Surface Trough East of Florida (Is Invest 90L)

[TheStormExpert]

Well the 12z Euro basically drops it.

[cycloneye]

Latest WPC discussion:

A SUBTROPICAL/HYBRID LOW IS STILL EXPECTED TO COALESCE OVER THE BAHAMAS BY MID-PERIOD, THEN DRIFT ABOUT WELL OFF THE SOUTHEAST COAST. THERE WAS LESS OPERATIONAL CLUSTERING FOR A SIGNIFICANTLY DEVELOPED LOW AMONG THE MOST RECENT MODEL RUNS, SO FOR NOW, THREATS WITH THIS DISTURBANCE APPEAR MINIMAL.

[TheStormExpert]

With the latest trends in the models I'd put the chances of anything coming from this between 20-40%(no higher).

[gatorcane]

Latest WPC discussion:

A SUBTROPICAL/HYBRID LOW IS STILL EXPECTED TO COALESCE OVER THE BAHAMAS BY MID-PERIOD, THEN DRIFT ABOUT WELL OFF THE SOUTHEAST COAST. THERE WAS LESS OPERATIONAL CLUSTERING FOR A SIGNIFICANTLY DEVELOPED LOW AMONG THE MOST RECENT MODEL RUNS, SO FOR NOW, THREATS WITH THIS DISTURBANCE APPEAR MINIMAL.

I am not really sure why they think there is less operational clustering for development looking at the latest models. The ECMWF doesn't develop in the last run I will give them that, but the GFS, NAVGEM, GEM, FIM, and UKMET haven't changed from their 00Z runs. In fact the GFS shows an even more developed low in the 12Z down to 995MB as opposed to only 1007MB on the 00Z run. The GEM also shows an even more developed low with 1003MB low on 00Z and 996MB on 12Z.

[Riptide]

Can't really say much until the players enter the field. Euro could just be doing what it does in the mid-range.

[gatorcane]

18Z GFS is rolling, much weaker than the 12Z run (down to only 1007MB), a stronger ridge and the low moving north then bending sharply W then SW moving onshore the East-Central Florida coastline as a weak low. Could be some good rainfall for the Eastern half of Florida if this verifies.

[floridasun78]

rain chance going up here miami on tue

[TheStormExpert]

Any idea as to why the models are suddenly backing off of development? I'm guessing environmental conditions won't be favorable.

[Frank2]

Weather to our east has been consistently unsettled for most of the past week, so I wouldn't be surprised if something forms, but hopefully it doesn't include the 5" PWAT mentioned in today's discussion!

[TropicalAnalystwx13]

Any idea as to why the models are suddenly backing off of development? I'm guessing environmental conditions won't be favorable.

They're not. The GFS, CMC, NAVGEM, and JMA all still portray the system. The 12z ECMWF run was the only to drop it.

[AJC3]

Weather to our east has been consistently unsettled for most of the past week, so I wouldn't be surprised if something forms, but hopefully it doesn't include the 5" PWAT mentioned in today's discussion!

That has to be a typo or a misstatement. In the most extreme cases, a fully saturated atmosphere in the summertime can only support about 75mm of PWAT, or about 2.9" to 3.0". Operationally, I don't think I've seen a non-contaminated upper air sounding that has shown more than 2.75". I'm sure there have been some that have been a tenth or so higher, and I imagine sounder imagery in the deep tropics has shown values of around 3.0"

I you did indeed find a discussion that mentioned 5" of PWAT, can you post a link to it? Thanks.

Edit: I found the discussion you referenced. It was the SAT afternoon AFD from NWS MIA (AFDMFL) and, as I suspected, they were talking about the SREF ensemble QPF output (which is nonetheless impressive), as opposed to PWAT values.

GFS SHOWS A MOISTURE SURGE (PWATS INCREASING TO NEAR 1.9 INCHES)
ALONG A DEVELOPING SURFACE TROUGH AXIS WITH LOW LEVEL WINDS
STRENGTHENING NORTH OF ITS AXIS ALONG WITH AN INCOMING MID LEVEL
LOW AND UPPER LEVEL DIVERGENCE...A SET UP WHERE IN THE PAST VERY
LOCALIZED BUT EXTREME RAINFALL AMOUNTS HAVE OCCURRED. INSTABILITY
LOOKS TO BE THERE WITH COOLING MID LEVELS...SO THUNDERSTORMS WITH
TORRENTIAL RAINS COULD RESULT. HOWEVER, THE ECMWF IS MUCH LESS
BULLISH AND GIVES PAUSE TO CONFIDENCE IN HEAVY RAINFALL WITH THIS
FORECAST...AS THIS MODEL SHOWS THE MAX QPF WELL TO THE EAST WITH
LESS CONVERGENCE LOCALLY. SREF ENSEMBLE MEMBERS SHOW A LARGE
SPREAD IN QPF ALONG THE SOUTHEAST FLORIDA COAST WITH RUNS RANGING
FROM LESS THAN AN INCH TO AS HIGH AS 5"+! SO THERE IS MUCH
UNCERTAINTY...BUT BEARS WATCHING, NO DOUBT.

[NDG]

0z Euro back to development.

[Frank2]

Thanks for correcting me on that, AJC3 - that's what happens when I post in the middle of a plumbing crisis! But, as you said that is impressive still - if that happens, then I'll have a leaky roof crisis, too...

Frank

[SeGaBob]

SPECIAL TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
1030 AM EDT SUN MAY 3 2015


For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

A non-tropical area of low pressure is expected to form north of
the Bahamas later this week. This system could gradually acquire
some subtropical characteristics by Thursday or Friday as it moves
slowly northward. The next Special Tropical Weather Outlook will be
issued on this system by 11 AM EDT Monday.
* Formation chance through 48 hours...low...near 0 percent
* Formation chance through 5 days...low...30 percent

$$
Forecaster Brennan

[NDG]

When a model storm has such consensus from all models even the NHC pays attention to it.

[TheAustinMan]

Currently the models picking up on this system expect it to begin as a disorganized mass of convection in this area around Monday/Tuesday, which will eventually travel northward. (Cuba, Pinar del Rio) There's a little bit of activity going around there but nothing notable at the moment.


What you are looking at: Colorized water vapor imagery superimposed on visible imagery of an area in the Western Caribbean.
Source: NASA/MSFC

[cycloneye]

12z ECMWF was weaker than 00z run.

[TheStormExpert]

SPECIAL TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
1030 AM EDT SUN MAY 3 2015


For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

A non-tropical area of low pressure is expected to form north of
the Bahamas later this week. This system could gradually acquire
some subtropical characteristics by Thursday or Friday as it moves
slowly northward. The next Special Tropical Weather Outlook will be
issued on this system by 11 AM EDT Monday.
* Formation chance through 48 hours...low...near 0 percent
* Formation chance through 5 days...low...30 percent

$$
Forecaster Brennan

TWO 5-Day Graphic.
*Note that the 30% chance of development is now categorized as a Low(Yellow) chance of development instead of Medium(Orange) like in the past.

[bamajammer4eva]

Decent agreement from the main models

[Hammy]

12z ECMWF was weaker than 00z run.

I'd personally put the chances at 10% at this point, given that all the models seem to be trending weaker now as the formation point gets closer.