[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 081051
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT FRI MAY 08 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 CENTERED ALONG 5N8W 1N20W CROSSING THE EQUATOR
NEAR 32W TO NE BRAZIL NEAR 3S41W. CLUSTERS OF SCATTERED MODERATE
CONVECTION ARE FROM 1N-6N BETWEEN 11W-22W AND FROM THE EQUATOR
TO 3N BETWEEN 23W-30W.

...DISCUSSION...

GULF OF MEXICO...
THE GULF IS DOMINATED BY FAIR WEATHER SUPPORTED BY N-NW FLOW
ALOFT AND DRY STABLE AIR ON THE ERN PERIPHERY OF AN UPPER RIDGE
CENTERED OVER NW MEXICO. AT THE SURFACE...S TO SE WINDS ARE
FAIRLY UNIFORM ACROSS THE REGION DUE TO A QUASI-STATIONARY RIDGE
AXIS EXTENDING FROM THE W ATLC TO THE N GULF COAST. WINDS ARE
STRONGEST...15-20 KT...OVER THE WRN WATERS ACCORDING TO BUOY
OBSERVATIONS AND A RECENT ASCAT PASS IN RESPONSE TO LOW PRESSURE
OVER THE SRN PLAINS. LITTLE SIGNIFICANT CHANGE IN THE PATTERN IS
EXPECTED THROUGH THE WEEKEND UNTIL THE NEXT FRONT SLIDES SWD
ACROSS THE SE CONUS AND REMAINS INLAND ALONG THE NRN GULF COAST
BY SUNDAY.

CARIBBEAN SEA...
SCATTERED SHOWERS AND ISOLATED TSTMS CONTINUE ACROSS THE VIRGIN
ISLANDS...PUERTO RICO...HISPANIOLA AND NEARBY WATERS N OF 17N
BETWEEN 63W-77W. THIS UNSETTLED WEATHER IS BEING FUELED BY
STRONG SW FLOW ALOFT AND AN OVERALL DIFFLUENT PATTERN TO THE E
OF A SHORTWAVE TROUGH ACROSS THE BAHAMAS AND ERN CUBA. STRONG
ELY TRADES AND ASSOCIATED LOW-LEVEL WIND SPEED CONVERGENCE IN
THIS AREA ARE PROVIDING ENHANCED LIFT. LOCALLY HEAVY RAINS ARE
FORECAST TO CONTINUE THROUGH LATE SATURDAY OVER HISPANIOLA AS
THE MIDDLE TO UPPER LEVEL TROUGH GRADUALLY WEAKENS AND SHIFTS
E-NE INTO THE CENTRAL ATLC. ELSEWHERE...CONDITIONS ARE
GENERALLY TRANQUIL THOUGH ISOLATED SHOWERS ARE POSSIBLE ACROSS
THE ENTIRE BASIN...ESPECIALLY OVER THE LESSER ANTILLES WHERE
SHALLOW MOISTURE FETCH IS OBSERVED STREAMING IN FROM THE ATLC.

ATLANTIC OCEAN...
THERE ARE ONLY A COUPLE AREAS OF ACTIVE WEATHER ACROSS THE ATLC
DISCUSSION AREA. ONE OF THESE IS OVER THE NW BAHAMAS AND CENTRAL
CUBA IN ASSOCIATION WITH A SURFACE TROUGH ALONG 78W AND UPPER
DIFFLUENCE E OF A MIDDLE TO UPPER LEVEL SHORTWAVE TROUGH OVER
THE STRAITS OF FLORIDA AND THE BAHAMAS. SCATTERED SHOWERS AND
ISOLATED TSTMS ARE FROM 24N-29N BETWEEN 72W-76W. THE LOW-LEVEL
BOUNDARY WILL LIKELY BECOME DIFFUSE OVER THE NEXT 24 HOURS AS
UPPER LEVEL WINDS SHIFT AND AN UPPER RIDGE BUILDS OVER THE W
ATLC WATERS. THE OTHER AREA OF INTEREST IS S OF 23N BETWEEN
57W-70W...N OF THE ERN GREATER ANTILLES ISLANDS. INSTABILITY AND
DIFFLUENCE ALONG AND TO THE E OF ANOTHER SHORTWAVE TROUGH IS
ENHANCING SCATTERED SHOWERS ACROSS HISPANIOLA...PUERTO RICO...
THE US/UK VIRGIN ISLANDS AND NEARBY WATERS TO THE N. REFER TO
THE CARIBBEAN SECTION FOR MORE DETAILS. THE REMAINDER OF THE
ATLC IS VOID OF ORGANIZED DEEP LAYERED CLOUDINESS SUPPRESSED BY
A STABLE ATMOSPHERE...ESPECIALLY OVER THE SUBTROPICAL E ATLC
WHERE THE FLOW IS HIGHLY CONFLUENT. OVER THE TROPICAL E ATLC...
CLUSTERS OF MODERATE CONVECTION ARE LOCATED WITHIN THE ITCZ E OF
22W AND OVER AFRICA ENHANCED BY BROAD SURFACE LOW PRESSURE AND
AN UPPER RIDGE CENTERED NEAR 16N5W. A CONSIDERABLE AMOUNT OF
SAHARAN DUST HAS SPREAD TO ABOUT 50W...ACCORDING TO THE CIMSS
SAL PRODUCT.

$$
HUFFMAN





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