Trop Wave in Central Caribbean

[Berwick Bay]

New trop wave enters E Carib with "inverted V signature" as noted by NHC. No shear here, or interaction with ULL, as wave in and of itself makes it way across Carib.

[cycloneye]

000
FXCA62 TJSJ 221010
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
610 AM AST SUN JUL 22 2007

.SYNOPSIS...A TROPICAL WAVE HAS ENTERED THE EASTERN CARIB
OVERNIGHT AND WAS FLARING UP CONVECTIVELY ACROSS NORTH PORTIONS OF
WAVE ACROSS THE LEEWARDS AND ADJACENT ATLC AND SHIFTING WSW INTO
THE OPEN NE CARIB. TUTT AXIS EXTENDED FROM THE NW CARIB AND
YUCATAN NE INTO THE SW ATLC WITH SMALL UPPER HIGH NOW JUST NW OF
LOCAL AREA PRODUCING MILD SUBSIDENCE ALOFT OVER THE LOCAL AREA IN
NELY FLOW...WHILE JUST TO THE SE CNVTN WAS INCREASING AS NW AND N
PORTION OF WAVE HAS ENCOUNTERED DEEP ELYS.

&&

.DISCUSSION...AEW MOVING INTO E CARIB ATTM REMAINS TILTED SW TO
NE IN THE HORIZONTAL. THIS WAVE WAS A TEXTBOOK EXAMPLE OF A NV-SV
COUPLET AS IT EXITED AFRICA LAST WEEK...WITH SV TRAILING NV TO THE
ESE NOW THE DOMINANT SIGNAL AS IT CROSSES THE LESSER ANTILLES. A
25-30 KT AEJ SEGMENT ACCOMPANIES THIS WAVE COMPLEX AND WILL BE
MOVING ACROSS THE LOCAL AREA DURING THE NEXT 24-30 HOURS AND WILL
PROVIDE THE DYNAMICS TO INDUCE QUICK MOVING DEEP CNVTN ACROSS THE
LOCAL AREA...WITH DOWNDRAFTS LIKELY TO PRODUCE SQUALLY CONDITIONS
ACROSS THE LOCAL ISLANDS AND WATERS...BEGINNING LATE THIS
AFTERNOON AND EVENING. LOOK FOR STABLE CONDITIONS ACROSS THE LOCAL
AREA THIS MORNING TO GRADUALLY BE REPLACED BY INCREASING LOW TO
MID LEVEL FLOW AND MOISTURE...WITH SOME DIURNAL CNVTN DEVELOPING
ACROSS WRN P.R. AND IN LEEWARD STREAMERS...WITH SCATTERED TO
NUMEROUS SQUALLS AND TSTORMS THEN MOVING QUICKLY INTO THE AREA
FROM THE EAST AROUND SUNSET AND INTERMITTENTLY AFFECTING THE AREA
OVERNIGHT THROUGH MONDAY MORNING. WAVE WILL EXIT THE AREA DURING
THE MORNING MONDAY...BUT LINGERING MOISTURE AND CONVERGENT BAND
WELL TO THE EAST OF WAVE AXIS TO MOVE ACROSS THE AREA MONDAY
AFTERNOON FOR CONTINUED RAIN CHANCES. UPPER HIGH VENTING CNVTN
LOCALLY SINCE LAST WAVE PASSAGE THURSDAY WILL AMPLIFY AND SHIFT
SLIGHTLY W NEXT 48 HOURS...AND IS EXPECTED TO PRODUCE MODERATELY
UNSTABLE CONDITIONS ACROSS MOST OF THE LOCAL AREA. ATLC LLVL RIDGE
FORECAST TO PERSIST THROUGHOUT THE WEEK YET WEAKEN...WITH SAL AND
MORE STABLE CONDITIONS PREVAILING ACROSS THE LOCAL AREA TUESDAY
INTO WEDNESDAY. NEXT TROPICAL WAVE ALSO HAS NV-SV COUPLET BUT
WITH GFS FORECASTING A WIND SURGE TO RACE OUT AHEAD OF SLOW MOVING
SV...AND ACROSS THE LOCAL AREA WEDNESDAY. WE HAVE ADVERTISED THIS
WIND SURGE PASSAGE AS A TROPICAL WAVE FOR WEDNESDAY...BUT WILL
LIKELY NEED TO CORRECT THIS MODEL INTERPRETATION. GFS FORECASTS
ELONGATED MONSOONAL TROUGHING TO PREVAIL ACROSS THE E AND CENTRAL
TROPICAL ATLC THIS WEEK AND WILL MAKE WAVE TRACKING MORE
CHALLENGING AS VORTICITY IS LEFT BEHIND IN TROF FROM NEXT COUPLE
OF WAVES. INDUCED MID TO UPPER LEVEL TROFFING ACROSS THE LOCAL
AREA FOR THE LATTER HALF OF THE WEEK IS EXPECTED TO PRODUCE
MOISTURE CONVERGENCE ACROSS THE REGION AND DESTABILIZE THE
ATMOSPHERE SUFFICIENTLY FOR SCATTERED RAIN CHANCES WEDNESDAY
THROUGH FRIDAY MORNING...BEFORE SAL AND MORE STABLE CONDITIONS
BEGIN TO DOMINATE LOCAL REGION AGAIN FOR NEXT WEEKEND.

&&

.MARINE...AS MENTIONED...A LOW TO MID LEVEL JET OF 25-30 KT
ACCOMPANYING CURRENT TROPICAL WAVE WILL HELP TO INITIATE
THUNDERSTORMS ACROSS THE REGIONAL WATERS THIS AFTERNOON THROUGH
MONDAY...AND COULD BE TRANSFERED DOWN TO THE SURFACE IN RAINFALL
TO PRODUCE WIND GUSTS OF 35 KNOTS AND GREATER. MARINERS ARE URGED
TO EXERCISE CAUTION AND BE PREPARED FOR THIS SQUALLY WEATHER. WIND
AND SEAS ASSOCIATED WITH TROPICAL WAVE PASSAGE EXPECTED TO BE AT
OR JUST UNDER SCA CONDITIONS...AND HAVE CHOSEN NOT TO ISSUED ANY
SCA AS OF YET.



This is what we can expect here in the Puerto Rico/Virgin islands area from this wave.Nothing out of the ordinary at this time.

Berwick,if you remember,this was the wave that had a naked surface low when it emerged Africa but the low went away midway between Africa and the Lesser Antillesa.Remember the thread that I made about the surface low?

mj,let's see if your garden gets some rain from this.

[wxman57]

New trop wave enters E Carib with "inverted V signature" as noted by NHC. No shear here, or interaction with ULL, as wave in and of itself makes it way across Carib.

Are you implying that an upper-level low would be detrimental to development? An upper-level low can be a feature that assists in the development of a tropical cyclone. Convergence to the southeast of an upper low can produce increased convection with an approaching wave, increasing the chances that a low center will form at the surface. A wave like the one in the eastern Caribbean, with minimal convection, won't have much chance of developing without interacting with an upper low or a trof to enhance that convection. This wave will likely follow the path of the wave ahead of it that's just reaching the coast of Nicaragua - no development in the Caribbean. The place to watch will be the BoC and SW Gulf. Both of these waves may cause increased thunderstorms there next week as they turn NW and move into Mexico. Chances are development are slim, but not nonexistent.

[Berwick Bay]

Well 57, I guess a ULL can provide a positive stimulus. But can is the operative word. Actually I was simply remarking that the shower activity associated with the wave was simply that--associated with the wave, and not as last week where the big blow up was always a combination of the wave working in tandem with the ULL. If thats okay with you. BTW thank you Cyclone Eye for the reminder that this was in fact the same system which exited the African Coast with the attached swirl. I do remember your thread.

[Aric Dunn]

its not going to be the one that develops south of cuba..

[Cyclone1]

So far, it has a better chance than SW Carib. But, that's not saying much.

[Berwick Bay]

Might want to change the name of this thread to "Central Carribean", or perhaps I could have started a new thread. But this wave is giving us a pretty healthy dose of convection now as it moves south of Hispaniola. I may be feeling the effects of the upper level high which is now parked in the W Carib. I would expect more convection as the wave moves further west. Will look for some signs of organization as it moves south of Cuba in the next couple of days. Here's the IR.

[Cyclone1]

Wow! It's looking really good lately!

[Berwick Bay]

CARIBBEAN TROPICAL WAVE IS ALONG 76W S OF 21N MOVING W NEAR 20
KT. LOW LEVEL INVERTED-V SIGNATURE IS OBSERVED EXTENDING FROM
68W-81W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG
CONVECTION ARE FROM 14N-20N BETWEEN 74W-82W INCLUDING JAMAICA
AND SE CUBA.

[StormTracker]

CARIBBEAN TROPICAL WAVE IS ALONG 76W S OF 21N MOVING W NEAR 20
KT. LOW LEVEL INVERTED-V SIGNATURE IS OBSERVED EXTENDING FROM
68W-81W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG
CONVECTION ARE FROM 14N-20N BETWEEN 74W-82W INCLUDING JAMAICA
AND SE CUBA.

Lot's of convection, but southbound? What's causing that

[tailgater]

CARIBBEAN TROPICAL WAVE IS ALONG 76W S OF 21N MOVING W NEAR 20KT. LOW LEVEL INVERTED-V SIGNATURE IS OBSERVED EXTENDING FROM
68W-81W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG
CONVECTION ARE FROM 14N-20N BETWEEN 74W-82W INCLUDING JAMAICA
AND SE CUBA.

Lot's of convection, but southbound? What's causing that

It's moving west, it's just the shear from UH over western Caribbean

[Aric Dunn]

watch the area south of Jamaica.. close today.. there appears to be a bit more concentrated convection and.. there is pretty discernible curvature.. little more than yesterday the trade wind in the carrib and relaxed alot.. which is why i think there should be some renewed interest.. .. as it reaches the NW carrib... later to and tomorrow..

if nothing happen then it will cross into the BOC and into mexico without any fan fair.. but if it keeps up today ... it may get interesting..

the ramsdis site on the second floater has it over the system http://www1.cira.colostate.edu/ramm/rms ... PICAL.html


with an upper ridge in place this wave has a better shot at developing than any of the previous waves..

[Aric Dunn]

925mb.. vort. has increased slightly.. with what i said about there being a little more curvature.(or spin ) happening




too bad the buoy's are not working in the area..

[Bane]

i'd give it a 5% chance to get organized.

[Aric Dunn]

there may actually be a small low forming within the southern most area of convection

[Bane]

doubtful

[Berwick Bay]

You know Aric, you may be right about this one (possible low developing south of Jamaica). Perhaps you are someone else might have a closer image in which to examine this, but I'm tending to agree with you that a low is forming right now in the W Carribean. But, the thing is, its motoring along at close to 20kts and it won't have much time to develop before impacting the Nicaraguan coast. Another thing, I wasn't much concerned earlier, but I'm beginning to take another look at the Eastern GOM. I know that shear is high off Tampa. But, if you look a little further north, not far south of Panama City, conditions don't appear as hostile there and thunderstorm activity is increasing. Matter of fact, convection across the entire E GOM is becoming more impressive.

[Aric Dunn]

i have re looked at that area south of jamaica .. it is not as impressive as i first thought.. it is moving nearly 20mph which would bring it into central america later today and it does not have enough time. although there maybe something trying to get going at the surface (maybe a small low) it is moving too fast and still only has minimul convection ! so i doubt anything will become of this in the carrib. maybe the next wave. focus should probably be turned the eastern atlantic waves they have i think a some more pontential over the next few days.

unless the wave slows down it does not have much of a chance..