000 AGXX40 KNHC 160821 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 421 AM EDT THU APR 16 2015 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 VERY ACTIVE CONVECTION CONTINUES TO PROPAGATE ENE ACROSS THE N GULF AGAIN THIS MORNING AS NUMEROUS IMPULSES IN SW UPPER JET ACROSS THE REGION CONTINUE TO SIGNIFICANTLY ENHANCE DEVELOPMENT. DEEP LAYERED CUT OFF LOW ACROSS WRN U.S. SLOWLY SINKING S INTO THE SW OF THE U.S. FORECAST TO CONTINUE TO DIG S THROUGH NEXT 24 HOURS BEFORE BRIEFLY BECOMING STATIONARY THEN LIFTING SLOWLY OUT TO THE NE THROUGH TUE. THIS WILL CONTINUE TO PROVIDE JET ENERGY AND ADDITIONAL MID-UPPER IMPULSES ACROSS NW AND N SECTIONS FOR DEEP CONVECTIVE OUTBREAKS. AT PRESENT...SAT AND SUN LOOK TO BE MOST LIKELY ACTIVE PERIODS WITH SHARP TROUGH AXIS SHIFTING ENE ACROSS THE REGION. AT THE SURFACE...WEAK RIDGING PERSISTS FROM NE GULF TO SW SECTIONS...WHILE WEAK LLVL TROFFING CONTINUES TO DEVELOP ACROSS NW AND N CENTRAL PORTIONS IN RESPONSE TO DEVELOPING CONVECTIVE BANDS AND LINES. OUTSIDE OF CONVECTION...WINDS GENERALLY LIGHT TO MODERATE WITH RECENT 03Z ASCAT PASS DEPICTING 20 KT SE WINDS OFF N COAST OF YUCATAN ASSOCIATED WITH EVENING THERMAL TROUGH SHIFTING W THERE. SEAS THERE LIKELY TO 5 FT POSSIBLY 6...WHILE 2-4 FT ELSEWHERE ACROSS THE BASIN...EXCEPT NEAR THE DEEP CNVTN S OF MOUTH OF MS RIVER. LITTLE CHANGE EXPECTED NEXT 24 HOURS BEFORE DEVELOPING LOW PRES OFFSHORE OF SE U.S. COAST BEGINS TO SHIFT ENE AND INTO CENTRAL ATLC AND ALLOWS HIGH ACROSS SE U.S. TO BUILD MODESTLY INTO THE CENTRAL GULF TO TIGHTEN PRES GRADIENT SLIGHTLY AND FRESHEN THE SE FLOW CENTRAL PORTIONS LATE FRI AND SAT. HIGH THEN SHIFTS WELL NE AND INTO NW ATLC WITH FLOW ACROSS THE GULF BECOMING MORE SLY SUN AND MON. MODELS IN GOOD AGREEMENT ON NEXT WEAK FRONTAL SYSTEM BARELY MAKING IT INTO NW COASTAL WATERS MON...REACHING N CENTRAL TEXAS WATERS...THEN LAYING DOWN NE TO SW FROM NEAR FAR WRN FL PANHANDLE TO NEAR GALVESTON THROUGH TUE. ...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... MODEL PREFERENCE: GFS ATLC RIDGE EXTENDS FROM HIGH PRES ACROSS E CENTRAL PORTIONS SW TO CENTRAL FLORIDA ATTM. INDUCED PRES GRADIENT CONTINUES TO WEAKEN VERY SLOWLY...WITH FRESH TO STRONG FLOW RECENTLY DEPICTED BY 02-04Z SCAT PASSES CONFINED TO S CENTRAL PORTIONS...AND SOLID 20 KT NOW EXTENDING N TO 14.5N. BUOY 42058 NOW FLUCTUATING AT 7-8 FT. MAX WIND OFF OF COLOMBIA LIKELY JUST BELOW 30 KT ATTM...PER THESE SCAT OBS AND TYPICAL NOCTURNAL TRENDS. MEANWHILE...FRESH ELY WINDS ACROSS GULF OF HONDURAS CAPTURED BY 03Z ASCAT PASS WITH 20 KT S OF 17.5N AND SEAS LIKELY 6-7 FT ATTM. RIDGE ACROSS SW N ATLC TO SINK S AND WEAKEN NEXT 24-36 HOURS AS A COLD FRONT MOVES S INTO THE REGIONAL ATLC WATERS. THIS TO FURTHER WEAKEN PRES GRADIENT ACROSS ALL BUT WRN CARIB WITH GFS RESPONDING BY CONFINING FRESH TRADES S OF 13-13.5N BY FRI NIGHT AND GENERALLY PERSISTING THROUGH MID NEXT WEEK. ACROSS THE TROPICAL N ATLC...FRESH TRADES PREVAIL S OF ABOUT 12N WHILE WEAK INVERTED TROUGHS MOVING SLOWLY WWD BETWEEN 55W AND 65W AIDING IN REDUCING PRES GRADIENT AND TRADES. ALTIMETER DATA CONTINUES TO SHOW MODELS AROUND 1 FT LOW IN ENE SWELL ACROSS S PORTIONS OF AREA EXTENDING UPSTREAM IN THE ENE TRADE REGIME AND HAVE HAND EDITED SWH GRIDS TO BRING MORE IN LINE FIRST 48 HRS. CENTRAL ATLC FRONTAL SYSTEM AND ASSOCIATED VERY DEEP LOW CURRENTLY DEVELOPING ATTM TO SEND SIGNIFICANT N SWELL INTO REGIONAL WATERS OVER THE WEEKEND....REACHING N PORTIONS OF ATLC WATERS AND NE CARIB ISLANDS LATE SAT AFTERNOON-EVENING AND BUILDING THROUGH SUN. WW3 STILL LOOKS LOW WHICH IS TO BE EXPECTED WITH ITS LOW SWELL BIAS...AND ECWAVE SOLUTION PREFERRED. THIS PRODUCES 1.5-2 FT DIFFERENCE IN SWH FORECAST ACROSS THE NE CARIB AND ADJACENT TROPICAL ATLC REGION SAT NIGHT THROUGH MON. DIMINISHING TREND IN SEAS EXPECTED BY MON AFTERNOON WITH NEXT BOMB ACROSS THE CENTRAL ATLC POISED WITH SEND ANOTHER PULSE OF NNE SWELL INTO THE REGIONAL WATERS BEYOND TUE. ...SW N ATLANTIC INCLUDING THE BAHAMAS... MODEL PREFERENCE: GLOBAL MODEL CONSENSUS THROUGH DAY 2 THEN WEIGHTED HEAVILY TOWARD GEFS WEAKENING RIDGE CONTINUES ACROSS THE AREA THIS MORNING WITH MODERATE TO FRESH TRADES S OF 23-24N AND THEN WNW THROUGH STRAITS OF FLORIDA. CENTRAL ATLC LOW BEGINNING TO BOMB OUT ATTM WITH ALREADY STORM FORCE WINDS INDICATED AND RECENT ALTIMETER SHOWING SEAS TO 23 FT IN WRN QUAD. ASSOCIATED FRONT ANCHORED TO WEAK AND DEVELOPING LOW OFFSHORE OF S/GA COASTS AND WILL BEGIN TO SINK INTO N AND NE WATERS THIS MORNING. I AM STILL LEANING TOWARD ECMWF SOLUTION WITH THIS LOW IN THE SHORT TERM...AND ITS ASSOCIATED FRONTAL POSITION...REACHING SRN MOST POINT AT 28N64W THIS EVENING BEFORE CONTINUING MOVING FARTHER SE ACROSS CENTRAL ATLC AND DRIFTING NWD ACROSS LOCAL WATERS AS LOW OFF OF SE COASTS BEGINS TO SHIFT ENE. RIDGE TO COLLAPSE DURING THIS TIME AND WEAK TROUGH TO BE DRAGGED SE ACROSS NW PORTIONS AS LOW MOVES INTO CENTRAL ATLC THROUGH SAT. THIS WEAK FRONTAL TROUGH TO REACH CENTRAL FLORIDA SAT EVENING BEFORE STALLING...PRODUCING MODERATE NLY FLOW ACROSS NW PORTIONS AND S TO SW FLOW AHEAD OF FRONTAL TROUGH. AS MENTIONED ABOVE...NLY SWELL ASSOCIATED WITH CENTRAL ATLC BOMB TO MOVE INTO ATLC WATERS GENERALLY E OF 70W BY EARLY SAT AND REACH SE WATERS NE N COASTS OF NE CARIB ISLANDS SAT EVENING. PREFER ECWAVE SOLUTION TO WW3...WHERE THERE IS ABOUT A 2 FT DIFFERENCE...AND HAVE BLENDED LARGE PORTION OF ECWAVE TO ADJUST UPWARDS. ALTHOUGH THERE REMAINS REASONABLE DIFFERENCES IN EVOLUTION OF NEXT DEEP LOW ACROSS CENTRAL ATLC...GLOBAL MODELS BEGIN TO COME IN LINE SUN-MON WITH THIS FEATURE...WITH FRONTAL TROUGH DRAGGING EWD AND EXITING ERN WATERS LATE SUN WHILE HIGH ACROSS NW ATLC BUILDS S INTO AREA. SLY FLOW TO FRESHEN SUN-MON AHEAD OF NEXT FRONTAL SYSTEM SWEEPING ACROSS THE ERN U.S. $$ .WARNINGS...ANY CHANGES IMPACTING COASTAL NWS OFFICES WILL BE COORDINATED THROUGH AWIPS 12 PLANET CHAT OR BY TELEPHONE: .GULF OF MEXICO... NONE. .CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... NONE. .SW N ATLANTIC INCLUDING THE BAHAMAS... NONE. $$ *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.