[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 212308
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT MON MAR 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2300 UTC.

...ITCZ...

ITCZ AXIS IS ANALYZED ALONG 06N10W 00N20W 01S35W 01S46W CROSSING
46W INTO SOUTH AMERICA. ISOLATED MODERATE CONVECTION IS
OCCURRING FROM 05S TO 03N BETWEEN 14W AND 22W.

...DISCUSSION...

GULF OF MEXICO...
AS OF 2100 UTC...A 1025 MB SURFACE HIGH WAS LOCATED IN THE NE
GULF OF MEXICO NEAR 29N85W.  STABLE CONDITIONS PREVAIL IN THE
POST-FRONTAL AIRMASS WITH NO DEEP CONVECTION OCCURRING.  SOME
SHOWERS ARE SEEN IN WESTERN CUBA ALONG THE TAIL END OF THE
DECAYING COLD FRONT BOUNDARY.  A SECOND AREA OF LOW-TOPPED
RAINFALL IS OBSERVED IN THE BAY OF CAMPECHE ALONG THE
CONVERGENCE OF EASTERLIES COMING ACROSS THE YUCATAN OF MEXICO
AND NORTHERLIES FUNNELING ACROSS THE CHIVELA PASS.  SURFACE
WINDS ARE GENERALLY EASTERLY TO SOUTHEASTERLY 20 KT OR LESS.  IN
THE UPPER LEVELS...SUBSIDENT RIDGING DOMINATES OVER THE CENTRAL
GULF OF MEXICO WITH SOME HIGH CLOUDINESS ADVECTING OVER THE
NORTHERNMOST GULF FROM CONVECTION FORMING OVER NORTH MEXICO.
DURING THE NEXT DAY...LITTLE CHANGE IS EXPECTED IN THESE
CONDITIONS.

CARIBBEAN SEA...
A DISSIPATING FRONTAL BOUNDARY HAS REACHED CUBA TODAY WITH
MINIMAL COOL AIR BUT SCATTERED SHOWERS ALONG THE NORTHERN HALF
OF THE ISLAND...AS SEEN FROM THE CUBAN RADAR NETWORK.  SOME
LOW-TOPPED RAINFALL IS ALSO OCCURRING OVER THE NORTH AND
EAST FACING SLOPES OF JAMAICA...HISPANIOLA AND PUERTO RICO.
AS IS TYPICAL FOR THIS TIME OF YEAR...NO DEEP CONVECTION IS
OBSERVED ACROSS THE CARIBBEAN OR CENTRAL AMERICA.  A MODERATE
PRESSURE GRADIENT BETWEEN A 1028 MB HIGH NEAR 34N72W OFF OF THE
U.S. CAROLINAS AND LOW PRESSURE OVER SOUTH AMERICA IS PRODUCING
15 TO 25 KT NE SURFACE TRADEWINDS.  IN THE UPPER LEVELS...
ANTICYCLONICALLY-TURNING SOUTHWESTERLY WINDS PREVAIL...WHICH ARE
ADVECTING SOME HIGH CLOUDINESS OVER THE SOUTHERN AND EASTERN
PORTION OF THE CARIBBEAN FROM DEEP CONVECTION OVER SOUTH
AMERICA.  DURING THE NEXT DAY...LITTLE CHANGE IS EXPECTED IN
THESE CONDITIONS.

ATLANTIC OCEAN...
THE MAIN FEATURE OF INTEREST IS A COLD FRONT THAT EXTENDS FROM
32N45W SOUTHWESTWARD TO 22N60W AND WESTWARD TO 22N72W NEAR THE
TURKS AND CAICOS.  FROM THERE THE BOUNDARY CONTINUES WESTWARD AS
A DISSIPATING COLD FRONT INTO CUBA.  PEAK WINDS NEAR 30N JUST
WEST OF THE FRONT ARE AT 30 KT...THE ONE GALE REPORT OF 36 KT
NNW WIND FROM SHIP WCPU APPEARS TO BE BIASED ABOUT 5 KT TOO
HIGH.  ELSEWHERE BEHIND THE FRONT...WINDS ARE NORTHERLY 15 TO 25
KT.  NO DEEP CONVECTION IS OCCURRING IN ASSOCIATION WITH THE
FRONT THOUGH SOME SHOWERS ARE BEING GENERATED WITHIN 120 NM OF
THE FRONTAL BOUNDARY.  HOWEVER...A LARGE AREA OF SCATTERED
SHOWERS WITHIN 240 NM E OF A PRE-FRONTAL TROUGH AXIS ARE SEEN IN
THE GEOSTATIONARY SATELLITE IMAGERY.  THE TROUGH EXTENDS FROM
29N44W TO 25N42W TO 15N49W.  SURFACE WINDS EAST OF THE TROUGH
ARE ENHANCED WITH 20 TO 30 KT SE WINDS.  A WEAK 1018 MB SURFACE
HIGH IS AT 28N28W...WEST OF THE CANARY ISLANDS.  BECAUSE OF THE
WEAK HIGH...THE PRESSURE GRADIENT IS RELAXED WITH SURFACE WINDS
THROUGHOUT MOST OF THE TROPICAL AND SUBTROPICAL NORTH ATLANTIC
QUITE WEAK...5 TO 15 KT.  IN THE UPPER LEVELS...A TROUGH EXTENDS
FROM NORTH OF OUR AREA SOUTHWARD TO 32N48W TO 28N48W...WHICH IS
PROVIDING SOME UPPER LEVEL SUPPORT FOR THE FRONT AND THE SURFACE
TROUGH.  ELSEWHERE...ZONAL WESTERLY FLOW PREVAILS NORTH OF A
RIDGE EXTENDING ALONG ROUGHLY 07N ACROSS THE EQUATORIAL
ATLANTIC.  DURING THE NEXT DAY...THE FRONTAL BOUNDARY SHOULD
CONTINUING MOVING SOUTHEASTWARD WITH THE PRE-FRONTAL TROUGH
RETAINING ITS IDENTITY AHEAD OF THE FRONT.  THE COLD FRONT
SHOULD BECOME ILL-DEFINED WEST OF 65W...BUT MAY CONTINUE TO
CAUSE SOME SHOWERS OVER THE GREATER ANTILLES.

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

$$
LANDSEA




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