108
AGXX40 KNHC 050735
MIMATS

MARINE WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
335 AM EDT TUE MAY 5 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: 00 UTC GFS BLENDED WITH PREVIOUS/OFFICIAL
FORECAST. 00 UTC TAFB NWPS FOR WAVE PARAMETERS. HIGH CONFIDENCE.

A FAIRLY TIGHT PRESSURE GRADIENT IS IN PLACE AT THE SURFACE THIS
MORNING BETWEEN STRONG HIGH PRES OFF THE CAROLINA COAST AND A
BROAD SURFACE TROUGH FROM THE WESTERN TIP OF CUBA TO THE GULF OF
HONDURAS. THE SURFACE TROUGH IS RELATED TO A BROAD UPPER TROUGH
REACHING FROM THE NE GULF ACROSS WESTERN CUBA TO THE SW CARIBBEAN.
BUOY OBSERVATIONS AND A 0345 UTC SCATTEROMETER PASS INDICATED 20
TO 25 KT WINDS ACROSS MUCH OF THE CENTRAL GULF WITH SEAS REACHING
8 FT OVER THE N CENTRAL GULF AND SE GULF. JET DYNAMICS ALOFT ARE
SUPPORTING AREAS OF SHOWERS AND THUNDERSTORMS OVER THE SE GULF AND
THE STRAITS OF FLORIDA.

THE TROUGH TO THE SOUTH WILL DAMPEN OUT AS THE HIGH PRES SHIFTS
INTO THE TENNESSEE VALLEY...ALLOWING WINDS OVER THE EASTERN GULF
TO DIMINISH. SEAS WILL SUBSIDE ACCORDINGLY THROUGH
TODAY...WITH 3 TO 5 FT OVER THE WESTERN GULF AND 1 TO 3 FT OVER
THE FAR EASTERN GULF THROUGH MID WEEK. SE RETURN FLOW WILL
INCREASE HOWEVER OVER THE WESTERN GULF STARTING MID WEEK BETWEEN
THE HIGH PRES OVER THE SOUTHEASTERN UNITED STATES AND LOW PRES
MOVING INTO THE SOUTHERN PLAINS. WITH SEAS BUILDING 5 TO 7 FT.
MEANWHILE WINDS WILL PULSE TO FRESH LEVELS ALONG AND JUST
OFFSHORE OF THE NW YUCATAN PENINSULA DURING THE EVENING AND
OVERNIGHT HOURS EACH NIGHT THROUGH THE WEEK.

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

MODEL PREFERENCE: 00 UTC GFS BLENDED WITH PREVIOUS/OFFICIAL
FORECAST. 00 UTC TAFB NWPS FOR WAVE PARAMETERS. HIGH CONFIDENCE.

SURFACE TROUGHING IS LOCATED IN THE NW CARIBBEAN WHICH CAN BE
ATTRIBUTED BROAD AND ELONGATED UPPER TROUGHING REACHING FROM THE
N CENTRAL GULF OF MEXICO THROUGH THE NW CARIBBEAN INTO THE SW
CARIBBEAN THIS MORNING. DIVERGENCE ALOFT ASSOCIATED WITH THE LEFT
FRONT EXIT REGION OF A JET STREAK ON THE WEST SIDE OF THE TROUGH
AND THE RIGHT REAR ENTRANCE REGION ON ANOTHER JET STREAK ON THE
EAST SIDE OF THE TROUGH IS ENHANCING A SCATTERED THUNDERSTORM
ACTIVITY N OF 18N E OF 85W THROUGH CUBA.

A TIGHT PRES GRADIENT IS IN PLACE ACROSS THE S CENTRAL CARIBBEAN
BETWEEN SUBTROPICAL RIDGING AND LOWER PRES ALONG NW COLOMBIA.
THIS PATTERN IS SUPPORTING FRESH TO STRONG NE TO E WINDS ALONG THE
NORTHERN COASTS OF COLOMBIA AND VENEZUELA. RESULTANT SEAS ARE 8 TO
11 FT ACCORDING TO THE LATEST TAFB NWPS LOCAL MODEL GUIDANCE. THE
FORECAST CONTINUES TO CALL FOR THIS AREA OF FRESH TO STRONG TRADES
TO EXPAND ACROSS THE CENTRAL CARIBBEAN THROUGH TONIGHT AND
PERSISTING THROUGH FRI WITH SEAS BUILDING TO 10 TO 13 FT AS THE
SUBTROPICAL RIDGE BUILDS TO THE NORTHEAST. MODERATE TO FRESH
TRADES WILL PERSIST OVER THE TROPICAL N ATLC WITH SEAS 5 TO 8 FT.

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

MODEL PREFERENCE: BLEND OF 00 UTC ECMWF/GFS. 00 UTC TAFB NWPS FOR
WAVE PARAMETERS. MEDIUM CONFIDENCE THEN LOW CONFIDENCE FRI AND SAT.

JET DYNAMICS ALOFT ASSOCIATED WITH AN UPPER TROUGH FROM THE NE
GULF THROUGH THE NW CARIBBEAN CONTINUES TO ENHANCE NUMEROUS
SHOWERS AND SCATTERED TSTMS ACROSS THE BAHAMAS...CUBA AND JUST
OFFSHORE OF S FLORIDA. LATEST OBSERVATIONS INDICATE FRESH EASTERLY
WINDS BETWEEN THE BAHAMAS AND STRAITS OF FLORIDA WITH A TIGHT PRES
GRADIENT IN PLACE BETWEEN ATLC RIDGING AND TROUGHING OVER THE NW
CARIBBEAN. SEAS ARE 5 TO 7 FT OVER MOST AREAS OUTSIDE THE BAHAMAS.

THE FORECAST ISSUE FOR THE REMAINDER OF THE WEEK CONTINUES TO BE
THE DEVELOPMENT OF LOW PRES OVER THE NORTHERN BAHAMAS. RUN TO RUN
CONSISTENCY AMONG THE MAJOR MODELS IS POOR...BUT LATEST TRENDS
SHOW THE ECMWF AND GFS IN SLIGHTLY BETTER AGREEMENT ON
POSITION...TIMING...AND INTENSITY THROUGH THU...WITH A TROUGH
FORMING OVER THE CENTRAL BAHAMAS THIS MORNING...LOW PRES FORMING
ALONG THE TROUGH OVER THE NORTHERN BAHAMAS EARLY WED...THEN
SHIFTING NNE THROUGH THU REACHING NEAR 31N75W BY LATE THU. THE GFS
HAS MODERATED SLIGHTLY AND DOES NOT SHOW RAPID DEEPENING IN OF THE
LOW AS IN EARLY RUNS AND IS NOW MORE IN LINE WITH THE OPERATIONAL
ECMWF. THE ECMWF IN TURN HAS SHIFTED ITS TRACK SLIGHTLY MORE TO
THE EAST IN LINE WITH THE GFS. THE UKMET TRACK REMAINS EVEN
FARTHER EAST. THE PATTERN BECOMES MORE UNCERTAIN LATE IN THE WEEK
WITH THE GFS SHOWING A DUE WEST MOVEMENT ALONG 31N AND DEEPENING
THE LOW SLIGHTLY...WITH THE ECMWF LARGELY DISSIPATING THE LOW. THE
OFFICIAL FORECAST FOLLOWS A GFS/ECMWF BLEND WITH ONLY A SLIGHT
EASTWARD TWEAK TO THE PREVIOUS FORECAST TRACK. ELSEWHERE MODERATE
SE FLOW PERSIST ACROSS THE REGION IN THE WAKE OF THE TROUGH/LOW.

$$

.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 CHRISTENSEN. NATIONAL HURRICANE CENTER.