NHC Marine Weather Discussion

000

AGXX40 KNHC 300623

MIMATS

MARINE WEATHER DISCUSSION

NWS NATIONAL HURRICANE CENTER MIAMI FL

223 AM EDT THU APR 30 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 PREFERRED FOR WINDS. BLEND OF TAFB

NWPS AND 12Z EC WAVE FOR WAVES. MEDIUM CONFIDENCE.

THE 0300Z ASCAT-B PASS SHOWS 20-25 KT N WINDS S OF 22N IN THE SW

GULF. THE STRONGER 12Z ECMWF SEEMS TO HAVE A BETTER HANDLE ON THE

CURRENT CONDITIONS THAN THE 00Z GFS. THEIR SURFACE WIND FORECASTS

ARE VERY SIMILAR THROUGH SAT AS HIGH PRES DEVELOPS IN THE NW GULF

THEN TRACKS E ALONG THE N GULF COASTAL PLAIN...BUT DIFFERENCES

ALOFT BEGIN TO ARISE BY SAT NIGHT. THE 00Z GFS CARRIES A STRONGER

SYSTEM FROM N CENTRAL MEXICO TODAY INTO THE NW GULF LATE FRI AND

IS FASTER TO CARRY IT ACROSS FLORIDA SAT THAN THE 12Z ECMWF AND

THE GEFS AND EC ENS MEANS. THESE MODEL BOTH SHOW WINDS PICKING

UP TO A FRESH BREEZE IN THE E GULF BY 06Z SUN...WITH THE GFS

FOCUSED OFF SARASOTA AND THE ECMWF FARTHER S IN THE STRAITS OF

FLORIDA. THE GFS GOES ON TO EXPAND THAT AREA OF FRESH TO STRONG

WINDS ACROSS ZONE GMZ015. THE OTHER MODELS ARE WEAKER HERE.

ALOFT...THE MODEL AGREE ON MOVING THE BULK OF THE ENERGY IN THIS

TROUGH QUICKLY INTO THE ATLC...BUT LEAVE SOME BEHIND AS RIDGING

BUILDS ACROSS THE S CENTRAL ATLC. THIS ALLOWS FOR A DEEP LAYERED

LOW TO DEVELOP INVOF THE NORTHERN BAHAMAS BY TUE NIGHT BEYOND THE

FORECAST PERIOD. THE GFS CONTINUES TO BE ON THE STRONG SIDE OF THE

GUIDANCE WITH THIS SYSTEM. THE 12Z ECMWF WAS USED FOR THE WIND

FORECAST. THE EC WAVE WAS BLENDED WITH THE HEAVILY WEIGHTED NWPS

FOR SEAS.

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

55W AND 64W...

MODEL PREFERENCE: 12Z ECMWF PREFERRED FOR WINDS. BLEND OF TAFB

NWPS AND 12Z EC WAVE FOR WAVES. MEDIUM CONFIDENCE.

SATELLITE IMAGERY SHOWS SMOKE STILL LINGERS PRIMARILY S OF 20N W

OF 84W DUE TO AGRICULTURAL FIRES OVER HONDURAS. A PRE-FRONTAL

TROUGH FROM 17N87W TO THE WESTERN TIP OF CUBA IS FOCUSING THE

SMOKE TO ITS E. THE COLD FRONT OVER THE SOUTHERN GULF OF MEXICO

WILL MOVE INTO THE AREA TODAY AND USHER IN SOME N WINDS OVER MUCH

OF THIS REGION WHICH SHOULD HELP KEEP THE SMOKE OVERLAND. BOTH

THE GFS AND 12Z ECMWF AGREE ON WASHING OUT THE COLD FRONT IN THE

NW GULF ON SUN.

THE PRESSURE GRADIENT HAS BUILT OVER THE SE CARIB BETWEEN THE

SUBTROPICAL RIDGE AND LOWER PRES IN THE WESTERN CARIB ASSOCIATED

WITH THE APPROACHING COLD FRONT. AN AREA OF FRESH TO STRONG TRADES

IS EXPECTED TO PERSIST THROUGH FRI MORNING PRIMARILY OFF THE N

CENTRAL AND NW COAST OF VENEZUELA. WINDS SHOULD DIMINISH LATE FRI

AS THE SUBTROPICAL RIDGE IS FORCED E BY THE COLD FRONT IN THE SW N

ATLC...WITH FRESH TO STRONG TRADES RETURNING ALONG THE COAST OF

COLOMBIA IN THE OVERNIGHT/EARLY MORNING HOURS DURING THE WEEKEND

AND ALONG THE S CENTRAL CARIB SUN NIGHT AS HIGH PRES BUILDS BEHIND

THE FRONT IN THE SW N ATLC AND THEN IN THE CENTRAL ATLC AND THE

FRONT TO THE N WEAKENS. USED THE ECMWF FOR WINDS AS IT IS

PREFERRED FOR THE DRIVING PATTERN TO THE N AND THE EC WAVE WAS

BLENDED WITH THE TAFB NWPS FOR SEAS...RELYING HEAVILY ON THE NWPS.

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

MODEL PREFERENCE: 12Z ECMWF PREFERRED FOR WINDS. BLEND OF TAFB

NWPS AND 12Z EC WAVE FOR WAVES. MEDIUM CONFIDENCE.

THE GENERAL TREND IN THE MODELS THE LAST FEW DAYS HAS BEEN TOWARD

LESS DEVELOPMENT OF THE LOW IN THE GULF OF MEXICO AND A MORE SLY

TRACK AS IT MOVES INTO THE ATLC TODAY. THE 18Z GFS HAD BEEN ON THE

STRONGER AND MORE NLY EDGE OF THE GUIDANCE...BUT THE 00Z RUN HAS

ADJUSTED TOWARD THE CONSENSUS AND THE ECMWF. THE PREVIOUS FORECAST

RELIED TOO HEAVILY ON OLDER...MORE WRAPPED UP SOLUTIONS...SO IT

WAS LARGELY SCRAPPED FOR THE LATEST ECMWF SOLUTION HERE WHICH IS

NOT FAR FROM THE GFS. THE EC WAVE MODEL IS CLOSER TO THE SEAS

SEEN BY THE 0256Z ALTIMETER PASS ALONG 67W THAN THE MW3 WHICH IS

2-3 FT TOO LOW. THE EC WAVE WAS RELIED ON MORE HEAVILY EARLY IN

THE PERIOD WITH THE NWPS RELIED ON MORE BY FRI NIGHT AS THE

SYSTEM MOVES AWAY. THE 12Z ECMWF IS ALSO PREFERRED WITH THE UPPER

TROUGH MOVING INTO THE GULF OF MEXICO...WHICH APPEARS TO BE TOO

AMPLIFIED IN GFS. DETAILS WITH THIS SYSTEM ARE DISCUSSED IN THE

GULF OF MEXICO SECTION. BEYOND THE FORECAST PERIOD...THE 00Z GFS

CONTINUES TO BE ON THE STRONG SIDE OF THE GUIDANCE WITH THE DEEP

LAYERED LOW EXPECTED TO DEVELOP INVOF THE NORTHERN BAHAMAS BY TUE

NIGHT BEYOND THE FORECAST PERIOD.

$$

.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:

WWW.NHC.NOAA.GOV/ABOUTTAFBPROD.SHTML#OWF

NOTE: GRIDDED MARINE FORECASTS ARE AVAILABLE IN THE

NATIONAL DIGITAL FORECAST DATABASE (NDFD) AT:

WWW.NHC.NOAA.GOV/MARINE/GRIDS.PHP

FOR ADDITIONAL INFORMATION PLEASE VISIT:

HTTP://WWW.HURRICANE WARNINGS.GOV/MARINE

$$

.FORECASTER SCHAUER. NATIONAL HURRICANE CENTER.

http://www.nhc.noaa.gov/text/MIAMIMATS.shtml