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AGXX40 KNHC 271746
MIMATS

MARINE WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
146 PM EDT WED JUL 27 2016

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: FOR WINDS USED BLEND OF 12Z GFS WITH PREVIOUS OFFICIAL. FOR WAVEHEIGHTS USED BLEND OF 12Z MWW3 AND TAFB NWPS OUTPUT WITH PREVIOUS OFFICIAL FORECAST. HIGH CONFIDENCE.

A MID-UPPER LEVEL LOW OVER S LOUISIANA CONTINUES TO BRING UNSETTLED WEATHER IN THE WAY OF SCATTERED SHOWERS AND ISOLATED TSTMS TO MUCH OF THE NW AND N CNTRL GULF PORTIONS. AT THE SURFACE...A WEAK HIGH PRES RIDGE EXTENDS FROM THE WRN ATLC WESTWARD ACROSS THE GULF ALONG 27N E OF 90W...AND SLIGHTLY NW FROM THERE TO CNTRL TEXAS.

LATEST BUOY OBSERVATIONS AND RECENT ASCAT DATA INDICATE THAT THE PRES GRADIENT OVER THE AREA SUPPORTS GENERALLY GENTLE TO MODERATE WINDS THROUGHOUT. THE BUOY OBSERVATIONS ALONG WITH RECENT ALTIMETER PASSES SHOW RELATIVELY LOW SEAS OF 1-2 FT RANGE...EXCEPT FOR HIGHER SEAS IN THE 3-5 FT RANGE FROM 23N-25N E OF 89W.

THE MID-UPPER LEVEL LOW IS FORECAST TO WEAKEN TONIGHT AS IT MOVES WESTWARD. GLOBAL MODELS REMAIN IN VERY GOOD AGREEMENT THAT THE ATLC RIDGE WILL CHANGE VERY LITTLE THROUGH THE FORECAST PERIOD. OTHERWISE...THE TYPICAL CLIMO THERMAL TROUGH IN THE YUCATAN PENINSULA WILL PUSH OFFSHORE INTO THE SW GULF EACH NIGHT THROUGH THE PERIOD ATTENDANT BY A BRIEF PERIOD OF FRESH NE WINDS AND A SLIGHT INCREASE OF SEAS.


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

MODEL PREFERENCE: FOR WINDS USED BLEND OF 12Z GFS WITH PREVIOUS OFFICIAL. FOR WAVEHEIGHTS USED BLEND OF 12Z MWW3 AND TAFB NWPS OUTPUT WITH PREVIOUS OFFICIAL FORECAST. HIGH CONFIDENCE.

THE PRES GRADIENT BETWEEN HIGH PRES ACROSS THE CNTRL ATLC AND LOWER PRES IN THE NRN PORTIONS OF S AMERICA...AND ALSO IN THE SW CARIBBEAN WHERE THE ERN PORTION OF THE E PACIFIC MONSOON TROUGH IS LOCATED IS MAINTAINING FRESH TO STRONG ELY WINDS ACROSS THE S CNTRL CARIBBEAN. THE GRADIENT PRODUCING THESE WINDS WILL CONTINUE TO TIGHTEN THROUGH THU. THIS WILL ALLOW FOR THESE WINDS TO EXPAND IN COVERAGE N TO JUST S OF HISPANIOLA ON THU...AND EWD TO NEAR 69W BY THU WITH RESULTANT SEAS BUILDING TO 11 FT. AS THE GRADIENT RELAXES ON FRI...THE WINDS WILL RESPOND BY DECREASING IN BOTH COVERAGE AND IN SPEEDS. HOWEVER...MAX SEAS OF 11 FT WILL BE SLOW IN SUBSIDING IN THE CNTRL CARIBBEAN FRI AND SAT.

A TROPICAL WAVE IS OVER THE CNTRL CARIBBEAN WITH AXIS ROUGHLY ALONG 73W AND EXTENDS N TO 22N. SCATTERED SHOWERS AND ISOLATED TSTMS ARE NOTED WITHIN 120 NM W OF THE WAVE FROM 15N-18N. THE WAVE WILL MOVE ACROSS THE REMAINDER OF THE CNTRL CARIBBEAN THROUGH TONIGHT...AND THE WRN CARIBBEAN THU AND THU NIGHT. ANOTHER TROPICAL WAVE WILL REACH THE FAR ERN PORTION OF THE TROPICAL N ATLC EARLY THU EVENING...AND MOVE THROUGH REMAINDER OF THE TROPICAL N ATLC THROUGH FRI. THE WAVE IS FORECAST TO CROSS THE LESSER ANTILLES EARLY FRI EVENING...THEN MOVE ACROSS THE ERN CARIBBEAN THROUGH SAT EVENING...AND ERN SECTION OF THE CNTRL CARIBBEAN SUN AND SUN NIGHT. MODELS ARE CONSISTENTLY SUGGESTING THAT THIS WAVE WILL BE ACCOMPANIED BY A WELL PRONOUNCED NE TO SE WIND SHIFT ALONG A WITH A POCKET OF TIGHT PRES GRADIENT AND BUILDING SEAS ALONG ITS NRN SEGMENT. SCATTERED SHOWERS AND TSTMS WITH GUSTY WINDS MAY BE ASSOCIATED WITH THIS WAVE. A TROUGH WILL MOVE THROUGH THE TROPICAL N ATLC SAT AND SAT NIGHT AND ERN CARIBBEAN ON SUN.


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

MODEL PREFERENCE: FOR WINDS USED BLEND OF 12Z GFS WITH PREVIOUS OFFICIAL. FOR WAVEHEIGHTS USED BLEND OF 12Z MWW3 AND TAFB NWPS OUTPUT WITH PREVIOUS OFFICIAL FORECAST. HIGH CONFIDENCE...EXCEPT AVERAGE CONFIDENCE SE AND S CNTRL PORTIONS SAT THROUGH SUN NIGHT.

THE 12Z ANALYSIS HAS A RIDGE AXIS EXTENDING FROM A 1020 MB HIGH NEAR 27N70W W TO ACROSS FLORIDA...AND CONTINUING WESTWARD TO THE GULF OF MEXICO. THE NRN PORTION OF CARIBBEAN TROPICAL WAVE IS ALONG 73W S OF 22N. SCATTERED SHOWERS AND TSTMS ARE NOTED BETWEEN THE CENTRAL BAHAMAS AND W CUBA TODAY. THE ANALYSIS REVEALS A RATHER WEAK PRES GRADIENT THROUGHOUT WITH LIGHT TO GENTLE E-SE WINDS ACROSS MUCH OF THE BASIN...EXCEPT FOR THE NE PORTION WHERE WINDS ARE LIGHT AND VARIABLE MAINLY W-NW IN DIRECTION...AND ALONG AND NEAR THE TROPICAL WAVE BETWEEN THE SE BAHAMAS AND HISPANIOLA WHERE E WINDS ARE IN THE MODERATE TO FRESH RANGE. BOTH BUOY AND ALTIMETER DATA SHOW SEAS IN THE RANGE OF 4-5 FT E OF THE BAHAMAS. LOWER SEAS OF 2-3 FT ARE N OF 27N...AND SLIGHTLY LOWER IN THE 1-2 FT RANGE SW OF THE BAHAMAS EXCEPT IN THE STRAITS OF FLORIDA WHERE HIGHER SEAS OF 3-5 FT WERE ANALYZED. A SMALL POCKET OF SEAS IN THE 5-6 FT RANGE ARE NOTED BETWEEN THE SE BAHAMAS AND HISPANIOLA.

THE RIDGE IS FORECAST TO CHANGE LITTLE THROUGH FRI...THEN WILL BE REPLACED BY STRONGER CNTRL ATLC RIDGING THAT BUILDS WESTWARD NEAR 28N FRI THROUGH SAT BEFORE LIFTING SLIGHTLY N SUN THROUGH MON. THE NRN PORTION OF THE TROPICAL WAVE ALONG 73W WILL MOVE THROUGH THE REMAINDER OF THE FAR SRN WATERS THROUGH THU.

MODELS SUGGEST THAT TIGHTENING OF THE PRES GRADIENT WITH FRESH TO STRONG WINDS SHIFTING FROM NE TO SE IS LIKELY TO OCCUR IN THE SE PORTION OF THE BASIN BEGINNING LATE ON SAT AS THE NRN PORTION OF A TROPICAL WAVE MOVES THROUGH THAT AREA. THESE WINDS THEN TRANSLATE WESTWARD TO THE WATERS BETWEEN THE BAHAMAS AND HISPANIOLA SUN AND MON. SEAS RESULTING FROM THESE WINDS ARE PRESENTLY EXPECTED TO BUILD TO AROUND 8 FT...BUT COULD POSSIBLY BE HIGHER. OTHERWISE...THE FLOW PATTERN S OF THE RIDGE WILL BECOME E-SE WITH WINDS IN THE GENTLE TO MODERATE RANGE...EXCEPT FOR THE STRONGER PULSING STRONG E WINDS BETWEEN THE BAHAMAS AND HISPANIOLA PRIOR TO THE ARRIVAL OF THE WINDS ASSOCIATED WITH THE NRN PORTION OF THE AFOREMENTIONED TROPICAL WAVE.

$$


.WARNINGS...ANY CHANGES IMPACTING COASTAL NWS OFFICES WILL BE COORDINATED THROUGH AWIPS II COLLABORATION 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 FORMOSA. NATIONAL HURRICANE CENTER.

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