[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 102258
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST MON DEC 10 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
2145 UTC

...SPECIAL FEATURE...
SATELLITE IMAGES AND SURFACE OBSERVATIONS INDICATE THAT THE AREA
OF LOW PRESSURE IS CENTERED OVER THE VIRGIN ISLANDS NEAR 18N63W
WITH A SURFACE TROUGH EXTENDING S TO NEAR 13N65W. THIS SYSTEM
HAS BECOME A LITTLE BETTER ORGANIZED THIS AFTERNOON WITH
WIDESPREAD SHOWERS/THUNDERSTORMS REMAINING MOSTLY N AND E OF THE
ISLANDS FROM 19N-22N BETWEEN 57W-66W AND UP TO GALE FORCE WINDS
FROM 19N-23N BETWEEN 60W-70W. AN UPPER LEVEL LOW IS JUST TO THE
W OF THE SURFACE LOW NEAR 18N65W. WHILE A TROPICAL OR
SUBTROPICAL CYCLONE COULD FORM ANY TIME DURING THE NEXT 24
HOURS...UPPER-LEVEL WINDS ARE EXPECTED TO BECOME GRADUALLY LESS
FAVORABLE FOR DEVELOPMENT OVER THE NEXT COUPLE OF DAYS. THIS
SYSTEM COULD PRODUCE HEAVY SQUALLS AND GUSTY WINDS ACROSS THE
VIRGIN ISLANDS...PUERTO RICO...AND HISPANIOLA TONIGHT AND INTO
TUESDAY AS IT MOVES W OR WSW AT NEAR 15 KT. HEAVY RAINS OVER
PUERTO RICO AND HISPANIOLA COULD CAUSE LIFE-THREATENING FLASH
FLOODS AND MUD SLIDES. INTERESTS IN THESE AREAS SHOULD CONTINUE
TO MONITOR THE PROGRESS OF THIS SYSTEM.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 6N7W 5N13W 6N32W EQ51W. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 90 NM OF LINE FROM
4N38W TO THE EQUATOR NEAR 43W. CLUSTERS OF SIMILAR CONVECTION
ARE WITHIN 120 NM OF THE ITCZ AXIS FROM 28W-35W.

DISCUSSION...
GULF OF MEXICO...
BROAD UPPER RIDGE COVERS THE ENTIRE GULF ANCHORED BY AN UPPER
HIGH OFF THE W COAST OF FLORIDA NEAR 28N84W. A SURFACE RIDGE
AXIS EXTENDS FROM THE W ATLC ACROSS THE SE US TO E TEXAS ALSO
COVERING THE ENTIRE GULF. DRY STABLE AIR COVERS THE GULF EXCEPT
WITH SOME ISOLATED LOW LEVEL RETURN FLOW SHOWERS DOTTING THE W
GULF. OTHERWISE SKIES ARE CLEAR THIS EVENING.

CARIBBEAN SEA...
BROAD UPPER RIDGE COVERS THE W CARIBBEAN W OF 78W WITH THE RIDGE
AXIS EXTENDING FROM COLOMBIA TO W CUBA. BROAD UPPER TROUGH
COVERS THE REMAINDER OF THE CARIBBEAN EXTENDING FROM THE UPPER
LOW MENTIONED IN THE SPECIAL FEATURES ABOVE. MODERATE/STRONG NE
TO E SURFACE WINDS COVER THE CARIBBEAN DUE TO THE TIGHT PRESSURE
GRADIENT INDUCED BY THE STRONG SURFACE RIDGE ACROSS THE ATLC.
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS OVER THE NE CARIBBEAN N
OF 17N E OF 70W INCLUDING PORTIONS OF HISPANIOLA TO OVER THE
LEEWARD ISLANDS AND ARE ALSO ASSOCIATED WITH THE SYSTEM IN THE
SPECIAL FEATURES. THE REMAINDER OF THE CARIBBEAN REMAINS MOSTLY
CLEAR THIS EVENING WITH SOME ISOLATED SHOWERS INLAND AND WITHIN
60 NM ALONG THE COAST OF W PANAMA...COSTA RICA...AND SE
NICARAGUA DUE TO THE CLOSE PROXIMITY OF THE ITCZ AXIS IN THE E
PACIFIC REGION.

ATLANTIC OCEAN...
THE MOST SIGNIFICANT FEATURE THIS EVENING IS IN THE SPECIAL
FEATURES ABOVE. OTHERWISE...BROAD UPPER RIDGE COVERING THE GULF
OF MEXICO EXTENDS OVER THE FAR W ATLC W OF 78W. UPPER TROUGH
EXTENDS INTO THE E ATLC N OF 22N FROM 20W-42W WITH AN UPPER LOW
CENTERED NEAR 28N27W. A SURFACE TROUGH IS ASSOCIATED WITH THE
UPPER LOW EXTENDING FROM 26N28W 30N28W TO 32N27W WITH ISOLATED
SHOWERS WITHIN 60 NM OF THE SURFACE TROUGH. AN UPPER HIGH IS IN
THE TROPICAL ATLC NEAR 4N42W COVERING THE AREA S OF 20N E OF 60W
TO THE COAST OF AFRICA PROVIDING UPPER DIFFLUENCE ENHANCING THE
ACTIVITY IN THE ITCZ SECTION ABOVE. BROAD SURFACE RIDGE COVERS
THE ENTIRE ATLC AND THE GULF OF MEXICO WITH A WEAKNESS ALONG THE
SURFACE TROUGH AND THE SURFACE LOW IN THE SPECIAL FEATURES.

$$
WALLACE


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