[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 280540
TWDAT

TROPICAL WEATHER DISCUSSION...
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT THU AUG 28 2008

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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0345 UTC.

...SPECIAL FEATURES...
TROPICAL STORM GUSTAV IS CENTERED NEAR 18.5N 75.7W AT 28/0600
UTC OR ABOUT 70 NM EAST-NORTHEAST OF KINGSTON JAMAICA AND ABOUT
91 NM SOUTH-SOUTHWEST OF GUANTANAMO CUBA MOVING WEST-SOUTHWEST
AT 7 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 999 MB. MAXIMUM
SUSTAINED WIND SPEED IS 40 KT WITH GUSTS TO 50 KT. PLEASE SEE
THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT2/WTNT22 KNHC AND/OR THE PUBLIC ADVISORY MIATCPAT2/
WTNT32 KNHC FOR MORE DETAILS. GUSTAV IS EXPECTED TO TURN TO THE
WEST LATER TODAY AND TO THE WEST-NORTHWEST ON FRI PASSING VERY
CLOSE TO JAMAICA LATER TODAY. SLOW RESTRENGTHENING IS FORECAST
OVER THE NEXT 48 HOURS AND GUSTAV COULD REGAIN HURRICANE
STRENGTH BY FRI. SCATTERED MODERATE/STRONG CONVECTION HAS
REGENERATED S OF THE CENTER FROM 17N-19N BETWEEN 74W-75W
INCLUDING THE SW TIP OF HAITI AND THE E TIP OF JAMAICA. CLUSTERS
OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE WITHIN
60-75 NM OF LINE FROM 17N72W TO 16N81W. GUSTAV IS EXPECTED TO
PRODUCE TOTAL RAINFALL ACCUMULATIONS OF 6 TO 12 INCHES OVER
HAITI...E CUBA... JAMAICA...AND THE CAYMAN ISLANDS...WITH
ISOLATED MAXIMUM AMOUNTS OF UP TO 25 INCHES POSSIBLE. THESE
RAINS WILL LIKELY PRODUCE LIFE-THREATENING FLASH FLOODS AND MUD
SLIDES.

A 1008 MB SURFACE LOW IS CENTERED ENE OF THE LEEWARD ISLANDS
NEAR 19N58W. ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BECOME
MORE CONDUCIVE FOR A TROPICAL DEPRESSION TO FORM TONIGHT OR THU
AS IT DRIFTS NORTHWESTWARD. SCATTERED MODERATE/STRONG CONVECTION
IS FROM 17N-21N BETWEEN 55W-59W.

...TROPICAL WAVES...
TROPICAL WAVE IS ALONG 35W/36W S OF 21N WITH A 1009 MB LOW ALONG
THE WAVE NEAR 16N MOVING W 15-20 KT. BROAD AREA OF DEEP LAYERED
MOISTURE EVIDENT ON MIMIC-TPW ANIMATION AND A BROAD INVERTED-V
CURVATURE OBSERVED ON SATELLITE IMAGERY. CLUSTERS OF SCATTERED
MODERATE/ISOLATED STRONG CONVECTION ARE N OF THE LOW CENTER FROM
18N-21N BETWEEN 33W-39W.

TROPICAL WAVE IS ALONG 50W S OF 15N MOVING W NEAR 20 KT. LOW
AMPLITUDE AND REMAINS EMBEDDED WITHIN SOME RATHER DRY AIR...THUS
NO ASSOCIATED SHOWERS/DEEP CONVECTION. THIS WAVE IS MOVING INTO
THE AREA OF THE 1008 MB LOW IN THE SPECIAL FEATURES AND DOES NOT
APPEAR AS WELL DEFINED AS 24 HOURS AGO.

TROPICAL WAVE IN THE SW CARIBBEAN ALONG 83W WAS PREVIOUSLY
ASSOCIATED WITH WHAT IS NOW T.S. GUSTAV AND SHORTENED TO S OF
13N. BASED ON SCATTEROMETER SATELLITE WIND DATA THERE IS SW
ANTICYCLONIC FLOW ACROSS THE WAVE INDICATING THE WAVE WAS
ACTUALLY ABSORBED INTO GUSTAV AND WILL BE DROPPED ON THE 0600
UTC ANALYSIS.

TROPICAL WAVE THAT WAS ALONG 97W IS NO LONGER IN THE ATLC BASIN.

...THE ITCZ...
THE ITCZ AXIS IS ANALYZED ALONG 14N15W 17N27W 10N43W 8N54W
7N60W. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION
ARE WITHIN 60 NM OF LINE FROM 9N18W TO 14N19W. SCATTERED
MODERATE CONVECTION IS E OF LINE FROM 6N12W TO 10N17W TO THE
COAST OF W AFRICA AND WITHIN 60 NM OF THE ITCZ AXIS BETWEEN
27W-30W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER TROUGH IS OVER THE E US ENTERING THE NW GULF NEAR NEW
ORLEANS SW TO OFF THE MEXICAN COAST NEAR 23N96W WITH AN UPPER
HIGH REMAINING ANCHORED IN THE FLORIDA STRAITS NEAR 24N80W
COVERING THE E GULF ACROSS THE FLORIDA PENINSULA INTO THE W
ATLC. A WEAK UPPER RIDGE AXIS EXTENDS FROM S MEXICO NEAR THE
ISTHMUS OF TEHUANTEPEC NE TO OVER THE N YUCATAN PENINSULA E OF
MERIDA PROVIDING UPPER DIFFLUENCE TO GENERATE SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS IN THE BAY OF CAMPECHE WITHIN 45
NM ALONG THE COAST OF THE YUCATAN AND S MEXICO BETWEEN 90W-96W
WITH CLUSTERS OF SIMILAR ACTIVITY S OF 23N W OF 94W. AT THE
SURFACE...A WEAK 1013 MB HIGH IS CENTERED NEAR 28N92W AND IS
KEEPING THE REMAINDER OF THE GULF WITH MOSTLY CLEAR SKIES
TONIGHT.

CARIBBEAN SEA...
THE MAIN CONCERN AGAIN TONIGHT FOR THE CARIBBEAN IS T.S. GUSTAV
BETWEEN HAITI...CUBA...AND JAMAICA...SEE SPECIAL FEATURES ABOVE.
AN UPPER HIGH CENTERED OVER THE FLORIDA STRAITS COVERS THE NW
CARIBBEAN N OF 18N BETWEEN 77W-85W WITH THE UPPER RIDGE OVER THE
YUCATAN COVERING THE REMAINDER OF THE NW CARIBBEAN INTO THE GULF
OF HONDURAS. THE UPPER LEVEL DIFFLUENCE ASSOCIATED WITH THESE
UPPER RIDGES ARE ABLE TO PRODUCE CLUSTERS OF SCATTERED
SHOWERS/ISOLATED THUNDERSTORMS OFF THE S CUBA FROM 19N-21N
BETWEEN 79W-81W AND WITHIN 60 NM ALONG THE COAST OF THE GULF OF
HONDURAS S OF 17N W OF 86W LEAVING THE FAR NW CARIBBEAN RATHER
CLEAR TONIGHT. AN UPPER LEVEL RIDGE IS ACROSS THE E CARIBBEAN
ALONG 15N BETWEEN 70W TO OVER THE LESSER ANTILLES PROVIDING
UPPER DIFFLUENCE TO GENERATE CLUSTERS OF SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS E OF 68W FROM THE MONA PASSAGE AND PUERTO
RICO TO OVER THE LESSER ANTILLES N OF SAINT VINCENT AND
BARBADOS.

ATLANTIC OCEAN...
AN UPPER RIDGE ANCHORED IN THE FLORIDA STRAITS NEAR 24N80W
COVERS THE W ATLC W OF 72W. A DEEP LAYERED TROUGH IS OVER THE NW
ATLC DIPPING S TO 30N WITH THE ASSOCIATED FRONTAL BOUNDARY
MAINLY N OF THE REGION DIPPING S TO BERMUDA. THE UPPER LOW N OF
PUERTO RICO HAS BECOME CUT-OFF NEAR 22N65W GENERATING ISOLATED
SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS FROM 25N TO OVER THE
E GREATER ANTILLES BETWEEN 60W-70W INCLUDING PUERTO RICO AND THE
VIRGIN ISLANDS. AN UPPER RIDGE IS DEVELOPING OVER THE 1008 MB
SURFACE LOW IN THE SPECIAL FEATURES PROVIDING UPPER DIFFLUENCE
TO GENERATE CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG
CONVECTION FROM 12N-21N BETWEEN 52W-62W. A SECOND BENIGN UPPER
LOW IS WEAKENING BUT STILL COVERS THE CENTRAL ATLC CENTERED NEAR
31N45W EXTENDING S TO 25N. AN UPPER RIDGE COVERS THE E ATLC E OF
39W ANCHORED ON AN UPPER HIGH BETWEEN THE CAPE VERDE ISLANDS AND
THE CANARY ISLANDS NEAR 22N22W. BROAD SURFACE RIDGE REMAINS OVER
THE ATLC N OF 25N E OF 50W ANCHORED BY A 1029 MB HIGH N OF THE
AZORES.

$$
WALLACE






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