[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 082333
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...THE ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 6N10W 3N20W 1N30W CROSSING THE
EQUATOR NEAR 34W TO NE BRAZIL NEAR 3S42W.  SCATTERED MODERATE
CONVECTION IS WITHIN 150 NM N OF THE AXIS BETWEEN 25W-29W.

...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 NRN MEXICO. AT THE SURFACE...A QUASI-STATIONARY
RIDGE AXIS EXTENDING FROM THE W ATLC TO THE N GULF COAST IS
PRODUCING S TO SE WINDS ACROSS THE ENTIRE AREA. SHIP/BUOY
OBSERVATIONS AND RECENT SCATTEROMETER PASSES SHOW THE STRONGEST
WINDS...15-20 KT...OVER THE WRN WATERS IN RESPONSE TO LOW
PRESSURE OVER THE S CENTRAL CONUS. A FRONT IS EXPECTED TO
APPROACH THE FAR N WATERS THIS WEEKEND...BUT LATEST MODEL
GUIDANCE SUGGESTS THAT IT SHOULD STAY JUST N OF THE GULF WATERS.
THIS SHOULD ALLOW FOR A CONTINUATION OF THE MAINLY FAIR
WEATHER.

CARIBBEAN SEA...
SCATTERED SHOWERS AND TSTMS ARE AFFECTING PORTIONS OF PUERTO
RICO...HISPANIOLA AND NEARBY COASTAL WATERS. THE LARGE SCALE
FORCING CONSISTS OF STRONG SW FLOW ALOFT TO THE E OF A SHORTWAVE
TROUGH OVER THE BAHAMAS. HOWEVER...LOCAL EFFECTS ARE
ENHANCING THE ACTIVITY AS MUCH OF THE COLDER CLOUD TOPS AND
LIGHTNING STRIKES ARE OVER THE ISLANDS. SIMILAR ACTIVITY IS
OCCURRING OVER PARTS OF CENTRAL AMERICA...COLOMBIA AND VENEZUELA
ENHANCED BY STRONG WLY FLOW ALOFT NEAR THE BASE OF THE UPPER
TROUGHING. ELSEWHERE...CONDITIONS ARE GENERALLY TRANQUIL THOUGH
ISOLATED SHOWERS ARE POSSIBLE ACROSS THE ENTIRE BASIN...
ESPECIALLY OVER THE LESSER ANTILLES WHERE A SHALLOW MOISTURE
FETCH IS OBSERVED STREAMING IN FROM THE ATLC. TRADE WINDS ARE
MAINLY 15-20 KT...EXCEPT 20-25 KT IN THE TOPOGRAPHICALLY
ENHANCED ZONE NEAR THE COAST OF COLOMBIA. LITTLE CHANGE IS
EXPECTED IN THIS FLOW OVER THE NEXT COUPLE OF DAYS AS STRONG
HIGH PRES REMAINS QUASI-STATIONARY OVER THE CENTRAL ATLC.

ATLANTIC OCEAN...
THERE ARE ONLY A COUPLE OF SMALL AREAS OF UNSETTLED WEATHER
ACROSS THE ATLC DISCUSSION ZONE. ONE OF THESE IS LOCATED MIDWAY
BETWEEN BERMUDA AND THE CENTRAL BAHAMAS. LOW-LEVEL CONVERGENCE
ALONG A WEAKENING SFC TROUGH AND INSTABILITY ASSOCIATED WITH AN
UPPER SHORTWAVE IS PRODUCING SCATTERED SHOWERS AND ISOLATED
TSTMS FROM 26N-29N BETWEEN 73W-75W. THE LOW-LEVEL BOUNDARY IS
EXPECTED TO DISSIPATE SHORTLY...LIKELY CAUSING MUCH OF THE
ACTIVITY TO DIMINISH LATER TONIGHT. THE OTHER AREA OF DISTURBED
WEATHER IS S OF 20N BETWEEN 64W-71W...N OF THE ERN GREATER
ANTILLES. INSTABILITY AND DIFFLUENCE ALONG AND TO THE E OF THE
AFOREMENTIONED SHORTWAVE IS ENHANCING SCATTERED SHOWERS ACROSS
HISPANIOLA...PUERTO RICO 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...MUCH OF THE STRONG CONVECTION NOTED YESTERDAY HAS
DIMINISHED. A CONSIDERABLE AMOUNT OF SAHARAN DUST HAS SPREAD TO
ABOUT 50W...ACCORDING TO THE CIMSS SAL PRODUCT.

$$
CANGIALOSI







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