[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 281752
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT FRI JUL 28 2006

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND THE ATLANTIC OCEAN TO THE
AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION
IS BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...
AND METEOROLOGICAL ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1730 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS ALONG 31W/32W SOUTH OF 17N MOVING WEST NEAR
16 KT. THIS WAVE CONTINUES TO SHOW BROAD LOW-MID LEVEL
CURVATURE. LOW LEVEL CONVERGENCE AND ASSOCIATED CONVECTION IS
STRONGEST WEST OF THE WAVE AXIS EMBEDDED IN THE ITCZ WHERE THERE
IS SCATTERED MODERATE/ISOLATED STRONG CONVECTION FROM 5N TO 12N
BETWEEN 36W AND 45W. A TROF HAS BEEN ADDED ALONG THIS FEATURE
ALONG A LINE EXTENDING NE FROM 5N40W TO NEAR 9N36W DUE TO
AFTERNOON CLOUD MOTION ANALYSIS AND RECENT SHIP OBSERVATIONS
SHOWING A CYCLONIC WIND FIELD. SOME SLOW DEVELOPMENT IS POSSIBLE
WITH THIS WAVE AS IT PROGRESSES WESTWARD OVER THE NEXT FEW DAYS.

A TROPICAL WAVE IS ALONG 55W/56W SOUTH OF 21N MOVING QUICKLY
WEST 20 TO 25 KT. SURFACE OBSERVATIONS AT BARBADOS OVER THE PAST
12 HRS SHOW A CLASSIC EASTERLY WAVE WIND SHIFT...WITH ENE THEN E
WINDS LATE LAST NIGHT AND EARLY THIS MORNING SHIFTING MORE SE
AFTER 14/15Z SUGGESTING THE WAVE HAS RECENTLY MOVED THROUGH THE
AREA. IT IS UNCLEAR...HOWEVER...IF SOME OF THIS VEERING IS DUE
TO THE LOCAL SEA BREEZE CIRCULATION. THE WAVE SHOWS A DEFINITE
INVERTED V SHAPE AND LOW LEVEL CYCLONIC TURNING AROUND ITS AXIS.
SCATTERED MODERATE CONVECTION ASSOCIATED WITH THIS WAVE IS
SPREADING THROUGH THE LESSER ANTILLES FROM 12N TO 18N BETWEEN
58W AND 66W. THE WAVE WILL CONTINUE SPREADING SHOWERS AND
THUNDERSTORMS WESTWARD THROUGH THE CARIBBEAN SEA AND SURROUNDING
ISLANDS OVER THE WEEKEND.

A TROPICAL WAVE IS IN THE CENTRAL CARIBBEAN ALONG 73W SOUTH OF
24N MOVING WEST NEAR 15 KT. THIS WAVE CONTINUES TO INTERACT WITH
AN UPPER TROUGH EXTENDING NE FROM THE BAHAMAS/TURKS AND CAICOS
AND IS PRODUCING PATCHES OF SCATTERED MODERATE CONVECTION WITHIN
250 NM EITHER SIDE OF THE ANALYZED WAVE AXIS. CONVECTION PULSED
STRONGER NEAR THE WAVE AXIS THIS MORNING SOUTH OF HISPANIOLA
FROM 13 TO 18N AND BETWEEN 70W AND 74W...WITH A NOTED OUTFLOW
BOUNDARY SEEN SPREADING RADIALLY OUTWARD FROM THE CONVECTIVE
COMPLEX ON VISIBLE IMAGERY FROM 13 TO 16Z. THE NW PORTION OF THE
OUTFLOW BOUNDARY HAS SINCE PUSHED ASHORE THE S COAST OF HAITI
AND THE CONVECTION HAS BEEN TRENDING WEAKER OVER THE PAST FEW
HOURS. GFS SEEMS TO HAVE A DECENT HANDLE ON THE MOISTURE
ASSOCIATED WITH THIS WAVE...AND SEEMS TO MOVE A HEAVILY SHEARED
AND THUS WEAKER NORTHERN PORTION OF MOISTURE AND INSTABILITY
THROUGH THE BAHAMAS AND FLORIDA LATER TONIGHT AND TOMORROW WHILE
THE CENTRAL/SOUTHERN AND POTENTIALLY MORE ACTIVE EXTENT OF THE
WAVE CONTINUING TO PROGRESS WESTWARD INTO THE WESTERN
CARIBBEAN.


...ITCZ...
ITCZ AXIS IS CENTERED ALONG 17N15W 11N30W 7N42W 11N54W TO INLAND
OVER SOUTH AMERICA NEAR 9N61W TO PUERTO LIMON COSTA RICA NEAR
10N83W. BESIDES FOR THE CONVECTIVE ACTIVITY ASSOCIATED WITH THE
TROPICAL WAVES...THE CLUSTER OF MODERATE CONVECTION THAT MOVED
OFF THE COAST OF AFRICA E OF 17W FROM 13N-18N EARLIER TODAY HAS
SINCE DIMINISHED IN BOTH COVERAGE AND INTENSITY. SCATTERED
MODERATE CONVECTION IS ACROSS SOUTH AMERICA ENHANCED BY THE
CENTRAL CARIBBEAN WAVE FROM 2N-10N BETWEEN 69W-74W. A PATCH OF
MODERATE CONVECTION LIES JUST NORTH OF THE AXIS OFF THE CENTRAL
CARIBBEAN COAST OF NICARAGUA...DUE SOUTH OF THIS AREA LIES
ANOTHER PATCH OF SCATTERED MODERATE CONVECTION SOUTH OF MAL PIAS
COSTA RICA TO 6N THAT IS MOVING INTO THE EAST PACIFIC.

...DISCUSSION...
GULF OF MEXICO...
WATER VAPOR LOOP SHOWS EASTERLY FLOW BLANKETING THE ENTIRE GULF
OF MEXICO THIS AFTERNOON BETWEEN AN UPPER HIGH CENTERED JUST
WEST OF GALVESTON TEXAS AND AND UPPER TROF SPINNING AROUND THE
YUCATAN PENINSULA. ANOTHER UPPER LOW IS SEEN IN WV IMAGERY OVER
CENTRAL FLORIDA WITH ITS CENTER APPROACHING TAMPA. UPPER
DIFFLUENCE BETWEEN THESE FEATURES ALONG WITH THE UPPER HIGH IN
THE WESTERN CARIBBEAN IS PRODUCING SCATTERED MODERATE CONVECTION
THROUGH TH FLORIDA STRAITS AND INTO THE SW GULF AND SOUTH
CENTRAL FLORIDA FROM 23N TO 27N BETWEEN 78W AND 86W. MINIMAL
SHOWER/THUNDERSTORM ACTIVITY NOTED IN THE CENTRAL AND WESTERN
GULF THIS AFTERNOON. AT THE SURFACE...THE WESTERN EXTENSION OF
THE BERMUDA HIGH LIES ACROSS THE GULF WITH MODEST 5-15KT E/SE
FLOW DOMINATING AND OVERALL NOT MUCH IS EXPECTED TO CHANGE WITH
THIS FLOW THROUGH THE WEEKEND. HOWEVER...MOISTURE ASSOCIATED
WITH THE TROPICAL WAVE IN THE CENTRAL CARIBBEAN ALONG 73W MAY
INCREASE PRECIP/THUNDER CHANCES OVER THE GULF OVER THE
WEEKEND...AND FROM THE WAVE THAT MOVED THROUGH BARBADOS THIS
MORNING EARLY TO MID NEXT WEEK.

CARIBBEAN SEA...
THE MAIN FEATURE IN THE REGION IS THE SHOWER AND THUNDERSTORM
ACTIVITY ASSOCIATED WITH THE TROPICAL WAVE MOVING WEST FROM ITS
12Z ANALYZED POSITION ALONG 73W. SCATTERED MODERATE CONVECTION
IS ALSO SPREADING THROUGH THE LESSER ANTILLES AND THE EASTERN
CARIBBEAN WITH THE NEXT TROPICAL WAVE WHICH IS NOW BEGINNING TO
MOVE INTO THE CARIBBEAN. AN UPPER LEVEL HIGH IS NOTED IN THE
WESTERN CARIBBEAN...CENTERED NEAR 17N84W. ANOTHER UPPER HIGH IS
EXTENDING INTO THE WEST AND CENTRAL CARIBBEAN FROM THE TROPICAL
ATLANTIC WHICH IS CENTERED NEAR 20N61W. UPPER TROUGHING
CONTINUES TO DOMINATE THE AREA EXTENDING NE FROM THE SE BAHAMAS
AND TURKS AND CAICOS ISLANDS...WITH THE SOUTH EXTENT OF THIS
TROF AFFECTING THE NORTHERN CARIBBEAN. PRONOUNCED UPPER
DIFFLUENCE BETWEEN THIS FEATURES AND ABOVE THE TROPICAL WAVE IN
THE CENTRAL CARIBBEAN AIDING IN THE CONVECTION AS DESCRIBED
ABOVE. 10-20KT TRADE WINDS PREVAIL OVER MUCH OF THE CARIBBEAN ON
THE S/SW SIDE OF THE BERMUDA SFC HIGH. SIMILAR CONDITIONS
GENERALLY EXPECTED THROUGH THE WEEKEND ALTHOUGH GUSTIER WINDS
AND SHOWERS/THUNDERSTORMS EXPECTED IN THE VICINITY OF THE
TROPICAL WAVES MOVING THROUGH.


ATLANTIC OCEAN...
LARGE SCALE UPPER RIDGING CONTINUES TO DOMINATE MUCH OF THE ATLC
WATERS TODAY...WITH A SERIES OF FOUR SHORT WAVE RIDGES NOTED IN
WV IMAGERY FROM 13N TO 26N BETWEEN 17W AND 67W...WITH NEARLY ALL
OF THIS REGION SHOWING FAIR/DRY WEATHER WITH MINIMAL SHOWER
ACTIVITY NOTED. MUCH OF THIS REGION IS ALSO HOVERED BY A DENSE
LAYER OF SAHARAN DUST. JUST WEST OF THIS REGION LIES AN UPPER
TROF EXTENDING NE FROM THE BAHAMAS AND TURKS AND CAICOS ISLANDS.
THE DISTURBED WEATHER/CONVECTION WEST OF THE TROPICAL WAVE ALONG
32W/ABOUT 1000 MILES WSW OF THE CAPE VERDE ISLANDS HAS POTENTIAL
FOR SLOW DEVELOPMENT...THOUGH COMPUTER MODEL GUIDANCE IS NOT
SUGGESTING MUCH AT THIS TIME. AT THE SURFACE...A 1029MB HIGH IS
EXTENDING INTO THE TROPICAL ATLANTIC FROM ITS CENTER NEAR
33N55W. GUIDANCE SUGGESTS THIS HIGH WILL GRADUALLY WEAKEN AS WE
MOVE THROUGH THE WEEKEND.


$$
WILLIS



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