000 AXNT20 KNHC 161801 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 205 PM EDT WED JUL 16 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 FEATURES... TROPICAL STORM BERTHA IS CENTERED NEAR 36.6N 60.7W AT 16/1500 UTC. ESTIMATED MINIMUM CENTRAL PRESSURE IS 995 MB. MAXIMUM SUSTAINED WIND SPEED IS 60 KT WITH GUSTS TO 75 KT. PLEASE SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC AND THE PUBLIC ADVISORY UNDER MIATCPAT2/WTNT32 KNHC FOR MORE DETAILS. BERTHA IS MAINTAINING TROPICAL STORM STRENGTH AT THIS TIME. MODELS ARE SHOWING AN INCREASE IN VERTICAL SHEAR IN A FEW DAYS...LEADING TO POSSIBLE WEAKENING. BERTHA IS EXPECTED TO BECOME EXTRATROPICAL WITHIN 4 TO 5 DAYS DUE TO THE EFFECT OF STRONG MID-LATITUDE WINDS AND RAPIDLY COOLING WATERS. SCATTERED MODERATE CONVECTION IS WITHIN 100 NM NE OF THE CENTER FROM 36N-38N BETWEEN 59W-61W AND W OF THE CENTER FROM 36N-38N BETWEEN 62W-63W. A STRONG TROPICAL WAVE IS ALONG 56W/57W S OF 17N MOVING W 20 KT WITH A 1009 MB LOW ANALYZED ALONG THE AXIS NEAR 13N. SATELLITE IMAGERY SHOWS GOOD ORGANIZATION WITH SCATTERED MODERATE CONVECTION FROM 9N-12N BETWEEN 55W-58W AND FROM 11N-14N BETWEEN 57W-61W. THERE IS STILL SOME POTENTIAL FOR THIS SYSTEM TO BECOME A TROPICAL DEPRESSION TODAY. THIS SYSTEM IS EXPECTED TO BRING GUSTY WINDS AND LOCALLY HEAVY RAINFALL TO THE WINDWARD ISLANDS OVER THE NEXT COUPLE OF DAYS. ...TROPICAL WAVES... TROPICAL WAVE IS ALONG 36W S OF 18N MOVING W 15-20 KT. THIS WAVE EXHIBITS VERY LITTLE IN THE WAY OF DEEP CONVECTION WITH ONLY SCATTERED SHOWERS S OF THE AXIS ASSOCIATED WITH THE ITCZ FROM 2N-4N BETWEEN 33W-38W. HOWEVER...THE WAVE REMAINS WELL DEFINED WITH AN INVERTED-V CURVATURE ON SATELLITE IMAGERY. TROPICAL WAVE IS ALONG 75W S OF 21 AT THE ERN SIDE OF HAITI TO INLAND NRN COLOMBIA MOVING W 15-20 KT. THIS FEATURE REMAINS WELL DEFINED WITH AN INVERTED-V CURVATURE ON SATELLITE IMAGERY. SCATTERED MODERATE CONVECTION IS FROM 11N-14N BETWEEN 73W-76W AND FROM 14N-17N BETWEEN 75W-79W. THE ITCZ... ITCZ AXIS IS CENTERED ALONG 8N13W 10N25W 4N44W 10N53W 11N70W AND ALONG THE N COAST OF SOUTH AMERICA ACROSS PANAMA INTO THE E PACIFIC REGION. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS FROM 5N-9N BETWEEN 10W-15W. SCATTERED MODERATE CONVECTION IS WITHIN 120NM S OF THE AXIS BETWEEN 15W-21W. DISCUSSION... GULF OF MEXICO... DEEP LAYERED TROUGH IS OVER THE E U.S. DIPPING S OVER THE N GULF WITH A EMBEDDED SHORTWAVE NEAR 28N88W. THIS IS PROVIDING SUPPORT FOR A STATIONARY FRONT THAT IS ACROSS CENTRAL FLORIDA AND FOR A 1016 MB SURFACE LOW NEAR THE COAST OF TAMPA FLORIDA NEAR 27N83W. A WEAK SURFACE TROUGH EXTENDS FROM THE LOW CENTER TO 24N85W. THIS SURFACE LOW ALONG WITH DIFFLUENCE ALOFT E OF THE SHORTWAVE IS GENERATING AN AREA OF SCATTERED SHOWERS AND THUNDERSTORMS FROM 26N-29N BETWEEN 82W-86W AND ACROSS THE WRN COAST OF THE FLORIDA PENINSULA AND THE WESTERN FLORIDA KEYS. ISOLATED SHOWERS AND THUNDERSTORMS ARE FROM 25N-28N W OF 86W. FLORIDA SHOULD EXPECT RAINFALL IN GENERAL FOR ABOUT THE NEXT 24 HOURS BECAUSE OF THE DEEP LAYER TROPICAL MOISTURE AND THE LOW PRESSURE AND CYCLONIC FLOW OVER THE STATE. SCATTERED MODERATE CONVECTION IS IN THE FAR SW GULF OF MEXICO WITHIN 30NM OF 20N96W. ELSEWHERE AT THE SURFACE ACROSS THE GULF S OF 25N...IT REMAINS FAIRLY TRANQUIL WITH LIGHT WINDS AS A WEAK SURFACE RIDGE BUILDS BACK INTO THE WRN GULF BY LATE WED. AN UPPER LEVEL RIDGE EXTENDS E FROM TEXAS/NRN MEXICO COVERING THE GULF W TO 90W. CARIBBEAN SEA... AN UPPER TROUGH IS ACROSS THE NW CARIBBEAN DRYING THE AIR NEAR ITS AXIS THAT EXTENDS FROM ERN CUBA TO THE HONDURAS BORDER AND KEEPING THE AREA N OF 16N W OF 77W CALM. THE ITCZ IS ALONG THE N COAST OF SOUTH AMERICA AND PANAMA. A SURFACE LOW IS IN THE SW CARIBBEAN ENHANCED BY UPPER LEVEL DIFFLUENT PATTERN. SCATTERED MODERATE CONVECTION IS FROM 10N-13N BETWEEN 76W-80W. SIMILAR CONVECTION IS ALONG THE NICARAGUAN COAST FROM 11N-15N BETWEEN 82W-85W. AN UPPER LEVEL HIGH DOMINATES THE ERN CARIBBEAN INTO THE W TROPICAL ATLC ANCHORED W OF THE WINDWARD ISLANDS NEAR 15N67W WHICH IS ENHANCING THE ACTIVITY ASSOCIATED WITH THE TROPICAL WAVE ALONG 75W. ATLANTIC OCEAN... BROAD UPPER LEVEL TROUGH IS OVER THE E U.S. AND INTO THE FAR W ATLC WITH A NARROW UPPER RIDGE EXTENDING ACROSS SOUTH FLORIDA TO 31N75W PROVIDING AMPLE DIFFLUENCE TO GENERATE SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS FROM 28N-32N BETWEEN 75W-80W. A STATIONARY FRONT REMAINS W OF THIS ACTIVITY. AN AREA OF SURFACE HIGH PRESSURE IS LOCATED S OF T.S. BERTHA CENTERED NEAR 28N60W. A BROAD DEEP LAYERED TROUGH IS OVER THE CENTRAL ATLC N OF 15N BETWEEN 42W-58W WITH A SURFACE TROUGH ENTERING THE REGION NEAR 30N45W TO 26N50W GENERATING SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS WITHIN 120 NM EITHER SIDE OF THE TROUGH N OF 30N. AN AREA OF SCATTERED SHOWERS AND POSSIBLE THUNDERSTORMS ARE NW OF THE TROUGH AXIS FROM 28N-30N BETWEEN 50W-53W. AN UPPER RIDGE EXTENDS FROM THE UPPER HIGH IN THE ERN CARIBBEAN TO OVER THE W ATLC W OF 55W. A LARGE UPPER LEVEL HIGH IS CENTERED OVER THE E ATLC ANCHORED NEAR 31N23W COVERING THE AREA E OF 41W. $$ WALTON/MT