Marine Interpretation Message
Issued by NWS

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000
AGXX40 KNHC 171806
MIMATS

MARINE WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
106 PM EST WED DEC 17 2014

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 GFS BLENDED WITH PREVIOUS OFFICIAL
FORECAST. 12Z TAFB-NWPS USED WAVE HEIGHTS. HIGH CONFIDENCE.

12Z SYNOPTIC ANALYSIS SHOWS A STATIONARY FRONT EXTENDING FROM
TAMPA BAY SW TO 25N90W THEN BECOMING A WARM FRONT TO BROWNSVILLE
TEXAS. THIS FRONT BRIDGES BROAD HIGH PRES ACROSS THE SOUTHERN
GULF WATERS AND A SLIGHTLY STRONGER RIDGE TO THE NORTH OF THE
FRONT ACROSS THE LOWER MISSISSIPPI RIVER VALLEY AND FAR NORTHERN
GULF WATERS. LATEST OBSERVATIONS AND SCATTEROMETER DATA
INDICATES GENTLE ANTICYCLONIC WINDS N OF 26N WITH BROADER
ANTICYCLONIC FLOW IN GENTLE TO MODERATE FLOW S OF THE WEAKENING
BOUNDARY. SEAS REMAIN GENERALLY IN THE 1-3 FT RANGE WITH A
SLIGHT UPTICK IN SEAS OF 2-4 FT ACROSS THE NW AND WEST-CENTRAL
ZONES IN AN AREA OF RE-ESTABLISHING RETURN FLOW.

WITH REGARDS TO RETURN FLOW BEGINNING ACROSS PORTIONS OF THE
WESTERN GULF...MODELS ARE IN GOOD AGREEMENT THROUGH FRI THAT THE
WARM FRONT WILL LIFT N ACROSS SOUTHERN TEXAS AND THE ADJACENT
COASTAL WATERS THU INTO FRI WITH CYCLOGENESIS OCCURRING ALONG
THE TEXAS COAST...AND A NEWLY FORMED LOW MOVING NE INTO SAT
LOCATING ITSELF NEAR MOBILE BAY. THE ASSOCIATED COLD FRONT WILL
DRAPE S-SW FROM THE LOW AND QUICKLY MOVE ACROSS THE GULF
EXTENDING FROM THE WESTERN GULF FRI LATE AND NIGHT...THEN TO THE
FLORIDA PANHANDLE TO EASTERN BAY OF CAMPECHE SAT NIGHT...AND
WEAKEN AS IT REACHES FROM CEDAR KEY TO 24N88W SUN. BETTER
AGREEMENT IS NOTED IN THE LATEST GLOBAL MODEL RUNS WITH TIMING
AND FORECAST POSITIONS. THE MAIN DIFFERENCE WITH THE MODELS
NOTED WITH THIS NEXT SYSTEM IS WIND SPEEDS BEHIND THE FRONT ACROSS
THE WESTERN GULF FRI AFTERNOON THROUGH EARLY ON SAT. MOST MODELS
AGREE WITH NLY WINDS OF 10-15 KT BEHIND THE FRONT WITH THE
EXCEPTION OF THE ECMWF AND UKMET GUIDANCE DEPICTING WINDS OF 20
KT. BLENDED WIND GRIDS RESULT IN A 15-20 KT WINDS BEHIND THE
FRONT FOR THOSE TIME PERIODS AS IT APPEARS THAT SURFACE HIGH PRES
BUILDING IN THE WAKE OF THE FRONT WILL BE A BIT STRONGER THAN THE
CURRENT HIGH PRES IN PLACE. THE COMBINATION OF THIS ALONG WITH THE
LOW PRES TAKING MORE OF A TRACK FARTHER S ALONG THE COASTAL PLAINS
THE RESULTANT PRES WILL BE SUFFICIENT TO SUPPORT THESE WINDS. THE
WINDS WILL DIMINISH QUICKLY DURING SAT AFTERNOON AND EVENING AS
THE LOW RACES NE FAR AWAY FROM THE REGION AND THE HIGH PRES
WEAKENS AS WELL. THE SUPPORT FOR THE FRONT WILL BE UNFAVORABLE AT
THAT TIME TO SUPPORT A SUSTAINABLE FRONTAL BOUNDARY...SO WILL
FORECAST THE FRONT AS STATED EARLIER.

SEAS THERE ARE EXPECTED TO PEAK UP TO 5 FT...ACROSS PORTIONS OF
THE WESTERN GULF NEAR THE TEXAS COAST LATE FRI AND SAT BEFORE
SUBSIDING ONCE AGAIN.

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

MODEL PREFERENCE: 12Z GFS BLENDED WITH PREVIOUS OFFICIAL
FORECAST. 12Z TAFB-NWPS USED FOR WAVE HEIGHTS. HIGH CONFIDENCE.

12Z SYNOPTIC ANALYSIS INDICATES A RIDGE EXTENDING SEWD FROM THE SW
GULF OF MEXICO TO NORTHERN NICARAGUA. THE INDUCED PRES GRADIENT
HAS TIGHTEN SOMEWHAT SINCE YESTERDAY ALLOWING FOR NORTHERLY WINDS
IN THE 20-25 KT RANGE OFF THE COAST OF NICARAGUA. AN EARLIER ASCAT
PASS CONFIRMED THIS WIND FIELD WHICH STRETCHES TO THE NORTH ACROSS
THE NW CARIBBEAN TO THE NW OF A SHEAR LINE FROM JAMAICA TO 15N81W.
THE SAME SWATH OF SCATTEROMETER DATA ALSO SHOWED NE WINDS
FUNNELING THROUGH THE WINDWARD PASSAGE AND THE SOUTHERN ADJACENT
COASTAL WATERS OF HISPANIOLA. THE PRES GRADIENT IS EXPECTED TO
RELAX SOMEWHAT DURING THE NEXT 24 HOURS TO ALLOW FOR THE WINDS
NEAR THE COAST OF CENTRAL AMERICA TO DIMINISH...HOWEVER THE NE 20
KT WINDS FROM 15N-19N BETWEEN JAMAICA AND 82W AND THROUGH THE
WINDWARD PASSAGE SHOULD PERSIST THROUGH THU MORNING.

ELSEWHERE ACROSS THE CARIBBEAN...BUOY AND ASCAT DATA ARE SHOWING
MAINLY GENTLE TO MODERATE NE-E WINDS THROUGHOUT EXCEPT FOR GENTLE
E WINDS ACROSS THE FAR NORTHERN TROPICAL N ATLC WHERE A WEAKENING
COLD FRONT EXTENDS FROM 19N55W SW TO GUADELOUPE AND W AS A
STATIONARY FRONT TO NEAR 17N76W. SEAS ELSEWHERE IN THE CARIBBEAN
ARE IN THE 3-5 FT RANGE...EXCEPT FOR LOWER SEAS OF 2-3 FT IN THE
FAR EASTERN CARIBBEAN. SEAS IN THE TROPICAL N ATLC ARE IN THE 5-6
FT RANGE PER CURRENT BUOY DATA AND RECENT ALTIMETER DATA. THESE
SEAS WILL REMAIN IN THAT SIMILAR RANGE DURING THE PERIOD.

...SW N ATLANTIC S OF 31N W OF 55W INCLUDING THE BAHAMAS...

MODEL PREFERENCE: 12Z GFS BLENDED WITH PREVIOUS OFFICIAL
FORECAST. 12Z TAFB-NWPS USED FOR WAVE HEIGHTS. HIGH CONFIDENCE.

12Z SYNOPTIC ANALYSIS SHOWS A 1021 MB HIGH CENTERED E OF THE
DISCUSSION AREA NEAR 30N59W EXTENDING A RIDGE AXIS W-SW TO 27N65W
TO THE SOUTHERN FLORIDA PENINSULA NEAR 25N80W. TO THE NORTH OF
THIS RIDGE AXIS...A SWIFT MOVING COLD FRONT EXTENDS FROM 31N74W TO
CAPE CANAVERAL. AN EARLIER MORNING ASCAT PASS INDICATED 20 KT
WINDS REMAINING GENERALLY N OF 30N E OF THE FRONT WITH MODERATE
TO FRESH NW WINDS W OF THE FRONT. BUOYS AND A FEW SHIP OBS SHOW
SEAS IN THE RANGE OF 4-5 FT E OF THE BAHAMAS...EXCEPT FOR 5-7 FT
SEAS IN NW SWELLS N OF 29N E OF 79W IN THE VICINITY OF THE FRONT.
LOWER SEAS OF 2-3 FT ARE SEEN ELSEWHERE.

THE AFOREMENTIONED HIGH PRES WILL WEAKEN WITH THE PASSAGE OF
ANOTHER COLD FRONT ALREADY MOVING ACROSS THE FAR NW PORTION.
WINDS ASSOCIATED WITH THE COLD FRONT ARE FORECAST TO QUICKLY
DIMINISH THROUGH FRI AS THE FRONT SWEEPS SEWD ACROSS THE FORECAST
WATERS. HIGH PRES WILL ONCE AGAIN BUILD ACROSS THE BASIN IN THE
WAKE OF THIS NEXT FRONT INTO SAT NIGHT...BUT SHIFT EASTWARD
THROUGH SUN IN RESPONSE TO ANOTHER COLD FRONT THAT MOVES INTO THE
FAR NW CORNER EARLY SUN.

$$

.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 HUFFMAN. NATIONAL HURRICANE CENTER.


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