000 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