ATL: EX-Tropical Depression FIVE - Discussion

[wxman57]

We've been discussing this possibility at work for a few days. Models have been indicating some type of frontal wave developing east of Florida for most of last week. Reminds me a lot of TD 10 from about 3 years ago. That system started out just about in the same area and the same state of organization (or disorganization). It moved and/or relocated west of Florida then tracked WNW and eventually became TD 10 just before moving inland into southern MS.

I'd say that this system may have about a 30% chance of becoming a TD/TS in the Gulf (not east of FL) before moving ashore. We did a study recently of all depressions, storms, hurricanes that developed IN the Gulf and had 48 hrs over water before moving inland. Of those 107 systems we identified, about 49% became hurricanes before reaching land.

So, if this system actually does have a 30% chance of becoming a TD/TS, then climatology alone suggest about a 15% chance (0.30 x 0.49) of reaching hurricane strength in the Gulf IF it reaches TD/TS strength 48 or more hours before moving inland. I think that it may have less time than that if it should develop, though, so odds are lower it would be a hurricane (based on climo alone, again).

More than likely, we'll see some heat-relieving thunderstorms across the central Gulf Coast later this week. Possibly a weak, sheared TS out of it, but not much wind.

[artist]

Palm Beach county getting lots of rain from this as we speak.

[CYCLONE MIKE]

Have not seen this mentioned, so check out this loop out of Melbourne, FL. Looks like some kind of mlc east of melbourne moving south. could this be the beginning of something?

http://radar.weather.gov/radar.php?rid=MLB&product=N0R&overlay=11101111&loop=yes

[chzzdekr81]

We've been discussing this possibility at work for a few days. Models have been indicating some type of frontal wave developing east of Florida for most of last week. Reminds me a lot of TD 10 from about 3 years ago. That system started out just about in the same area and the same state of organization (or disorganization). It moved and/or relocated west of Florida then tracked WNW and eventually became TD 10 just before moving inland into southern MS.

I'd say that this system may have about a 30% chance of becoming a TD/TS in the Gulf (not east of FL) before moving ashore. We did a study recently of all depressions, storms, hurricanes that developed IN the Gulf and had 48 hrs over water before moving inland. Of those 107 systems we identified, about 49% became hurricanes before reaching land.

So, if this system actually does have a 30% chance of becoming a TD/TS, then climatology alone suggest about a 15% chance (0.30 x 0.49) of reaching hurricane strength in the Gulf IF it reaches TD/TS strength 48 or more hours before moving inland. I think that it may have less time than that if it should develop, though, so odds are lower it would be a hurricane (based on climo alone, again).

More than likely, we'll see some heat-relieving thunderstorms across the central Gulf Coast later this week. Possibly a weak, sheared TS out of it, but not much wind.

Thanks Wxman. We can always trust you.

[alienstorm]

Live in western part of miami off the trail, i have measured slightly under 3 inches of rain since around noon today. A lot more headed south from Palm Beach and Broward, also had some westerly winds, that may be associated with thundrstorms.

[CronkPSU]

our last check in of the summer was a wet one, had no idea where all this rain came from, now it makes sense...looks like it will be a very wet last week of camp!

[ROCK]

flight into FT Lauderdale might be delayed or might be a bumping decent tonight......ugh....worried about tomorrow with a flight out at 11:45....

[srainhoutx]

You should be fine Paul. Heck, I've seen and have been on takeoffs at FLL in TS wind gusts.

[ROCK]

You should be fine Paul. Heck, I've seen and have been on takeoffs at FLL in TS wind gusts.

ewww...not what I wanted to hear...

[Nimbus]

There is an Upper level low rolling north into Texas and it looks like an anticyclone may develop over the gulf. Whole lot of shear pounding down from the north at the moment but once it moves across Florida into the gulf it may find better upper air support. Just eyeballing the upper air pattern it looks like this could stay out over the gulf for a few days rolling quite far south. Of course the further west it gets the more it should get steered back north again. What does the shallow BAM look like?

[KWT]

This one IMO has a good shot at becoming a weak system, not expecting anything too strong but maybe something like Edouard from 2008, interesting because that system occured at this time of year, and if this developed it'd possibly be the E storm, so we'd be about on track of 2008...

I do think its got a chance of being in the Gulf for a bit longer then Wxman57 believes, the ECM suggests steering currents being rather on the weak side, enough so that it barely manages to get it ashore at all even by 120hrs.

[wzrgirl1]

I am quite confused because we are getting pounded with rain right now but the line is coming from the northwest, not the east where all of the tropical moisture is from 94L. Is this another weather feature that we are getting rain from now down here?

[Dean4Storms]

If Shear lets up more-so than what the models are forecasting for now over the northern half of the GOM this week then this could ramp up quickly and reach Cat 1 hurricane status, but right now none of the models predict that so we shouldn't expect more than a TS Colin like sheared system at most. Once again UL winds save the day!!

[KWT]

Its a really messy systems, it reminds me of why I really do hate these sorts of systems that develop from nontropical features.

I'm not sure shear will be a issue really, its just going to take a while to organise, these sorts of systems always tend to take a while to get going I tend to find, a good 36-48hrs will probably be needed over water. I suspect it'll get that but we will see!

[JonathanBelles]

It's been WAY too wet here in St. Pete. My yard is beginning to turn brown due to all of the rain. I'm probably close to 5 inches of rain in the last week here at my house. Also of note, there was a waterspout off Indian Rocks Beach earlier today.

[KWT]

This is one of those systems where a low could possibly pop just about anywhere along the front, convection to the east of Florida sagging southwards quite alot though, if anything tries to develop there it'd be further south then the models expect.

[Aquawind]

Nice little twist on the backside of the current blob..

http://radar.weather.gov/radar.php?prod ... x&loop=yes

[KWT]

Yeah there is a spin but its real weak from the looks of things, notice how its just that area that is spinning, if it was even a moderate twist the whole convection blob would be rotating around with it.

Nothing too exciting just yet...plenty of time still though...

[tronbunny]

Interesting that, yeah, the center could develop anywhere along that line down the coast.
Here's the AFD from Melbourne
FXUS62 KMLB 081859
AFDMLB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MELBOURNE FL
259 PM EDT SUN AUG 8 2010

.DISCUSSION...

TONIGHT...MODELS A TAD SLOW IN MOVING THE SURFACE TROUGH DOWN THE
PENINSULA ONCE BUOY OBS AND METARS ARE ANALYZED. MSAS SURFACE
ANALYSIS PLACES TROUGH AXIS OVER SOUTHERN VOLUSIA AND NORTHERN
BREVARD COUNTIES AND HAS BEEN MOVING THE TROUGH DOWN THE PENINSULA
FASTER THAN MOST MODELS. LATEST RUC 500MB HEIGHT ANALYSIS HAS AN
UPPER RIDGE TRYING TO BUILD EASTWARD ACROSS THE SOUTHEAST AND GULF
IN BEHIND THE TROUGHING OVER THE WESTERN ATLANTIC RESULTING IN A
DIFFLUENT FLOW WHICH IS HELPING TO MAINTAIN STORMS AND SHOWERS
MOVING DOWN THE PENINSULA. WEAK VORT MAXES MOVING WEST TO EAST
ALONG THE TROUGHING WILL HELP KEEP A MENTION OF SHOWERS AND STORMS
OVER THE SOUTHERN AREAS OVERNIGHT WILL A QUOTED MORE STABLE
UNQUOTE AIR MASS BRIEFLY FOLLOWS THE TROUGH MOVING DOWN THE
STATES.

MONDAY...TROUGH STARTS LIFTING NORTH AS THE DEVELOPING AREA OF LOW
PRESSURES MOVES FROM THE ATLANTIC TOWARD THE GULF OF MEXICO. WITH
PRECIPITABLE WATER VALUES REMAINING AROUND 2 INCHES OVER THE
NORTHERN SECTIONS AND OVER 2 INCHES SOUTHERN AREAS A NORTH TO
SOUTH POP GRADIENT OF 40 NORTH TO 60 SOUTH WILL COVER RAIN
CHANCES. WARM UPPER LEVEL TEMPERATURES SUGGEST RAIN WITH ISOLATED
STORMS FOR THE AFTERNOON.

TUE...THE
UPPER-LEVEL LOW TRANSITS THE STATE ON TUES OVER THE SOUTH-CENTRAL
PENINSULA MON NIGHT WITH ASSOCIATED VORTICITY MAXIMA AND MOVING
OUT INTO THE EASTERN GOMEX DURING THE DAY. 500 MB TEMPERATURES
ASSOCIATED WITH THIS FEATURE ARE FORECAST AROUND -6C. DEPENDING ON
EVENTUAL TIMING...PLACEMENT AND STRENGTH OF WEAK SURFACE LOW
FEATURE FORECAST TO DEVELOP OVER THE SOUTH-CENTRAL
PENINSULA...PRECISE WIND DIRECTION MAY BE A BIT HARD TO PLACE THIS
FAR OUT. HAVE KEPT THE EAST/EAST-SOUTHEAST THROUGH THE PERIOD WITH
10-15 MPH DURING THE DAY WITH OCCASIONAL STRONGER GUSTS.

AS THE UPPER LOW MOVES OFF OF THE WESTERN PENINSULA...WE WILL SEE
WRAP-AROUND (DEEP LAYER) MOISTURE MOVE OVER EAST CENTRAL FLORIDA
WITH LIKELY (60%) POPS AREA WIDE. WILL NEED TO STAY VIGILANT FOR RAIN
BANDING NEAR THE COAST...ESPECIALLY FROM THE CAPE SOUTHWARD THROUGH
THE PERIOD...WITH LOW-TOPPED SHOWERS THAT MAY BE FAIRLY EFFICIENT AT
PRODUCING PRECIPITATION GIVEN DEEP LAYER MOISTURE PRESENT.

HIGH TEMPERATURES WILL RANGE UPPER 80S/LOWER 90S OVER COASTAL
COUNTIES & LOWER/MIDDLE 90S FURTHER INTO THE INTERIOR WITH CLOUD
COVER/PRECIPITATION POSSIBLY PLAYING A ROLE IN FINAL MAX READING
NUMBERS. LOW TEMPERATURES WILL REMAIN CONSISTENT IN THE MIDDLE/UPPER
70S.

WED-SAT...FROM PREVIOUS DISCUSSION...THE UPPER-LEVEL LOW WILL
CONTINUE TO TRACK ACROSS THE NORTH-CENTRAL GULF AND WEAKEN AS
VORTICITY MAXIMA ASSOCIATED WITH IT ARE DISPERSED INTO SOUTH
LOUISIANA AND EAST TEXAS. HIGH PRESSURE ALOFT FLATTENS OUT OVER THE
SOUTHEAST/MID ATLC STATES AS TROUGHING SETS UP NORTH ACROSS THE
GREAT LAKES STATES AND NORTHEAST U.S. CLOSER TOWARD THE
SURFACE...RIDGING OVER THE WESTERN ATLC WILL GRADUALLY SLIDE
WESTWARD TOWARD THE CENTRAL/SOUTH-CENTRAL PENINSULA. THE RIDGING
PATTERN STILL REMAINS FAIRLY WEAK WITH SOUTHERLY STEERING FLOW THU
GRADUALLY VEERING WEST-SOUTHWEST THROUGH THE PERIOD AND REMAINING
WEAK. DEEP LAYER MOISTURE DOES REMAIN FAIRLY IMPRESSIVE THROUGH THIS
PERIOD BUT WITH FORECAST HIGHS AT 500 MB AROUND -4C CANNOT GO HIGHER
THAN 30%-40% FOR POPS FROM THU-SAT. MAXES/MINS WILL CONTINUE A
COUPLE DEGREES ABOVE CLIMO ACROSS EAST CENTRAL FLORIDA.

[KWT]

Thats why I hate these systems because they often forms where you wouldn't quite expect, esp when the frontal system itself ends up drapping into the Gulf.