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AGXX40 KNHC 171801
MIMATS

MARINE WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
201 PM EDT FRI APR 17 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: LATEST GFS/ECMWF BLENDED WITH PREVIOUS OFFICIAL FOR WINDS. TAFB NWPS/MWW3 BLENDED WITH PREVIOUS OFFICIAL FOR WAVES. MEDIUM-HIGH CONFIDENCE.

AS OF 1700 UTC...THE FOG IS LIFTING IN THE NW GULF WITH NEARLY ALL STATIONS DROPPING FOG IN THEIR OBSERVATIONS. SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED TO REMAIN IN THE NORTHERN GULF OVERNIGHT BEFORE FOCUSING OFF THE TEXAS COAST SAT AND REACHING THE N CENTRAL GULF SUN AND NE GULF SUN NIGHT IN ASSOCIATION WITH THE REMAINS OF THE UPPER LOW CURRENTLY OVER THE NM/CO BORDER EXPECTED TO PHASE WITH A NORTHERN STREAM TROUGH AS IT PUSHES INTO THE MID MISSISSIPPI VALLEY MON. THE 12Z GFS AND 00Z ECMWF ARE GENERALLY IN GOOD AGREEMENT WITH THE UPPER LOW TRACK AND INTENSITY BUT THE GFS IS STRONGER WITH SHORTWAVE ENERGY SE OF THE LOW SUN AND MON OVER THE SERN U.S. THE GFS APPEARS TO BE A STRONGER OUTLIER COMPARED TO THE MODEL CONSENSUS SO BLENDING THE ECMWF WITH ITS SOLUTION HOPEFULLY DAMPENS OUT ANY DISCREPANCIES. WINDS AND SEAS WILL GENERALLY REMAIN BELOW ADVISORY CRITERIA THROUGH THE END OF THE PERIOD WED NIGHT WITH THE EXCEPTION OF LOCALIZED EVENING THERMAL ENHANCEMENT ALONG THE NW COAST OF THE YUCATAN PENINSULA. WINDS HERE ARE EXPECTED REACH THE 20-25 KT RANGE THROUGH SAT EVENING...AND THEN ONLY 15-20 KT EVENTS EXPECTED EACH EVENING THROUGH THE REMAINDER OF THE PERIOD. THESE E-SE PULSES WILL PROPAGATE W ACROSS THE E BAY OF CAMPECHE DURING THE MORNING DAYLIGHT HOURS WITH THE TROUGH...LOSING IDENTITY OVER THE CENTRAL BAY OF CAMPECHE BY THE EARLY AFTERNOONS.




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

MODEL PREFERENCE: LATEST GFS BLENDED WITH PREVIOUS OFFICIAL FOR WINDS THROUGH TUE THEN ECMWF ADDED TO BLEND. TAFB NWPS BLENDED WITH PREVIOUS OFFICIAL FOR WAVES...WITH THE EC WAVE ALSO ADDED IN THE TROPICAL N ATLC. HIGH CONFIDENCE.

ATLC RIDGING N OF THE AREA...COMBINED WITH LOW PRES OVER NW COLOMBIA...WILL SUPPORT 20-25 KT NE WINDS WITHIN 180 NM OF THE NW COAST OF COLOMBIA TONIGHT AND SAT NIGHT...THEN THE AFFECTED AREA SHOULD SHRINK TO WITHIN 90 NM OF THE COAST EACH NIGHT THROUGH TUE NIGHT. BY WED...THE GFS AND ECMWF DIFFER OVER THE SW N ATLC...WITH THE GFS SHOWING A RIDGE AND STRONGER WINDS OFF COLOMBIA AND THE ECMWF SHOWING A TROUGH. CONFIDENCE IS LOW IN THE DETAILS BY THIS POINT IN THE FORECAST...SO A BLEND OF THE GFS AND ECMWF WAS BLENDED FURTHER WITH THE OFFICIAL FORECAST WHICH ALLOWED FOR A SLIGHT EXPANSION OF THE 20-25 KT WINDS OFF COLOMBIA. A FRESH TO STRONG E-SE BREEZE IS EXPECTED OFFSHORE OF THE GULF OF HONDURAS EACH NIGHT THROUGH MON NIGHT...WITH SEAS BUILDING TO 8-9 FT. AS THE RIDGING TO THE N WEAKENS TUE AND WED...THE AREA SEEING A FRESH TO STRONG BREEZE SHOULD SHRINK AND SEAS SHOULD SUBSIDE ACCORDINGLY. ELSEWHERE...MODERATE TO FRESH TRADES ARE EXPECTED. NE SWELL WILL PROPAGATING SW THROUGH THE TROPICAL ATLC WATERS E OF LEEWARDS INCREASING THE COMBINED SEAS AROUND 8 FT ON SAT NIGHT...WITH THESE CONDITIONS SPREADING S ACROSS THE TROPICAL WATERS E OF THE WINDWARDS ON SUN. THIS TIMING IS SLIGHTLY FASTER THAN THAT SEEN IN THE NWPS AND MWW3...ADJUSTING FOR THE EC WAVE WHICH GENERALLY PERFORMS BETTER WITH LONG-PERIOD SWELL MOVING INTO THE REGION.


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

MODEL PREFERENCE: LATEST GFS/ECMWF BLENDED WITH PREVIOUS OFFICIAL FOR WINDS. TAFB NWPS/EC WAVE BLENDED WITH PREVIOUS OFFICIAL FOR WAVES. MEDIUM-HIGH CONFIDENCE.

AT 1200 UTC A COLD FRONT WAS ANALYZED FROM 31N40W TO 28N47W TO 27N58W THEN STATIONARY THROUGH 28N70W TO 31N74W. A 1327 UTC ALTIMETER PASS SHOWED SEAS TO 11 FT N OF THE FRONT ALONG 66W AND BUOY 41049 NEAR 27.5N62.9W SAW SEAS IN THE 10-11 FT RANGE FROM 1200 UTC TO 1700 UTC. THESE CONDITONS BEST MATCH THE EC WAVE. THE 1400 UTC ASCAT PASS SHOWED A FRESH TO STRONG E-NE BREEZE STILL PERSISTED N OF THE FRONT BETWEEN 54W AND 60W. NEITHER THE 00Z ECMWF NOR THE 12Z GFS SHOWED 25 KT WINDS HERE AT 12Z THIS MORNING. WINDS WERE BUMPED UP HERE SLIGHTLY INITIALLY BUT A BLEND OF THE GFS AND ECMWF WAS USED OVERALL FOR THE WIND FORECAST. THESE MODELS ARE IN REASONABLE AGREEMENT UNTIL TUE WHEN THE GFS BECOMES FASTER TO CARRY A FRONT OFF THE U.S. EAST COAST...WITH THE GFS APPEARING TO HAVE SOME CONVECTIVE FEEDBACK PROBLEMS BY TUE NIGHT NEAR 39N63W WHICH CAUSE IT TO DRAG THE FRONT EASTWARD TOO QUICKLY. THE GFS AND ECMWF DIFFER SIGNIFICANTLY BY WED AFTERNOON WHEN THE GFS PLACES A HIGH ALONG 31N74W WHILE THE ECMWF CARRIES A SECONDARY COLD FRONT THROUGH THE AREA. THE EC ENS MEAN SUPPORTS THE OPERATIONAL RUN WHILE THE GEFS IS SLOWER WITH THE FRONT AND THE HIGH BEHIND IT THAN THE GFS...MORE LIKE THE ECMWF. BLENDING IN THE ECMWF FORECAST ALSO SUPPLIED MORE CONFIDENCE TO USING THE EC WAVE IN THE BLEND FOR ADJUSTING THE WAVE FIELD.

$$


.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 SCHAUER. NATIONAL HURRICANE CENTER.

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