Marine Interpretation Message
Issued by NWS

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000
AGXX40 KNHC 180800
MIMATS

MARINE WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
258 AM EST THU DEC 18 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: 00Z GFS BLENDED WITH PREVIOUS OFFICIAL
FORECAST. FOR WAVEHEIGHTS USED BLEND OF 00Z MWW3 WITH PREVIOUS
OFFICIAL AND NWPS WAVE PARAMETERS. HIGH CONFIDENCE...EXCEPT
MEDIUM CONFIDENCE DAYS 4 AND 5 WITH FRONTAL POSITION.

06Z PRELIMINARY SYNOPTIC ANALYSIS SHOWS A WEAKENING STATIONARY
FRONT EXTENDING FROM FORT MYERS SW TO 25N90W...THEN BECOMES A
WARM FRONT NW TO INLAND TEXAS JUST N OF GALVESTON...AND SW TO
WEAK LOW PRES OF 1014 MB OVER S TEXAS. HIGH PRES IS BRIDGING
EASTWARD ACROSS THE FRONT. LATEST OBSERVATIONS AND SCATTEROMETER
PASSES FROM 0300 UTC LAST NIGHT SHOW GENTLE NE-E WIND FLOW N OF
THE FRONT E OF 90W. GENTLE E WINDS ARE S OF THE FRONT E OF
90W...AND MOSTLY SE-S WINDS ARE OVER THE WESTERN GULF S OF THE
WARM FRONT. THE OBSERVATIONS SHOW SEAS IN THE 1-2 FT RANGE WITH
SEAS NOW HAVING BUILT TO 4-5 FT OVER THE WESTERN GULF UNDER THE
MODERATE SE-S FLOW.

MODELS IN AGREEMENT THAT THE WARM FRONT WILL LIFT N ACROSS
SOUTHERN CENTRAL AND NE TEXAS AND THE ADJACENT COASTAL WATERS
THROUGH FRI AS JET STREAM ENERGY AHEAD OF AN UPPER LEVEL TROUGH
PERSIST OVER EASTERN TEXAS. WITH AMPLE SLY MOIST FLOW COMING IN
FROM THE WESTERN GULF AND WITH THE ENERGY ALOFT IN PLACE...THE
LOW PRES WILL BE REINFORCED OR REFORM AS TRACKS NE-E ALONG THE
COASTAL PLAINS FROM NE TEXAS TO NEAR THE MOUTH OF THE
MISSISSIPPI RIVER BY SAT. MODELS CONTINUE TO BE IN GOOD IN
AGREEMENT WITH TRACK OF THE LOW AND WITH THE FORECAST POSITIONS
OF THE ASSOCIATED COLD FRONT. THE COLD FRONT IS FORECAST TO MOVE
ACROSS THE FAR WESTERN PORTION OF THE GULF BEGINNING FRI
EVENING. BY SAT AS THE LOW APPROACHES NEAR THE MOUTH OF THE
MISSISSIPPI RIVER...THE FRONT WILL EXTEND FROM IT SW TO NEAR
TAMPICO...FROM NEAR APALACHICOLA SW TO THE EASTERN BAY OF
CAMPECHE BY EARLY SAT NIGHT...THEN BEGIN TO WEAKEN AS IT REACHES
FROM APALACHEE BAY TO NEAR 26N89W WHERE IT BECOMES A DISSIPATING
STATIONARY FRONT TO THE EASTERN BAY OF CAMPECHE SUN...AND TO A
POSITION SLIGHTLY E FROM THERE ON MON. FORECAST CONFIDENCE WILL
BE MEDIUM LATE SUN INTO MON WITH RESPECT TO THE FRONTAL BOUNDARY
IDENTITY...WHETHER ALL OF IT BECOMES STATIONARY AT THAT POINT OR
JUST THE NE PART REMAINS COLD. BASED ON UPPER LEVEL MODEL FLOW
GUIDANCE...IT APPEARS BY LATE SUN AND INTO MON THE UPPER FLOW
WILL BE MAINLY SWLY. THAT ALONG WITH THE THERMAL GRADIENT BEING
ABOUT THE SAME ON EITHER SIDE OF IT...THE FRONT WILL MOST LIKELY
BE STALLED ALONG THE SAME POSITION AS THE ONE FROM MON.

WITH RESPECT TO WINDS BEHIND THE FRONT...MODELS ARE IN GENERAL
AGREEMENT WITH A BRIEF ONSET OF NLY 15-20 KT BEHIND THE FRONT
OVER THE FAR WESTERN WATERS BORDERING THE COASTAL OFFSHORE
WATERS FRI NIGHT AS THE PRES GRADIENT BETWEEN HIGH PRES BUILDING
EASTWARD BEHIND THE FRONT AND AFOREMENTIONED LOW PRES IS
CONDUCIVE FOR INITIATING SUCH WINDS. THESE WINDS THEN QUICKLY
WEAKEN TO 10-15 KT EARLY SAT AFTERNOON AS THEY BEGIN TO SHIFT TO
THE NE IN DIRECTION...AND WEAKEN SLIGHTLY TO 10 KT LATE SAT
NIGHT INTO SUN. BY LATE SUN NIGHT WINDS OVER THE WESTERN GULF
BECOME SE AT MODERATE SPEEDS AND MORE SLY BY EARLY MON. GFS IS
THE ONLY MODEL THAT DEVIATES FROM SHOWING THESE WINDS DIRECTIONS
LATE SUN NIGHT AND MON AS IT SHOWS N-NE WINDS INSTEAD. SEAS IN
THE WESTERN GULF BEHIND THE FRONT ARE EXPECTED TO BE IN THE 4-6
FT RANGE FRI NIGHT INTO SAT...WITH SOME POCKETS OF 6-7 FT SEAS
OR BRIEF INSTANCE OF SEAS TO 8 FT MAINLY IN THE COASTAL WATERS
OF CENTRAL TEXAS. SEAS SUBSIDE QUICKLY TO 3-5 FT SAT NIGHT AND
TO 2-3 FT SUN.

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

MODEL PREFERENCE: 00Z GFS BLENDED WITH PREVIOUS OFFICIAL
FORECAST. FOR WAVEHEIGHTS USED BLEND OF 00Z MWW3 WITH PREVIOUS
OFFICIAL AND NWPS WAVE PARAMETERS. HIGH CONFIDENCE.

THE 06Z SYNOPTIC ANALYSIS INDICATES A RIDGE...SLIGHTLY WEAKER
THAN PREVIOUS DAYS...EXTENDING SEWD FROM THE SW GULF OF MEXICO
TO NORTHERN NICARAGUA. AN ASCAT PASS FROM 0258 UTC LAST NIGHT
AGAIN REVEALED A SWATH OF NE 20-25 KT SW OF CUBA TO 18N BETWEEN
78W-81W. THE EDGE OF THE SAME SWATH SUGGESTED SIMILAR WINDS TO
EXIST ALONG AND WITHIN 120 NM OF THE COAST OF COLOMBIA. MODEL
GUIDANCE ALONG WITH SURFACE ANALYSIS EXTRAPOLATION INDICATES
THAT THESE WINDS WILL CONTINUE THROUGH THE 24 HOURS SW OF CUBA
AND THROUGH THE FORECAST PERIOD NEAR THE COAST OF COLOMBIA...BUT
IN A PULSING FASHION DURING THE NIGHT TIME AND EARLY MORNING
HOURS WITH SEAS THERE BUILDING TO 8 FT.

ELSEWHERE ACROSS THE CARIBBEAN...BUOY AND ASCAT DATA ARE SHOWING
MAINLY GENTLE TO MODERATE NE-E WINDS THROUGHOUT EXCEPT FOR
GENTLE E-SE WINDS ACROSS THE FAR NORTHERN TROPICAL N ATLC WHERE
A WEAKENING COLD FRONT EXTENDS FROM 19N55W SW TO GUADELOUPE AND
W AS A DISSIPATING COLD FRON15N74W. 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 AND 5-7 FT SEAS IN THE SW
CARIBBEAN NEAR THE COAST OF COLOMBIA. RECENT ALTIMETER DATA
VERIFIED WELL WITH THE MWW3 GUIDANCE VALUES. SEAS IN THE TROPICAL
N ATLC ARE IN THE 5-6 FT RANGE IN A NE TO E SWELL COMPONENT 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: 00Z GFS BLENDED WITH PREVIOUS OFFICIAL
FORECAST. FOR WAVEHEIGHTS USED BLEND OF 00Z MWW3 WITH PREVIOUS
OFFICIAL AND NWPS WAVE PARAMETERS. HIGH CONFIDENCE.

06Z PRELIMINARY SYNOPTIC ANALYSIS SHOWS A 1020 MB HIGH CENTERED
E OF THE DISCUSSION AREA NEAR 30N54W EXTENDING A RIDGE AXIS W-SW
TO 27N65W TO THE SOUTHERN FLORIDA PENINSULA NEAR 25N80W. TO THE
NORTH OF THIS RIDGE AXIS...A RATHER FAST MOVING COLD FRONT NOW
EXTENDS FROM 31N68W TO WEST PALM BEACH. AN ASCAT PASS FROM 0120
UTC LAST NIGHT INDICATED GENERALLY W-NW 15-20 KT N OF 30N W OF
THE FRONT TO ABOUT 71W...WITH GENTLE NW WINDS ELSEWHERE N 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 30N
BETWEEN THE FRONT AND 71W. LOWER SEAS OF 1-2 FT ARE PRESENT SW
OF THE BAHAMAS.

THE COLD FRONT WILL WEAKEN AS IT REACHES FROM NEAR 28N65W TO
26N72W...AND DISSIPATING STATIONARY TO THE NW BAHAMAS
TONIGHT...THEN CONTINUE TO WEAKEN AS MOVES ACROSS THE SE PORTION
FRI THROUGH SAT. HIGH PRES WILL ONCE AGAIN BUILD ACROSS THE
BASIN IN THE WAKE OF THE THROUGH SAT NIGHT...BUT SHIFT EASTWARD
THROUGH SUN IN RESPONSE TO ANOTHER COLD FRONT THAT APPROACHES
THE FAR NW CORNER OF THE AREA EARLY ON SUN ASSOCIATED WITH LOW
PRES MOVING NEWD OFF THE SE U.S. COAST. RIGHT NOW GUIDANCE
SUGGESTS THAT THE UPPER FLOW WILL NOT BE ADEQUATE ENOUGH TO
ALLOW THIS NEXT COLD FRONT TO ADVANCE MUCH TOWARDS THE FORECAST
WATERS AS IT MOST LIKELY WILL BECOME STATIOANRY JUST NW OF THE
BASIN.

$$

.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 AGUIRRE. NATIONAL HURRICANE CENTER.


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