[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 232357
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT THU AUG 23 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
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...METEOROLOGICAL ANALYSIS...
WEATHER OBSERVATIONS...AND RADAR.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2345 UTC.

...TROPICAL WAVES...
LOW AMPLITUDE TROPICAL WAVE IS OVER THE OPEN ATLANTIC ALONG 44W
S OF 14N IS MOVING W 10-15 KT. THE WAVE IS MARKED BY LOW LEVEL
CYCLONIC TURNING MAINLY ALONG THE ITCZ. THIS TURNING MAY BE MORE
ASSOCIATED WITH THE ITCZ. HOWEVER...THERE IS A SLIGHTLY HIGHER
AMPLITUDE INVERTED V PATTERN NOTED FURTHER NW FROM 17N-23N
BETWEEN 45W-53W...HOWEVER THE EVOLUTION OF THIS FEATURE OVER THE
LAST FEW DAYS IS A LITTLE UNCLEAR AND COULD BE MORE ASSOCIATED
WITH LIFT AHEAD OF THE UPPER LOW NEAR 21N56W. IN GENERAL NEITHER
AREA IS WELL ORGANIZED AND DEEP CONVECTION IS ABSENT.

TROPICAL WAVE ALONG 67W/68W HAS FRACTURED WITH THE MAIN WAVE
S OF 17N MOVING W NEAR 20 KT IN MODERATE ELY FLOW OVER THE
CARIBBEAN...WHILE THE NORTHERN PORTION OF THE WAVE HAS SEPARATED
INTO A WEAK SFC TROUGH JUST NORTHEAST OF PUERTO RICO...FROM 19N
TO 23N ALONG 65W. SCATTERED WEAKENING SHOWERS WITH THIS SRN
PORTION HAVE BEEN RACING W THROUGH THE ABC ISLANDS AND NRN
VENEZUELA OVER THE LAST FEW HOURS. ADDITIONAL SHOWERS AND TSTMS
ARE OCCURRING OVER THE COASTAL WATERS OF PUERTO RICO AND THE
VIRGIN ISLANDS.

TROPICAL WAVE IS ALONG 81/82W S OF 22N MOVING W 15-20 KT. THE
WAVE HAS BECOME DETACHED FROM A 1014 MB SFC LOW NEAR GRAND
BAHAMA ISLAND. THIS WAVE APPEARS TO BE HIGHLY AMPLIFIED WITH
LOW CLOUD MOTIONS E OF THE WAVE AXIS INDICATING SE FLOW INTO THE
WAVE AND AN INCREASING COVERAGE OF SCATTERED SHOWERS AND TSTMS
JUST W OF JAMAICA AND EXTENDING NWD OVER ERN CUBA.

ITCZ...
ITCZ AXIS IS CENTERED ALONG 12N20W 11N35W 10N43W 11N55W 9N61W.
SCATTERED BUT WEAKENING MODERATE CONVECTION WAS INDICATED WITHIN
120 NM OF THE AXIS W OF 52W..AND WITHIN 45-60 NM OF A LINE FROM
7N34W TO 7N39W...AND JUST OFFSHORE THE AFRICAN COAST FROM
13N-16N E OF 20W. THE EASTERN MOST CONVECTION IS ASSOCIATED WITH
A TROPICAL WAVE THAT RECENTLY MOVED OFF THE COAST AS PER DAKAR
RAOB DATA.

DISCUSSION...

GULF OF MEXICO...
RESIDUAL LONG PERIOD SWELLS OF 12 SEC FROM FORMER HURRICANE DEAN
CONTINUE TO REGISTER AT MANY OF THE BUOYS OVER THE E-CENTRAL
GULF AND IN THE NEAR SHORE WATERS AS WELL. THIS WILL ALSO
CONTINUE TO SLOWLY SUBSIDE THROUGH THE END OF THE WEEK. WIDELY
SCATTERED SHOWERS AND TSTMS DOT THE CENTRAL GULF MAINLY S OF
29N BETWEEN 87W AND 92W...IN A REGION OF DIFFLUENT FLOW ALOFT
BETWEEN AN INVERTED UPPER TROUGH EXTENDING THROUGH THE REGION
AND AN UPPER HIGH OVER GEORGIA. EXCEPT FOR RESIDUAL MOISTURE
NOTED IN THE BAY OF CAMPECHE...DRY/STABLE MID TO UPPER AIR IS
OVER THE WRN GULF E OF 90W WITH E TO NE UPPER FLOW. A WEAK
TROPICAL WAVE WILL MOVE INTO THE SE GULF OF MEXICO EARLY
FRI...CROSS THE MIDDLE GULF SAT...AND REACH THE FAR WESTERN GULF
SUN. MEANWHILE...WEAK SFC RIDGING WILL PERSIST ALONG 30N THROUGH
THE WEEKEND.

CARIBBEAN SEA...
A PAIR OF TROPICAL WAVES ARE MOVING THROUGH THE BASIN AND ARE
RESPONSIBLE FOR MOST OF THE WEATHER ACROSS THE BASIN...SEE ABOVE
FOR MORE DETAILS. THE SHOWERS/TSTMS JUST S OF CUBA NOTED WITH
THE WAVE NEAR 81W/82W ARE ALSO BEING SUPPORTED BY DIFFLUENCE
ALOFT BETWEEN THE INVERTED TROUGHING EXTENDING UP THE NW CARIB
AND RIDGING BUILDING INTO THE CENTRAL CARIB FROM THE ATLC.
OTHERWISE TRADES ARE MODERATE AND GENERALLY EXPECTED TO PERSIST
THROUGH FRI.

ATLANTIC OCEAN...
THE MAIN FEATURE IN THE WRN ATLC IS THE SLOW MOVING...WEAK
1015 MB SFC LOW NEAR GRAND BAHAMA ISLAND. THIS FEATURE HAS BEEN
GENERATING ISOLATED TSTMS WITHIN 180 NM IN THE NW QUADRANT TO
THE CENTRAL FLORIDA COAST. MUCH OF THE REMAINDER OF THE SFC
PATTERN IS DOMINATED BY A WEAK 1020 MB HIGH NEAR 27N61W. A
SMALL LOW LEVEL CYCLONIC SWIRL OR 'SCREAMING EAGLE' WAS NOTED
ROTATING AROUND THIS RIDGING NEAR 22N56W. THE SFC HIGH WILL
SLIDE S THROUGH FRI IN ADVANCE OF THE FRONTAL SYSTEM JUST N OF
THE AREA. THE TRADES ARE MOSTLY LIGHT ACROSS THE CENTRAL AND ERN
ATLC DUE TO THE WEAKNESS OF THE SFC RIDGE. FAIR/STABLE WEATHER
IS WIDESPREAD N OF 13N E OF 65W...ALTHOUGH SCATTERED SHOWERS AND
TSTMS WITH THE APPROACHING FRONT ARE NOW N OF 30N BETWEEN
47W-54W. BENIGN UPPER LOWS NOTED NEAR 21N55W AND 32N34W...WITH
TYPICAL UPPER RIDGING OVER THE REMAINDER OF THE E ATLC.

$$
COBB




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