[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 180550
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT WED OCT 18 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...TROPICAL WAVES...
AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 38W SOUTH OF 18N MOVING
WEST NEAR 10 KT. THE WAVE SHOWS A WELL DEFINED INVERTED-V SHAPE.
CONVECTION IS BEING DISPLACED TO THE NE BY UPPER SW LEVEL FLOW.
SCATTERED MODERATE CONVECTION FROM 12N-18N BETWEEN 36W-39W.

THE TROPICAL WAVE THAT WAS PREVIOUSLY ANALYZED ALONG 66W/67W ON
THE 1800 UTC MAP IS NO LONGER IDENTIFIABLE BASED ON LATEST
SATELLITE IMAGERY AND EARLIER QUIKSCAT PASS. ONLY A SURFACE
TROUGH REMAINS OVER THIS AREA ASSOCIATED WITH THE NEARLY
STATIONARY AREA OF LOW PRESSURE THAT HAS BEEN MEANDERING JUST
NORTH OF PUERTO RICO. THIS IS ALSO A REGION OF UPPER DIFFLUENCE
WHICH IS HELPING SUPPORT THE CONVECTION.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 10N14W 10N25W 12N34W 9N40W 5N52W.
CLUSTERS OF MODERATE TO STRONG CONVECTION ARE FOUND OFF THE
COAST OF GUINEA AND GUINEA BISSAU IN AFRICA AND FROM 11N-15N
BETWEEN 27W-31W. SIMILAR CONVECTION IS ALONG THE ITCZ AXIS
BETWEEN 31W-35W.

...DISCUSSION...
GULF OF MEXICO...
MAIN FEATURE IN THE GULF TONIGHT IS THE SQUALL LINE EXTENDING NE
THROUGH THE NE GULF AND THE FLORIDA PANHANDLE INTO SOUTHERN
GEORGIA. THIS IS ASSOCIATED WITH A COMPLEX SURFACE PRESSURE
PATTERN OVER THE SE STATES. THE REMAINDER OF THE GULF REMAINS
DOMINATED BY 10-20 KT SLY FLOW AT THE SURFACE BETWEEN HIGH
PRESSURE WELL NE OF THE AREA AND LOWER PRESSURE OVER MEXICO. IN
THE UPPER LEVELS...THE GULF IS DOMINATED BY A LARGE UPPER HIGH
CENTERED NEAR 24N90W. UPPER LEVEL MOISTURE COVERS THE GULF E OF
92W AND THE FLORIDA PENINSULA WHILE DRY AIR IS FOUND WEST OF 92W.
A NEW COLD FRONT WILL ENTER THE NW GULF WATERS ON THU AND EXTEND
FROM BIG BEND FLORIDA TO NEAR TAMPICO ON FRIDAY.

CARIBBEAN SEA...
THE LARGE UPPER UPPER HIGH ANCHORED IN THE GULF OF MEXICO
EXTENDS A RIDGE EWD ACROSS MOST OF THE CARIBBEAN SEA  AND
CENTRAL AMERICA GIVING THE REGION UPPER NE FLOW AND MOSTLY DRY
AIR. A VERY ELONGATED UPPER TROUGH FROM THE ATLC EXTENDS S OVER
THE FAR EAST CARIBBEAN. A 1007 MB AREA OF LOW PRESSURE REMAINS
JUST NORTH OF PUERTO RICO. THIS FEATURE IS PRODUCING
DISORGANIZED SHOWERS AND TSTMS AND  UPPER-LEVEL WINDS REMAIN
UNFAVORABLE FOR TROPICAL CYCLONE DEVELOPMENT. A SURFACE TROUGH
EXTENDS S FROM THIS LOW TO THE ABC ISLANDS...WHERE IS GENERATING
SCATTERED SHOWERS AND TSTMS. THE ARE OF LOW PRESSURE IS FORECAST
TO MOVE SLOWLY NE AND AWAY FROM PUERTO RICO DURING THE NEXT FEW
DAYS. SCATTERED SHOWERS AND ISOLATED TSTMS ARE ALSO OVER THE SW
CARIBBEAN DUE TO THE PRESENCE OF THE ITCZ AXIS. TRADE WINDS ARE
LIGHT DUE TO A WEAK PRESSURE PATTERN.

ATLANTIC OCEAN...
THE LARGE UPPER RIDGE SITUATED IN THE GULF OF MEXICO ALSO
EXTENDS ACROSS THE W ATLC TO 65W DRYING OUT THE AREA. A SURFACE
HIGH OVER THE W ATLC NORTH OF THE AREA EXTENDS A RIDGE ACROSS
THE BAHAMAS AND CUBA. DEEP LAYERED TROUGH EXTENDS INTO THE
W-CENTRAL ATLC ALONG 60W/61W TO THE FAR E CARIBBEAN. THE
ATTENDANT COLD FRONT ENTERS THE REGION NEAR 32N50W THEN
CONTINUES SW TO 25N57W. A SURFACE TROUGH RUNS FROM THIS POINT TO
THE LOW PRESSURE THAT REMAINS NORTH OF PUERTO RICO. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS AFFECTING THE
VIRGIN/LEEWARD ISLANDS. CLUSTERS OF SIMILAR CONVECTION ARE SEEN
FROM 18N-20N BETWEEN 60W-64W. ANOTHER DEEP LAYERED TROUGH
EXTENDS FROM THE E ATLC THROUGH 32N20W SW TO A WEAKENING UPPER
LOW CENTERED NEAR 21N45W. ISOLATED SHOWERS ARE RELATED TO THIS
LOW. A STATIONARY FRONT IS JUST NORTH OF THE CANARY ISLANDS.
A 1019 MB SURFACE HIGH IS NEAR 30N39W AND DOMINATES THE ATLC
BETWEEN 20W-50W.

$$
GR


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