Tropical Depression TEN: Discussions & Images

[jdray]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSONVILLE FL
230 PM EDT WED SEP 19 2007

...WIDESPREAD RAINFALL WILL CONTINUE FLOOD POTENTIAL THROUGH TONIGHT...
...WINDY CONDITIONS WITH GUSTS TO 50 MPH IN STRONGER SHOWERS TONIGHT...
...HAZARDOUS BOATING CONDITIONS WITH GALE FORCE GUSTS THROUGH LATE EVENING...

.SHORT TERM...MSAS ANALYSIS SHOWS A CIRCULATION CENTER AT THE SURFACE
BETWEEN THE BAHAMAS AND THE SOUTHEAST FLORIDA COAST WHILE
SATELLITE IMAGERY DEFINITELY INDICATES A CIRCULATION AT SOME LEVEL
OFF THE CANAVERAL COAST. RADAR IMAGERY ALSO REFLECTS THE NORTHERN
CIRCULATION WELL AND INVERTED TROUGH EMANATING FROM THIS FEATURE
IS PRODUCING WIDESPREAD SHOWER ACTIVITY SOUTH OF A LINE FROM JAX
TO JUST NORTH OF GNV. ALTHOUGH WIDESPREAD AND VERY
PERSISTENT...STILL HAVE NOT SEEN THE BANDED STRONG ACTIVITY OF
THIS PAST MONDAY AND CONSEQUENTLY MOST RAINFALL AMOUNTS HAVE BEEN
MANAGEABLE. HOWEVER...AS THE EVENT LENGTHENS...AND SOME STRONGER
ACTIVITY MOVES INTO THE COAST...WE WILL NEED SOME ADDITIONAL FLOOD
ADVISORIES AND PERHAPS WARNINGS THROUGH TONIGHT.

VERY TIGHT GRADIENT HAS DEVELOPED NORTH OF THE SURFACE CIRCULATION
AND HAVE SEEN GUSTS CLOSE TO 50 MPH ALONG THE COAST IN SOME OF THE
STRONGER SHOWERS. HAVE THEREFORE HOISTED WIND ADVISORIES THROUGH
THE EVENING HOURS WITH LAKE WIND LIKELY NEEDED THEREAFTER.

LOOKS AS THOUGH THE NAM12 HAS THE BEST REPRESENTATION OF SURFACE
LOW FOR THE INITIALIZED FIELD BUT BOTH THE NAM12 AND GFS DEPICT
MAIN MOISTURE AXIS VERY WELL. THROUGH 12Z...MODELS REALLY SHIFT
AXIS QUICKLY NORTH AND WESTWARD AND GIVE A REPRIEVE TO THE COASTAL
SECTIONS OF NORTHEAST FLORIDA BY 06Z. LOOKING AT RADAR
TRENDS...FEEL THIS MAY BE A BIT QUICK AND WILL HOLD ONTO
WIDESPREAD SHOWERS WELL INTO THE EVENING FOR COASTAL SECTIONS.
OTHER BIG QUESTION OVERNIGHT WILL BE HOW MUCH RAIN WILL MAKE IT TO
THE FAR NORTHWEST ZONE WHERE PRECIP EFFICIENCY TOOLS INDICATE 60 TO
70 PERCENT. WILL NOT GO THIS HIGH GIVEN THE AMOUNT OF DRY AIR THAT
IS CURRENTLY UNDERCUTTING THE SYSTEM AND WILL CAP IN THE HIGH END
SCATTERED RANGE FOR NOW. FLOOD WATCH LOOKS ON TRACK FOR THE CURRENT
AREAS AND NO CHANGES PLANNED.

FOR THU...SURFACE LOW LOOKS TO RESIDE OVER THE EASTERN GULF WITH
THE GFS A LITTLE FASTER IN THE PROGRESSION OF MAIN MOISTURE AXIS
OUT OF THE AREA. WILL FAVOR THE SLOWER AND WETTER NAM12 FOR NOW
AND INDICATE HIGH END CHANCE POPS FOR INTERIOR GA AND LIKELY POPS
FOR THE WESTERN FRINGES OF THE SUWANNEE VALLEY.

WITH LOW PROGGED TO LIFT NORTH INTO THE GULF OF MEXICO...THE
REMAINDER OF THE FORECAST WILL BE HIGHLY DEPENDENT UPON WHERE MAIN
MOISTURE FEED AXIS SETS UP WITH 50 MILES EITHER WAY MAKING A BIG
DIFFERENCE. FOR NOW...WILL CARRY HIGH END CHANCE POPS IN MOIST
SOUTHERLY FLOW FOR FRIDAY WITH INDICATIONS AT THIS POINT THAT
COASTAL AREAS WILL AGAIN BE FAVORED AND FLOODING CONCERNS WILL
NEED TO BE MONITORED.

.LONG TERM...MOIST SOUTHEAST FLOW TO CONTINUE INTO THE WEEKEND.
CURRENT GRID SET SHOWS ABOVE CLIMO POPS AND THIS LOOKS REASONABLE
WITH LIMITED CHANGES PLANNED.

[Stormcenter]

This is an excrpt from the HPC afternoon discussion.
So what happened to the SE La. landfall.

...GULF COAST...

TROPICAL SYS MOVING WWD ALONG JUST OFF THE GULF COAST NEXT FEW
DAYS MAY BRING SOME LOCALLY HEAVY RAINFALL FROM THE FL PANHANDLE
TO THE SE TX COAST BEFORE IT TURNS NW THEN N INTO TX SUN/MON.

[hurricanetrack]

Ok, here is my take, FWIW.

Look at the 24 hour GFS from 12Z this morning:

http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_024l.gif

Notice the glob of precip off the Carolinas- that nice slug of moisture that seems to be coming north as energy at the surface with our low near Cape Canaveral.

Now notice the low west of Naples in the GOM.

My belief is that any low over the Atlantic will move north or at least its energy will and bring some rain to the coastal Carolinas and maybe GA.

The upper low is obviously becoming more tropical with time. Why? When is the last time you could see an upper level low SO CLEARLY on visible satellite imagery? Plus, the UL is not moving much anymore- and is working over nice and warm waters.

Bottom line- the two pieces of energy spearate- one goes in to the Carolina offshore waters and the other becomes TD10 later tomorrow and heads generally W-WNW as it gets better organized.

Makes sense to me at this point considering the data that is available now.

[Wx_Warrior]

From Jeff Masters: Sorry if posted already

Recent Satellite loops and the Tampa Bay long range radar show that a non-tropical low pressure system (93L) appears to be reforming off the southwest coast of Florida. This is an important shift, since it brings the surface low underneath the upper level low pressure system aloft--the same kind of situation one finds in ordinary non-tropical "cutoff lows". This is an unusual event in September over the Gulf of Mexico, and is good news for those potentially living in the path of 93L. A surface low pressure system vertically aligned with a cold-cored upper level low will usually take a day or two to make the transition to a warm-cored tropical storm. During this kind of transition, rapid strengthening is rare, and the chances of 93L ever reaching hurricane strength now appear dim. The latest (12Z, 8am EDT) intensity forecasts from the GFDL and HWRF computer models keep keep 93L below hurricane strength, as does the 18Z (2pm EDT) SHIPS intensity model. The HWRF model indicates that 93L will come ashore at tropical depression strength, and this is entirely possible.

The forecast tracks from the latest cycle of model runs all show a landfall between central Louisiana and Pensacola, Florida on Saturday morning. The exceptions are the NOGAPS and ECMWF models, which show a Sunday morning landfall near the Texas/Louisiana border.

[HURAKAN]

[Wx_Warrior]

I work with a Jerry and he is married to a Rita...SERIOUSLY

[redstick]

I work with a Jerry and he is married to a Rita...SERIOUSLY

I have to say that I chuckled at that comment.

[Stormcenter]

No surprise here whatsoever. This is what the models saw last weekend.
This great news for anyone living along the Gulf coast as it stands right
now if this pans out.

[Wx_Warrior]

I know a little but can some explain why it would be good news? You can pm or e-mail if preferred:

cooper@theexaminer.com

[jhamps10]

Larry Cosgrove update:

Update as of 4 PM ET:

The low is now taking shape west of Sarasota FL. This is bad news in a way as the formation is far to the south of the tamer model output that suggested only a rain event for Louisiana and Mississippi. ECMWF solution of a Houston TX strike looks very good at this point.

[chadtm80]

Seems to be slightly North of Melbourne.. Off the Cocoa area

[Brent]

I work with a Jerry and he is married to a Rita...SERIOUSLY

I'm very confused and unimpressed with this storm...

[Stormcenter]

Seems to be slightly North of Melbourne.. Off the Cocoa area

What is north of Melbourne....not another center?
How many is that now?

[Wx_Warrior]

Im serious guys...And we live here in Beaumont, where Rita was in 2005...Now a possible Jerry.

[Derek Ortt]

Jeff Masters forgets to metnion that SHIPS is run off of the medium BAM, which is initialized in the completely wrong location. The surface temperatures rapidly cool as the system is in CENTRAL ALABAMA!!! That is why SHIPS keeps this below hurricane intensity.

He may have the right outcome, but the reasoning is quite hard to understand

[Wx_Warrior]

That's why I asked....

Anyhow, I see the L forming west of Ft Myers...Anyone agree?

[Ed Mahmoud]

West winds in the Keys, per NDBC obs.

1008.8 mb with falling pressure at Long Key, for example. Very light West winds

[marcane_1973]

Seems to be slightly North of Melbourne.. Off the Cocoa area

What is north of Melbourne....not another center?
How many is that now?

Too many. Nothing will probably develop now but at least some areas of Florida, Georgia and the Carolinas will get some rain. Former Ingrid has a better shot than this invest as well as the ULL west of Florida.

[dixiebreeze]

Based on Recon coordinates for flights Thurs., I'd have to go with S. Louisiana for landfall -- if it develops.

[Wx_Warrior]

Yes...would love for this 2 stay sub-tropical and nothing serious form but...