[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 211719
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU APR 21 2011

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTION
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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1715 UTC.

...THE ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 5N9W EQ21W 4S33W EQ50W.
SCATTERED MODERATE TO STRONG CONVECTION IS FROM 6N-1S BETWEEN
6W-20W. ISOLATED MODERATE CONVECTION IS FROM EQ-4N BETWEEN
20W-30W...AND FROM 4N-2S BETWEEN 40W-50W. WIDELY SCATTERED
MODERATE CONVECTION IS FROM 2N-7S BETWEEN 30W-40W.

...DISCUSSION...

THE GULF OF MEXICO...
10-20 KT SE RETURN FLOW DOMINATES FLORIDA AND THE GULF OF MEXICO
WITH STRONGEST WINDS OVER THE W GULF W OF 90W...AND OVER THE
STRAITS OF FLORIDA. FAIR WEATHER IS NOTED OVER THE ENTIRE GULF.
IN THE UPPER LEVELS...NW FLOW PREVAILS. AN AREA OF UPPER
LEVEL MOISTURE AND SCATTERED HIGH CLOUD ARE OVER THE COAST OF
THE N GULF STATES. STRONG SUBSIDENCE IS OVER THE REMAINDER OF
GULF. EXPECT...SOME AIR MASS SHOWERS AND THUNDERSTORMS OVER S
MEXICO S OF 18N...IN THE AFTERNOON AND EVENING HOURS.
OTHERWISE EXPECT LITTLE CHANGE OVER THE NEXT 24 HOURS.

THE CARIBBEAN SEA...
10-20 KT TRADEWINDS ARE OVER THE CARIBBEAN SEA WITH HIGHEST
WINDS OVER THE WINDWARD PASSAGE. SCATTERED SHOWERS ARE OVER
COSTA RICA...THE GULF OF HONDURAS...AND S OF HISPANIOLA. SIMILAR
SHOWERS ARE OVER THE SE CARIBBEAN AND VENEZUELA S OF 12N BETWEEN
60W-72W. MOSTLY FAIR WEATHER IS OVER THE REMAINDER OF THE
CARIBBEAN. IN THE UPPER LEVELS...ZONAL FLOW DOMINATES THE AREA.
UPPER LEVEL MOISTURE WITH BANDS OF SCATTERED HIGH CLOUDS ARE
OVER THE CENTRAL CARIBBEAN FROM HONDURAS TO GUADELOUPE. STRONG
SUBSIDENCE IS OVER THE REMAINDER OF THE SEA. EXPECT MORE SHOWERS
OVER THE SE CARIBBEAN S OF 13N OVER THE NEXT 24 HOURS. ALSO
EXPECT AIRMASS THUNDERSTORMS OVER W HONDURAS...EL SALVADOR...AND
GUATEMALA OVER THE NEXT 24 HOURS.

THE ATLANTIC OCEAN...
SURFACE RIDGING AND FAIR WEATHER DOMINATES THE W ATLANTIC W OF
70W. A SURFACE TROUGH IS FURTHER E FROM 27N61W TO 21N65W. AN
EMBEDDED 1009 MB LOW IS ON THE TROUGH AXIS AT 24N63W. ISOLATED
MODERATE CONVECTION IS N OF THE LOW CENTER FROM 24N-28N BETWEEN
56W-64W. A TIGHT SURFACE PRESSURE GRADIENT N OF THE LOW IS
PRODUCING GALE FORCE WINDS WITHIN 180 NM OF THE NE QUADRANT.
ELSEWHERE...A 1030 MB HIGH IS CENTERED OVER THE CENTRAL ATLANTIC
NEAR 34N42W. IN THE UPPER LEVELS...AN UPPER LEVEL LOW IS OVER
THE W ATLANTIC NEAR 29N67W SUPPORTING THE E ATLANTIC SURFACE
SYSTEM. A 70 KT SUBTROPICAL JETSTREAM EXTENDS FROM OVER E CUBA
AT 20N77W TO 23N60W TO 20N30W PRODUCING A LOT OF WESTERLY
VERTICAL WINDSHEAR OVER THE SURFACE LOW. EXPECT OVER THE NEXT 24
HOURS FOR...THE SURFACE LOW TO MOVE NW TO 26N63W WITH CONTINUED
CONVECTION. WINDS ARE ALSO FORECAST DECREASE TO JUST BELOW GALE
FORCE N OF THE CENTER IN ABOUT 6 HOURS.

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

$$
FORMOSA





This weather bulletin was brought to you by:
www.nashvilleweather.net