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AGXX40 KNHC 261800
MIMATS

MARINE WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT TUE JUL 26 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 TO UPPER LEVEL LOW NEAR 30N91W ALONG WITH AMPLE DEEP MOISTURE PRESENT ACROSS THE AREA IS PROVIDING INSTABILITY LEADING TO THE EXISTENCE OF SCATTERED SHOWERS AND ISOLATED TSTMS OVER MUCH OF THE CENTRAL AND ERN GULF PORTIONS. IN ADDITION...A SURFACE TROUGH EXTENDS FROM NEAR 30N88W NW TO A 1013 MB LOW OVER SE LOUISIANA TO THE NW GULF NEAR 28N96W. WEAK HIGH PRES RIDGING IS PRESENT OVER N FLORIDA.

LATEST BUOY OBSERVATIONS AND RECENT ASCAT DATA INDICATE THAT THE PRES GRADIENT OVER THE AREA IS SUPPORTING GENERALLY GENTLE TO MODERATE WINDS THROUGHOUT WITH WINDS NOTED IN A CYCLONIC FASHION OVER THE N CENTRAL WATERS BETWEEN 86W-92W. 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 S OF 25N BETWEEN 89W- 97W AND FROM 25N-29N BETWEEN 84W-91W.

THE MID TO UPPER LEVEL LOW IS FORECAST TO WEAKEN AS IT CONTINUES WESTWARD TO NW GULF TONIGHT. GLOBAL MODELS ARE IN GOOD AGREEMENT THAT THE ATLC RIDGE WILL EXTEND WESTWARD ACROSS THE REMAINDER OF THE GULF TODAY THROUGH SAT NIGHT. 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 N TO 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 TIGHTEN FURTHER TONIGHT...AND CONTINUE TO DO SO THROUGH THU. THIS WILL ALLOW FOR THESE WINDS TO EXPAND IN COVERAGE N TO JUST S OF HISPANIOLA...AND EWD TO NEAR 69W BY THU WITH RESULTANT SEAS BUILDING TO 10 FT. AS THE GRADIENT RELAXES ON FRI...THE WINDS WILL RESPOND BY DECREASING IN BOTH COVERAGE AND IN SPEEDS. HOWEVER...THE SEAS TO 10 FT WILL BE SLOW IN SUBSIDING IN THE CNTRL CARIBBEAN ON FRI.

A TROPICAL WAVE MOVING RAPIDLY WWD UNDER THE ATLC RIDGE CROSSED THE LESSER ANTILLES ON MON EVENING...AND IS ANALYZED OVER THE ERN CARIBBEAN AS OF 12Z. SCATTERED SHOWERS AND TSTMS ARE OCCURRING ALONG AND NEAR THE NRN PORTION OF THE WAVE OVER PUERTO RICO AND EASTERN HISPANIOLA. THE WAVE WILL MOVE ACROSS THE REMAINDER OF THE ERN CARIBBEAN TONIGHT...THEN ACROSS THE CNTRL CARIBBEAN WED AND WED NIGHT...AND THE WRN CARIBBEAN THU AND THU NIGHT BEFORE MOVING INLAND CENTRAL AMERICA. ANOTHER TROPICAL WAVE WILL REACH THE TROPICAL N ATLC LATE FRI NIGHT...AND THE ERN CARIBBEAN SAT AND SAT NIGHT. MODELS SUGGEST 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.


...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 PORTION SAT AND SAT NIGHT.

A RIDGE AXIS EXTENDING FROM A 1021 MB HIGH NEAR 27N67W WNW TO NE FL IS THE MAIN FEATURE OVER THE BASIN. ISOLATED SHOWERS AND TSTMS ARE NOTED FROM 22N-25N BETWEEN 76W-79W AT THIS TIME.

THE 12Z 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 FROM THE SE BAHAMAS TO THE COAST OF HISPANIOLA WHERE E WINDS ARE IN THE MODERATE TO FRESH RANGE. BOTH BUOY AND ALTIMETER DATA SHOW SEAS IN THE RANGE OF 3- 5 FT E OF THE BAHAMAS...EXCEPT FOR SEAS OF 2-3 FT N OF 25N AND ALSO N OF THE BAHAMAS W OF 77W. SEAS IN THE LOWER RANGE OF 1-2 ARE SW OF THE BAHAMAS...AND 1-2 FT N OF 27N W OF 70W. 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 THU NIGHT...THEN WILL BE REPLACED BY STRONGER CNTRL ATLC RIDGING THAT BUILDS WESTWARD NEAR 29N FRI THROUGH SAT NIGHT. MODELS SUGGEST THAT TIGHTENING OF THE PRES GRADIENT 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. WINDS THERE WILL RESPOND IN A NE TO SE FASHION WILL INCREASING IN SPEEDS WITH RELATED SEAS POSSIBLY BUILDING TO AROUND 7 OR 8 FT. 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 E WINDS TO THE STRONG CATEGORY BETWEEN THE BAHAMAS AND HISPANIOLA. WITH THESE WINDS SEAS ARE EXPECTED TO BUILD TO 7 FT...WITH WAVEWATCH GUIDANCE AND NWPS OUTPUT SHOWING SEAS BUILDING TO 8 FT WED NIGHT AND AGAIN ON SAT NIGHT.

$$


.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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