[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 072354
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EDT MON NOV 07 2011

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...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL
ANALYSIS.

BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURES...

A 1005 MB OCCLUDED LOW IS CENTERED NEAR 27N69W AND CONTINUES TO
DEVELOP CHARACTERISTICS OF A SUBTROPICAL SYSTEM. THE DISSIPATING
OCCLUDED FRONT EXTENDS FROM THE LOW ALONG 30N70W TO 29N64W WHERE
THE DISSIPATING COLD FRONT EXTENDS S ALONG 25N63W THROUGH THE
MONA PASSAGE INTO THE NE CARIBBEAN NEAR 17N69W. CLUSTERS OF
SCATTERED SHOWERS/THUNDERSTORMS ARE FROM 27N-32N BETWEEN
63W-72W. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS ARE WITHIN 200
NM E OF THE DISSIPATING COLD FRONT. THIS SYSTEM HAS A HIGH
CHANCE OF BECOMING A SUBTROPICAL CYCLONE DURING THE NEXT 48
HOURS AS IT MOVES SLOWLY WESTWARD TONIGHT THEN MOVES
NORTHWESTWARD ON TUESDAY.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS AFRICA INTO THE E TROPICAL
ATLC NEAR 13N17W TO 11N18W. THE ITCZ AXIS EXTENDS FROM 11N18W
ALONG 6N34W TO 7N50W. SCATTERED MODERATE WITH EMBEDDED CLUSTERS
OF SCATTERED STRONG CONVECTION IS FROM 4N-9N BETWEEN 44W-48W.
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE
WITHIN 120/150 NM S OF THE ITCZ AXIS BETWEEN 27W-42W.

...DISCUSSION...

GULF OF MEXICO...
A BROAD LOW AMPLITUDE UPPER RIDGE REMAINS OVER THE GULF WITH THE
AXIS EXTENDING ACROSS S MEXICO NEAR CIUDAD DEL CARMEN OVER THE E
BAY OF CAMPECHE TO THE N GULF COAST NEAR MOBILE ALABAMA. A
SURFACE RIDGE REMAINS OVER THE GULF WITH THE AXIS EXTENDING INTO
THE GULF NEAR PANAMA CITY FLORIDA TO THE W BAY OF CAMPECHE NEAR
VERACRUZ MEXICO WITH RETURN FLOW OVER THE W GULF. THE WESTERLY
FLOW ALOFT CONTINUES TO BRING MOISTURE ALOFT ACROSS THE N GULF.
PATCHES OF LOW/MID CLOUDS WITH POSSIBLE ISOLATED SHOWERS ARE
ACROSS THE GULF WATERS AND INCLUDING THE FLORIDA PENINSULA.
SURFACE RIDGE WILL BEGIN TO SHIFT E TONIGHT AND WEAKEN AS THE
NEXT COLD FRONT MOVES OFF THE TEXAS COAST TUE EVENING. THE FRONT
WILL THEN FROM NE FLORIDA TO FAR EASTERN BAY OF CAMPECHE BY LATE
THU AND MOVE JUST SE OF THE GULF EARLY FRI.

CARIBBEAN SEA...
THE BROAD LOW AMPLITUDE UPPER RIDGE COVERING THE GULF OF MEXICO
COVERS THE W CARIBBEAN W OF 76W. THE BROAD UPPER TROUGH OVER THE
W ATLC EXTENDS TO OVER THE E AND CENTRAL CARIBBEAN BETWEEN E OF
75W SUPPORTING A DISSIPATING COLD FRONT THAT EXTENDS THROUGH THE
MONA PASSAGE TO 17N69W AND A SURFACE TROUGH OVER THE CENTRAL
CARIBBEAN FROM 15N72W ALONG 13N75W TO THE COAST OF COLOMBIA NEAR
10N76W. A SHARP UPPER RIDGE IS OVER THE W TROPICAL ATLC JUST E
OF THE LESSER ANTILLES PROVIDING DIFFLUENCE ALOFT TO GENERATE
SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS WITHIN 60
NM OF LINE FROM COLOMBIA NEAR 11N74W ALONG 16N69W ACROSS PUERTO
RICO AND THE VIRGIN ISLANDS NEAR 18N64W. THE MONSOON TROUGH
EXTENDS FROM COLOMBIA ALONG THE S COAST OF PANAMA AND COSTA RICA
WITH ISOLATED SHOWERS/THUNDERSTORMS S OF 10N TO INLAND OVER
PANAMA BETWEEN 75W-83W. THIS SCENARIO IS LEAVING THE REMAINDER
OF THE CARIBBEAN UNDER FAIR WEATHER THIS EVENING. SURFACE RIDGE
FROM THE GULF OF MEXICO WILL EXTEND S INTO THE NW CARIBBEAN AND
BEGIN TO WEAKEN TONIGHT THROUGH THU AS THE LOW IN THE SPECIAL
FEATURES ABOVE DRIFTS W OVER THE W ATLC. NEXT COLD FRONT IS
FORECAST TO REACH THE FAR NW CARIBBEAN BY FRI AND EXTEND FROM E
CUBA TO THE GULF OF HONDURAS ON SAT.

ATLANTIC OCEAN...
A BROAD UPPER TROUGH COVERS THE W ATLC WITH THE UPPER LOW
CENTERED NEAR 27N69W SUPPORTING THE SURFACE LOW/FRONTAL SYSTEM
IN THE SPECIAL FEATURES SECTION ABOVE. VERY DRY AIR ALOFT COVERS
THE AREA W OF 74W AND S OF 26N W OF 64W AND IS BEING DRAWN INTO
THE UPPER LOW. BROKEN STRATOCUMULUS CLOUDS WITH POSSIBLE
ISOLATED SHOWERS REMAIN IN THE LOWER LEVELS OF THE S OF 74W TO
ACROSS THE FLORIDA PENINSULA AND THROUGH THE STRAITS OF FLORIDA
AND FROM 21N-26N W OF 66W. A BROAD UPPER TROUGH IS OVER THE
CENTRAL ATLC N OF 30N SUPPORTING A COLD FRONT THAT ENTERS THE
E/CENTRAL ATLC NEAR 32N30W TO 27N40W WHERE IT CONTINUES AS A
STATIONARY FRONT ALONG 27N47W TO 29N57W. A SURFACE TROUGH
EXTENDS FROM 28N36W TO 23N45W. THE BROAD UPPER RIDGE OVER THE W
TROPICAL ATLC JUST E OF THE LESSER ANTILLES EXTENDS AN AXIS FROM
18N57W NE ALONG 27N35W NARROWING TO 28N22W AND IS PROVIDING
DIFFLUENCE ALOFT TO GENERATE CLUSTERS OF SCATTERED SHOWERS AND
POSSIBLE ISOLATED THUNDERSTORMS FROM 18N-30N BETWEEN BETWEEN
48W-60W. A SURFACE RIDGE DOMINATES THE E ATLC ANCHORED BY A 1020
MB HIGH W OF THE CANARY ISLANDS NEAR 28N22W. THE LOW IN THE
SPECIAL FEATURES ABOVE WILL BEGIN TO MOVE SLOWLY NW ON
TUE...POSSIBLY A SUBTROPICAL CYCLONE...REACHING TO NEAR 28N71W
BY EARLY WED WITH A SURFACE TROUGH EXTENDING SW TO E CUBA THEN
MOVE TO NEAR 29N71W BY EARLY THU. THE LOW IS FORECAST TO MOVE N
OF THE AREA AHEAD OF AN APPROACHING COLD FRONT LATE THU. THIS
NEXT COLD FRONT WILL REACH FROM NEAR 31N70W SW TO CENTRAL CUBA
BY LATE FRI AND FROM 28N65W TO E CUBA BY LATE SAT.

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

$$
PAW





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