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AGXX40 KNHC 230755
MIMATS

MARINE WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
355 AM EDT TUE SEP 23 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: LATEST GFS BLENDED WITH PREVIOUS/OFFICIAL FORECAST. LATEST MWW3 USED FOR WAVE PARAMETERS. HIGH CONFIDENCE.

LATEST SURFACE ANALYSIS HAS A STATIONARY FRONT EXTENDING FROM NE FLORIDA SW TO 28N85W TO 26N91W. A COLD FRONT EXTENDS FROM THE FLORIDA BIG BEND TO 28N91W. WHILE WEAK HIGH PRES IS PRESENT ELSEWHERE...EXCEPT FOR THE FAR N CENTRAL GULF. LATEST SATELLITE- DERIVED WINDS AND BUOY DATA SHOW MODERATE TO FRESH NE TO E WINDS N OF THE COLD FRONT WHERE STRONGER HIGH PRESSURE IS BUILDING S...AND GENTLE E WINDS S OF 26N. THE OBSERVATIONS SHOW SEAS IN THE RANGES OF 1-2 FT OVER MOST ZONES...WITH THE EXCEPTION OF NW OF A LINE FROM 27N86W TO 25N92W TO 24N98W WHERE SEAS ARE HIGHER
...IN THE 4-5 FT RANGE EXCEPT ALONG THE IMMEDIATE COAST OF TEXAS WHERE SEAS ARE IN THE 2-4 FT RANGE.

NWPS WAVE PARAMETERS ARE RUNNING 1-2 FT UNDER CURRENT AND LATEST REPORTED VALUES FOR THE WESTERN GULF. OBSERVED VALUES ARE CLOSER TO THE MWW3 GUIDANCE.

SATELLITE WATER VAPOR SHOWS AMPLE DEEP LAYER MOISTURE CONFINED TO OVER THE EASTERN PORTION OF THE GULF TO THE SE OF AN UPPER TROUGH THAT STRETCHES FROM THE EASTERN U.S. SW TO THE WESTERN FLORIDA TO 25N89W AND TO THE NW YUCATAN PENINSULA. THE UPPER TROUGH IS ENHANCING INSTABILITY ALONG AND TO THE S OF THE STATIONARY FRONT WHERE SCATTERED TO NUMEROUS SHOWERS AND TSTMS ARE OBSERVED. ISOLATED SHOWERS AND TSTMS ARE OVER THE REMAINDER OF THE GULF.

JUST AS AUTUMN HAS SET IN THE SYNOPTIC PATTERN ACROSS MOST OF THE AREA IS APPEARING AS SUCH WITH THE AFOREMENTIONED COLD FRONT AND STRONG AREA OF HIGH PRES BEHIND IT SETTLING IN OVER THE NORTHERN WATERS. A DRY AIR MASS BEHIND THE HIGH PRES AREA WILL SURGE SOME TO THE E AND SE OVER THE NE GULF AS THE COLD FRONT MERGES WITH THE WEAKENING STATIONARY FRONT THIS AFTERNOON ROUGHLY ALONG A PSN FROM NEAR CEDAR KEY FLORIDA TO 27N90W TO 27N94W. THE STRONG HIGH PRESSURE ARE WILL CONTINUE TO BUILD S...AND BRIDGE ACROSS THE MERGED FRONT FROM NEAR TAMPA BAY TO NEAR 25N94W WED AND WED EVENING. A TIGHT PRES GRADIENT N OF THE COLD FRONT IS ALREADY BRINGING MODERATE TO FRESH NE TO E WINDS OVER THE NORTHERN WATERS N OF 27N AS NOTED IN CURRENT BUOY REPORTS...AND CONFIRMED BY A PARTIAL ASCAT PASS FROM 0240 UTC LAST NIGHT. SEAS THERE ARE IN THE 4-6 FT RANGE. THE CULPRIT GRADIENT SHOULD HOLD THROUGH PART OF FRI BEFORE IT SLACKENS ALLOWING FOR THE WINDS TO DIMINISH. SEAS OVER THE NORTHERN GULF ARE FORECAST TO POSSIBLY BUILD TO AROUND 7 OR 8 FT OVER THE FAR NORTHERN BOUNDARY OF THE OFFSHORE WATERS...BUT MAINLY IN THE ALABAMA COASTAL WATERS...AND SE LOUISIANA COASTAL WATERS. SEAS ARE FORECAST TO SUBSIDE FRI THROUGH SAT.

AN INVERTED TROUGH THAT SETS-UP OFF THE FLORIDA COAST LATE TODAY OR THIS EVENING WILL MOVE WESTWARD ACROSS FLORIDA AND INTO THE EASTERN GULF LATE THU INTO FRI WHILE DISSIPATING. LOW-LEVEL MOISTURE RELATED TO THIS TROUGH IN COMBINATION WITH THAT FROM THE TROUGH ALOFT SHOULD HELP TRIGGER ADDITIONAL SHOWER AND TSTM ACTIVITY OVER THE EASTERN PORTION. SOME MOISTURE FROM THE EASTERN CARIBBEAN TROPICAL WAVE COULD GET CAUGHT UP IN SW FLOW AHEAD OF THE UPPER TROUGH AND MOVE INTO THE SE GULF TONIGHT AND WED...AND ACROSS THE SW GULF WED NIGHT AND THU ADDING TO THE ALREADY ONGOING SHOWER AND TSTM ACTIVITY THERE.


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

MODEL PREFERENCE: LATEST GFS BLENDED WITH PREVIOUS/OFFICIAL FORECAST. FOR WAVE HEIGHTS USED NWPS WAVE PARAMETERS. HIGH CONFIDENCE.

RELATIVELY QUIET CONDITIONS CONTINUE OVER THE CARIBBEAN AND TROPICAL N ATLC WATERS PER LATEST SHIP AND BUOY DATA ALONG WITH PARTIAL ASCAT DATA FROM LAST NIGHT. BASED ON LATEST MODEL DATA THESE CONDITIONS ARE EXPECTED TO CHANGE VERY LITTLE THROUGH THE PERIOD WITH ELY WINDS REMAINING IN THE GENTLE TO MODERATE CATEGORY...AND SEAS AT RATHER LOW LEVELS THROUGH THE PERIOD.

THE SUBTROPICAL RIDGE N OF THE AREA IS WEAK MAINTAINING A LIGHT PRES GRADIENT ACROSS THE CARIBBEAN. THE 06 UTC SURFACE ANALYSIS REVEALS A TROPICAL WAVE OVER THE EASTERN CARIBBEAN NEAR 67W... MOVING W ABOUT 10-15 KT. ANOTHER WAVE IS OVER THE WESTERN CARIBBEAN NEAR 84W...MOVING W AT 10 KT. DEEP LAYER MOISTURE PRODUCING SCATTERED SHOWERS AND TSTMS IS PRESENT ACROSS THE AREA WITH WAVES HELPING TO FURTHER ENHANCE THE ACTIVITY. THE TROPICAL WAVE ALONG 67W WILL MOVE ACROSS THE REST OF THE EASTERN CARIBBEAN TONIGHT...THEN ACROSS THE CENTRAL CARIBBEAN WED THROUGH THU....AND ACROSS THE WESTERN CARIBBEAN FRI THROUGH SAT. THE WAVE OVER THE WESTERN CARIBBEAN WILL MOVE INLAND TONIGHT. ANOTHER TROPICAL E OF THE FORECAST WATERS NEAR 45W IS EXPECTED TO ENTER THE EASTERN TROPICAL N ATLC LATE EARLY ON WED...AND MOVE ACROSS THE REST OF THOSE WATERS DURING WED AND WED NIGHT...THE EASTERN CARIBBEAN THU INTO FRI...AND THE CENTRAL CARIBBEAN FRI NIGHT AND SAT. THESE TROPICAL WAVES ARE EXPECTED TO HAVE LITTLE IMPACTS ON WINDS AND SEAS. GUSTY WINDS ARE POSSIBLE WITH ASSOCIATED SHOWER AND TSTM ACTIVITY.


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

MODEL PREFERENCE: LATEST GFS BLENDED WITH PREVIOUS/OFFICIAL. MWW3/NWPS BLEND USED FOR WAVE PARAMETERS. MEDIUM-HIGH CONFIDENCE.

THE 06 UTC SURFACE ANALYSIS HAS A COLD FRONT JUST NW OF THE BASIN...WHILE A WEAKENING STATIONARY FRONT EXTENDS FROM NEAR 31N79W WSW TO INLAND NE FLORIDA. A RELATIVELY WEAK RIDGE EXTENDS FROM NEAR 30N67W SW TO S FLORIDA. PARTIAL ASCAT DATA PASS FROM 0240 UTC LAST NIGHT SHOWED GENTLE E-SE WINDS N OF 24N W OF 71W
...AND GENTLE TO MODERATE E WINDS S OF 24N W OF 71W. THE BUOYS ARE REPORTING MOSTLY MODERATE E-SE WINDS ELSEWHERE. THE BUOY AND SHIP OBSERVATIONS ALONG WITH A ALTIMETER PASSES SHOW SEAS IN THE 4-5 FT RANGE E OF THE BAHAMAS AND 1-2 FT SEAS W OF THE BAHAMAS...AND ALSO N OF 27N W OF 79W. HIGHER SEAS OF 5-6 FT ARE N OF 29N BETWEEN 76W-79W.

THE COLD FRONT JUST NW OF THE BASIN WILL MOVE INTO THE FAR NW CORNER OF THE AREA THIS MORNING. WITH THE UPPER TROUGH MOVING VERY LITTLE OVER THE EASTERN GULF...THE FRONT WILL HAVE VERY LITTLE IN THE WAY OF UPPER SUPPORT FOR FORWARD MOTION...AND SO IT IS EXPECTED TO STALL FROM NEAR 31N80W TO NE FLORIDA BY LATE THIS MORNING. GUIDANCE IN GOOD AGREEMENT IN DEPICTING STRONG HIGH PRES FROM THE EASTERN U.S. THAT BUILDS SWD JUST TO THE NW OF THE AREA THROUGH THU NIGHT. THIS WILL PROVIDE A WEDGE TYPE PATTERN OF HIGH PRES RIDGING OVER NE FLORIDA WITH AN INVERTED TROUGH SETTING UP ALONG THE N AND CENTRAL FLORIDA COAST. THE PRES GRADIENT BETWEEN THE RIDGE AND TROUGH WILL ALLOW FOR ELY WINDS TO INCREASE OVER THE FAR NW WATERS BEGINNING THIS AFTERNOON. THE INVERTED TROUGH WILL MOVE W OF THE AREA...AND INTO THE EASTERN GULF THU NIGHT INTO FRI ALLOWING FOR THE GRADIENT OVER THE FAR NW WATERS TO SLACKEN.

$$


.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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