[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 071754
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURE....

HURRICANE BERTHA IS CENTERED NEAR 19.6N 51.3W AT 07/1500 UTC OR
ABOUT 670 NM E OF THE NORTHERN LEEWARD ISLANDS MOVING WNW AT 13
KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 975 MB. MAXIMUM
SUSTAINED WIND SPEED IS 80 KT WITH GUSTS TO 100 KT. SEE LATEST
NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT42
KNHC FOR MORE DETAILS. BERTHA CONTINUES TO EXHIBIT AN EYE OF
ROUGHLY 10-20 NM IN DIAMETER...WHICH IS INDICATIVE OF ITS
GRADUAL STRENGTHENING OVER THE PAST 12 HOURS. DEEP CONVECTION
NOW SURROUNDS THE EYE BUT THE LARGEST AREA REMAINS TO THE NORTH
AND WEST. SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 120
NM OF THE CENTER IN THE NORTHERN QUADRANT WITH REMAINING
SCATTERED MODERATE CONVECTION FROM 20N-23N BETWEEN 49W-52W.
BERTHA IS EXPECTED TO GRADUALLY STRENGTHEN UNDER FAVORABLE
ATMOSPHERIC CONDITIONS OVER THE NEXT DAY OR SO.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 36W S OF 12N MOVING W NEAR 20 KT. THIS
WAVE REMAINS LOW AMPLITUDE WHILE MOSTLY EMBEDDED WITHIN THE
ITCZ. CLUSTERS OF ISOLATED MODERATE CONVECTION ARE WITHIN 200 NM
ON EITHER SIDE OF THE WAVE AXIS.

TROPICAL WAVE IS ALONG 27N76W 19N78W TO 9N78W MOVING WNW NEAR 20
KT. WAVE REMAINS HIGHLY AMPLIFIED AND EXTENDS FROM ERN PANAMA
ACROSS CENTRAL CUBA TO THE NW BAHAMAS. SATELLITE IMAGERY CLEARLY
INDICATES AN INVERTED-V CURVATURE AND IS MOVING OUT OF THE AREA
OF SOMEWHAT DRY AIR INTO MOISTER CONDITIONS. ANY CONVECTION IN
THE VICINITY IS ASSOCIATED WITH AN UPPER LEVEL FEATURE ACROSS
FLORIDA AND THE WRN CARIBBEAN SEA.

TROPICAL WAVE IS ALONG 94W S OF 25N MOVING W 15-20 KT. WAVE
REMAINS BENEATH A BROAD UPPER RIDGE MASKING ANY SATELLITE
SIGNATURE. ANY CONVECTION IN THE VICINITY...NAMELY ACROSS THE
WRN GULF OF MEXICO...IS MOST LIKELY ASSOCIATED WITH UPPER LEVEL
RIDGE.

...ITCZ...
ITCZ AXIS IS CENTERED ALONG 12N16W 7N33W 7N38W 6N47W 9N54W AND
INTO NE VENEZUELA NEAR 9N61W. CLUSTERS OF SCATTERED MODERATE
CONVECTION ARE FROM 5N-9N BETWEEN 19W-25W. SIMILAR CONVECTION IS
FROM 2N-5N BETWEEN 39W-46W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LOW IS INLAND OVER N CENTRAL MEXICO WITH A BROAD UPPER
RIDGE ANCHORED OVER S CENTRAL MEXICO AND A RIDGE AXIS EXTENDING
INTO THE SW GULF NEAR TUXPAN MEXICO AND COVERING MUCH OF THE WRN
AND CENTRAL GULF W OF 85W. THE DIFFLUENCE ALOFT BETWEEN THESE
UPPER FEATURES COUPLED WITH THE ABUNDANCE OF MID TO UPPER LEVEL
MOISTURE IS GENERATING NUMEROUS SHOWERS WITH ISOLATED TSTMS SW
OF A LINE FROM CORPUS CHRISTI TEXAS TO INTO THE BAY OF CAMPECHE
NEAR 19N92W. A SHARP UPPER TROUGH OVER THE ERN CONUS DIPS S OVER
THE FLORIDA PANHANDLE WITH A WEAK SHEAR ZONE ACROSS THE FAR ERN
GULF. THIS ALONG WITH THE TROPICAL WAVE OVER THE NW BAHAMAS
MOVING WNW IS ENHANCING SCATTERED SHOWERS/ISOLATED TSTMS OVER
THE ERN GULF N OF 23N E OF 85W...INCLUDING THE FLORIDA STRAITS.
AT THE SURFACE...A WEAK RIDGE EXTENDS FROM THE W ATLC ACROSS THE
SE U.S. ALONG THE N GULF COAST TO NEAR GALVESTON TEXAS.

CARIBBEAN SEA...
WEAK UPPER LOW IS IN THE CENTRAL CARIBBEAN JUST S OF JAMAICA
WITH STRONG NNW FLOW OVER THE WRN CARIBBEAN DUE A BROAD UPPER
RIDGE OVER THE WRN GULF OF MEXICO. WEAKER E TO SE UPPER FLOW IS
OVER THE E CARIBBEAN DUE TO AN UPPER RIDGE EXTENDING FROM NEAR
BERTHA ACROSS THE LEEWARD ISLANDS AND PUERTO RICO. AN ABUNDANCE
OF UPPER LEVEL MOISTURE COUPLED WITH DIFFLUENCE ALOFT IS
GENERATING SCATTERED SHOWERS/ISOLATED TSTMS FROM 18N-23N BETWEEN
79W-85W. THIS ACTIVITY IS FURTHER ENHANCED BY THE TROPICAL WAVE.
ISOLATED SHOWERS AND TSTMS ARE IN THE GULF OF HONDURAS S OF 18N
W OF 85W. SIMILAR ACTIVITY IS INLAND OVER CENTRAL AMERICA AND
PORTIONS OF COASTAL PANAMA. STRONG SUBSIDENCE AND DRY STABLE AIR
DOMINATES THE ERN CARIBBEAN WITH MODERATE/STRONG EASTERLY TRADE
WINDS USHERING IN SOME ISOLATED BUT FAST MOVING SHOWERS ACROSS
THE NE CARIBBEAN E OF 68W.

ATLANTIC OCEAN...
THE MAIN FOCUS ACROSS THE ATLANTIC OCEAN REMAINS HURRICANE
BERTHA. OTHERWISE...AN UPPER TROUGH COVERS THE ERN CONUS AND
EXTENDS INTO THE FAR W ATLC. SCATTERED SHOWERS AND ISOLATED
TSTMS ARE ACROSS THE NW BAHAMAS AND W ATLC WITHIN 60 NM OF A
LINE FROM 32N71W TO THE FLORIDA STRAITS. THIS ACTIVITY IS ALSO
BEING ENHANCED BY THE TROPICAL WAVE THAT LIES ACROSS THE CENTRAL
BAHAMAS. STRONG SUBSIDENCE AND DRY STABLE AIR ARE S OF 24N INTO
THE TROPICS AND THE ERN CARIBBEAN W OF BERTHA TO 72W. WEAK UPPER
RIDGE AXIS EXTENDS E-W ALONG 20N AND COVERS THE WRN TROPICAL
ATLC INTO THE NE CARIBBEAN. UPPER TROUGH EXTENDS INTO THE N
CENTRAL ATLC NW OF BERTHA WITH A SECOND STRONG UPPER TROUGH
EXTENDING INTO THE E ATLC OVER THE MADEIRA ISLANDS TO W OF THE
CANARY ISLANDS. OVERALL THESE ARE RATHER BENIGN UPPER LEVEL
FEATURES AS A BROAD SURFACE RIDGE DOMINATES THE ATLC ANCHORED BY
A PAIR 1027 MB HIGHS N OF THE REGION NEAR 36N37W AND 33N61W.

$$
HUFFMAN




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