Marine Interpretation Message
Issued by NWS

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000
AGXX40 KNHC 260603
MIMATS

MARINE WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
203 AM EDT SUN APR 26 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: 12Z ECMWF BLENDED WITH PREVIOUS OFFICIAL. TAFB
NWPS BLENDED WITH PREVIOUS OFFICIAL SEAS. MEDIUM CONFIDENCE.

THE 00Z GFS HAS TRENDED TOWARD THE MORE CONSISTENT ECMWF SOLUTION
WITH THE COLD FRONT EXPECTED TO MOVE THROUGH THE GULF TUE AND WED.
THE GFS HAS SPED UP CONSIDERABLY OVER THE LAST 24 HOURS. ITS 00Z
RUN IS NOW FASTER THAN THE 12Z ECMWF. HOWEVER...SOME OF THIS SPEED
IS LIKELY DUE TO GRID-SCALE FEEDBACK WHICH IS LOWERING HEIGHTS
AHEAD OF THE TROUGH ALOFT...ALLOWING THE SYSTEM TO SHIFT EASTWARD
WITH LESS RIDGE TO BATTLE AHEAD OF IT. THE FORECAST FOR TUE
AFTERNOON LOOKS PARTICULARLY RIDDLED WITH FEEDBACK AS THE GFS DEVELOPS
A SPURIOUS LOW OVER THE NE GULF WITH GALE FORCE WINDS AROUND IT.
THE GEFS SHOWS NO CHANCE OF GALES HERE. THE ECMWF CONTINUES TO BE
PREFERRED WITH THIS SYSTEM. THE TAFB NWPS IS BASED PRIMARILY IN
ECMWF WINDS...SO IT WAS USED TO ADJUST THE SEAS.

NESDIS/SAB SMOKE PRODUCTS INDICATE FIRES MAINLY FROM AGRICULTURAL
BURNING CONTINUE TO SUPPLYING SMOKE AND HAZE TO A LARGE PORTION
OVER THE GULF...WITH THE HIGHEST CONCENTRATION OF SMOKE FOUND S OF
24N W OF 93W. THERE ARE SCATTERED OBSERVATIONS...PRIMARILY IN THE
NW GULF...OF VISIBILITIES IN THE 3-5 SM RANGE. A SURFACE TROUGH
WILL MOVE W OFF THE YUCATAN PENINSULA EACH NIGHT THROUGH MON NIGHT
AND MOVE W ACROSS THE SW GULF DURING THE EARLY MORNING HOURS...AND
DISSIPATE BY MIDDAY. THIS WILL HELP KEEP THE HIGHEST CONCENTRATION
OF SMOKE IN THE SW GULF. WINDS SHIFT NORTHERLY BEHIND THE FRONT
TUE NIGHT INTO WED. THIS WILL CLEAR OUT THE WESTERN GULF...WITH
SMOKE LIKELY TO TRACK EASTWARD AHEAD OF THE FRONT BEFORE IT MOVES
SE OF THE GULF WED NIGHT.

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

MODEL PREFERENCE: 12Z ECMWF BLENDED WITH PREVIOUS OFFICIAL. TAFB
NWPS FOR SEAS. MEDIUM CONFIDENCE.

A FRESH TO STRONG SE BREEZE IS EXPECTED TO PULSE EACH OVERNIGHT
THROUGH TUE MORNING IN THE GULF OF HONDURAS ON THE S SIDE OF A
DEEP LAYERED RIDGE. THE 0328Z ASCAT PASS CAPTURED THESE
CONDITIONS. ASCAT ALSO SHOWED THE WINDS ALONG THE COAST OF
COLOMBIA HAVE DIMINISHED PRIMARILY TO A FRESH BREEZE. AS LOW PRES
BUILDS OVER THE SW N ATLC...THE SUBTROPICAL HIGH WILL SHIFT
EASTWARD AND THE PRES GRADIENT WILL WEAKEN IN THE SW CARIB. LOOK
FOR THE GRADIENT TO BUILD OVER THE S CENTRAL AND SE CARIB MON
THROUGH THU BETWEEN THE SUBTROPICAL RIDGE AND LOWER PRES IN THE
WESTERN CARIB ASSOCIATED WITH THE COLD FRONT PASSING FROM THE GULF
OF MEXICO THROUGH THE YUCATAN CHANNEL OVERNIGHT WED NIGHT. A
GROWING AREA OF FRESH TO STRONG TRADES IS EXPECTED MON NIGHT
THROUGH THU NIGHT PRIMARILY OFF THE N CENTRAL AND NW COAST OF
VENEZUELA. WITH THE ECMWF PREFERRED WITH THE PATTERN TO THE
N INCLUDING THE COLD FRONT...IT SEEMS REASONABLE TO GO WITH ITS
FORECAST HERE AS WELL. THIS LENDED ITSELF FOR USING THE NWPS
PRIMARILY FOR THE ADJUSTMENT OF THE WAVES SINCE IT WAS BASED
PRIMARILY ON EC WINDS.

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

MODEL PREFERENCE: 12Z ECMWF BLENDED WITH PREVIOUS OFFICIAL. EC
WAVE AND TAFB NWPS FOR SEAS. MEDIUM CONFIDENCE.

THE AREA OF 20-25 KT WINDS OBSERVED BY THE 0244Z ASCAT-B PASS
SUGGESTS BOTH THE 00Z GFS AND 12Z ECMWF ARE UNDERDOING THE WIND
FIELD OFF THE NE FLORIDA COAST THIS MORNING. BOTH MODELS SHOW
WINDS INCREASING FURTHER THIS AFTERNOON IN THE NE PORTION...WITH
THE GFS CALLING FOR A GALE AND THE ECMWF WAITING TILL EVENING TO
POST A GALE JUST E OF ZONE AMZ115. THE 00Z GEFS SHOWS NO CHANCE OF
GALES WHILE THE LATEST SREF SHOWS UP TO A 25 PERCENT CHANCE HERE.
GIVEN THE WEAK INITIALIZATIONS AND THE TREND IN THE ECMWF TOWARD A
STRONGER SOLUTION...WILL ADJUST THE WINDS HERE TO REFLECT GALE
CONDITIONS EXPECTED IN FAR NE WATERS LATE TODAY.

ELSEWHERE...CONFIDENCE HAS IMPROVED SLIGHTLY IN ABIDING BY THE
MORE CONSISTENT ECMWF FORECAST WHICH CARRIES A LOW PRES SYSTEM
THROUGH FAR NW WATERS LATE WED AND DEEPENS IT JUST N OF THE AREA.
THE GFS HAS MADE A CHANGE TOWARD THIS SOLUTION.
HOWEVER...CONFIDENCE IS LOW IN THE DETAILS OF THE GFS FORECAST AS
IT APPEARS TO HAVE SOME GRID- SCALE FEEDBACK ISSUES WHICH IMPACT
ITS MASS FIELDS. SEE THE GULF OF MEXICO SECTION FOR DETAILS ABOUT
FEEDBACK SEEN IN THE NE GULF. THIS FEEDBACK LIKELY DRAGS THE MEAN
TROUGH SEEN IN THE GFS EASTWARD ACROSS THE FLORIDA PENINSULA ON A
MORE SOUTHEASTERLY PATH. THE ECMWF WAS USED TO ADJUST THE
FORECAST. ITS WAVE MODEL WAS USED AS WELL...WITH CONFIDENCE HIGHER
IN ITS HANDLING OF SWELL ORIGINATING N OF THE AREA THAN THE MWW3.
THE TAFB NWPS WAS USED PRIMARILY AROUND THE BAHAMAS WHERE
BATHYMETRY PLAYS A LARGER ROLE IN THE FORECAST FOR SEAS.

$$

.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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