000 AGXX40 KNHC 040842 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 442 AM EDT MON AUG 4 2014 MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W...AND THE SW N ATLANTIC INCLUDING THE BAHAMAS. ...GULF OF MEXICO... MODEL PREFERENCE: GLOBAL MODEL CONSENSUS ERN U.S. UPPER TROUGH REALIGNING ATTM AND EXPECTED TOP EVOLVE INTO ELONGATED NARROW TROUGH NE TO SW ACROSS W PORTIONS NEXT 48 HOURS. THIS TO BE REFLECTED IN THE LOWER LEVELS WITH DIVERGENT ASYMPTOTE EVOLVING ACROSS CENTRAL NE PORTIONS OF THE GULF...WITH LLVL CONVERGENCE ACROSS FLORIDA...AND W OF 90W. PRESENTLY...OLD FRONTAL ZONE HAS WASHED OUT ACROSS NE PORTIONS...AND OLDER FRONTAL TROUGH ACROSS SE PORTIONS STILL EVIDENT AND PROVIDING LLVL CONVERGENCE FOR VERY ACTIVE CNVTN ACROSS SW FLORIDA AND ADJACENT WATERS. THIS BOUNDARY AND ASSOCIATED MOISTURE WILL DRIFT N AND NE EXIT 24 HOURS BEFORE BECOMING DIFFUSE. AT THE SURFACE...RECENT ASCAT PASSES SHOW VERY WEAK WIND ACROSS ENTIRE BASIN EXCEPT FOR FLORIDA COASTAL WATERS...ACTING AS IN FLOW TO CURRENT CNVTN. LITTLE CHANGE IN RECENT TRENDS IN GUIDANCE WITH VERY WEAK FLOW AND SLIGHT SEAS PERSISTING THROUGH TONIGHT BEFORE ATLC RIDGE BEGINS TO BUILD SW AND UNDERNEATH EXITING BERTHA...AND ATTEMPTING TO BUILD THROUGH THE STRAITS TONIGHT AND TUE. RIDGE TO DRIFT SLOWLY N THOUGH THE WEEK WITH HIGH CENTER DEVELOPING ACROSS ERN GULF DURING THIS PROCESS...AND GRADUALLY ALLOWING FOR MODERATE RETURN FLOW TO SET UP W AND NW PORTIONS...AND LEAD TO ACTIVE YUCATAN LATE AFTERNOON THERMAL TROUGH...WHERE DIURNAL WINDS WILL PULSE TO 15-20 KT EACH EVENING. THIS PATTERN WILL ALSO ALLOW FOR MORE MOISTURE AND ENERGY OF TROPICAL WAVES MOVING ACROSS THE CARIB TO PROPAGATE WNW ACROSS THE YUCATAN AND INTO S GULF TUE NIGHT THROUGH FRI. ...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... MODEL PREFERENCE: GFS TUTT LOW ACROSS YUCATAN SHIFTING SLOWLY WWD WHILE E TO SE FLOW ALOFT IS BUILDING ACROSS THE ERN CARIB ATTM. BERTHA LIFTING GRADUALLY NNW AND OUT OF REGION AND ELY TRADES ARE BUILDING ACROSS E PART OF BASIN E OF 70W...ASSOCIATED WITH TROPICAL WAVE ALONG ABOUT 64W. VERY BROAD TROPICAL WAVE WITH LONG WAVE LENGTH FOLLOWING THIS FIRST WAVE ACROSS THE ATLC...AND ALONG ABOUT 54W ATTM AT H700. BOTH THESE FEATURES WILL CONTINUE WWD NEXT 48 HOURS AND BRING A LONG FETCH OF AROUND 20 KT ENE WINDS FROM CENTRAL ATLC THROUGH NE CARIB AND ADJACENT ATLC TO PRODUCE SEAS 6-8 FT IN ENE WIND SWELL. ATLC RIDGE WILL BUILD SW AND UNDERNEATH EXITING BERTHA ALSO DURING THIS TIME AND INTO THE STRAITS OF FLORIDA AND FRESHEN FLOW ACROSS GREATER ANTILLES AND THROUGH SE BAHAMAS. BROAD SECOND TROPICAL WAVE WITH H700 VORTEX CENTERED ALONG ABOUT 15-16N WILL MOVE MORE WNW ACROSS THE NE CARIB 36-72 HRS AND TRANSPORT MODEST MOISTURE AND WAVE DYNAMICS ACROSS THE GREATER ANTILLES AND N WATERS OF THE BASIN. BROAD CYCLONIC TURNING ACROSS THE CENTRAL CARIB DURING THIS TIME WILL ALSO REDUCE PRES GRADIENT ACROSS S CENTRAL PORTIONS AND LIFT MAX WINDS CLOSER TO 13N FOR A SLIGHT SHIFT IN TYPICAL WIND/SEA PATTERN THERE. GFS CONTINUES TO FORECAST WINDS PULSING TO 30 KT THIS EVENING AND TONIGHT OFFSHORE OF COLOMBIA BEFORE GRADIENT THERE BEGINS TO WEAKEN TUE. GFS AND UKMET SUGGEST SLIGHT POTENTIAL FOR BRIEF GALES TONIGHT THERE...WHILE ECMWF DOES NOT...AND THUS NOT GOING WITH GALE WARNING ATTM. AFTER SECOND WAVE PASSAGE ACROSS E CARIB TUE AND INTO CENTRAL CARIB WED...LOOK FOR MODERATE TO FRESH TRADE WIND FLOW TO BECOME ESTABLISHED THROUGH REMAINDER OF THE WEEK. ...SW N ATLANTIC INCLUDING THE BAHAMAS... MODEL PREFERENCE: GLOBAL MODEL CONSENSUS LARGE AREA OF ABUNDANT LLVL MOISTURE HAS SHIFTED NW ACROSS THE BAHAMAS AND ACROSS FLORIDA AND ADJACENT ATLC WATERS PAST 24 HOURS...WITH BERTHA MOVING NNW AND JUST E OF SE BAHAMAS ATTM. ACTIVE CNVTN WILL CONTINUE WITH BOTH OF THESE FEATURES AS THEY LIFT N AND THEN NE OUT OF AREA NEXT 48-72 HRS. CONVECTIVE PATTERN WITH BERTHA CONTINUES SKEWED TO E AND SE OF LLVL CENTER...AND ALIGNED WITH LLVL WIND FIELD. RECENT PARTIAL ASCAT PASS SHOWED BROAD SELY FETCH ACROSS E AND SE SEMICIRCLES THAT WILL CONTINUE TO GENERATE SELY SWELL AS BERTHA LIFTS OUT OF AREA BY 36 HOURS. BERTHA HAS NEARLY REACHED ITS WRN MOST LONGITUDE AND W EDGE OF 20 KT WIND FIELD EXPECTED TO ONLY BRUSH THE CENTRAL BAHAMA ISLANDS TODAY. E TO SE SWELL EXPECTED TO AFFECT THE BAHAMIAN ISLAND CHAIN WITH ONLY MODEST ENERGY PASSING THROUGH PASSAGES AND ACROSS BANKS AND TO SE FL. BEST SE SWELL ENERGY LIKELY TO HIT COASTS FROM VERO BEACH AREA NORTHWARD. OTHERWISE...AS STATED ABOVE...ATLC RIDGE TO BUILD SW UNDERNEATH THE EXITING BERTHA NEXT FEW DAYS AND THEN SHIFT SLOWLY NWD TO ALONG 26-27N BY WEEKS END. BROAD FETCH OF ENE WINDS AROUND 20 KT OCCURRING WITH AND N OF TROPICAL WAVE MOVING TOWARD TROPICAL N ATLC WATERS ATTM TO BRING INCREASE IN ENE WIND SWELL AND RAISE SEAS ACROSS SE WATERS TO 6-7 FT TONIGHT THROUGH TUE NIGHT BEFORE FADING. OTHERWISE...EXPECT MAINLY MODERATE TO LOCALLY FRESH RETURN FLOW TO DOMINATE THE BASIN BY THE MIDDLE THROUGH THE END OF THE WEEK WITH THIS PATTERN. EXPECT GENERALLY 4-6 FT SEAS E OF 77W AND 1-3 FT SEAS W OF 77W AND INSIDE THE BAHAMAS IN THE WAKE OF BERTHA. $$ .WARNINGS...ANY CHANGES IMPACTING COASTAL NWS OFFICES WILL BE COORDINATED THROUGH AWIPS 12 PLANET CHAT OR BY TELEPHONE: .GULF OF MEXICO... NONE. .CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... NONE. .SW N ATLANTIC INCLUDING THE BAHAMAS... .AMZ113...ATLANTIC FROM 27N TO 31N BETWEEN 70W AND 77W... TROPICAL STORM WARNING EARLY TODAY INTO TONIGHT. .AMZ119...ATLANTIC FROM 22N TO 27N E OF BAHAMAS TO 70W... TROPICAL STORM WARNING EARLY TODAY INTO TODAY. $$ *FOR DETAILED ZONE DESCRIPTIONS PLEASE VISIT: HTTP://WWW.NHC.NOAA.GOV/ABOUTTAFBPROD.SHTML#OWF NOTE: GRIDDED MARINE FORECASTS ARE AVAILABLE IN THE NATIONAL DIGITAL FORECAST DATABASE (NDFD) AT: HTTP://WWW.NHC.NOAA.GOV/MARINE/GRIDS.PHP FOR ADDITIONAL INFORMATION PLEASE VISIT: HTTP://WWW.HURRICANE WARNINGS.GOV/MARINE $$ .FORECASTER STRIPLING. NATIONAL HURRICANE CENTER.