Invest 99L,Near Windwards,Thread #4

[MiamiensisWx]

It resembles a sfc trough interaction - weak convergence generates spontaneous persistent bursts of convection. Low-level winds have been oriented from the south, hence the shear. I do think a stable mid-level air mass is the primary negative factor. Additionally, this system has been shallow and weak from the day of its ITCZ birth. I think shortwave has revealed some interesting truths about this system. Any low-level circulation is weak, but the lack of convection probably revealed its well-defined nature. If it can survive through the next 18 hours, it could still develop - I wouldn't completely kill its chances.

[Normandy]

^This looks like a definite semi-closed low now that thunderstorms havn't completely covered its structure. Its not a very strong one, but I think it might be there,

[Meso]

000
ABNT20 KNHC 010906
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
530 AM EDT WED AUG 1 2007

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

THE AREA OF LOW PRESSURE ASSOCIATED WITH A TROPICAL WAVE HAS
CONTINUED TO MOVE WESTWARD AND IS CENTERED A COUPLE HUNDRED MILES
EAST OF THE SOUTHERN WINDWARD ISLANDS. THIS SYSTEM HAS CHANGED
LITTLE OVERNIGHT...BUT IT STILL HAS THE POTENTIAL TO BECOME A
TROPICAL DEPRESSION DURING THE NEXT DAY OR TWO AS IT MOVES WESTWARD
NEAR 15 MPH. EVEN IF DEVELOPMENT DOES NOT OCCUR...THIS SYSTEM WILL
LIKELY BRING A FEW SQUALLS TO THE WINDWARD ISLANDS DURING THE NEXT
DAY OR SO. AN AIR FORCE PLANE IS SCHEDULED TO INVESTIGATE THE AREA
THIS AFTERNOON...IF NECESSARY.

[HURAKAN]

[Nimbus]

This system is taking the same track as Earl in 2004.

http://www.nhc.noaa.gov/2004earl.shtml

The only differences in development factors are the slower forward speed thus far, and the preceding wave that is increasing moisture ahead of the circulation.

If convection continues on an uptrend they may send recon. That would be the only way they would upgrade to depression before the windwards.

[HURAKAN]

Even if it develops, the effects to the islands will be the same as if 99L doesn't develop.

[colbroe]

Over the last few hours Cloud tops have started to get cold and are building around the center of circulation, if this strengthening continues it might even be a storm before it gets to the islands , remember the waters in that general region is very warm , and there is no SAL to deal with

[wxman57]

I don't see any improvement in organization this morning. Can't identify any LLC. Weak MLC appears to be around 11.7N/55.2W. Convection is out ahead of this MLC. Can't see any reason for recon today,and probably not tomorrow, either. If any development does occur, it might have to wait 4-5 days until it reaches the western Caribbean near Honduras.

[drezee]

surface circulation looks much better on the shortwave and first three visible shots...yesterday it was elongated and diffuse...

[caneman]

I agree it does look much better. Still think it would be a day away from recon and/or depression. If it doesn't happen before the islands I don't think it will til central or west/Caribb.

[Hyperstorm]

I don't see any improvement in organization this morning. Can't identify any LLC. Weak MLC appears to be around 11.7N/55.2W. Convection is out ahead of this MLC. Can't see any reason for recon today,and probably not tomorrow, either. If any development does occur, it might have to wait 4-5 days until it reaches the western Caribbean near Honduras.

I agree, Chris. That's what I've been saying for the the past day or so. Development possible in the central or western Caribbean.

This tropical wave is a persistent system and has the look of one that will decidedly develop when conditions improve. I'm still monitoring it as it approaches the islands for some very squally weather.

Its structure has improved some since yesterday as any low-mid level shear that was present yesterday is not as pronounced today and the dry air shouldn't be a problem with less shear affecting it. Finally, I think the actual slow development that we've been anticipating will begin soon as there are less inhibiting factors. However, any development should wait until it reaches the area SW of Puerto Rico and on westward because tropical systems take a while to consolidate, even when conditions are optimum.

One sign that shows its structure has improved is...watch how convection is blossoming right now and should continue doing so during the morning hours (as it's supposed to under normal circumstances)...

[Hyperstorm]

Forgot to add that it wouldn't be surprising if the system resembles a tropical cyclone on satellite later today with blossoming of convection, but it shouldn't be there just yet. In other words, on satellite it should look similar to what it looked like two days ago. If it wasn't for yesterday's "bump" we could have seen it classified yesterday afternoon. I'd give it 36-60 hours for any tropical cyclone classification.

[punkyg]

This picture of 99L looks poopy
http://www.ssd.noaa.gov/goes/flt/t2/vis.jpg

*SIGH*

[Fego]

Area Forecast Discussion, from NWS in Puerto Rico (5:15 a.m.)
... WAVES ARE MOVING
OFF OF AFRICA IN A VIGOROUS STATE AND EVEN SHOW SOME
ROTATION...BUT CURRENTLY THE GFS WEAKENS THEM RATHER
QUICKLY...PERHAPS BEING WEAKENED BY DRIER NORTHERN VORTICITY
CENTERS. IN ANY EVENT THEY REMAIN WAVES AS THEY APPROACH THE AREA
THROUGH THE NEXT SEVEN DAYS. THE DISTURBANCE N0W NEAR 12 NORTH 56
WEST WILL CONTINUE IN A WEST NORTHWEST TRACK THAT WILL TAKE IT
WELL SOUTH OF OUR OUTER CARIBBEAN WATERS. CURRENT GUIDANCE
SUGGESTS THAT IT WILL GRADUALLY ORGANIZE AND STRENGTHEN...BUT WILL
BE OF NO EFFECT HERE.

[punkyg]

I don't get it. are they talking about 99L or that wave thats coming off or
should i say already off africa?

[NDG]

Definitely looking a little better this morning, convectionwise, than last evening, looking at the first vis sat loop, still has a descent organization, I put the symbol L where I think the low's center is this morning. I don't know if flying a recon into it will be necessary, between Barbabos and the sat loops should give us a good indication later on this afternoon if the system is TD worthy or not.

[punkyg]

NDG if your correct then some convection in forming over the center.

[Fego]

I don't get it. are they talking about 99L or that wave thats coming off or
should i say already off africa?

Both. First they analyze the waves near Africa, then, Invest 99L

[punkyg]

Are they suppose to fly in 99L today or tomorrow?

[HURAKAN]

Are they suppose to fly in 99L today or tomorrow?

Today.

TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
530 AM EDT WED AUG 1 2007

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

THE AREA OF LOW PRESSURE ASSOCIATED WITH A TROPICAL WAVE HAS
CONTINUED TO MOVE WESTWARD AND IS CENTERED A COUPLE HUNDRED MILES
EAST OF THE SOUTHERN WINDWARD ISLANDS. THIS SYSTEM HAS CHANGED
LITTLE OVERNIGHT...BUT IT STILL HAS THE POTENTIAL TO BECOME A
TROPICAL DEPRESSION DURING THE NEXT DAY OR TWO AS IT MOVES WESTWARD
NEAR 15 MPH. EVEN IF DEVELOPMENT DOES NOT OCCUR...THIS SYSTEM WILL
LIKELY BRING A FEW SQUALLS TO THE WINDWARD ISLANDS DURING THE NEXT
DAY OR SO. AN AIR FORCE PLANE IS SCHEDULED TO INVESTIGATE THE AREA
THIS AFTERNOON...IF NECESSARY.