[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 281733
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU APR 28 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 1730 UTC.

...THE ITCZ...

FROM THE COAST OF SIERRA LEONE NEAR 7N12W...SW TO NEAR 3N20W TO
NEAR THE EQUATOR AROUND 1N32W. THEN..IT RESUMES ALONG THE
COASTAL WATERS OF BRAZIL NEAR 3S38W TO 2N50W. A BROAD AREA OF
NUMEROUS MODERATE TO HEAVY SHOWERS AND THUNDERSTORMS IS FROM
5S-7N BETWEEN 10W-21W. SIMILAR CONVECTION IS OCCURRING WITHIN 80
NM N OF THE ITCZ AXIS BETWEEN 20W-31W...AND WITHIN 100 NM ON
EITHER SIDE OF THE AXIS BETWEEN 42W-51W.

...DISCUSSION...

GULF OF MEXICO...
A COLD FRONT IS MOVING EASTWARD ACROSS THE GULF AT ABOUT 15 KT.
THIS BOUNDARY IS ANALYZED ENTERING THE FLORIDA COAST NEAR 30N84W
EXTENDING SW ALONG 27N87W TO 25N92W WHERE IT BECOMES NEARLY
STATIONARY INTO THE BAY OF CAMPECHE NEAR 20N95W. SATELLITE
IMAGERY ALONG WITH DOPPLER DATA SHOWED SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS ALONG THE BOUNDARY N OF 25N. GUSTY
NORTHERLY WINDS UP TO 25 KT ARE OBSERVED BEHIND THE FRONT.
CONSEQUENTLY...SOUTHERLY...RETURN FLOW UP TO 25 KT IS AHEAD OF
THE FRONT. A SURFACE TROUGH PARALLELS THE WESTERN COAST OF THE
YUCATAN PENINSULA. OTHER THAN CYCLONIC CURVATURE AROUND THE
TROUGH...NO CONVECTION IS NOTED ON SATELLITE IMAGERY. LOOK FOR
THE COLD FRONT TO CONTINUE TO TRACK EAST WITH CONVECTION OVER
THE NEXT 24 HOURS. IN THE MEAN TIME...SURFACE RIDGING BUILDS
BEHIND THE FRONT.

CARIBBEAN SEA...
MOST OF THE CARIBBEAN SEA W OF 70W IS EXPERIENCING FAIR WEATHER
CONDITIONS DUE TO DRY AND STABLE AIR ALOFT MOVING ACROSS THE
AREA. AT SURFACE...SURFACE AND MARINE OBSERVATIONS INDICATE
15-20 KT TRADE WINDS TURNING N WESTWARD W OF 77W N OF 14N. THE
OVERALL FLOW CONTINUES TO ADVECT LOW LEVEL MOISTURE FROM THE
TROPICAL ATLANTIC INTO THE EASTERN CARIBBEAN NOTED ON TOTAL
PRECIPITABLE WATER IMAGERY. WITHIN THIS AREA OF LOW LEW LEVEL
MOISTURE...A SURFACE TROUGH IS ANALYZED RIGHT OVER THE LESSER
ANTILLES FROM MARTINIQUE TO TRINIDAD AND TOBAGO. THIS SYSTEM IS
GENERATING SCATTERED SHOWERS AND THUNDERSTORMS TO THE ISLANDS S
OF MARTINIQUE. HOWEVER...THE CONVECTION ASSOCIATED TO THIS AREA
OF MOISTURE EXTENDS TO THE N CENTRAL BASIN...WITHIN 40 NM ON
EITHER SIDE OF A LINE FROM 14N61W TO 17N71W. AS THIS AREA OF
CONVECTION MOVES WEST...THIS GROUP OF ISLANDS WILL CONTINUE TO
EXPERIENCE BAD WEATHER FOR AT LEAST THE NEXT 24 HOURS AS THE
TROUGH MOVES WEST AT ABOUT 12 KT. ON A SECONDARY NOTE...SMOKE
FROM THE FIRES IN CENTRAL AMERICA ARE AFFECTING VISIBILITIES
DOWN TO LESS THAN 5 SM OVER THE FAR WEST CARIBBEAN SEA W OF 85W
S OF 19N.

ATLANTIC OCEAN...
MOST OF THE DISCUSSION AREA IS DOMINATED BY A STRONG UPPER LEVEL
RIDGE COVERING ALMOST THE ENTIRE ATLC BASIN. THIS UPPER RIDGE IS
SUPPORTING A 1031 MB HIGH WOBBLING AROUND 34N56W. HOWEVER...
SCATTERED SHOWERS AND THUNDERSTORMS WILL BE ENTERING THE WEST
ATLC AS AN UPPER LEVEL TROUGH MOVES OFF THE CONUS EASTERN
SEABOARD SUPPORTING A COLD FRONT CURRENTLY OVER THE SE UNITED
STATES AND GULF OF MEXICO. A WEAK 1009 MB LOW PRESSURE SYSTEM IS
OVER THE FAR EAST ATLC NEAR 31N16W. A SURFACE TROUGH EXTENDS SSW
FROM THE LOW CENTER TO NEAR 23N20W. NO SIGNIFICANT CONVECTION IS
OBSERVED IN THE VICINITY OF THE LOW NOR THE SURFACE TROUGH. THIS
SYSTEM WILL DISSIPATE OVER THE NEXT 12 TO 24 HOURS.

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

$$

GARCIA



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