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AXNT20 KNHC 071037
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT THU MAY 07 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...THE ITCZ...

THE ITCZ AXIS IS ALONG 5N8W 1N20W CROSSING THE EQUATOR NEAR 22W
AND CONTINUING S OF THE EQUATOR ALONG 2S28W AND INTO NE BRAZIL
NEAR 3S40W. SCATTERED MODERATE/STRONG CONVECTION IS FROM THE
EQUATOR TO 6N BETWEEN THE PRIME MERIDIAN TO 12W.

...DISCUSSION...

GULF OF MEXICO...
THE GULF REMAINS UNDER 10-20 KT E TO SE SURFACE FLOW AS A
SURFACE RIDGE OF HIGH PRESSURE EXTENDS FROM THE FAR W ATLC
ACROSS THE FLORIDA PENINSULA AND INTO THE GULF. ALOFT IN THE
MIDDLE TO UPPER LEVELS...A DRY AND SUBSIDENT NORTHWEST FLOW IS
EVIDENT ON WATER VAPOR IMAGERY WITH WEAK TROUGHING OBSERVED
ACROSS THE NE GULF AND NRN FLORIDA. A TROUGH CONTINUES TO MOVE
ACROSS THE ERN CONUS AND TRACK NEWD KEEPING ANY FRONTAL
BOUNDARIES WELL NORTH OF THE GULF WATERS. ONLY MIDDLE TO HIGH
LEVEL CLOUDINESS IS NOTED ON SATELLITE IMAGERY N OF 24N E OF
86W...INCLUDING THE FLORIDA PENINSULA. LOOKING AHEAD...LITTLE
CHANGE IS EXPECTED IN THE OVERALL PATTERN DURING THE NEXT 24-48
HOURS WITH FAIR WEATHER CONDITIONS PREVAILING THROUGH SUNDAY.

CARIBBEAN SEA...
AN UPPER LEVEL RIDGE AXIS EXTENDS FROM COLOMBIA NW ACROSS
CENTRAL AMERICA AND IS PROVIDING THE WRN CARIBBEAN WITH MAINLY
WLY ZONAL FLOW AND A DRY SUBSIDENT ATMOSPHERE IN THE MIDDLE AND
UPPER LEVELS. ACROSS THE ERN CARIBBEAN...A MIDDLE TO UPPER LEVEL
TROUGH RESIDES E OF 70W WITH ABUNDANT MOISTURE NOTED ON WATER
VAPOR IMAGERY. THIS MOISTURE IS BEING LIFTED IN A LARGE
DIFFLUENT ZONE E OF THE TROUGH AXIS AND SUPPORTS A SURFACE
TROUGH THAT EXTENDS FROM THE N/CENTRAL CARIBBEAN NEAR 16N73W NWD
ACROSS THE SE BAHAMAS INTO THE W ATLC. SCATTERED SHOWERS
CONTINUE N OF 14N AND E OF THE SURFACE TROUGH. THIS AREA OF
PRECIPITATION ACROSS THE NE CARIBBEAN IS FORECAST TO PERSIST
THROUGH THE WEEKEND UNTIL THE MIDDLE TO UPPER LEVEL TROUGH
SHIFTS EWD INTO THE CENTRAL ATLC BY LATE SUNDAY. ELSEWHERE...
MODERATE TO FRESH TRADE WINDS COVER THE CARIBBEAN WITH POSSIBLE
ISOLATED LOW LEVEL SHOWER ACTIVITY MOVING WESTWARD IN CONVERGENT
SURFACE FLOW ACROSS THE BASIN.

ATLANTIC OCEAN...
THE W ATLC CONTINUES TO BE DOMINATED BY A SURFACE HIGH PRESSURE
RIDGE ANCHORED BY A 1031 MB HIGH LOCATED N OF THE DISCUSSION
AREA NEAR 35N53W. A WEAKNESS IN THE SURFACE RIDGE...ANALYZED AS
A SURFACE TROUGH EXTENDS FROM 17N73W IN THE N/CENTRAL CARIBBEAN
SEA ACROSS THE SE BAHAMAS TO 25N73W. THIS ALONG WITH AN UPPER
LEVEL TROUGH WITH AXIS ALONG 70W IS GENERATING AN AREA OF UPPER
LEVEL DIFFLUENCE TO THE E OF THE SURFACE TROUGH PRODUCING
SCATTERED SHOWERS EXTENDING WITHIN 150 NM OF A LINE FROM THE
MONA PASSAGE N-NW TO 28N74W. SCATTERED SHOWERS ARE FARTHER TO
THE SE ACROSS THE NE CARIBBEAN SEA...THE LESSER ANTILLES AND
TROPICAL ATLC FROM 14N-20N BETWEEN 58W-70W. THE REMAINDER OF THE
CENTRAL AND ERN ATLC IS UNDER THE INFLUENCE OF THE SURFACE RIDGE
WITH 15 TO 20 KT NE TO ELY TRADES.

$$
HUFFMAN





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