[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 081035
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT TUE JUL 08 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1015 UTC.

...SPECIAL FEATURE....

HURRICANE BERTHA IS CENTERED NEAR 21.4N 53.3W AT 08/0900 UTC OR
ABOUT 585 NM ENE OF THE NORTHERN LEEWARD ISLANDS MOVING NW AT 9
KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 955 MB. MAXIMUM
SUSTAINED WIND SPEED IS 105 KT WITH GUSTS TO 130 KT. SEE LATEST
NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT42
KNHC FOR MORE DETAILS. BERTHA REMAINS A CATEGORY THREE HURRICANE
ON THE SAFFIR-SIMPSON HURRICANE SCALE. SOME FLUCTUATIONS IN
INTENSITY ARE EXPECTED TODAY WITH A GRADUALLY WEAKENING TREND TO
BEGIN WITHIN THE NEXT COUPLE OF DAYS. SCATTERED MODERATE/
ISOLATED STRONG CONVECTION IS WITHIN 60 NM OF THE CENTER OVER
THE EAST SEMICIRCLE AND WITHIN 45 NM OF THE CENTER IN THE WEST
SEMICIRCLE. SCATTERED MODERATE CONVECTION IS FROM 22N-25N
BETWEEN 48W-52W.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 43W S OF 12N MOVING W NEAR 20 KT. LOW
AMPLITUDE WAVE MOSTLY EMBEDDED WITHIN THE ITCZ. NO ASSOCIATED
DEEP CONVECTION.

TROPICAL WAVE IS ALONG 80W TO 83W IS NOW ALONG 85W/86W S OF 22N
MOVING W NEAR 20 KT. THE N PORTION OF THE WAVE IS MOVING NW AS A
SURFACE TROUGH...SEE BELOW. WAVE IS MOVING FURTHER W OF THE
UPPER LOW OVER THE CARIBBEAN AND INTO THE REGION OF STRONG N
UPPER FLOW GENERATING SCATTERED SHOWERS/ISOLATED THUNDERSTORMS
FROM 18N-22N BETWEEN 81W-86W.

...ITCZ...
ITCZ AXIS IS CENTERED ALONG 11N13W 8N21W 7N31W 6N49W 9N62W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 7N-12N
BETWEEN 18W-20W. CLUSTERS OF SIMILAR CONVECTION ARE FROM 7N-13N
BETWEEN 43W-48W AND FROM 4N-9N BETWEEN 46W-54W. CLUSTERS OF
SCATTERED MODERATE CONVECTION ARE FROM 6N-9N BETWEEN 24W-30W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LOW REMAINS INLAND OVER NE MEXICO WITH AN UPPER RIDGE
AXIS EXTENDING ALONG THE COAST OF MEXICO FROM VERACRUZ MEXICO TO
INLAND OVER S TEXAS. THE DIFFLUENCE ALOFT BETWEEN THIS UPPER
FEATURES COUPLED WITH THE ABUNDANCE OF UPPER LEVEL MOISTURE
CONTINUES TO GENERATE SCATTERED SHOWERS/THUNDERSTORMS SW OF A
LINE FROM BROWNSVILLE TEXAS TO INTO THE BAY OF CAMPECHE NEAR
18N92W. AN UPPER TROUGH EXTENDS FROM THE UPPER LOW IN THE
CARIBBEAN THROUGH THE YUCATAN CHANNEL TO OVER THE E GULF TO THE
BIG BEND AREA OF FLORIDA GENERATING SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS E OF A LINE FROM CENTRAL LOUISIANA NEAR 30N93W TO
23N86W ACROSS PORTIONS OF THE FLORIDA PENINSULA. THE N PORTION
OF THE TROPICAL WAVE IN THE CARIBBEAN IS NOW ANALYZED AS A
SURFACE TROUGH EXTENDING FROM THE DRY TORTUGAS ACROSS NAPLES
FLORIDA TO NEAR DAYTONA BEACH. ALSO AT THE SURFACE IS A WEAK
RIDGE EXTENDING FROM THE W ATLC ACROSS FLORIDA ALONG THE N GULF
COAST TO TEXAS.

CARIBBEAN SEA...
ELONGATED UPPER LOW IS IN THE CENTRAL CARIBBEAN S OF W JAMAICA
NEAR 16N79W TO NEAR 20N84W WITH AN UPPER TROUGH EXTENDING N INTO
THE GULF OF MEXICO ENHANCING THE ACTIVITY ASSOCIATED WITH THE
TROPICAL WAVE AND GENERATING A SMALL CLUSTER OF SHOWERS/ISOLATED
THUNDERSTORMS BETWEEN JAMAICA AND E CUBA. ABUNDANCE OF UPPER
LEVEL MOISTURE REMAINS OVER THE SW CARIBBEAN COUPLED WITH
DIFFLUENCE ALOFT IS GENERATING SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS OVER THE SW CARIBBEAN S OF 11N E OF 81W TO INLAND
OVER PANAMA AND COLOMBIA. STRONG SUBSIDENCE AND DRY STABLE AIR
STILL REMAIN ACROSS THE E CARIBBEAN WITH MODERATE/STRONG
EASTERLY TRADE WINDS USHERING IN SOME SCATTERED SHOWERS AND
POSSIBLE ISOLATED THUNDERSTORMS WITHIN 90 NM OF LINE FROM 15N70W
ACROSS THE LESSER ANTILLES NEAR GUADELOUPE TO 17N58W.

ATLANTIC OCEAN...
THE MAIN FOCUS TONIGHT IS HURRICANE BERTHA. OTHERWISE...AN UPPER
LOW IS OVER VIRGINIA DRAWING THE UPPER LEVEL MOISTURE ACROSS
FLORIA TO ALONG THE US E COAST AND GENERATING SCATTERED
SHOWERS/THUNDERSTORMS N OF 30N W OF 78W TO COAST FROM GEORGIA TO
NORTH CAROLINA. A WEAK UPPER BUT INSIGNIFICANT UPPER LOW IS NE
OF THE BAHAMAS NEAR 28N66W EMBEDDED WITHIN MODERATE SUBSIDENCE
AND SOMEWHAT DRY AIR. THIS IS INDUCING A WEAK UPPER RIDGE
BETWEEN THESE UPPER LOWS AND PROVIDING ENOUGH DIFFLUENCE ALOFT
TO GENERATE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF 26N W
OF 77W ACROSS THE N BAHAMA ISLANDS TO THE FLORIDA COAST. STRONG
SUBSIDENCE AND DRY STABLE AIR COVER THE REMAINDER OF THE W ATLC
INTO THE CENTRAL ATLC W OF BERTHA. WEAK UPPER TROUGH EXTENDS
INTO THE N/CENTRAL ATLC NE OF BERTHA WITH A SECOND WEAKENING
UPPER TROUGH EXTENDING INTO THE E ATLC OVER THE MADEIRA ISLANDS
W OF THE CANARY ISLANDS TO THE CAPE VERDE ISLANDS. IN ALL THESE
ARE RATHER BENIGN UPPER LEVEL FEATURES AS A BROAD SURFACE RIDGE
DOMINATES THE ATLC WITH A WEAKNESS INT HE VICINITY OF HURRICANE
BERTHA. A 1024 MB HIGH IS S OF THE AZORES WITH A SECOND 1024 MB
HIGH NEAR 32N40W AND A 1025 MB HIGH JUST NE OF BERMUDA.

$$
WALLACE





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