[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 070532
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT MON JUL 07 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
0445 UTC.

...SPECIAL FEATURE....

TROPICAL STORM BERTHA IS CENTERED NEAR 18.6N 48.9W AT 07/0000
UTC OR ABOUT 810 NM E OF THE NORTHERN LEEWARD ISLANDS MOVING
W AT 17 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 994 MB.
MAXIMUM SUSTAINED WIND SPEED IS 55 KT WITH GUSTS TO 65 KT. SEE
LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/
WTNT42 KNHC FOR MORE DETAILS. BERTHA IS EXPERIENCING SOME SHEAR
WITH THE CONVECTION TO THE W OF THE CENTER. SCATTERED MODERATE/
ISOLATED STRONG CONVECTION IS WITHIN 60/75 NM OF LINE FROM
18N50W TO 22N47W. BERTHA HAS BEEN STRENGTHENING GRADUALLY AS THE
SHEAR HAS BEEN WEAKENING SOMEWHAT. BERTHA WILL LIKELY BECOME A
HURRICANE LATER TODAY.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 31W/32W S OF 13N MOVING W NEAR 20 KT. LOW
AMPLITUDE WAVE MOSTLY EMBEDDED WITHIN THE ITCZ. CLUSTERS OF
SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE TO THE W OF
THE WAVE AXIS WITHIN WITHIN 75/90 NM OF LINE FROM 9N31W TO
12N37W.

TROPICAL WAVE IS ALONG 74W/75W S OF 25N MOVING W NEAR 20 KT.
WAVE REMAINS HIGHLY AMPLIFIED AND EXTENDS FROM N COLOMBIA ACROSS
THE TURKS AND CAICOS ISLANDS. SATELLITE IMAGERY CLEARLY
INDICATES AN INVERTED-V CURVATURE BUT REMAINS IN AN AREA OF
SOMEWHAT DRY AIR. ANY ACTIVITY/CONVECTION IN THE VICINITY IS
ASSOCIATED WITH AN UPPER LEVEL FEATURE.

TROPICAL WAVE IS ALONG 89W S OF 25N MOVING W 15-20 KT. WAVE
REMAINS MOSTLY OVER LAND AND BENEATH A BROAD UPPER RIDGE MASKING
ANY SATELLITE SIGNATURE. ANY ACTIVITY/CONVECTION IS MOSTLY
INLAND OVER CENTRAL AMERICA AND THE YUCATAN.

...ITCZ...
ITCZ AXIS IS CENTERED ALONG 12N16W 8N35W 12N48W 9N62W ACROSS N
VENEZUELA AND COLOMBIA INTO THE SW CARIBBEAN ACROSS PANAMA/COAST
RICA INTO THE E PACIFIC REGION NEAR 9N83W. ANY SIGNIFICANT
CONVECTION IS ASSOCIATED WITH THE TROPICAL WAVE ALONG 31W/32W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER TROUGH EXTENDS FROM TEXAS OVER N/CENTRAL MEXICO WITH A
BROAD UPPER RIDGE ANCHORED OVER THE SE COAST OF MEXICO NEAR
TUXPAN COVERING THE GULF SW OF A LINE FROM HOUSTON TEXAS TO THE
W TIP OF CUBA. THE DIFFLUENCE ALOFT BETWEEN THIS UPPER FEATURES
COUPLED WITH THE ABUNDANCE OF UPPER LEVEL MOISTURE IS GENERATING
SCATTERED SHOWERS/ISOLATED THUNDERSTORMS SW OF A LINE FROM
HOUSTON TEXAS TO NEAR MERIDA MEXICO ON THE YUCATAN PENINSULA
INCLUDING THE BAY OF CAMPECHE. A SHARP UPPER TROUGH OVER THE E
US DIPS S OVER THE FLORIDA PANHANDLE WITH A WEAK SHORTWAVE
CONTINUING S TO W CUBA ENHANCING DIMINISHING ISOLATED SHOWERS
OVER THE E GULF E OF 86W. AT THE SURFACE IS A WEAK RIDGE
EXTENDING FROM THE W ATLC ACROSS FLORIDA ALONG THE N GULF COAST
TO E LOUISIANA.

CARIBBEAN SEA...
WEAK UPPER LOW IS IN THE CENTRAL CARIBBEAN JUST S OF JAMAICA
WITH STRONG N FLOW OVER THE W CARIBBEAN DUE TO THE BROAD UPPER
RIDGE OVER THE W GULF OF MEXICO WITH WEAKER E TO SE UPPER FLOW
OVER THE E CARIBBEAN DUE TO AN UPPER RIDGE EXTENDING FROM NEAR
BERTHA ACROSS THE LEEWARD ISLANDS. ABUNDANCE OF UPPER LEVEL
MOISTURE COUPLED WITH DIFFLUENCE ALOFT IS GENERATING HEAVY
SHOWERS/SCATTERED THUNDERSTORMS INLAND OVER THE YUCATAN
PENINSULA AND CENTRAL AMERICA. THIS ACTIVITY IS FURTHER ENHANCED
BY THE TROPICAL WAVE OVER THE YUCATAN AND ARE MOVING INTO THE
GULF OF HONDURAS S OF 17N W OF 86W. SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS ARE N OF 20N TO OVER CUBA BETWEEN 77W-84W. STRONG
SUBSIDENCE AND DRY STABLE AIR CURRENTLY DOMINATE THE E CARIBBEAN
WITH MODERATE/STRONG EASTERLY TRADE WINDS USHERING IN SOME
ISOLATED BUT FAST MOVING SHOWERS ACROSS THE AREA E OF 67W.
SWELLS FROM BERTHA ARE EXPECTED TO REACH THE NE CARIBBEAN MON
NIGHT.

ATLANTIC OCEAN...
THE MAIN FOCUS TONIGHT IS TROPICAL STORM BERTHA THAT COULD
BECOME A HURRICANE LATE MON. OTHERWISE...AN UPPER TROUGH COVERS
THE W ATLC WITH A WEAK UPPER LOW NE OF THE BAHAMAS NEAR 28N83W.
THIS IS GENERATING CLUSTERS OF SCATTERED SHOWERS/THUNDERSTORMS W
OF THE TROPICAL WAVE WITHIN 90 NM OF LINE FROM CUBA NEAR 21N76W
TO 30N70W AND ISOLATED SHOWERS WITH POSSIBLE ISOLATED
THUNDERSTORMS FURTHER W BETWEEN 78W-81W FROM CUBA ACROSS THE E
FLORIDA COAST TO 30N. HEAVY SHOWERS/SCATTERED THUNDERSTORMS ARE
N OF 30N WITHIN 120 NM ALONG THE COAST FROM GEORGIA TO NORTH
CAROLINA. STRONG SUBSIDENCE AND DRY STABLE AIR ARE S OF 25N INTO
THE TROPICS AND THE E CARIBBEAN W OF BERTHA TO 65W. WEAK UPPER
RIDGE COVERS THE W TROPICAL ATLC INTO THE E CARIBBEAN. WEAK
UPPER TROUGH EXTENDS INTO THE N/CENTRAL ATLC JUST N OF BERTHA
WITH A SECOND STRONG UPPER TROUGH EXTENDING INTO THE E ATLC JUST
W OF THE CANARY ISLANDS. IN ALL THESE ARE RATHER BENIGN UPPER
LEVEL FEATURES AS A BROAD SURFACE RIDGE DOMINATES THE ATLC
ANCHORED BY A 1029 MB HIGH N OF THE REGION SW OF THE AZORES AND
A 1028 MB HIGH E OF BERMUDA NEAR 33N61W.

$$
WALLACE


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