Marine Interpretation Message
Issued by NWS

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000
AGXX40 KNHC 280621
MIMATS

MARINE WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
221 AM EDT TUE APR 28 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: 12Z ECMWF BLENDED WITH PREVIOUS OFFICIAL. TAFB
NWPS AND EC WAVE BLENDED WITH PREVIOUS OFFICIAL SEAS. MEDIUM
CONFIDENCE.

THE 00Z GFS CONTINUES TO HAVE SOME GRID-SCALE FEEDBACK ALONG THE
N CENTRAL AND NE GULF COAST. THE MASS FIELDS DO APPEAR TO BE
CORRUPTED INTO THE FORECAST BECAUSE OF THIS...WITH THE GFS
DEVELOPING A SURFACE LOW IN THE NE GULF TODAY THAT DISPLACES THE
LOWEST PRES AWAY FROM THE DEEP LAYER TROUGHING TO THE N AND DELAYS
THE AMPLIFICATION OF THAT SURFACE LOW OVER THE NORTHEASTERN GULF
COAST. THIS CAUSES THE GFS TO BE SLOWER TO BUILD HIGH PRES BEHIND
THE FRONT. THE GFS GOES ON TO HANG MORE TROUGHING OVER THE EASTERN
GULF THU IN THE WAKE OF THE FRONT IN RESPONSE TO A STRONG UPPER
LEVEL SYSTEM IT CARRIES THROUGH THE NE GULF. IT IS AN OUTLIER
SOLUTION WITH THIS FEATURE. THE ECMWF HAS BEEN MORE CONSISTENT
WITH ITS FORECAST. IT WAS USED TO ADJUST THE OFFICIAL FORECAST AND
ITS WAVE MODEL WAS ALSO ADDED TO THE MIX FOR SEAS IN ADDITION TO
THE TAFB NWPS.

NESDIS/SAB SMOKE PRODUCTS INDICATE FIRES MAINLY FROM AGRICULTURAL
BURNING CONTINUE TO SUPPLYING SMOKE AND HAZE PRIMARILY TO THE SW
AND S CENTRAL GULF...WITH THE HIGHEST CONCENTRATION OF SMOKE
CURRENTLY FOUND S OF 23N W OF 87W. WINDS IN THE WESTERN GULF ARE
SHIFTING NORTHERLY BEHIND THE COLD FRONT. 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
THROUGH WED THEN THE 00Z GFS ADDED TO THE BLEND. TAFB NWPS FOR
SEAS. MEDIUM CONFIDENCE.

A FRESH TO STRONG SE BREEZE IS PULSING FOR THE LAST TIME THIS MORNING
IN THE GULF OF HONDURAS. THE 0248Z ASCAT-A PASS CAPTURED THESE
CONDITIONS DEVELOPING N OF EASTERN HONDURAS. THE ECMWF IS
REASONABLY WELL INITIALIZED HERE AND IS THE PREFERRED SOLUTION
WITH THE COLD FRONT APPROACHING FROM THE GULF OF MEXICO WHICH WILL
REDUCE THE PRES GRADIENT OVER THE AREA AND DIMINISH THE WINDS
LATER TODAY. BOTH THE GFS AND 12Z ECMWF AGREE ON CARRYING THE
FRONT INTO THE YUCATAN CHANNEL WED AFTERNOON. DIFFERENCES IN THE
STRENGTH OF THE RIDGING N OF THE AREA BETWEEN THESE SOLUTIONS
PROMPTS THE CHANGE IN MODEL PREFERENCE TOWARD A BLEND BY WED
NIGHT. 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. 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. THE
ECMWF CARRIES THE SYSTEM IN THE SW N ATLC ON A MORE NLY TRACK THAN
THE GFS...ALLOWING FOR MORE RIDGING TO DEVELOP BETWEEN THE SYSTEM
AND THE N COAST OF S AMERICA. A BLEND OF THE GFS AND 12Z ECMWF IS
PREFERRED WITH THE PATTERN TO THE N BY WED NIGHT...SO IT WAS ALSO
ADOPTED HERE. SEE THE SECTION BELOW FOR DETAILS. THE TAFB NWPS
LOOKED REASONABLE TO BLEND WITH THE PREVIOUS SEAS FORECAST.

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

MODEL PREFERENCE: 12Z ECMWF BLENDED WITH PREVIOUS OFFICIAL
THROUGH WED THEN THE 00Z GFS ADDED TO THE BLEND. EC WAVE AND TAFB
NWPS FOR SEAS THROUGH WED THEN MWW3 ADDED TO BLEND. MEDIUM
CONFIDENCE THROUGH WED WITH LOW CONFIDENCE THEREAFTER.

AS MENTIONED IN THE GULF OF MEXICO SECTION...CONFIDENCE IS LOW IN
THE FEEDBACK-RIDDLED 00Z GFS FORECAST TODAY. THIS FEEDBACK HAS
IMPACTED THE MASS FIELDS AND LIKELY SENDS THE MAIN LOW PRES SYSTEM
TOO FAR S AS IT TRAVERSES FLORIDA AND MOVES INTO THE SW N ATLC.
HOWEVER...THE ECMWF APPEARS TO BE AN OUTLIER WITH THE LOW CENTER
FROM WED NIGHT ONWARD. ALOFT...THE ECMWF CARRIES A MORE NEGATIVELY
TILTED TROUGH OVER THE GREAT LAKES/OH VLY REGION. AS THE LOW PRES
SYSTEM MOVES OFFSHORE...IT ENCOUNTERS DEEPER TROUGHING COMPARED TO
THE OTHER MODELS WHICH CAUSES IT TO BE DEEPER AND MORE WESTERLY AT
THE SURFACE AS THE LOW DEVELOPS. THE GEFS AND EC ENS MEANS SUPPORT
A COMPROMISE BETWEEN THESE SOLUTIONS WITH THE STRENGTH AND PATH OF
THE LOW. A BLEND OF THE GFS AND 12Z ECMWF WAS USED TO ADJUST THE
FORECAST FROM WED NIGHT ONWARD AS A RESULT. THE TAFB NWPS AND EC
WAVE WERE BLENDED WITH THE OFFICIAL FORECAST EARLY IN THE
PERIOD...WITH THE MWW3 ADDED TO THE MIX WED NIGHT ONWARD WHEN THE
GFS WAS ADDED TO THE WIND BLEND.

$$

.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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