[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 200539
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT WED OCT 20 2010

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF
SOUTH AMERICA...AND 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0445 UTC.

...SPECIAL FEATURES...
A BROAD AREA OF LOW PRESSURE WITH ACCOMPANYING SHOWERS/
THUNDERSTORMS ARE OVER THE W CARIBBEAN SEA SW OF THE CAYMAN
ISLANDS. AT 20/0300 UTC A 1009 MB LOW IS CENTERED NEAR 18N83W.
SCATTERED/HEAVY SHOWERS AND ISOLATED THUNDERSTORMS ARE FROM
17N-20N BETWEEN 80W-83W. ALTHOUGH UPPER-LEVEL WINDS ARE
MARGINALLY CONDUCIVE FOR DEVELOPMENT...ONLY A SMALL INCREASE IN
ORGANIZATION OF THE THUNDERSTORM ACTIVITY COULD LEAD TO THE
FORMATION OF A TROPICAL DEPRESSION...THUS THERE IS A HIGH CHANCE
OF THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48
HOURS. INTERESTS IN THE NORTHWEST CARIBBEAN SEA SHOULD CONTINUE
TO MONITOR THE PROGRESS OF THIS SYSTEM.

...ITCZ...

ITCZ AXIS IS ANALYZED ALONG 7N11W 5N20W 9N31W 6N42W 2N52W. A
SURFACE TROUGH IS N OF THE ITCZ EXTENDING FROM 16N37W THROUGH A
1010 MB LOW NEAR 12N38W TO 9N40W WITH CLUSTERS OF SCATTERED
MODERATE CONVECTION WITHIN 60 NM OF A LINE FROM 13N31W TO 17N40W
AND SCATTERED SHOWERS WITHIN 120 NM E OF THE TROUGH FROM 11N-14N.
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE
FROM 4N-13N BETWEEN 11W-20W AND FROM 2N-7N BETWEEN 20W-23W.

...DISCUSSION...

GULF OF MEXICO...
A BROAD UPPER TROUGH COVERS THE GULF WITH THE ASSOCIATED FRONTAL
BOUNDARY INLAND OVER THE SE CONUS. THE BROAD UPPER RIDGE
ANCHORED IN THE CARIBBEAN IS OVER THE FLORIDA PENINSULA
PROVIDING DIFFLUENCE ALOFT AND COUPLED WITH RESIDUAL LOW LEVEL
MOISTURE OVER THE FAR E GULF IS PRODUCING ISOLATED SHOWERS S OF
28N E OF 85W. STRONG SUBSIDENCE AND DRY AIR ALOFT COVER ALL BUT
THE FLORIDA STRAITS GIVING THE REMAINDER OF THE AREA CLEAR SKIES
TONIGHT. A WEAK SURFACE RIDGE REMAINS OVER THE GULF ANCHORED BY
A 1016 MB HIGH OVER THE MISSISSIPPI DELTA NEAR 29N90W.

CARIBBEAN SEA...
SEE SPECIAL FEATURES ABOVE FOR THE ACTIVITY ASSOCIATED WITH THE
1009 MB LOW IN THE W CARIBBEAN. BROAD UPPER RIDGE DOMINATES THE
CARIBBEAN ANCHORED OVER JAMAICA ENHANCING THE ACTIVITY IN THE
SPECIAL FEATURES AND PROVIDING DIFFLUENCE ALOFT TO GENERATE
CLUSTERS OF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF 15N
BETWEEN 72W-80W AND SCATTERED SHOWERS AND POSSIBLE ISOLATED
THUNDERSTORMS N OF 17N BETWEEN 80W-84W. ALTHOUGH AN ELONGATED
N/S UPPER LOW REMAINS OVER THE LESSER ANTILLES...THE AREA IS
DOMINATED BY DRY AIR ALOFT AND IS STILL NOT PRODUCING ANY
SIGNIFICANT WEATHER LEAVING THE REMAINDER OF THE CARIBBEAN WITH
MOSTLY CLEAR SKIES AND SOME POSSIBLE ISOLATED LOW LEVEL SHOWERS.

ATLANTIC OCEAN...
BROAD UPPER TROUGH THAT COVERS THE GULF OF MEXICO AND THE E
CONUS EXTENDS INTO THE W ATLC N OF 26N W OF 73W. A BROAD UPPER
RIDGE ANCHORED IN THE W CARIBBEAN EXTENDS AN AXIS OVER THE W
ATLC THROUGH THE WINDWARD PASSAGE TO ACROSS BERMUDA COVERING THE
W ATLC WITHIN 400 NM OF THE RIDGE AXIS. THIS UPPER RIDGE IS
PROVIDING DIFFLUENCE ALOFT TO GENERATE SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS S OF 25N ACROSS THE BAHAMA ISLANDS TO
OVER CUBA AND HAITI BETWEEN 72W-78W AND SCATTERED SHOWERS AND
POSSIBLE ISOLATED THUNDERSTORMS WITHIN 120 NM OF LINE FROM
CUBA NEAR 23N79W TO 32N68W. A SURFACE RIDGE EXTENDS FROM A 1022
MB HIGH NEAR 33N54W SW INTO THE W ATLC TO NEAR 27N72W. BROAD
UPPER TROUGH IS OVER THE E/CENTRAL ATLC N OF 22N BETWEEN 30W-55W
SUPPORTING A DEVELOPING COLD FRONT THAT ENTERS THE REGION NEAR
32N27W SW TO 24N44W WITH SCATTERED SHOWERS POSSIBLE WITHIN 60 NM
OF THE FRONTAL BOUNDARY.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
PAW





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