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AGXX40 KNHC 041837
MIMATS

MARINE WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
237 PM EDT MON MAY 4 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.

MODEL PREFERENCE: 12 UTC GFS BLENDED WITH PREVIOUS/OFFICIAL FORECAST. 12 UTC TAFB NWPS FOR WAVE PARAMETERS. HIGH CONFIDENCE.

A SURFACE TROUGH IS IN THE CENTRAL GULF EXTENDING FROM THE SE LOUISIANA COAST NEAR 29N90W TO THE CENTRAL GULF NEAR 24N90W. ISOLATED TSTMS ARE OCCURRING NEAR THE AXIS. THIS TROUGH WILL EXIT OFF TO THE NW BY TUE MORNING. PLENTIFUL MOISTURE IS ADVANCING INTO THE SE GULF ASSOCIATED WITH SURFACE TROUGHING IN THE NW CARIBBEAN. MEANWHILE RIDGING EXTENDS FROM THE CENTRAL ATLC TOWARD THE NE GULF SUPPORTING A TIGHT PRES GRADIENT BETWEEN THE TROUGHS. FRESH TO STRONG NE TO E WINDS ARE IN THE SE GULF ALONG WITH SEAS TO 8 FT NEAR THE STRAITS OF FLORIDA. THESE WINDS WILL PERSIST THROUGH THIS EVENING...THEN WILL DIMINISH BY TUE MORNING AS THE PRES GRADIENT SLACKENS. HIGH PRES WILL MOVE INTO THE LOWER TENNESSEE VALLEY BY WED MORNING WITH HIGH PRES RIDGING DOMINATING THE GULF BY THE MIDDLE OF THE WEEK. SEAS WILL START OUT 4 TO 6 FT W OF 90W WED MORNING AND 2 TO 4 FT E OF 90W...DIMINISHING TO 1 TO 3 FT BY THU MORNING...AND THEN 2 FT OR LESS BY THE END OF THE WEEK AS HIGH PRES BECOMES CENTERED OVER THE NE GULF. WINDS WILL PULSE TO FRESH LEVELS ALONG AND JUST OFFSHORE OF THE NW YUCATAN PENINSULA DURING THE EVENING AND OVERNIGHT HOURS EACH NIGHT THROUGH THE WEEK.


...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W...

MODEL PREFERENCE: 12 UTC GFS BLENDED WITH PREVIOUS/OFFICIAL FORECAST. 12 UTC TAFB NWPS FOR WAVE PARAMETERS. HIGH CONFIDENCE.

SURFACE TROUGHING IS LOCATED IN THE NW CARIBBEAN WHICH CAN BE ATTRIBUTED TO AN OLD STATIONARY FRONT. MEANWHILE BROAD AND ELONGATED UPPER TROUGHING REACHES FROM THE N CENTRAL GULF OF MEXICO THROUGH THE NW CARIBBEAN INTO THE SW CARIBBEAN THIS MORNING. DIVERGENCE ALOFT ASSOCIATED WITH THE LEFT FRONT EXIT REGION OF A JET STREAK ON THE WEST SIDE OF THE TROUGH AND THE RIGHT REAR ENTRANCE REGION ON ANOTHER JET STREAK ON THE EAST SIDE OF THE TROUGH IS ENHANCING A SCATTERED THUNDERSTORM ACTIVITY BETWEEN GRAND CAYMAN AND CENTRAL CUBA EASTWARD TO THE WINDWARD PASSAGE THIS MORNING WITH VERY HEAVY RAINFALL OCCURRING OVER ESPECIALLY CENTRAL CUBA WITH LOCALIZED FLASH FLOODING POSSIBLE.

A TIGHT PRES GRADIENT IS IN PLACE ACROSS THE S CENTRAL CARIBBEAN BETWEEN SUBTROPICAL RIDGING AND LOWER PRES ALONG NW COLOMBIA. THIS PATTERN IS SUPPORTING FRESH TO STRONG NE TO E WINDS ALONG THE NORTHERN COASTS OF COLOMBIA AND VENEZUELA. RESULTANT SEAS ARE 8 TO 11 FT ACCORDING TO THE LATEST TAFB NWPS LOCAL MODEL GUIDANCE. THE FORECAST CONTINUES TO CALL FOR THIS AREA OF FRESH TO STRONG TRADES TO EXPAND ACROSS THE CENTRAL CARIBBEAN THROUGH TONIGHT AND PERSISTING THROUGH FRI WITH SEAS BUILDING TO 10 TO 13 FT AS THE SUBTROPICAL RIDGE BUILDS TO THE NORTHEAST. MODERATE TO FRESH TRADES WILL PERSIST OVER THE TROPICAL N ATLC WITH SEAS 5 TO 8 FT.


...SW N ATLANTIC INCLUDING THE BAHAMAS...

MODEL PREFERENCE: 12 UTC ECMWF BLENDED WITH PREVIOUS/OFFICIAL FORECAST. 12 UTC TAFB NWPS FOR WAVE PARAMETERS. HIGH CONFIDENCE TODAY...THEN MEDIUM CONFIDENCE THEREAFTER MOST PARTICULARLY WITH THE POSSIBLE FORMATION OF LOW PRES IN VICINITY OF BAHAMAS.

JET DYNAMICS ALOFT ASSOCIATED WITH AN UPPER TROUGH FROM THE NE GULF THROUGH THE NW CARIBBEAN IS ENHANCING NUMEROUS SHOWERS AND SCATTERED TSTMS ACROSS THE BAHAMAS...CUBA AND JUST OFFSHORE OF S FLORIDA. MEANWHILE A STATIONARY FRONT IS TRANSITIONING TO A TROUGH FROM 25N65W TO FAR EASTERN CUBA WHILE ANOTHER SURFACE TROUGH IS IN THE NW CARIBBEAN SEA EXTENDING INTO WESTERN CUBA. LATEST OBSERVATIONS INDICATE FRESH TO STRONG EASTERLY WINDS BETWEEN THE BAHAMAS AND STRAITS OF FLORIDA WITH A TIGHT PRES GRADIENT IN PLACE BETWEEN ATLC RIDGING AND THE TROUGHING. MAINLY MODERATE TO LOCALLY FRESH NE TO E WINDS ARE ELSEWHERE NW OF THE FRONTAL BOUNDARY/ TROUGH ALONG WITH MAINLY 4 TO 7 FT SEAS...EXCEPT IN THE N CENTRAL PORTION OF THE BASIN WHERE BUOY OBSERVATIONS ARE STILL 7 TO 9 FT WHICH REMAINS 2 TO 3 FT ABOVE MODEL WAVEWATCH MODEL GUIDANCE.

THE FORECAST ISSUE FOR TUE THROUGH THE FIRST PART OF THE UPCOMING WEEKEND CONTINUES TO BE THE POSSIBLE DEVELOPMENT OF LOW PRES OVER THE NORTHERN BAHAMAS. DISAGREEMENT PERSISTS IN MODEL OUTPUT REGARDING THE TIMING...POSITION AND STRENGTH OF THE LOW PRES. THE GFS APPEARS TO CONTINUE TO SUFFER FROM SOME CONVECTIVE FEEDBACK ISSUES WHICH IS LEADING TO A STRONGER SOLUTION...AND ALSO MUCH AND EVEN CLOSER TO THE SE UNITED STATES COAST COMPARED TO THE LATEST ECMWF AND UKMET SOLUTIONS. THE NEW 12 UTC ECMWF IS A GOOD COMPROMISE BETWEEN THE GFS AND MORE EASTWARD UKMET SOLUTION HOWEVER IT HAS TRENDED MORE TO THE EAST. THE ECMWF ALSO INDICATES SOME STRENGTHENING WED INTO THU AS THE LOW DRIFTS N OF THE AREA...BUT STILL WELL BELOW THE MORE AGGRESSIVE GFS AND CANADIAN SOLUTIONS. NEEDLESS TO SAY MUCH UNCERTAINTY REMAINS WITH THIS LOW AND THE FORECAST WILL CONTINUE TO FOLLOW THE MORE CONSERVATIVE ECMWF SOLUTION. ELSEWHERE MODERATE SE FLOW PERSIST ACROSS THE REGION IN THE WAKE OF THE TROUGH/LOW.

$$


.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 LEWITSKY. NATIONAL HURRICANE CENTER.

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