ATL: DEBBY - Post-Tropical

[Air Force Met]

The GFS Ensemble Mean/ECMWF shows that wind shear will not be a problem for 96L. There is an anticyclone located in the Gulf that should eventually become stacked with the system and provide a low shear environment for the next several days. If 96L goes east, I could see it being a problem close to landfall, but if it goes west, it shouldn't be a problem.

Really not sure what you are looking at. The 72H 250 MB GFS ensembles show an upper low off the S TX coast (25/12z)...as does the operational model. This places 20 kts of southerly shear over the central Gulf.

By 120 hrs+ a high does build over the Gulf but it is over the SOUTHERN Gulf. This places 10-20 kts of westerly shear across the northern Gulf...which is where Debby/96L will be (north of 25N...which is what I was saying).

There is NO anticyclone over the Gulf now...only shear...and the northern Gulf will remain hostile according to the GFS ensembles AND the GFS operational model.

[Rgv20]

12zGFS sticking with the eastern solution....Of all the Global Models GFS is alone with that idea as of right now.

[Dean4Storms]

12z GFS really backdoors the trough down the eastern CONUS Seaboard backing down the plains ridge capturing Debby and dragging it across Florida.

Really strong trough for this time of year, but if it occurs it would likely pull whatever is in the eastern half of the Gulf eastward.........


http://raleighwx.americanwx.com/models/ ... SLoop.html

[Hurricane Andrew]

0z HWRF at 93 and 126 hrs -

Where do you get those?

[Dean4Storms]

That sure would put the squeeze play in over the Panhandle gradient and wind wise!!

[hurricanefloyd5]

http://www.sfwmd.gov/portal/page/portal ... el%20plots

[ROCK]

the 12Z GFS is the same as the 06Z so not much change. I think its over doing the trof but we shall see...the CMC and EURO come out in a few....I doubt they will clear anything up though....

[PTrackerLA]

Amazing the GFS continues to move this east into Florida while the overnight Euro sent it even further south and west into southern TX. Can't remember the last time the globals were holding their ground on such divergent solutions for about two days now.

[Hurricane Andrew]

9z SREF has a 999mb storm S of LA
http://raleighwx.americanwx.com/models/ ... TUS087.gif

[SoupBone]

Jeff masters said there is dry air hampering development in the central gulf. He also said moderate shear will allow for slow development through Saturday night then shear will increase again. So this has alot going against it becoming too strong

And I agree. This thing will never be free of the shear once it moves north of 25. When I sent out my update yesterday to the State I mentioned this very reason for not buying into the Euro/CMC solution on strength. It always looks to me like it will be battling 10-20 kts of shear. Nothing that will kill it...but enough to keep a lid on it.

I believe that a few Louisiana NWS offices agree with this line of thinking as well. While the shear has lessened and may allow for minimal strengthening, 10-20 kts will take most of the punch out of it. For us (in Louisiana), we need to be worried about a slower moving system giving us large amounts of rain, and considering we're already drenched, we have flash flood potentials. Also, we have to worry about the possibility of increased tides and wave action for our coastal parishes.

Personal Forecast Disclaimer:The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

[Dean4Storms]

I think the differences are two fold between the GFS and ECMWF. The GFS has the Low further north and east and backs the ridging down more. Whereas the ECMWF has the Low closer to 90W and not as far north missing the trough and build the ridge back in much faster.

If the Low forms closer to the NE Tip of the Yucatan I think you have to give the GFS solution more plausibility. All will depend on exactly where the Low develops and with the deeper convection all on the eastern periphery I tend to side with the GFS for now.

[tgenius]

pretty safe to say this is going to make for a rainy weekend this weekend in Miami.. maybe that's why they pushed the parade to Monday.

[Dean4Storms]

Unless convection gets around to the western periphery I think the GFS is more plausible with this staying east of 90W. Thus getting pulled by the trough.

[N2Storms]

[quote="Dean4Storms"]That sure would put the squeeze play in over the Panhandle gradient and wind wise!! [/quote]


I would love to see us get some good soaking rains but for some reason, Bay County (Panama City) just seems to have some kind of "rain shield" around it and when folks to our West and to our East are picking up fair amounts of Precip, we seem to be left high and dry.

[wxman57]

I'm fixing some old links on my models page and have another one that changed. I had the link to the current HWRF/GFDL output in text form as being:

ftp://ftp.ncep.noaa.gov/pub/data/nccf/com/hur/prod/

Now that data on the website above is zipped into a grib file and I can't view it. Used to be links there to display the HWRF and GFDL as a table of lat/lon, pressure, max winds. What did that link change to?

[SouthDadeFish]

This is the 72 hour 12Z GFS forecast, which illustrates what AFM is talking about with the ULL:



That ULL is producing 20-30 knots of wind in the upper-levels which will most likely lead to our typical sheared June Gulf system. Nothing new here.

Disclaimer: Not a professional forecast, just my opinion.

[Rgv20]

I'm kind of lost if the following discussion belongs in the model thread......I'm going to put it here because it breakdowns the 6zGFS.

MONSOON DEPRESSION IN THE GULF OF MEXICO...
PREFERENCE: SOUTHEAST-SHIFTED 00Z CANADIAN/00Z ECMWF COMPROMISE
CONFIDENCE: ABOVE AVERAGE FOR TRACK SHAPE/BELOW AVERAGE FOR
PROGRESSION/SPEED

THE 06Z GFS CONTINUES TO DRAG THIS CYCLONE TOWARDS TAMPA...USING A
PAIR OF CONVECTIVE FEEDBACK BULL'S EYES/QPF BOMBS TO LURE ITS
CENTER NORTHEASTWARD...IMPLYING SOUTHWESTERLY VERTICAL WIND SHEAR.
IT HAS BEEN PERSISTENT IN SHOWING THIS TYPE OF SOLUTION FOR THREE
DAYS NOW. THE GENERAL FLOW PATTERN FEATURES A BUILDING WARM CORE
RIDGE ACROSS CENTRAL PLAINS WITH A SECOND WEAKER RIDGE NORTH OF
THE GREATER ANTILLES...AND A NEGATIVELY TILTED UPPER TROUGH
EXTENDING FROM THE EAST COAST INTO THE WESTERN ATLANTIC WITH A
SLIGHT BREAK AT 500/700 HPA ACROSS THE SOUTHEAST. THE GUIDANCE
CONTINUES TO INDICATE THAT THE COL POINT IN THE STEERING PATTERN
IS NEAR NORTHERN FLORIDA/SOUTHERN GEORGIA...WHICH WOULD FORCE A
SYSTEM IN THE GULF TO STEER NORTH AND ULTIMATELY WEST UNDER THE
PLAINS RIDGE DURING THE LATE SHORT RANGE/MEDIUM RANGE PERIOD.
THERE IS ABOVE AVERAGE CONFIDENCE IN THIS IDEA.

HOWEVER...ONCE THE RIDGE BUILDS...THE LOW COULD EASILY ACCELERATE
WEST/WEST-SOUTHWEST SIMILAR TO CLAUDETTE IN 2003. THE ONLY OTHER
ANALOGS TO THIS TYPE OF TROPICAL CYCLONE-TYPE TRACK ARE OCTOBER
1938 AND JUNE 1913. THE GLOBAL ENSEMBLE SPREAD CONTINUES TO WAVER
EACH DAY...WITH ABOVE AVERAGE SPREAD SEEN TODAY AND WEDNESDAY
WHILE LOWER THAN NORMAL SPREAD WAS SEEN TUESDAY AND THURSDAY.
WHEN THE ENSEMBLE GUIDANCE SHOWS SUCH VARIABILITY...IT IS UNCLEAR
HOW/WHEN TO START ITS WESTWARD PROGRESSION. THE HURRICANE
GUIDANCE BASED ON THE GFS MIRRORS THE GFS...WHICH INCREASES THE
APPARENT MODEL SPREAD WITH THIS SYSTEM. THE PREFERENCE IS FOR A
SOUTHEAST-SHIFTED 00Z CANADIAN/00Z ECMWF COMPROMISE TO SPLIT THE
DIFFERENCE IN THE LARGE SPREAD WITH BELOW AVERAGE CONFIDENCE IN
ITS ULTIMATE WESTWARD PROGRESSION/SPEED. THIS KEEPS GOOD
CONTINUITY WITH MEDIUM RANGE. CONSULT THE LATEST TROPICAL WEATHER
OUTLOOK FROM THE NATIONAL HURRICANE CENTER /NHC/ FOR ITS CURRENT
STATUS.

[tolakram]

I see clouds moving SW near the NE YP, just left of some persistent convection. Perhaps this is the start of something.



Loop: http://wwwghcc.msfc.nasa.gov/cgi-bin/ge ... mframes=10

[FutureEM]

MM5 +72 - http://smn.cna.gob.mx/cartas/mm5/p01d10025.gif

[bella_may]

I'm just wondering here. Is it possible the TC misses the ridge and the trough and heads due north?