Posible GOM development?

[Dean4Storms]

00z ECM is showing some Gales off the upper TX Gulf Coast come Monday morning!

[NDG]

Great Discussion by the NWS office in Slidell, couldn't agree with them more, glad they see what I see.

NATIONAL WEATHER SERVICE NEW ORLEANS LA
408 AM CDT FRI SEP 25 2015

.SHORT/LONG TERM...
850 MB LOW OVER GEORGIA WILL MOVE WEST AND ADVECT DRY AIR INTO THE
REGION TODAY INTO THE WEEKEND. THIS WILL ALL BUT CUT OFF CHANCES
OF SH/TS THROUGH AT LEAST SATURDAY. THE UPPER LOW OVER GEORGIA
WILL MOVE NW AND WEAKEN ALOWING MOISTURE TO RETURN ONCE AGAIN TO
THE AREA BY SUNDAY INTO MONDAY. THE MERIDIONAL UPPER TROUGH FROM
MINNESOTA INTO TEXAS WILL DEEPEN AND DIG INTO NE MEXICO OVER THE
WEEKEND. THIS WILL SET THE STAGE FOR A VERY DEEP PLUME OF TROPICAL
MOISTURE TO FEED NORTHWARD. THE BEST DIFLUENT AREA WILL MOVE
NORTHWARD OVER THE EASTERN GULF CAUSING SFC PRESSURES TO DROP. THE
ATTENDANT SFC LOW SHOULD FOLLOW THIS UPPER DIFLUENT AREA BUT SHEAR
PROFILES OF 40 TO 50 KNOTS ALOFT WILL MAKE FOR A VERY HOSTILE
ENVIRONMENT FOR A TROPICAL SYSTEM TO DEEPEN VERY MUCH. BUT A
HYBRID SYSTEM...FRONTOGENETIC SYSTEM WOULD NOT BE OFF THE TABLE.
PRESSURES WILL BE RELATIVELY LOW OVER MUCH OF THE WESTERN AND
CENTRAL GULF WHILE THE EASTERN GULF WILL FIND ITSELF BETWEEN THE
SFC LOW AND THE HIGH OVER THE ATLANTIC CAUSING A MUCH TIGHTER
PRESSURE GRADIENT AND RESULTANT HIGHER WIND SPEEDS. THE MAIN ISSUE
TO WATCH WITH THIS SYSTEM WILL BE RAINFALL PROBABILITIES AND
TORNADIC ACTIVITY. OVER MARINE AREAS IT SHOULD BE WINDS AND
WATERSPOUTS. WILL NEED TO WATCH FOR WHERE THE FEED OF THIS
MOISTURE MOVES INTO THE NORTHERN GULF. THERE WILL BE QUITE A
PRECIP GRADIENT WITH THIS BY EARLY NEXT WEEK. FARTHER EAST AND WE
SEE LITTLE IN THE WAY OF RAINFALL AND SLIGHTLY HIGHER THAN NORMAL
TIDES. FARTHER WEST AND THOSE NUNBERS RAMP UPWARD. THE TROPICAL
NATURE OF THIS SYSTEM SHOULD REMAIN RATHER WEAK DUE TO THE HOSTILE
ENVIRONMENT BUT THE SYNOPTIC EVOLUTION OF A BAROCLINIC SYSTEM
SHOULD NOT.

&&

http://forecast.weather.gov/product.php ... glossary=1

[Janie2006]

A hybrid system....that's *certainly* not off the table. In any case, an interesting weekend and early week ahead.

That's a reminder for me to always take a peek at Slidell. Sometimes their AFDs are much more detailed than neighbouring offices.

[ronjon]

Our local CBS TV station in Tampa this morning showed their RPM model (yeah I know sounds dorky) which showed rapid development of the system in the eastern GOM. I can see that as upper level conditions there are favorable. However, all the global guidance I have seen shows the low pressure system developing more toward the central GOM where conditions are more hostile. Probably a baroclinic low that develops without much tropical characteristics.

Note: RPM: Rapid Precision Mesoscale model. A numerical weather prediction system based on the Advanced Research Weather Research and Forecast system (WRF-ARW). Not available to the public.

[Janie2006]

Does that one have anything to do with the "FSU Supermodel"? If I recall correctly, that one isn't available to the general public either.

[ronjon]

Does that one have anything to do with the "FSU Supermodel"? If I recall correctly, that one isn't available to the general public either.

Janie, No I believe the RPM is a mesoscale type model purchased by local weather stations for their in-house forecasts. In Florida, they're used extensively because of our local convective thunderstorm activity in the summer which they attempt to predict on a daily basis.

[ronjon]

Look out northern gulf coast - QPF totals quite impressive.

http://www.wpc.ncep.noaa.gov/qpf/p120i.gif?1443186521

[lovingseason2013]

We get that much rainfall from frontal systems in the spring, rain is nothing to worry about down here. We have 24 inches in less than 24 hours last year and we survived it. Too much hype.

[wxman57]

I'm fairly certain that a low pressure area will form north of the Yucatan on Monday morning. The low should track northward and move inland between SE LA and the FL Panhandle by Wednesday. I don't think there is too much question whether or not it will form. Upper-level winds would be rather hostile as far as tropical development. Big question is whether or not the NHC would classify such a sheared low center that may not be fully tropical in nature. Their outlooks indicate that they're tending to think they won't classify the low as a TD, as I'm sure they believe that the low will form as well.

Regardless of whether or not it becomes classified as a TD or a highly-sheared TS, the effects will be the same across the Gulf and eventually into the Gulf Coast - squalls and winds of 25-35 mph, mostly east of the low center.

[NDG]

Our local CBS TV station in Tampa this morning showed their RPM model (yeah I know sounds dorky) which showed rapid development of the system in the eastern GOM. I can see that as upper level conditions there are favorable. However, all the global guidance I have seen shows the low pressure system developing more toward the central GOM where conditions are more hostile. Probably a baroclinic low that develops without much tropical characteristics.

Note: RPM: Rapid Precision Mesoscale model. A numerical weather prediction system based on the Advanced Research Weather Research and Forecast system (WRF-ARW). Not available to the public.

RPM models are not good to follow for tropical development, too aggressive, they do that all the time with any little disturbance in the gulf.

[Steve]

Regardless of whether or not it becomes classified as a TD or a highly-sheared TS, the effects will be the same across the Gulf and eventually into the Gulf Coast - squalls and winds of 25-35 mph, mostly east of the low center.

Agreed. NAM was spinning up a secondary vortex around the greater area of surface low pressure that was what ended up hammering Mobile Bay. This coincided with the GFS which showed that second vortex sort of dumping at landfall. Not sure if this will be a multiple vortex system, possibly. It could also be subtropical based on all the shear. Again, for those of you hammering shear, you don't get an STS in the Gulf in the Fall without it. Nothing city-destroying or anything, but there could be some flooding and power outages.

lovingseason,

I'm assuming you are in/near Pensacola with the 24 in 24 (some areas had way more than that). Several people lost their homes and possessions in that flooding. Sure, most people survived. But there was a lot more property damage than you might realize. Last week we dealt with gutting a moldy house that had been idle since that event. Don't downplay that kind of rain, flash flooding and such. It's not as major of an issue where the soils are sandy, but deluges like that have been known to drown people and cause roof failures, downed trees and such. Hell, the roadway washed out on Fairfield Drive next to the bridge over Bayou Grande. JMO

[caneman]

That's right Steve. We live in the Clearwater Beach are and there was flooding, house damage etc.. IF there is enough rain and rivers crest, poorly designed streets, poor drainage etc...it's a problem. If it happened here it can happen in Pensacola. Further, in both Tampa and St. Pete the the cities couldn't handle the rain and tons of wasterwater was dumped into the Bay. See here: http://www.tampabay.com/news/localgover ... ns/2246180

[Steve]

12z GFS at 850mb is farther east where the vorticity looks like it comes up around Pensacola/Navarre with the corresponding heaviest rainfall now more over toward 30-A (South Walton County) vs. Mobile Bay where it was at yesterday afternoon. Still closing something off - though not much. Looks like a possible TD or minor TS would be the max limit based on this run.

[N2FSU]

12z GFS at 850mb is farther east where the vorticity looks like it comes up around Pensacola/Navarre with the corresponding heaviest rainfall now more over toward 30-A (South Walton County) vs. Mobile Bay where it was at yesterday afternoon. Still closing something off - though not much. Looks like a possible TD or minor TS would be the max limit based on this run.

[stormlover2013]

JMA and CMC showing to lows, like the euro was showing,elongates system


http://www.tropicaltidbits.com/analysis ... 0&ypos=255



http://www.tropicaltidbits.com/analysis ... =0&ypos=55

[Dean4Storms]

Nice turning starting to show up on the Low just off the Belize north coast when you speed up the loop. Appears it is trying to organize.

http://weather.msfc.nasa.gov/GOES/GANIMmZtku717.jpg

[Dean4Storms]

12z GFS at 850mb is farther east where the vorticity looks like it comes up around Pensacola/Navarre with the corresponding heaviest rainfall now more over toward 30-A (South Walton County) vs. Mobile Bay where it was at yesterday afternoon. Still closing something off - though not much. Looks like a possible TD or minor TS would be the max limit based on this run.

12z GFS with 40kt wind gusts at 10m on this run like you said moving east of the center and then over South Walton County or Me!

[tropicwatch]

Close to live loop of the area se of Yucatan.

http://weather.msfc.nasa.gov/cgi-bin/get-goes?satellite=GOES-E%20CONUS&lat=18&lon=-88&type=Animation&info=vis&numframes=10

[Dean4Storms]

Close to live loop of the area se of Yucatan.

http://weather.msfc.nasa.gov/cgi-bin/get-goes?satellite=GOES-E%20CONUS&lat=18&lon=-88&type=Animation&info=vis&numframes=10

Yep, you speed that up and you see the early signs of a counterclockwise rotation trying to go!

[LarryWx]

Nice turning starting to show up on the Low just off the Belize north coast when you speed up the loop. Appears it is trying to organize.

http://weather.msfc.nasa.gov/GOES/GANIMmZtku717.jpg

This looks to be about where and when the model consensus has the low forming.