Pouch PGI51L : East of the Windwards (Is part of invest 97L)

[bvigal]

[quote=Blown Away]Why is this area not getting more attention? The convection has increased and persisted all day and there is some model support? In a few days it seems the upper level conditions will improve. [/quote]
Well, that's what I was wondering this morning, not because of models, but because some foul weather is going to strike the islands by tomorrow, so who cares whether it develops in 48hrs? I also said upper level features could make it difficult to organize short term, but would still like to see an invest.

But TAFB has defended their position that it's 2 troughs with no future by offering this detailed description in 8am TWD:
...ITCZ...

ITCZ AXIS IS CENTERED ALONG 08N14W 07N24W 10N33W 08N37W 09N48W.
A SMALL COMPLEX OF SCATTERED MODERATE TO STRONG CONVECTION IS
ALONG THE W AFRICA COAST FROM 08N-12N BETWEEN 12W-16W AND IS
LIKELY ASSOCIATED WITH THE NEXT TROPICAL WAVE TO EMERGE OFF THE
W AFRICA COAST OVER THE NEXT DAY OR TWO. SCATTERED MODERATE AND
ISOLATED STRONG CONVECTION IS WITHIN 210 NM S OF THE AXIS
BETWEEN 17W-33W. FARTHER WEST...A PAIR OF SURFACE TROUGHS ARE
NEARING THE LESSER ANTILLES. ONE IS ANALYZED FROM 10N50W TO
18N49W MOVING W AT 10-15 KT. LOCATED ON THE SW PERIPHERY OF AN
UPPER LEVEL ANTICYCLONE...UPPER LEVEL DIFFLUENCE ALONG WITH THE
LOW-LEVEL SURFACE CONVERGENCE NEAR THE TROUGH AXIS IS GENERATING
A LARGE AREA OF NUMEROUS MODERATE AND SCATTERED STRONG
CONVECTION FROM 08N-20N BETWEEN 44W-54W. THE OTHER SURFACE
TROUGH EXTENDS FROM 10N57W TO 16N56W. AS THIS SURFACE TROUGH
MOVES W AT 10-15 KT AND COMES UNDER INCREASED VERTICAL WIND
SHEAR DUE TO UPPER LEVEL TROUGHING BETWEEN 56W-62W...ISOLATED
MODERATE CONVECTION IS WITHIN 120 NM EITHER SIDE OF THE AXIS
WHICH CONTINUES TO DISSIPATE THIS EVENING.

Btangy, I'll chime in with the others here, really have enjoyed the pouch program this season! You mention the TUTT and divergence, and we certainly know it's there. But seniors Bevin, Blake, etc. call this a twave, and despite no cyclonic turning evident via satellite, I think it is, too. We'll just have to see it the energy persists beyond the present hostile upper level conditions. Since the EC is in the path of some nasty weather next 48hrs, and I'm traveling, I sure hope I'm wrong and it is 2 dissipating troughs! Will be interesting to see what the flight finds tomorrow.

[ROCK]

nice little area...will have to keep a eye on it....

[Vortex]

I really dont see why the NHC says the environment will become less favorable for it with the upper level conditions the NAM is showing... Only problem I see right now is the second wave has wayyyy more vorticity than this one.

I don't understand it either. The nam does well with synoptics and suggests the conditions over the islands/eastern carribean becoming more favorable not less...This one I can't figure out what the Nhc is looking at...I would expect something like "conditions are currently unfavorable for development, however environmental conditions may become more conducive over the next few days for slow development"...

[Vortex]

Take a look at the 200mb charts in 66hours over the eastern carribean..looks good to me...


http://www.nco.ncep.noaa.gov/pmb/nwprod ... 0_066l.gif

[bvigal]

Here's that divergence, it is significant.

[caribsue]

[quote=Blown Away]Why is this area not getting more attention? The convection has increased and persisted all day and there is some model support? In a few days it seems the upper level conditions will improve.

Well, that's what I was wondering this morning, not because of models, but because some foul weather is going to strike the islands by tomorrow, so who cares whether it develops in 48hrs? I also said upper level features could make it difficult to organize short term, but would still like to see an invest.

Hi bvigal.... you said it "some foul weather is going to strike the islands by tomorrow, so who cares whether it develops in 48 hrs. We had some showers this afternoon here in Barbados and I expect that we will get quite a bit more tomorrow barring a miracle. Lets hope it is not too bad for us here or our other neighbours

[gatorcane]

Seems there just isn't much interest with this despite the fact it has some of the most impressive convection of any wave east of the leewards this season.

Frankly I think there is some burnout going on and lack of faith in what models are showing in the long range because of what just happened with Nicole. That and it's not august or prime-time September so seems like many think it is not going to impact them. Now if this were gom bound, this board would be jumping.

[Vortex]

18Z Nogaps turns it wsw as a ridge builds to the North of DR...Canadian also turns it due west and runs it into DR...



https://www.fnmoc.navy.mil/wxmap_cgi/cg ... t=Tropical

[Vortex]

at H84 notice ridge building N of DR..



http://www.nco.ncep.noaa.gov/pmb/nwprod ... 0_084l.gif

[cycloneye]

What is for sure is that the Eastern Caribbean islands will get plenty of rain from this.


AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
944 PM AST WED SEP 29 2010

.UPDATE...
A PERTURBATION IN THE
EASTERLIES LOCATED AT AROUND 55 WEST LATE THIS EVENING...WILL
CONTINUE TO MOVE SLOWLY WEST AND WILL REACH OUR LOCAL AREA ON
FRIDAY. VERY DEEP TROPICAL MOISTURE ASSOCIATED WITH THIS
PERTURBATION...WILL ADVECT ACROSS THE LOCAL ISLANDS LATE FRIDAY.
WITH FAVORABLE ATMOSPHERIC CONDITIONS...VERY LIGHT WINDS...AND
DEEP MOISTURE IN PLACE ACROSS THE REGION...PRESENTLY EXPECTING THE
POTENTIAL FOR A VERY WET END OF THE WEEK/WEEKEND ACROSS PUERTO
RICO AND THE U.S. VIRGIN ISLANDS. THE POTENTIAL FOR HEAVY RAIN IS
ALREADY IN FORECAST FOR BOTH FRIDAY AND SATURDAY...AND MAY
ACTUALLY SEE THIS VERY WET PERIOD PERSIST INTO THE FIRST PORTION
OF NEXT WEEK IF LATEST COMPUTER MODELS ARE CORRECT.

[Vortex]

00Z NAM loop: large system


http://www.nco.ncep.noaa.gov/pmb/nwprod ... loop.shtml

[srainhoutx]

Nice AFD Luis. If the Upper air pattern collapses in the Caribbean, things could get interesting IMO.

[btangy]

Btangy, I'll chime in with the others here, really have enjoyed the pouch program this season! You mention the TUTT and divergence, and we certainly know it's there. But seniors Bevin, Blake, etc. call this a twave, and despite no cyclonic turning evident via satellite, I think it is, too. We'll just have to see it the energy persists beyond the present hostile upper level conditions. Since the EC is in the path of some nasty weather next 48hrs, and I'm traveling, I sure hope I'm wrong and it is 2 dissipating troughs! Will be interesting to see what the flight finds tomorrow.

To all: thanks for your nice comments about PREDICT. We have been getting lots of great feedback from the public and it's really rare for any science mission to get that real-time, so thanks from all of us in St. Croix at PREDICT HQs.

I'll let you know what the GV finds tomorrow, but there was some discussion late today about the large uncertainty in whether the area we're targeting will really reveal anything. It's a shot in the dark, but who knows. I'm not sure PGI51L is an African easterly wave. I think it's more enhanced intertropical convergence zone convection that rolls up (very weakly) into a wave, but that's been a common theme this year (e.g. Matthew).

And I'm hoping I'm wrong too about PGI51L making it to the Leeward Islands. Could really screw up our team's flights out of here on Friday.

[Gustywind]

[Gustywind]

[Gustywind]

000
ABNT20 KNHC 300534
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
200 AM EDT THU SEP 30 2010

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

THE REMNANT CIRCULATION OF FORMER TROPICAL STORM NICOLE...LOCATED
ABOUT 35 MILES EAST OF FORT LAUDERDALE FLORIDA AND ABOUT 65 MILES
WEST-SOUTHWEST OF FREEPORT BAHAMAS...IS EXPECTED TO MERGE WITH A
FRONTAL SYSTEM DURING THE NEXT 12 TO 24 HOURS. THUNDERSTORM
ACTIVITY IS CONFINED MAINLY TO THE EAST SIDE OF THE LOW...AND WIND
GUSTS TO GALE FORCE WILL BE POSSIBLE IN SOME OF THE STRONGER RAIN
SQUALLS. LOCALLY HEAVY RAINFALL WILL ALSO BE POSSIBLE OVER PORTIONS
OF THE NORTHWESTERN BAHAMAS TODAY. THERE IS A LOW CHANCE...10
PERCENT...OF THIS SYSTEM BECOMING A SUBTROPICAL CYCLONE DURING THE
NEXT 48 HOURS AS IT MOVES NORTH-NORTHEASTWARD AT 15 TO 20 MPH.

A TROPICAL WAVE OVER THE CENTRAL ATLANTIC LOCATED ABOUT 600 MILES
EAST OF THE WINDWARD ISLANDS IS PRODUCING DISORGANIZED SHOWERS AND
THUNDERSTORMS. UPPER-LEVEL WINDS ARE EXPECTED TO BECOME LESS
FAVORABLE FOR DEVELOPMENT AS THE SYSTEM MOVES TO THE WEST-NORTHWEST
AT ABOUT 15 MPH. THERE IS A LOW CHANCE...10 PERCENT...OF THIS
SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

ANOTHER TROPICAL WAVE LOCATED OVER THE EAST-CENTRAL TROPICAL
ATLANTIC ABOUT 1200 MILES EAST OF THE WINDWARD ISLANDS IS ALSO
PRODUCING DISORGANIZED SHOWER AND THUNDERSTORM ACTIVITY. HOWEVER...
CONDITIONS APPEAR CONDUCIVE FOR SLOW DEVELOPMENT OF THIS SYSTEM
DURING THE NEXT COUPLE OF DAYS AS IT MOVES WESTWARD AT 15 TO 20
MPH. THERE IS A LOW CHANCE...20 PERCENT...OF THIS SYSTEM BECOMING
A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER STEWART

[cycloneye]

The 8 AM Tropical Weather Outlook statement combines this system with the one behind and now invest 97L consists of a big area that enroaches both. As is part of 97L,the thread will be locked.

TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 AM EDT THU SEP 30 2010

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

A LARGE AREA OF DISTURBED WEATHER...ASSOCIATED WITH TWO TROPICAL
WAVES...IS CENTERED ABOUT 800 MILES EAST OF THE WINDWARD ISLANDS.
SHOWERS AND THUNDERSTORMS IN THIS AREA ARE CURRENTLY
DISORGANIZED...BUT UPPER-LEVEL WINDS ARE FORECAST TO BE MARGINALLY
FAVORABLE FOR DEVELOPMENT AS THE SYSTEM MOVES WEST-NORTHWESTWARD
AROUND 15 MPH. THERE IS A MEDIUM CHANCE...30 PERCENT...OF THIS
SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER PASCH