ATL: EX-Tropical Depression FIVE - Discussion

[Ivanhater]

[Aric Dunn]

well looking at some obs.. it seems the sea breeze has developed all along the panhandle. That means the surface circ is very weak at the moment. So tonight when we lose the sea breeze is when things should start taking shape.

Yeah that may help to disrupt the southern part of the circulation a little but I've imagine given the broad nature of the low that won't cause too many issues, I'm liking this one Aric, what do you think about it?

It has potential thats for sure. the upper environment and over all environment seems quite conducive once it gets over water. Im expecting lightly farther south track that most of the models simply because once the circulation tightens up it should rotate farther south similar to what happened when many other system that get pushed south like this. Katrina for instance bottomed out quite a bit south of the models before it begin to turn. it of course wont be that strong but the types of tracks systems take in these types of situations are similar. So I am expecting to become a TC and could become a decent TS.

[KWT]

Interesting Ivanhater, those obs obviously suggest a weak closed circulation at the surface nut those winds aren't too impressive just yet even out to sea, just 15kts at the moment.

[baygirl_1]

A little surprised there has been a lot of lighting going on now in Pensacola. I thought it would be mostly tropical downpours. Maybe when the low gets over water, it will take on more tropical characteristics....pretty loud outside now

Yeah, it's been fairly loud here in Mobile, too, and looks to get even louder acc. to radar (http://radar.weather.gov/radar.php?rid=MOB&product=NCR&overlay=11101111&loop=yes. It will be interesting to see if these thunderstorms transition to the heavy tropical downpours we usually see in depressions and storms once the low gets over water. Not that I want all that rain... we've had quite a bit lately.
And here's the latest Mobile NWS Area Forecast Discussion:

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOBILE AL
410 PM CDT SUN AUG 15 2010
.SHORT TERM...(TONIGHT THROUGH TUESDAY)...MORNING MODELS RUNS HAVE
COME INTO AGREEMENT THAT THE SFC LOW PRESSURE (REMNANTS OF TD 5) OVER
AL/FL BOARDER WILL MOVE FARTHER SOUTH INTO THE COASTAL WATERS BEFORE
MAKING THE TURN TO THE WEST. THIS WILL DO TWO THINGS...DECREASE THE
HEAVY RAIN THREAT AND INCREASE THE CHANCE THAT IT WILL REDEVELOP.
THE NATIONAL HURRICANE CENTER HAS UPPED THE PROBABILITIES OF
DEVELOPMENT TO 30 PERCENT. THIS LOW WILL EMERGE OVER THE WATER
TONIGHT AND CONTINUE TO MOVE SOUTHWEST OVERNIGHT BEFORE TURNING
WESTWARD ON MONDAY. THIS WILL TAKE THE HEAVIEST RAIN OFFSHORE WITH A
GENERAL 2 TO 4 INCHES EXPECTED IN MOST LOCATIONS WITH THE HEAVIER
TOTALS ALONG COASTAL AREAS. THIS SHOULD NOT BE ENOUGH TO CAUSE
WIDESPREAD FLOODING PROBLEMS SO WILL NOT ISSUE A FF WATCH AT THIS
TIME. THE LOW WILL MOVE WEST INTO LOUISIANA BY TUESDAY AFTERNOON
TAKING THE CHANCE OF HEAVY RAIN WITH IT. THIS WILL LEAD TO
DECREASING RAIN CHANCES LATE TUESDAY AND TUESDAY NIGHT. MODEL
GUIDANCE CONTINUES TO RUN TOO WARM WITH MAX TEMPS ESPECIALLY ALONG
THE COAST AND HAVE BUMPED THEM DOWN A COUPLE OF DEGREES. /13

[srainhoutx]

Lake Charles afternoon AFD...snip...

THINGS GET MORE INTERESTING AS WE MOVE INTO THE TUESDAY/WEDNESDAY
TIME FRAME. AN AREA OF LOW PRESSURE WHICH IS THE REMNANTS OF T.D.
FIVE CURRENTLY LOCATED OVER THE FLORIDA PANHANDLE WILL EMERGE
INTO THE NORTHERN GULF OF MEXICO LATER TONIGHT. ALL GLOBAL MODELS
HAVE BEEN CONSISTENT WITH THIS FEATURE AND MOVING IT TOWARDS THE
WEST ACROSS THE SOUTHERN LA COAST BY LATE TUESDAY INTO WEDNESDAY.
GFS AND NAM A BIT MORE AGGRESSIVE THAN THE ECMWF. NHC HAS UPGRADED
THEIR OUTLOOK ON THIS SYSTEM TO 30% OR MEDIUM CHANCE THIS WILL
DEVELOP INTO A TROPICAL DEPRESSION BY TUESDAY. HURRICANE HUNTERS
ARE SCHEDULE TO INVESTIGATE THIS LOW PRESSURE AREA TOMORROW
AFTERNOON IF NECESSARY. REGARDLESS IF IT DOES DEVELOP OR NOT THIS
WILL BRING A GOOD AMOUNT OF RAINFALL ACROSS THE SOUTHERN AND
EASTERN AREAS OF THE CWA. LATEST HPC QPF TOTALS HAS ROUGHLY 3 TO
5 INCHES ACROSS PORTIONS OF ACADIANA AND SOUTH CENTRAL LA. 2 TO 3
INCHES FOR SWLA AND LESSER AMOUNTS FOR SE TX AT 1 TO 2 INCHES
POSSIBLE. THIS SYSTEM APPEARS IT WILL SLOWLY MOVE WEST-
NORTHWESTWARD TUESDAY NIGHT INTO WEDNESDAY ACROSS OUR CWA WHICH
HAS THE POTENTIAL TO PRODUCE SOME HEAVY RAINFALL. FORECAST PW
VALUES ARE UP TO 2.8 IN WHICH IS A VERY TROPICAL. DEPENDING ON
THE EVOLUTION AND TRACK OF THIS LOW WILL GREATLY AFFECT THE
FORECAST AND WILL NEED TO BE FINE TUNED. WE MAY BE LOOKING AT A
FLASH FLOODING THREAT FOR PORTIONS OF ACADIANA IF THIS SCENARIO
PANS OUT. STAY TUNED.

[Ivanhater]

SYNOPSIS FOR THE GULF OF MEXICO
430 PM CDT SUN AUG 15 2010

.SYNOPSIS...HIGH PRES RIDGE ALONG 26N WILL WEAKEN AS A LOW
DEVELOPS OVER THE FAR NE GULF MON AND MAY STRENGTHEN AS IT
DRIFTS W TOWARDS SE LOUISIANA TUE.

[KWT]

Looking at the Sat.loops the westerly wind has weakened a little on the southern side bit the sea breezes probably are to blame...

The other thing to note is the convection which is developing at a decent clip now around the eastern and southern sid of the circulation.

[wxman57]

Here's an animation I made of the 12Z GFS positions. Isobars are plotted every 0.25 millibar to give better resolution. Valid times are at the bottom of the animation. I'll just post a link to the animation, as it's about 1MB in size.

http://myweb.cableone.net/nolasue/GFSloop.gif

[cycloneye]

Almost reaching the water.

[Dean4Storms]

http://www.weather.gov/forecasts/wfo/images/tae/WindSpd4_tae.png

Yep, that clearly shows the Low near Mariana, FL as I indicated earlier, still dropping southward.

[MiamiHurricanes10]

Based on latest satellite and Doppler radar loops, the lower level circulation of ex-05L appears to be halfway through the coast. It will likely be fully emerged into open Gulf waters by 7:00 to 8:00 PM EDT tonight.

[DTWright]

Getting some big TS's here now. Loads of Thunder & Lightning & Heavy Rain.

[Aric Dunn]

radar, satellite and some surface obs are hinting at something just sse of the Eglin radar site sitting just inland from the coast. it could be a reformation taking place so could be place to watch ..

[KWT]

I don't think its quite at the water yet, the surface obs suggests its a little bit away just yet, probably its the increasing northerly winds at higher levels which is forcing the convection southwards.

I maybe wrong but looks like the LLC maybe weakening a little as it gets closer to the coast, but its hard to tell due to the increase in the convection.

[Dean4Storms]

radar, satellite and some surface obs are hinting at something just sse of the Eglin radar site sitting just inland from the coast. it could be a reformation taking place so could be place to watch ..

Actually you are correct, looks to be just ENE of Panama City. The Eglin Radar site is kind of misleading because the actual radar site is near Bruce, FL between Ebro and I-10, I pass the radar all the time taking the shortcut from here to I-10. Whereas the Eglin base proper is back to the west a good 40 miles or so just north of FT Walton Bch. FL

[MiamiHurricanes10]

Considering that this will be making its second landfall in a maximum time of 60 hours, I would think that the NHC would raise the percentage (since the chance if for the next 48 hours). I would raise it to 60% if I were the NHC.

[ROCK]

12Z EURO would suggest even more west to mid-Texas coast...if that was the case then it would have plenty of water to get going....I wouldnt discount it WXMN57.....

this whole scenario seems eerily similar to IVAN II....it also hugged the coast a good ways before coming ashore in SWLA....

[KWT]

radar, satellite and some surface obs are hinting at something just sse of the Eglin radar site sitting just inland from the coast. it could be a reformation taking place so could be place to watch ..

Yeah could well be a relocation occuring, just in the last couple of hours its become more difficult to find the west winds on the old circulation so I wouldn't be all that surprised if its relocating towards the sea...

[Dean4Storms]

Looks like Aric nailed it, the low has dropped south to a position about 20 miles ENE of Panama City. Convection is sustaining and rotating there on radar.

[southerngale]

Here's an animation I made of the 12Z GFS positions. Isobars are plotted every 0.25 millibar to give better resolution. Valid times are at the bottom of the animation. I'll just post a link to the animation, as it's about 1MB in size.

http://myweb.cableone.net/nolasue/GFSloop.gif

Interesting... thanks. It's so hard to tell where the center goes from the maps, at least for me. Sure looks to meander around a little... even taking a tiny dip back into the GOM in SW LA. lol