[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 021728
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SAT MAY 02 2009

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...METEOROLOGICAL ANALYSIS...WEATHER
OBSERVATIONS...AND RADAR.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1330 UTC.

...THE ITCZ...

THE ITCZ AXIS EXTENDS FROM W AFRICA AT 05N08W TO THE EQUATOR AT
25W TO NE BRAZIL NEAR 04S39W. SCATTERED MODERATE CONVECTION IS
WITHIN 120 NM OF THE ITCZ.

...DISCUSSION...

GULF OF MEXICO...
SOUTHEASTERLY SURFACE WINDS OF 10-20 KT PREVAIL ACROSS THE GULF
OF MEXICO...THE HIGHER VALUES IN THE WESTERN GULF...UNDER THE
INFLUENCE OF A RIDGE OF HIGH PRESSURE NORTHEAST OF FLORIDA AND A
BROAD LOW OVER TEXAS.  THERE ARE NO AREAS OF ORGANIZED DEEP
CONVECTION AT THIS TIME.  IN THE UPPER LEVELS...A WEAK TROUGH
LIES ACROSS THE GULF WITH SUBSIDING STABLE CONDITIONS
DOMINATING.  LITTLE CHANGE IS ANTICIPATED FOR MOST OF THE GULF
IN THE NEXT TWO DAYS...THOUGH THE BAROCLINIC SYSTEM OVER TEXAS
MAY SEE THE COOL FRONTAL BOUNDARY JUST REACHING THE EXTREME NW
GULF MONDAY MORNING.  IF IT DOES...THEN THIS PORTION OF THE GULF
MAY SEE INCREASED CHANCES FOR PRECIPITATION AND A RELATIVELY
BRIEF SWING OF THE SURFACE WINDS TO A NORTHERLY COMPONENT.

CARIBBEAN SEA...
EAST TO NORTHEASTERLY SURFACE WINDS RANGING FROM 10 TO 25 KT ARE
OCCURRING TODAY...SOUTH OF THE RIDGE OVER THE WESTERN ATLANTIC.
THE STRONGEST WINDS JUST SOUTH OF HISPANIOLA AND NORTH OF
COLUMBIA ARE WELL-DEPICTED BY THE 1042 UTC QUIKSCAT PASS.  A
SURFACE TROUGH EXTENDS FROM THE LESSER ANTILLES
NORTH-NORTHEASTWARD INTO THE ATLANTIC.  THIS TROUGH IS KICKING
UP SCATTERED LOW-TOPPED PRECIPITATION IN THE LESSER ANTILLES AS
DEPICTED BY THE GUADELOUPE AND MARTINIQUE RADARS.  ADDITIONAL
SHALLOW CONVECTION IS SEEN FROM THE VISIBLE SATELLITE IMAGERY
JUST SOUTHWEST OF HAITI...LIKELY DUE TO THE CONVERGENCE OF
SURFACE WINDS ON THE LEE SIDE OF HISPANIOLA.  IN THE UPPER
LEVELS...ANTICYCLONICALLY TURNING WINDS WITH GENERAL SUBSIDENCE
PREVAIL.  UPPER LEVEL CLOUDINESS IS BEING SPREAD EASTWARD BY
THESE WINDS FROM CONVECTION OCCURRING OVER SOUTH AMERICA AND THE
NORTHEAST PACIFIC'S ITCZ.

ATLANTIC OCEAN...
THE MAIN PLAYER TODAY IS THE VERY LARGE SURFACE HIGH CENTERED
NORTH OF THE AZORES WITH THE RIDGE LINE EXTENDING SOUTHWESTWARD
FROM THE HIGH TO 32N64W TO THE FLORIDA PENINSULA.  EASTERLY
WINDS OF 20 KT OR LESS AND NO AREAS OF DEEP CONVECTION...WITH
ONE EXCEPTION... COVER THE ATLANTIC.  THE ONLY EXCEPTION TO THE
BENIGN CONDITIONS IS THE PROMINENT AFOREMENTIONED SURFACE TROUGH
THAT EXTENDS FROM THE LESSER ANTILLES NORTH-NORTHEASTWARD TO
25N58W.  THE TROUGH IS ASSOCIATED WITH A MID LEVEL LOW CENTERED
NEAR 25N55W...WHICH CAN BE SEEN IN THE WATER VAPOR IMAGERY.
SCATTERED MODERATE CONVECTION IS OCCURRING WITHIN 180 NM EAST OF
THE SURFACE TROUGH NORTH OF 23N...THOUGH IT HAS BEEN DIMINISHING
TODAY.  ISOLATED SHOWERS ARE ALSO OCCURRING OVER THE LESSER
ANTILLES AND WITHIN 300 NM EAST OF THE TROUGH AXIS.  THE TROUGH
IS ANTICIPATED TO SLOWLY WEAKEN AS IT MOVES GRADUALLY TO THE
WEST.  ELSEWHERE...A WEAK COLD FRONT HAS REACHED OUR NORTHERN
BOUNDARY EXTENDING FROM 32N39W TO 29N41W.  IT IS POSSIBLE AN
EXTENSION OF THIS BOUNDARY EXISTS FROM THAT POINT WESTWARD ALONG
29N TO ABOUT 50W.  SCATTERED SHOWERS ARE OBSERVED WITHIN 60 NM
OF THE FRONT.  IN THE UPPER LEVELS...CYCLONICALLY CURVING
WESTERLIES PREVAIL WITH PEAK WINDS AT 200 MB AROUND 70 KT
BETWEEN 20-30N EAST OF 45W.  WIDESPREAD CIRRUS IS BEING ADVECTED
NORTHEASTWARD IN THIS FLOW.

$$
LANDSEA




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