southeast United States coastline next week. The low being forecast develops as a result of a stalled-out cold front that is currently pushing through South Florida. In the upper levels of the atmosphere, a negatively-tilted trough is forecast to push across the East United States, positioning the low in the left exit region (favors upper-level divergence--air pulling apart) and allowing for deepening. The trough is forecast to eventually detach into a cold-core upper-level low. While any potential system would likely be non-tropical initially, there would be a chance for subtropical or tropical transition as it meanders over anomalously warm ocean temperatures for several days. And though one could make a case that water temperatures are still marginal despite being several degrees warmer than average, this low would have the benefit of elevated instability between the cold upper levels and warm lower levels of the atmosphere (see also: Chris 2012).

Being a few days out still, details are certainly not set in stone. The GFS takes the storm out to sea, while the ECMWF and CMC both bring it into the North Carolina coastline. It is something to monitor for now.

The first name on the list is 'Ana'.

[NDG]

Yeah, I agree that this deserves its own thread now, model agreement is very good at this point.

[Yellow Evan]

Looks pretty intriguing. Is shear/dry air a problem.

[cycloneye]

Looks pretty intriguing. Is shear/dry air a problem.

Shear would not be detrimental if it is subtropical.

[cycloneye]

Dr Jeff Masters chims in on this potential development.

http://www.wunderground.com/blog/JeffMa ... rynum=2970

[Hypercane_Kyle]

The pressure gradient being as spread out as it is, and the development from an extratropical cyclone, all suggests a subtropical cyclone to me IMO.

[Ivanhater]

The pressure gradient being as spread out as it is, and the development from an extratropical cyclone, all suggests a subtropical cyclone to me IMO.

I don't think anyone thinks this would be purely tropical. Either way, looks pretty good to have an early start to the season and add to the overall numbers.

[northjaxpro]

Yeah, it looks good with the consensus with the models now that something will develop. It likely will be a hybrid/sub-tropical system to begin, but interesting nonetheless. We had Beryl in 2012 nearly become a hurricane as it made landfall here, so I definitely will state to everyone to never underestimate these early season entities in May! Good time to look at my avatar which I have had for some time to serve as a reminder of that historic strom here in Jax for sure!

[TropicalAnalystwx13]

12z GFS has a moderate subtropical/tropical storm by Wednesday:

[CrazyC83]

That almost looks frontal on that model run. But definitely an interesting setup...reminiscent of Andrea 2007, which reached hurricane intensity while in its initial extratropical stage.

[OuterBanker]

Local NWS 9:55 am discuss:

THURSDAY AND BEYOND...THE 01/00Z DETERMINISTIC RUNS OF THE GFS AND
ECMWF ARE IN VERY GOOD AGREEMENT IN DEVELOPMENT OF A DEEP LOW OFF
THE SE COAST LATER IN THE WEEK. THE MODELS THEN DIVERGE ON THE TRACK
WITH THE GFS PASSING THE LOW WELL OUT TO SEA OFFSHORE OF THE NC
COAST NEXT WEEKEND, WHILE THE EC TAKES IT RIGHT ALONG THE NC COAST.
WHATEVER THE EVENTUAL EXACT TRACK, AT LEAST MINIMAL COASTAL IMPACTS
WRT TO HIGH SURF/COASTAL FLOODING/SURF ZONE HAZARDS COULD BE
EXPECTED.

[Alyono]

not understanding why this is its own thread. This is purely a modelcane at this point. Not even a disturbance is present

[emeraldislenc]

I appreciate all the discussion and having its own thread makes it easier to read and follow the discussion.

[gatorcane]

12Z GEM more west and stronger. Low develops around SE Florida then deepens and hits Outerbanks:

[TheStormExpert]

not understanding why this is its own thread. This is purely a modelcane at this point. Not even a disturbance is present

Seriously? This has some of the best model consensus I've seen in awhile! Not to mention the disturbance that forms into this Subtropical Cyclone is not expected to develop until early next week in the Northern Bahamas. So all in all the GFS, ECWMF, CMC, and NAVGEM all show something coming out of this along with almost perfect agreement in track.

[TheStormExpert]

12Z GEM more west and stronger. Low develops around SE Florida then deepens and hits Outerbanks:

http://i.imgur.com/CcC03kK.png

http://i.imgur.com/LZjz79L.png

Reminds me a lot of Hurricane Arthur from last year.

[TropicalAnalystwx13]

not understanding why this is its own thread. This is purely a modelcane at this point. Not even a disturbance is present

Because all reliable model guidance has it, several local weather forecast offices are talking about it, and the cold front that the low should be born out of is already pushing off the East Coast.

[cycloneye]

Although,there is nothing on the weather charts about something off the SE U.S coast at this time,having a model consensus plus a high interest by the members and also having an upper disturbance in SE Texas that will be the trigger early next week about this is prudent to have a thread apart from the models thread.

[Alyono]

and the 12Z EC is really backing off on development. Development was pushed back by 24 hours.

Isn't this why the admins want model storms in the model thread? The models change significantly from run to run in the pre genesis phase

[wxman57]

Dr Jeff Masters chims in on this potential development.

http://www.wunderground.com/blog/JeffMa ... rynum=2970

He didn't offer any opinion on it, he just stated what the models were indicating. I'm thinking about a 40% chance of an STD/STS formation. Slim chance it could approach hurricane strength. More likely 40-45 mph at peak. May start out subtropical then transition to tropical.

12Z Euro pushed back the development time 24-36 hours (Thu/Fri vs. Wed). 12Z GFS trended closer to the Euro.