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AGXX40 KNHC 270633 CCA
MIMATS

MARINE WEATHER DISCUSSION...CORRECTED
NWS NATIONAL HURRICANE CENTER MIAMI FL
228 AM EDT MON APR 27 2015

CORRECTED FOR MODEL PREFERENCES

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: 00Z GFS/12Z ECMWF BLENDED WITH PREVIOUS OFFICIAL. TAFB NWPS BLENDED WITH PREVIOUS OFFICIAL SEAS. MEDIUM CONFIDENCE.

THE 00Z GFS HAS REMAINED IN GOOD AGREEMENT WITH THE ECMWF SOLUTION WITH THE COLD FRONT EXPECTED TO MOVE THROUGH THE GULF TUE AND WED. THE 00Z GFS HAS SOME GRID-SCALE FEEDBACK ALONG THE N CENTRAL AND NE GULF COAST...BUT THE MASS FIELDS DO NOT APPEAR TO BE CORRUPTED INTO THE FORECAST BECAUSE OF THIS. DIFFERENCES BETWEEN THE GFS AND ECMWF COME INTO PLAY BY WED WHEN THE ECMWF CARRIES A STRONG SHORTWAVE SYSTEM SOUTHWARD THROUGH THE EASTERN PLAINS IN THE BACKSIDE OF THE BROAD...POSITIVELY TILTED UPPER TROUGH CENTERED OVER GREAT LAKES. THE ECMWF IS AN OUTLIER COMPARED TO THE GEFS AND EC ENS MEANS BUT HAS THE SUPPORT OF THE CMC AND NAVGEM. CONFIDENCE IN THE DETAILS HERE IS NOT HIGH. DESPITE THESE DIFFERENCES...THE IMPACT ON THE FORECAST FOR WINDS AND SEAS IS MINIMAL. A BLEND OF THE GFS AND ECMWF WAS USED TO ADJUST THE FORECAST TO ACCOUNT FOR UNCERTAINTY IN THE DETAILS.

NESDIS/SAB SMOKE PRODUCTS INDICATE FIRES MAINLY FROM AGRICULTURAL BURNING CONTINUE TO SUPPLYING SMOKE AND HAZE TO A LARGE PORTION OF THE GULF...WITH THE HIGHEST CONCENTRATION OF SMOKE CURRENTLY FOUND S OF 26N W OF 92W. THERE ARE SCATTERED OBSERVATIONS IN THE NW AND N CENTRAL GULF OF VISIBILITIES IN THE 3-5 SM RANGE. A SURFACE TROUGH WILL MOVE W OFF THE YUCATAN PENINSULA...ACROSS THE SW GULF DURING THE EARLY MORNING HOURS...AND DISSIPATE BY MIDDAY TODAY AND TUE. 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: 00Z GFS BLENDED WITH PREVIOUS OFFICIAL THROUGH THU THEN THE 12Z ECMWF ADDED TO THE BLEND. TAFB NWPS FOR SEAS. MEDIUM CONFIDENCE.

A FRESH TO STRONG SE BREEZE IS EXPECTED TO PULSE IN THE OVERNIGHT HOURS THROUGH TUE MORNING IN THE GULF OF HONDURAS ON THE S SIDE OF A DEEP LAYERED RIDGE. THE 0042Z RAPIDSCAT PASS CAPTURED THESE CONDITIONS DEVELOPING N OF HONDURAS. THIS PASS ALSO SHOWED THE WINDS ALONG THE COAST OF COLOMBIA REMAIN 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 WED EVENING. 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 GFS AND ECMWF HAVE COME INTO MUCH BETTER AGREEMENT WITH THE STRENGTH AND LOCATION OF THE SUBTROPICAL RIDGE AND THE COLD FRONT MOVING INTO THE NW CARIB WED. THE GFS WAS USED TO ADJUST THE FORECAST THROUGH THU AS IT GENERALLY DOES BETTER WITH THE GRADIENT WINDS ALONG THE COAST OF S AMERICA. AFTER THIS POINT...THE ECMWF WAS BROUGHT INTO THE BLEND BECAUSE OF THE UNCERTAINTY WITH THE STRENGTH AND LOCATION OF THE SURFACE TROUGHING OVER THE SW N ATLC. THE TAFB NWPS LOOKED REASONABLE TO BLEND WITH THE PREVIOUS SEAS FORECAST.


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

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

THE 0130Z ASCAT-A PASS CAPTURED GALE FORCE WINDS E OF THE AREA N OF 30N BETWEEN 59W AND 63W. NEITHER THE 00Z GFS NOR THE 12Z ECMWF WERE STRONG ENOUGH HERE...SO CONFIDENCE IS LOWER THAN AVERAGE AT THE GET GO. THE 12Z ECMWF WAS STRONGER WITH THE WIND FIELD OVER ZONE AMZ115 INITIALLY. THE 12Z ECMWF AND 00Z UKMET BRING THE COLD FRONT S INTO THE FORECAST AREA TODAY FASTER THAN THE GFS...BUT THE SENSIBLE WX DIFFERENCES DO NOT AMOUNT TO MUCH UNTIL WED WHEN THE NEXT SYSTEM MOVES INTO THE AREA FROM THE GULF. THE 12Z ECMWF CARRIES A SPURIOUS LOW PRES SYSTEM MOVING E ALONG 28-29N ALONG THE RETROGRADING FRONT ON WED AHEAD OF THE GULF SYSTEM. THIS LOOKS OUT OF LINE COMPARED TO THE CONSENSUS. DIFFERENCES ALSO COME INTO PLAY WITH THE TRACK OF THE GULF SYSTEM AS IT MOVES INTO THE ATLC...WITH THE ECMWF KEEPING THE LOW ON A MORE SLY TRACK THAN THE GFS. THE UKMET IS EVEN MORE SLY...BUT THE ENS MEANS PREFER A TRACK BETWEEN THE GFS AND ECMWF. DIFFERENCES WITH THE LOW TRACK ARE HIGHLY TIED TO THE FORECAST FOR THE UPPER LEVEL TROUGHING OVER THE GREAT LAKES AREA ATTM. THIS TROUGH WAS DISCUSSED IN THE GULF OF MEXICO SECTION. FOR NOW...A BLEND OF THE 00Z GFS AND 12Z ECMWF SEEMS PRUDENT THU THROUGH FRI NIGHT. THE EC WAVE GENERALLY DOES BETTER WITH THE SWELL...BUT CONFIDENCE LOWERS IN ITS FORECAST BY THU SINCE IT IS BASED ON THE ECMWF WINDS. THE MWW3 WAS BLENDED INTO THE MIX AT THAT POINT. 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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