Wave in Central Caribbean

[KatDaddy]

WEST CENTRAL AND SOUTHWEST FLORIDA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL
237 AM EDT THU JUL 27 2006


Excerpt:

.LONG TERM (SAT NGT-WED)...AS MENTIONED YESTERDAY...THERE WERE
SOME MODEL DIFFERENCES IN THE WAY THE TROPICAL WAVE NEAR THE
LESSER ANTILLES WOULD IMPACT THE SYNOPTIC REGIME OVER THE STATE.
THE GFS AND DGEX WERE INDICATING A STRONG WAVE/WEAK LOW THAT WOULD
BREAK THE SURFACE RIDGE WHILE THE ECMWF HELD THE RIDGE FIRMLY IN
PLACE AND FORCED A WEAKER WAVE TO PASS BENEATH THE RIDGE TO OUR
SOUTH. SINCE THEN...THE LAST FEW RUNS OF THE GFS HAVE JOINED THE
ECMWF IN DEPICTING A WEAKER TROPICAL WAVE WITH CONTINUED RIDGING.

[KatDaddy]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOBILE AL
355 AM CDT THU JUL 26 2006

Excerpt:

THE TROPICAL WAVE CURRENTLY NEAR THE ANTILLES IS
DIFFICULT TO TRACK IN THE EXTENDED RANGE BUT LOOKS TO MOVE ACROSS
THE CENTRAL GULF SUNDAY THROUGH TUESDAY.

[tgenius]

Sure seems like no one has a good handle on what they think that wave is going to do.

[storms in NC]

From the WV loop this morning it looks as if there is a weakness in there and will break off. It is moving wnw now like I thought it would. Where will it goes who knows yet.To many iffs.

[bvigal]

PR/VI under flash flood watch this morning. Overnight was some incredible lightning - keeping the sky lit up almost constantly, thunder that lasted 10-15 seconds and rattled the windows, very gusty winds, and periods of heavy rain. Most of the rain has moved west with the wave, and looks like south slope of PR may have heavy rains this morning. The wind right now is howling. A lot of energy, for sure.

http://www.goes.noaa.gov/HURRLOOPS/huwvloop.html

[bvigal]

Here's this morning's local discussion - very thorough!
FXCA62 TJSJ 271005
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
605 AM AST THU JUL 27 2006

.SYNOPSIS...AT UPPER LEVELS...LOW PRESSURE AT 200 MB IS NORTH OF PUERTO RICO AND A STRONG TROUGH EXTENDS NORTHEAST FROM THAT CENTER. THE LOW WILL MOVE WEST SOUTHWEST THROUGH SATURDAY. A SECOND LOW WILL SPLIT OFF OF THE NORTHEAST END OF THIS LOW ON SATURDAY AND SLOWLY ORBIT AROUND THE FIRST LOW UNTIL IT REACHES A POSITION ABOUT 300 NM NORTH OF PUERTO RICO NEXT THURSDAY.

AT MID LEVELS...HIGH PRESSURE IN THE CENTRAL ATLANTIC WILL MIGRATE TO THE SOUTHEASTERN UNITED STATES DURING THE NEXT 48 HOURS AND WEAKEN. ALTHOUGH THE RIDGE ACROSS THE ATLANTIC WILL NOT COMPLETELY DISAPPEAR...LOW PRESSURE WILL RIDDLE THE RIDGE IN THE CENTRAL ATLANTIC AS A LONG WAVE TROUGH MOVES EAST THROUGH THE HIGHER LATITUDES UNTIL HIGH PRESSURE REDEVELOPS LATE NEXT WEEK IN THE WESTERN ATLANTIC.

AT LOWER LEVELS...A BROAD AND ACTIVE TROPICAL WAVE IS CURRENTLY CROSSING PUERTO RICO WITH CONVECTION ALIGNED IN A CLASSIC INVERTED-V. MOISTURE FROM THE SOUTHEAST WHERE THE INTER TROPICAL CONVERGENCE ZONE CURRENTLY LIES WILL CONTINUE TO FLOW OVER PUERTO RICO AND THE U.S. VIRGIN ISLANDS THROUGH SATURDAY TRIGGERING SHOWERS AND THUNDERSTORMS. AFTER DRIER AIR MOVES IN ON SUNDAY...HIGH PRESSURE WILL BE THE DOMINATING INFLUENCE AND WILL MARK THE TRANSITION FROM THE CURRENT WET PATTERN.

.DISCUSSION...THE TROPICAL WAVE MOVED OVER PUERTO RICO SHORTLY AFTER MIDNIGHT...EXHIBITING AT THAT TIME...A CLASSICAL INVERTED-V PATTERN WITH THE STRONGER ARM EXTENDING SOUTHEAST ACROSS THE U.S. VIRGIN ISLANDS AND OVER THE LEEWARD ISLANDS. AT JUST AFTER 5 AM THE STRONG CONVECTION THAT DOGGED THE NORTHERN U.S. VIRGIN ISLANDS EARLIER THIS MORNING DEGENERATED INTO A WIDESPREAD MODERATE RAIN THAT IS JUST NOW CROSSING CULEBRA AND ENTERING ONTO PUERTO RICOS EASTERN TIP. NEW CONVECTION HAS FORMED TO THE SOUTHEAST OF SAINT CROIX AND SOME NEW CELLS ARE NOW DEVELOPING JUST SOUTH OF THE ISLANDS BEACHES. RADAR SHOWS THESE CELLS MOVING NORTHWEST TOWARD SAINT CROIX AND WILL LIKELY YIELD HEAVY RAIN IN SIGNIFICANT AMOUNTS. SATELLITE PICTURES SHOW THAT THE ACTIVE CONVECTION STILL LIES MOSTLY UPSTREAM FROM THE FORECAST AREA. THIS SAME INDICATION ALSO SUGGESTS THAT THE GFS IS MOVING THE MOISTURE AWAY FROM THE AREA TOO QUICKLY AND THEREFORE HAVE INCREASED THE POPS OVER THE NEXT SEVERAL DAYS. SHOWERY WEATHER WITH SCATTERED LONG-LIVED THUNDERSTORMS WILL CONTINUE FOR SOME TIME. WITH THIS IN MIND IT WAS DEEMED PRUDENT TO EXTEND THE EXISTING FLASH FLOOD WATCH TO 6 PM AST THIS EVENING AND ADD THE WESTERN END OF PUERTO RICO TO THE WATCH IN ANTICIPATION OF STRONG THUNDERSTORMS FORMING OVER THE WESTERN HALF OF THE ISLAND. ALTHOUGH THE BEST RAIN MAY HAVE ALREADY FALLEN OVER SAINT THOMAS AND SAINT JOHN...SIGNIFICANT SHOWERS MAY STILL DEVELOP THERE AND HEAVY RAINS HAVE YET TO FALL IN SAINT CROIX. THE GFS HAS BEEN CONSISTENTLY SHOWING 30 TO 40 KNOT WINDS AT THE 850 MB LEVEL OVER AND NORTH OF PUERTO RICO AND THE U.S. VIRGIN ISLANDS THAT LAST UNTIL FRIDAY EVENING. SAINT THOMAS HAS BEEN SHOWING GUSTS OVERNIGHT IN THE 25 TO 40 KNOT RANGE. THESE STRONG GUSTS WILL BE CHARACTERISTIC OF THE WEATHER WITH THIS WAVE AND STRONG GUSTS OF UP TO 45 KNOTS MAY BE EXPECTED THROUGH FRIDAY. FORECASTS WILL CONTINUE TO HIGHLIGHT GUSTY WINDS WITH THUNDERSTORMS.

THE GFS BEGINS TO BRING DRIER AIR IN FROM THE NORTHWEST...BUT THE DOWNWIND LEAN OF THE TROPICAL WAVE KEEPS PUMPING MOISTURE INTO THE AREA FROM THE TROPICAL AIR SOUTHEAST...AND THUS THE MODEL IS UNABLE TO CLEAR THE AREA OF GOOD MOISTURE UNTIL SATURDAY NIGHT. ON TOP OF THE GFS ALSO SHOWS DIVERGENCE AT THE 200 MB LEVEL WILL SUPPORT CONVECTIVE ACTIVITY EVEN AFTER THE BEST MOISTURE HAS LEFT THE AREA. FROM SUNDAY ON MOISTURE LEVELS RETURN TO NORMAL WITH MINOR FLUCTUATIONS THAT WILL DRIVE OUR NORMAL SUMMERTIME SHOWER EPISODES. THIS WILL ALSO COINCIDE WITH THE MIGRATION OF THE LOW AND MID LEVEL HIGH PRESSURE SYSTEM TO THE SOUTHWESTERN ATLANTIC WHICH SHOULD BRING IN SIGNIFICANTLY WARMER WEATHER ON THE WINGS OF SOUTHEAST WINDS FOR THE NORTH COAST OF PUERTO RICO MONDAY THROUGH WEDNESDAY. SCATTERED SHOWERS AND THUNDERSTORMS WILL STILL OCCUR IN THEIR USUAL DIURNAL PATTERNS.

.MARINE...THE WAVE WATCH HAS BACKED OFF ITS EXTREME FORECAST OF UP TO 15 FOOT SEAS. IT IS NOW SHOWING THREE PEAKS...ONE TODAY...ONE SATURDAY AND ONE MONDAY. AT THIS TIME...THE MAXIMUM SEAS ON SATURDAY ARE THE STRONGEST...WITH SEAS UP TO 8.5 FEET IN THE CARIBBEAN AND 11 FEET IN THE ATLANTIC. THE CURRENT FORECAST FOR THE AREA IS SOMEWHAT MORE OPTIMISTIC AND WILL NOT CHANGE IT FROM A MAXIMUM OF 9 FEET. MARINERS SHOULD NOTE THE GUSTY CHARACTER OF THIS WAVE ABOVE MANY OTHERS THAT HAVE PASSED IN PAST SEASONS...AND TAKE APPROPRIATE PRECAUTIONS.

.AVIATION...STRONG GUSTY WINDS AND SCATTERED ELECTRICAL STORMS WILL PLAGUE PILOTS FOR THE NEXT TWO TO THREE DAYS...AND THERE IS SOME INDICATION THAT THE HAZE OF SAHARAN DUST WILL RETURN BEFORE THIS UNSETTLED EPISODE IS OVER AND LAST INTO NEXT WEEK. THESE THUNDERSTORMS HAVE WINDS OF UP TO 40 KNOTS AND PILOTS WILL ALSO NEED TO BE ALERT FOR OUTFLOW BOUNDARIES AND NEARLY ZERO VISIBILITIES IN TORRENTIAL RAINS GENERATED BY CONVECTION IN THE WAVE.

.HYDROLOGY...RIVERS HAVE SHOWN SOME RISES IN THE PAST 12 HOURS DUE TO PASSING SHOWERS...BUT NONE ARE IN DANGER OF FLOODING JUST YET. IF THE HEAVY RAINS JUST TO THE EAST OF PUERTO RICO ARE ANY INDICATION THOUGH...FLOODING ON MANY RIVERS COULD BE JUST HOURS AWAY. RESIDENTS SHOULD REMAIN ALERT AND PLAN NOT TO BE TRAPPED BY RAPIDLY RISING WATERS. MUDSLIDES ARE ALSO A STRONG POSSIBILITY...ESPECIALLY AS THIS EVENT DRAGS INTO TOMORROW.

.PRELIMINARY POINT TEMPS/POPS...
SJU 87 76 88 77 / 90 60 60 60
STT 86 77 86 77 / 80 70 70 50

.SJU WATCHES/WARNINGS/ADVISORIES...
PR...FLASH FLOOD WATCH UNTIL 4 PM AST THIS AFTERNOON FOR ALL OF PUERTO RICO.
SMALL CRAFT ADVISORY AMZ710-740.

VI...FLASH FLOOD WATCH UNTIL 4 PM AST THIS AFTERNOON FOR VIZ001- VIZ002.
SMALL CRAFT ADVISORY AMZ710-730.

$$

SNELL

[Extremeweatherguy]

I really don't see all this high wind shear the NHC is talking about. According to this wind shear map (not wind shear tendency), it looks like shear is low in most of the Caribbean:

http://cimss.ssec.wisc.edu/tropic/real- ... midshr.GIF

[NONAME]

That is Mid Level Shear the Upper level Shear is high

[beachbum_al]

So this is the wave that the local channel on Mobile is commenting on. Sorry I started that thread because I didn't know this is the same one. I know right now it doesn't seem favorable for development but what about when it gets in the GOM?

[HurricaneHunter914]

TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
530 AM EDT THU JUL 27 2006

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

CLOUDINESS AND SHOWERS...OCCASIONALLY HEAVY...FROM PUERTO
RICO...MUCH OF THE LESSER ANTILLES AND ADJACENT WATERS ARE
ASSOCIATED WITH A TROPICAL WAVE. THIS SYSTEM IS EXPECTED TO MOVE
WESTWARD ACROSS THE CARIBBEAN SEA WHERE UPPER-LEVEL WINDS ARE
HIGHLY UNFAVORABLE FOR TROPICAL CYCLONE FORMATION.

TROPICAL STORM FORMATION IS NOT EXPECTED THROUGH FRIDAY.

$$

FORECASTER AVILA

I'm not suprised, with the ULL to the north of it, it might be impossible for this to form.

[SouthFloridawx]

That is Mid Level Shear the Upper level Shear is high

http://cimss.ssec.wisc.edu/tropic/real- ... g8sht.html

[HurricaneHunter914]

Shear seems to be decreasing ahead of it so scratch out what i said earlier. Maybe a weak TS from this but that's it.

[cheezyWXguy]

i think this is gonna go into the gulf...not strngthen much, and then thats where it develops

[beachbum_al]

i think this is gonna go into the gulf...not strengthen much, and then that's where it develops

Do you mean it will not strengthen much before going into the Gulf or it will not strengthen much when it gets in the Gulf? It is early morning and my brain doesn't operate on one cup of coffee.

[boca]

Shear seems to be decreasing ahead of it so scratch out what i said earlier. Maybe a weak TS from this but that's it.

http://cimss.ssec.wisc.edu/tropic/real- ... g8sht.html

according to the shear map shear will be increasing in front of it by the solid lines ,but over Florida shear is decreasing by the dotted lines.

[cheezyWXguy]

i think this is gonna go into the gulf...not strengthen much, and then that's where it develops

Do you mean it will not strengthen much before going into the Gulf or it will not strengthen much when it gets in the Gulf? It is early morning and my brain doesn't operate on one cup of coffee.

ya im still asleep too...i meant to say its gonna go to gulf but before then it wont strengthen much... then when it gets to the gulf is when it has its chance

[Steve]

My guess is that the energy is going to split with a northern burst and southern burst. The northern burst could get split off into the upper feature to its NW while the southern burst could continue along westerly (perhaps disguised as nothing for a couple of days). It seems the main energy is north of the Greater Antilies which usually points to an east coast threat (obviously not the case with Katrina though). I wouldn't put any stock into the wave until at least Saturday. But as has been the norm the previous few seasons, the energy is coalescing west of 60W. It's wait and see for now.

Steve

[SouthFloridawx]

I am actually interested in seeing the affects that the ULL to the NE of PR has on this wave. It is a rather large wave and the surface forecast from TPC shows the wave extending northward into the bahamas. I think it will cause some pretty widespread rain here in South Florida for Friday and Part of the weekend.

[gatorcane]

I am actually interested in seeing the affects that the ULL to the NE of PR has on this wave. It is a rather large wave and the surface forecast from TPC shows the wave extending northward into the bahamas. I think it will cause some pretty widespread rain here in South Florida for Friday and Part of the weekend.

Yes, unfortunately yet another tropical wave rains out a South Florida weekend - it's been the story this summer - seems they roll in on Fri and leave by Sun.....

[boca]

If the wave splits maybe the southern end will miss us to the south,northern end will end up in the Carloinas. Hey I'm just trying to break the train of rainy weekends here.