[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 071759
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT THU APR 07 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.

...ITCZ...

ITCZ AXIS IS ALONG 07N11W 03N24W CROSSING THE EQUATOR NEAR 42W
THEN INTO NE BRAZIL NEAR 01S48W. SCATTERED MODERATE AND ISOLATED
STRONG CONVECTION IS FROM THE EQUATOR TO 05N BETWEEN 19W-31W.
ISOLATED MODERATE CONVECTION IS FROM THE EQUATOR TO 04N BETWEEN
37W-51W.

...DISCUSSION...

GULF OF MEXICO...
WATER VAPOR IMAGERY INDICATES A MIDDLE TO UPPER LEVEL RIDGE OVER
MUCH OF THE GULF THIS AFTERNOON ACCOMPANIED BY MOSTLY DRY AIR
AND OVERALL SUBSIDENCE. THIS UPPER LEVEL FEATURE CONTINUES TO
SUPPORT A SURFACE RIDGE AXIS WHICH EXTENDS FROM THE W ATLC
ACROSS THE FLORIDA PENINSULA TO THE SW GULF NEAR 20N97W. LOCATED
MOSTLY ON THE WESTERN PERIPHERY OF THE RIDGE...SOUTHERLY RETURN
FLOW IN THE RANGE OF 10 TO 20 KT IS EXPECTED THROUGH LATE
THURSDAY...WITH THE STRONGEST WINDS TO 20 KT MAINLY W OF 90W.
WINDS OVER THE WESTERN GULF WILL INCREASE SLIGHTLY OVER THE
WEEKEND WITH A WEAK COLD FRONT FORECAST TO IMPACT THE NW GULF
WATERS EARLY MONDAY.

CARIBBEAN SEA...
THE CARIBBEAN SEA REMAINS UNDER MOSTLY WEST-SOUTHWESTERLY UPPER
LEVEL FLOW DUE TO AN ANTICYCLONIC CIRCULATION CENTERED OVER
COASTAL NORTHERN VENEZUELA NEAR 10N67W PROVIDING MOSTLY DRY AIR
AND SUBSIDENCE OVER THE EASTERN CARIBBEAN E OF 72W. WATER VAPOR
IMAGERY INDICATES A STREAM OF MIDDLE TO UPPER LEVEL MOISTURE ON
THE WESTERN PERIPHERY OF THE RIDGE EXTENDING FROM PANAMA AND
NORTHERN COLOMBIA NORTHEASTWARD ACROSS JAMAICA AND OVER THE
WINDWARD PASSAGE. AT THE SURFACE...EASTERLY TRADES CONTINUE AND
ARE EXPECTED TO PERSIST THROUGH THE WEEKEND DUE TO A STATIONARY
RIDGE LOCATED IN THE SW NORTH ATLC. LOW-LEVEL MOISTURE CONTINUES
TO ADVECT WESTWARD ACROSS THE BASIN WITH ISOLATED SHOWERS NOTED
ON VISIBLE SATELLITE IMAGERY OVER PORTIONS OF THE NORTH-CENTRAL
CARIBBEAN N OF 17N BETWEEN 69W-78W...AND IN THE SW CARIBBEAN S
OF 12N W OF 77W. ALSO OF NOTE...LOW-LEVEL MOISTURE ASSOCIATED
WITH A REMNANT FRONTAL BOUNDARY IS ORIENTED FROM 16N57W TO
21N65W NE OF THE LEEWARD ISLANDS. THIS MOISTURE AND POSSIBLE
ISOLATED SHOWER ACTIVITY IS EXPECTED TO MOVE OVER THE LEEWARD
ISLANDS AND NE CARIBBEAN THROUGH THE NEXT 12 TO 24 HOURS.

ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH IS LOCATED OVER THE WESTERN NORTH ATLC
WITH TROUGH AXIS ALONG 50W THAT REMAINS MAINLY NORTH OF THE
DISCUSSION AREA. HOWEVER...THE UPPER LEVEL TROUGH SUPPORTS A
COLD FRONT ANALYZED INTO THE REGION NEAR 32N51W THAT EXTENDS SW
TO 26N63W THEN BECOMES STATIONARY WESTWARD TO 25N74W. WHILE
STRONG UPPER LEVEL DYNAMICS LACK IN VICINITY OF THE FRONT...
ISOLATED SHOWERS ARE OCCURRING WITHIN 90 NM EITHER SIDE OF THE
FRONTAL BOUNDARY. A 1025 MB HIGH IS CENTERED NW OF THE FRONT
NEAR 33N67W THAT IS PROVIDING FOR MOSTLY FAIR WEATHER CONDITIONS
OVER MUCH OF THE SW NORTH ATLC N OF 27N W OF 58W. FARTHER
EAST...A DEEP LAYER TROUGH IS CENTERED NEAR 35N25W THAT EXTENDS
A COLD FRONT INTO THE DISCUSSION AREA NEAR 32N19W AND EXTENDS
S-SW ALONG 27N20W TO 20N33W...THEN AS A DISSIPATING STATIONARY
FRONT TO 17N49W. LOSING FRONTAL IDENTITY FARTHER TO THE WEST...A
SHEAR LINE EXTENDS FROM THE WESTERN EXTENT OF THE STATIONARY
FRONT TO EAST OF THE LEEWARD ISLANDS NEAR 16N60W. RECENT ASCAT
AND WINDSAT PASSES FROM EARLIER THIS MORNING DEPICTED THE
FRONTAL BOUNDARY N OF 18N WHILE STRONGER NE WINDS OF 20 KT WERE
LOCATED WITHIN 150 NM N OF THE SHEAR LINE BETWEEN 50W-60W. THE
REMAINDER OF THE CENTRAL ATLC IS UNDER THE INFLUENCE OF A
SURFACE RIDGE ANCHORED BY A 1020 MB HIGH CENTERED NEAR 28N49W
PROVIDING MOSTLY FAIR WEATHER CONDITIONS N OF 20N BETWEEN THE
AFOREMENTIONED COLD FRONTS.

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

$$
HUFFMAN


WWWW
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