[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 251031
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT WED APR 25 2012

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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS W AFRICA INTO THE E TROPICAL
ATLC NEAR 12N16W TO 7N18W WHERE THE ITCZ CONTINUES ALONG 3N24W
ALONG 1N36W TO 1N47W THEN S OF THE EQUATOR AND INTO SOUTH
AMERICA NEAR 50W. SMALL CLUSTERS OF SCATTERED MODERATE/ISOLATED
STRONG CONVECTION ARE FROM 4N TO THE EQUATOR BETWEEN 26W-35W.
SCATTERED THUNDERSTORMS ARE IN THE TROPICAL WATERS FROM 2N-7N
BETWEEN 4W-15W.

...DISCUSSION...

GULF OF MEXICO...
BROAD UPPER TROUGH REMAINS OVER THE GULF INTO THE W ATLC WITH
ANY ASSOCIATED SURFACE FEATURES IN THE W ATLC. A SURFACE RIDGE
DOMINATES THE GULF ANCHORED BY A 1019 MB HIGH NEAR 27N87W.
STRONG SUBSIDENCE AND DRY STABLE AIR ALSO DOMINATE THE GULF WITH
CLEAR SKIES ACROSS THE ENTIRE BASIN. THE HIGH WILL MOVE ENE TO
THE W ATLC THIS AFTERNOON WITH A RIDGE EXTENDING W TO THE TEXAS
COAST THROUGH SAT. SOUTHERLY RETURN FLOW WILL DEVELOP OVER THE
FAR W GULF BEGINNING TONIGHT SPREADING E ACROSS MUCH OF THE AREA
BY FRI WITH LITTLE CHANGE INTO SAT. A WEAK COLD FRONT WILL SAG
TOWARD N GULF COAST SUN.

CARIBBEAN SEA...
THE UPPER TROUGH OVER THE GULF OF MEXICO AND W ATLC DIPS S OVER
THE FAR NW CARIBBEAN. A SURFACE TROUGH EXTENDS S FROM THE COAST
OF HISPANIOLA NEAR 18N72W CONTINUING ALONG 15N74W TO OFF THE
COAST OF COLOMBIA NEAR 12N75W GENERATING SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS ACROSS THE CENTRAL CARIBBEAN WITHIN 150
NM E OF THE TROUGH WITH ISOLATED SHOWERS WITHIN 120 NM W OF THE
TROUGH. BROAD UPPER RIDGE DOMINATES THE REMAINDER OF THE
CARIBBEAN BASIN ANCHORED OVER VENEZUELA. THE CONVERGENCE OF
UPPER AND LOWER LEVEL FLOW IS GENERATING SCATTERED SHOWERS AND
POSSIBLE ISOLATED THUNDERSTORMS INLAND AND WITHIN 90 NM ALONG
THE COAST FROM 80W IN PANAMA TO 12N IN NICARAGUA. THE SURFACE
TROUGH WILL MOVE W AND EXTEND FROM THE WINDWARD PASSAGE TO THE
SW CARIBBEAN BY LATE TONIGHT THEN FROM E CUBA TO THE SW
CARIBBEAN BY THU NIGHT AND THEN BEGIN TO WEAKEN AS IT REACHES
FROM CENTRAL CUBA TO OFF THE COAST OF COSTA RICA FRI. HIGH
PRESSURE WILL MOVE FROM GULF OF MEXICO INTO THE W ATLC LATE WED
ALLOWING WINDS TO INCREASE FROM E OF THE WINDWARD ISLANDS
THROUGH THE CENTRAL CARIBBEAN THROUGH SUN.

ATLANTIC OCEAN...
THE BROAD UPPER TROUGH OVER THE GULF OF MEXICO EXTENDS INTO THE
W ATLC SUPPORTING A STATIONARY FRONT THAT ENTERS THE W/CENTRAL
ATLC NEAR 32N62W EXTENDING TO 26N65W TO OVER HISPANIOLA NEAR
19N70W. SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS
ARE WITHIN 150/200 NM E OF THE FRONT WITHIN ISOLATED SHOWERS
WITHIN 120 NM W OF THE FRONT S OF 27W. A SURFACE TROUGH IS TO
THE W OF THE FRONT EXTENDING FROM 31N68W ALONG 27N70W TO 24N73W.
STRONG SUBSIDENCE AND DRY STABLE AIR ARE W OF THE FRONT THUS
LIMITING ANY SHOWER ACTIVITY TO ISOLATED SHOWERS IMMEDIATELY
ALONG THE TROUGH AXIS. THE UPPER RIDGE OVER THE CARIBBEAN
EXTENDS A RIDGE AXIS ACROSS THE VIRGIN/LEEWARD ISLANDS TO BEYOND
32N56W FURTHER ENHANCING THE ACTIVITY ASSOCIATED WITH THE FRONT.
AN UPPER LOW IS IN THE E/CENTRAL ATLC CENTERED NEAR 26N42W
EXTENDING AN UPPER TROUGH S INTO THE TROPICS TO NEAR 14N31W AND
SUPPORTING A SURFACE TROUGH THAT EXTENDS FROM 31N49W ALONG
26N46W TO 20N45W WITH SCATTERED SHOWERS/ISOLATED THUNDERSTORMS
FROM 22N-28N E OF THE TROUGH AXIS TO 37W. A BROAD SURFACE RIDGE
DOMINATES THE ATLC W OF 60W WITH A WEAKNESS IN THE IMMEDIATE
VICINITY OF THE ABOVE SURFACE TROUGH AND ANCHORED NE OF THE
CANADIAN MARITIMES GIVING THE REMAINDER OF THE ATLC FAIR WEATHER
THIS MORNING. THE STATIONARY FRONT WILL GRADUALLY DISSIPATE
THROUGH EARLY FRI. THE S PORTION WILL WEAKEN TO A TROUGH THAT
MOVES BACK W FROM THE SE BAHAMAS TO E CUBA THU FROM CENTRAL
BAHAMAS TO CENTRAL CUBA FRI AND FROM THE W BAHAMAS TO W CUBA SAT
AND SUN. HIGH PRESSURE OVER THE E GULF OF MEXICO WILL SHIFT E TO
THE FAR W ATLC TODAY AND TO THE FAR NE PORTION BY LATE TONIGHT.
BY THU A RIDGE WILL EXTEND FROM NEAR BERMUDA TO CENTRAL FLORIDA.
THE RIDGE WILL THEN SHIFT N TO 29N SAT AND TO 30N SUN. A
TIGHTENING PRESSURE GRADIENT BETWEEN THE RIDGE AND TROUGH WILL
ALLOW FOR INCREASING WINDS OVER THE SOUTHERN PORTION THROUGH THE
PERIOD.

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

$$
PAW





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