000
AGXX40 KNHC 201857
MIMATS

MARINE WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
157 PM EST FRI DEC 20 2013

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: PREVIOUS/OFFICIAL FORECAST BLENDED WITH LATEST
GFS AND ECMWF. PREVIOUS FORECAST AND MWW3 BLEND USED FOR WAVE
PARAMETERS. MEDIUM-HIGH CONFIDENCE.

MODERATE TO FRESH SOUTHERLY RETURN FLOW IS ACROSS THE BASIN WITH
RIDGING EXTENDING FROM CENTRAL ATLC HIGH PRES. LATEST BUOY AND
SHIP OBSERVATIONS REPORT 4-6 FT SEAS. RIDGING WILL GRADUALLY BREAK
DOWN AND SHIFT E THE REST OF TODAY INTO SAT AS THE NEXT COLD FRONT
APPROACHES FROM THE W. 

THAT FRONT IS FORECAST TO MOVE INTO THE NW GULF COASTAL WATERS
SAT NIGHT...BRIEFLY STALLING OUT FROM S CENTRAL LOUISIANA TO NE
MEXICO INTO SUN MORNING. CONFIDENCE IN THE GFS FORECAST WANES AS A
REINFORCING SURGE OF NORTHERLY WINDS AND COLD AIR ARRIVES IN THE
NW PORTION LATE SUN INTO MON. THE GFS IS STILL SLOWER THAN THE
ECMWF BRINGING IN THE REINFORCING TROUGH ALOFT...BUT THESE MODELS
AGREE ON FRESH TO STRONG WINDS ACROSS THE MAJORITY OF THE GULF
BEHIND THE FRONT AND GALE FORCE WINDS POSSIBLE IN GMZ023 MON. THE
ECMWF IS 6-12 HOURS FASTER WITH THE ONSET OF GALES IN THE SW GULF
THAN THE GFS WHICH WAITS TILL LATE MON. 09Z SREF 34 KT
PROBABILITIES HAVE INCREASED TO NEAR 90 PERCENT BY 21 UTC MON.
THE 12Z GEFS PROBABILITIES SHOWS AROUND A 70 PERCENT CHANCE OF
GALES. BLENDED THE GFS AND ECMWF WITH THE PREVIOUS OFFICIAL
FORECAST WHICH RESULTED IN GALES ONLY IN ZONE GMZ023 MON AFTERNOON
AND NIGHT. FRESH TO STRONG NORTHERLY WINDS WILL SPREAD ACROSS THE
REMAINDER OF THE GULF BEHIND THE FRONT THROUGH TUE...GRADUALLY
DIMINISHING AND TURNING MORE TO THE E AS HIGH PRES SLIDES ACROSS
THE CAROLINAS BY EARLY WED.

...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN
55W AND 65W...

MODEL PREFERENCE: PREVIOUS/OFFICIAL FORECAST BLENDED WITH LATEST
GFS THROUGH MON THEN A BLEND OF GFS AND ECMWF MON AND TUE.
NWPS/MWW3 BLEND USED FOR WAVE PARAMETERS. HIGH CONFIDENCE.

A GALE WARNING IS IN EFFECT FOR THE COAST OF COLOMBIA THROUGH SUN
MORNING. THE GFS SHOWS MAINLY 30 KT WITH THE ECMWF WEAKER...AND
THE UKMET ALSO SHOWING MAINLY SOLID 30 KT NEAR THE COAST. WILL
KEEP THE GALE WARNING UP FOR NOW GIVEN THAT PREVIOUS ASCAT PASSES
IN THE MORNING HOURS HAVE SHOWED 30-34 KT WINDS UNDER THE SAME
MODEL GUIDANCE. 

OTHERWISE...HIGH PRESSURE N OF THE AREA WILL MAINTAIN FRESH TO
STRONG TRADE WINDS ACROSS THE CARIBBEAN...EXCEPT MODERATE TO FRESH
IN THE NW CARIBBEAN WHERE THE PRESSURE GRADIENT WILL BE SLIGHTLY
WEAKER. TRADE WINDS WILL DIMINISH SIGNIFICANTLY LATE MON INTO TUE
AS THE PRESSURE GRADIENT N OF THE AREA WEAKENS DUE TO COLD FRONTAL
INTRUSION. WINDS WILL BE LIGHT TO MODERATE BASIN WIDE TUE INTO
WED...WITH SEAS DOWN TO 3-5 FT. THE GFS IS SLOWER WITH THIS
FRONT THAN THE ECMWF...AS NOTED IN THE GULF OF MEXICO SECTION. A
BLEND OF THEIR SOLUTIONS IS PREFERRED AS THE FRONT DROPS S OF THE
YUCATAN CHANNEL TUE NIGHT.

IN THE TROPICAL N ATLC...FRESH TO LOCALLY STRONG TRADE WINDS WILL
PREVAIL THROUGH THE WEEKEND...DIMINISHING OVER THE SOUTHERN WATERS
SUN INTO MON S OF A SHEAR LINE DROPPING INTO THE AREA. SEAS WILL
BE 8-12 FT IN PRIMARILY NE SWELL. BY TUE...WINDS WILL DIMINISH TO
MODERATE TO FRESH ACROSS THE TROPICAL N ATLC WITH 7-9 FT SEAS AS
A TROUGH MOVES FROM SE TO NW ACROSS THE WATERS.

...SW N ATLANTIC W OF 65W INCLUDING THE BAHAMAS...

PREVIOUS/OFFICIAL FORECAST BLENDED WITH LATEST GFS AND ECMWF
INCLUDED FOR COLD FRONT MOVING INTO NW WATERS MON/TUE. NWPS/MWW3
BLEND USED FOR WAVE PARAMETERS. HIGH CONFIDENCE.

THE BERMUDA HIGH IS DRIVING THE EASTERLY FLOW ACROSS THE AREA...
WITH A BELT OF FRESH NE WINDS N OF A WEAKENING SHEAR LINE DRAPPED
ACROSS 27N WITH MODERATE WINDS ELSEWHERE. SEAS ARE 7-10 FT IN E TO
SE SWELL S OF 27N (EXCEPT 1-3 FT INSIDE THE BAHAMAS)...AND 4-7 FT
N OF 27N. TRADE WINDS TO THE S WILL DIMINISH MON AFTERNOON AS THE
NEXT COLD FRONT APPROACHES FROM THE W. A COLD FRONT WILL MOVE
INTO THE NW WATERS LATE MON...REACHING FROM 31N70W TO CENTRAL CUBA
BY LATE TUE. FRESH TO STRONG NORTHERLY WINDS AND BUILDING SEAS
WILL ARRIVE BEHIND THE FRONT INTO WED.

$$

.WARNINGS...ANY CHANGES IMPACTING COASTAL NWS OFFICES WILL BE
COORDINATED THROUGH AWIPS 12 PLANET CHAT OR BY TELEPHONE:

.GULF OF MEXICO...
GMZ011...NONE.
GMZ013...NONE.
GMZ015...NONE.
GMZ017...NONE.
GMZ019...NONE.
GMZ021...NONE.
GMZ023...GALE CONDITIONS POSSIBLE MON INTO MON NIGHT. 
GMZ025...NONE.

.CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN
55W AND 64W...
AMZ011...NONE.
AMZ013...NONE.
AMZ015...NONE.
AMZ017...NONE.
AMZ019...NONE.
AMZ021...NONE.
AMZ023...NONE.
AMZ025...NONE.
AMZ027...NONE.
AMZ029...NONE.
AMZ031...GALE WARNING THROUGH SUN.
AMZ033...NONE.
AMZ035...NONE.
AMZ037...NONE.
AMZ039...NONE.

.SW N ATLANTIC INCLUDING THE BAHAMAS...
AMZ111...NONE.
AMZ113...NONE.
AMZ115...NONE.
AMZ117...NONE.
AMZ119...NONE.
AMZ121...NONE.
AMZ123...NONE.
AMZ125...NONE.
AMZ127...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.HURRICANES.GOV/MARINE

$$
.FORECASTER LEWITSKY. NATIONAL HURRICANE CENTER.