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

[cycloneye]

8 AM TWO

A TROPICAL WAVE OVER THE CENTRAL ATLANTIC LOCATED ABOUT 900 MILES
EAST OF THE WINDWARD ISLANDS IS PRODUCING LIMITED SHOWERS AND
THUNDERSTORMS. UPPER-LEVEL WINDS ARE BECOMING LESS FAVORABLE FOR
DEVELOPMENT AS IT MOVES WESTWARD TO WEST-NORTHWESTWARD AT
15 TO 20 MPH. THERE IS A LOW CHANCE...10 PERCENT...OF THIS SYSTEM
BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

[bvigal]

1. This area has been described repeatedly by NHC as a "tropical wave", yet TAFB has so far not identified it as a tropical wave on their 4-daily surface maps. Looks like a healthy twave to me.

Here in the eastern Caribbean, we all know well that tropical waves have weather consequences, they don't have to develop into cyclones. Garden-variety thunderstorms produce gusts of 20-30kt, tropical wave thunderstorms produce gusts 30-50kts, and I can refer you to some sailors who have experienced it first-hand in blow-downs, ripped sails and broken masts. Garden-variety clouds and rain produce showers that can be heavy, tropical waves dump buckets of water in a very short time.

It disturbs me that so far this season, TAFB has failed to identify so many tropical waves. And NWS/PR calls this a "perturbation in the westerlies" - isn't that part of the textbook definition of a tropical wave? (I believe I could go look this up and find those exact words in a definition online) Has it become politically incorrect to use the term? The general public here has come to understand what to expect from the term "tropical wave". They are much less informed what to expect from a "perturbation in the westerlies", or "trough".

2. The area is only days away from the islands, it deserves to have an invest, so that some information is available. Yes, I know about the experimental pouches. I'm talking about an invest that allows NRL sats, regular models, etc.

3. While it looks like upper air features could make it difficult to develop in the short term, the moisture is very deep (PW product, below). This looks like it could bring some very nasty weather to the islands, with potential threats in winds/seas, and rains/flooding/mudslides, even if not organized into a cyclone.

[cycloneye]

Forecaster Blake says showers are limited,but I see plenty of those.

[HURAKAN]

shear has certainly increased today

[bvigal]

Good morning Luis and Gusty!
Yes, that tropical wave at 33W. But this one, at about 50W, in same TWD is not mentioned as a wave, only troughs in ITCZ discussion.

(from Tropical Weather Discussion 8am)
.TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT WED SEP 29 2010

..TROPICAL WAVES...

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 18N33W 14N32W
10N31W MOVING WESTWARD 10 TO 15 KT. STRONG RAINSHOWERS
AND THUNDERSTORMS ARE FROM 8N TO 15N BETWEEN 27W AND 34W.

...THE ITCZ...

8N13W 9N20W 11N27W...7N34W 8N52W. ISOLATED MODERATE RAINSHOWERS
ARE ELSEWHERE FROM 3N TO 14N BETWEEN AFRICA AND 40W...AND FROM
3N TO 10N BETWEEN 40W AND 55W. ONE SURFACE TROUGH IS ALONG
44W/45W FROM 10N TO 17N. CONVECTIVE DEBRIS CLOUDS AND REMAINING
RAINSHOWERS ARE FROM 10N TO 18N BETWEEN 43W AND 46W.
A SECOND TROUGH IS ALONG 16N51W 9N55W. STRONG RAINSHOWERS
AND THUNDERSTORMS ARE FROM 11N TO 13N BETWEEN 51W AND 55W.
OTHER RAINSHOWERS ARE FROM 11N TO 17N BETWEEN 48W AND 54W.

THE ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH IS ALONG 26N47W...TO A 22N54W CYCLONIC
CIRCULATION CENTER...INTO THE NORTHEASTERN CARIBBEAN SEA NEAR
18N62W. ANOTHER TROUGH GOES FROM 33N49W TO 28N56W. RAINSHOWERS
AND THUNDERSTORMS ARE OCCURRING FROM 24N TO 28N BETWEEN 55W AND
60W. RAINSHOWERS ALSO ARE OCCURRING FROM 20N TO 28N BETWEEN
63W AND 70W...IN UPPER LEVEL DIFFLUENT FLOW. AN UPPER LEVEL
TROUGH PASSES THROUGH 33N25W TO 19N33W. THE 1018 MB REMNANT
LOW PRESSURE CENTER OF LISA THAT IS NEAR 30N33W. ISOLATED
MODERATE RAINSHOWERS ARE FROM 29N TO 32N BETWEEN 26W AND 30W.

(edited to include ITCZ portion of discussion of 2 troughs by TAFB)

[Gustywind]

Good morning Luis and Gusty!
Yes, that tropical wave at 33W. But this one, at about 50W, in same TWD is not even mentioned. NOTHING is mentioned south of 20N west of 33W! Are the satellite and PW products hallucinating?

(from same Tropical Weather Discussion 8am)
THE ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH IS ALONG 26N47W...TO A 22N54W CYCLONIC
CIRCULATION CENTER...INTO THE NORTHEASTERN CARIBBEAN SEA NEAR
18N62W. ANOTHER TROUGH GOES FROM 33N49W TO 28N56W. RAINSHOWERS
AND THUNDERSTORMS ARE OCCURRING FROM 24N TO 28N BETWEEN 55W AND
60W. RAINSHOWERS ALSO ARE OCCURRING FROM 20N TO 28N BETWEEN
63W AND 70W...IN UPPER LEVEL DIFFLUENT FLOW. AN UPPER LEVEL
TROUGH PASSES THROUGH 33N25W TO 19N33W. THE 1018 MB REMNANT
LOW PRESSURE CENTER OF LISA THAT IS NEAR 30N33W. ISOLATED
MODERATE RAINSHOWERS ARE FROM 29N TO 32N BETWEEN 26W AND 30W.

Thanks my BVIGAL, Gusty is here Nice analysis in your previous post, i will continue to keep an eye on this feature. I saw that Bvigal that's why i prefered (my previous post) to delete it, that's very strange no mention of this feature at 50W...

[GCANE]

Very high rain-rate cell firing off in low shear.

Building up cirrus.

[Aquawind]

The yellow area is behind this blob..nice blob though..

[Sanibel]

This one has a weak satellite appearance but is positioned to enter the Caribbean in a traditional way unlike Nicole. And it's a little close on the heels of Nicole.

[chrisjslucia]

The yellow area is behind this blob..nice blob though..

Then I have to agree with BVIGal, as the blob is what CIMMS Predict are referring to as PG1511L - and this is fast approaching the Windwards / Leewards

[MWatkins]

Of everything out there not named Nicole, this is probably the next area to watch, unless zombie Matthew comes back on us again.

MW

[HURAKAN]

TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT WED SEP 29 2010

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

THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON TROPICAL
STORM NICOLE...LOCATED ABOUT 80 MILES NORTHEAST OF HAVANA CUBA.

A TROPICAL WAVE OVER THE CENTRAL ATLANTIC LOCATED ABOUT 700 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 15 TO 20 MPH. THERE IS A LOW CHANCE...10 PERCENT...OF THIS
SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

SHOWERS AND THUNDERSTORMS HAVE INCREASED NEAR A TROPICAL WAVE OVER
THE EAST-CENTRAL TROPICAL ATLANTIC CENTERED ABOUT 850 MILES
WEST-SOUTHWEST OF THE CAPE VERDE ISLANDS. SOME SLOW DEVELOPMENT OF
THIS SYSTEM IS POSSIBLE OVER THE NEXT SEVERAL DAYS AS IT MOVES TO
THE WEST AT 15 TO 20 MPH. THERE IS A LOW CHANCE...10 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 BLAKE

[Aquawind]

Convection continues to expand and refire with this area..

http://weather.msfc.nasa.gov/cgi-bin/post-goes

[Gustywind]

[FireRat]

10% plus 10% gives a 20% likelihood of seeing one of these two waves developing in the next few days once they enter the Caribbean. We might want to pay close attention to the Caribbean October 7th-9th. This may be one of the better shots at seeing a hurricane down there, and has been the scene of the previous days' model runs hinting at some formation around that time. This would be likeliest should two or more of those waves combine into a stronger one in the Caribbean. I would start watching for development there by October 3rd, with the storm's likely landfall dates being the 7th-9th......just my opinion.

[Vortex]

This area looks very suspect this afternoon..It should move into the leewards within 48 hours...

[northjaxpro]

This area looks very suspect this afternoon..It should move into the leewards within 48 hours...

I agree. We may see our next invest out of this area if the convection continues on its approach to the Eastern Caribbean and the Leeward Islands in the next couple of days.

[Vortex]

18Z NAM moves it west to a position SE of PR in 3 days....200mb has a ridge N and NW of PR which would allow the system to track wnw...



H84


http://www.nco.ncep.noaa.gov/pmb/nwprod ... p_084l.gif

[Aquawind]

Oh NOOOOOO Not another "broad circulation"

[Vortex]

18Z NAM Loop...looks very interesting


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