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AGXX40 KNHC 311739
MIMATS

MARINE WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
139 PM EDT THU JUL 31 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: GFS/ECMWF BLENDED WITH OFFICIAL FOR WIND. MWW3/NWPS BLENDED WITH OFFICIAL FOR WAVES. HIGH CONFIDENCE.

NO SIGNIFICANT CHANGES FROM THE PREVIOUS THINKING. THE PREVIOUS DISCUSSION CAN BE FOUND BELOW.

WEAK FRONTAL BOUNDARY HAS SHIFTED SLOWLY S ACROSS E PORTIONS OF GULF PAST 6-8 HOURS...NOW EXTENDING FROM JUST N OF NAPLES...SW TO NEAR 24.5N86W THEN NW TO UPPER TEXAS COASTAL WATERS...WITH BROAD AND WEAK CYCLONIC FLOW ABOUT THE BOUNDARY E OF 90W...AND YIELDING W-SW WINDS ACROSS THE W STRAITS AND INTO THE KEYS ATTM. BOUNDARY TO DRIFT SSE TODAY ACROSS SE PORTIONS...THEN BEGIN TO DRIFT BACK TOWARDS THE NW FRI AND SAT AND GRADUALLY DISSIPATE. NW ATLC RIDGE TO SHIFT NW AND BUILD MODESTLY ACROSS NW PORTIONS OF SW N ATLC AND TO E COAST OF FLORIDA THU NIGHT AND FRI...AIDING FRONTAL MOVEMENT...WITH WEAK HIGH PREVAILING BETWEEN MOUTH OF MS AND BIG BEND REGION...YIELDING LIGHT TO MODERATE ANTICYCLONIC FLOW ACROSS THE BASIN. MODERATE S TO SE WINDS ACROSS UPPER MEXICAN AND TEXAS COASTAL WATERS LIKELY TO BECOME ENHANCED BY DIURNAL HEATING EACH AFTERNOON AND REACH 15-20 KT FOR A FEW HOURS...INCREASING SEAS LOCALLY TO 4 FT...AND VERY ISOLATED SPOTS TO 5 FT. LIKEWISE... LATE AFTERNOON/EVENING THERMAL TROUGH ALSO EXPECTED TO YIELD NEAR 20 KT WINDS OFF NW AND W COASTS OF YUCATAN EACH DAY...YIELDING SEAS PEAKING BRIEFLY AT 3-5 FT EACH DAY. OTHERWISE...TRANQUIL CONDITIONS EXPECTED THROUGH THE WEEKEND.


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

MODEL PREFERENCE: ECMWF BLENDED WITH OFFICIAL FOR WIND. NWPS BLENDED WITH OFFICIAL FOR WAVES. MEDIUM CONFIDENCE.

THE 12Z GFS CONTINUES TO BE A HAIR FASTER THAN THE MEDR FORECAST AGREED ON DURING THE WPC/NHC CONCALL...WITH THAT TRACK CLOSER TO THE 00Z ECMWF THROUGH THE CARIB. THE ECMWF WAS USED TO ADJUST THE BACKGROUND WINDS. HOWEVER...BOTH MODELS CARRY THE SYSTEM AS AN OPEN WAVE THROUGH THE NE CARIB. MAJOR ADJUSTMENTS TO THE GRIDDED FORECAST WERE NECESSARY TO ACCOMMODATE THE AGREED POINTS. ELSEWHERE...THE GFS IS SIGNIFICANTLY STRONGER WITH THE WINDS ALONG THE COAST OF COLOMBIA MON NIGHT/TUE MORNING THAN THE ECMWF. WITH THE THE ECMWF GENERALLY PREFERRED OVER THE GFS WITH THE POSSIBLE TROPICAL CYCLONE...WILL TONE DOWN WINDS ALONG THE COAST HERE TO 25 KT LIKE THE ECMWF. FEAR THE GFS MAY BUILD TOO MUCH RIDGING AS IT WEAKENS THE POSSIBLE TC MORE RAPIDLY THAN THE ECMWF.


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

MODEL PREFERENCE: ECMWF BLENDED WITH OFFICIAL FOR WIND. MWW3/NWPS BLENDED WITH OFFICIAL FOR WAVES. HIGH CONFIDENCE THROUGH FRI NIGHT THEN MEDIUM-LOW CONFIDENCE.

WHILE THERE IS PLENTY OF ACTIVE TSTMS OVER THE NW WATERS ASSOCIATED WITH A LINGERING FRONTAL BOUNDARY AS WELL AS OVER SE WATERS ASSOCIATED WITH A TUTT LOW...THERE ARE NO WINDS/SEAS NEAR ADVISORY CRITERIA OVER THE FORECAST AREA. THE FRONTAL BOUNDARY AND TSTMS WILL RETROGRADE NW TO THE COAST OVER THE NEXT 24 HOURS. THE TUTT WILL GRADUALLY BREAKDOWN THROUGH SAT. THEN...THE LOW PRES SYSTEM CURRENTLY IN THE TROPICAL ATLC BEGINS TO INFLUENCE THE FORECAST AS IT EMERGES INTO SE WATERS...POSSIBLY AS A TROPICAL CYCLONE. THE 12Z GFS WASHES OUT THIS SYSTEM ONCE IT PASSES THE TURKS AND CAICOS. THE ECMWF IS CLOSER TO THE TRACK AGREED ON DURING THE MEDR CONCALL WITH WPC AND HOLDS ONTO A DISTINCT SYSTEM LONGER THAN THE GFS. THE ECMWF BECOMES FASTER THAN THE AGREED POINTS AFTER MON...AND THE SYSTEM MAY WELL BE AN OPEN WAVE AT THAT TIME. THE GRIDS WILL REFLECT WEAKENING. THE ECMWF WAS USED FOR THE BACKGROUND WINDS...BUT MAJOR ADJUSTMENTS TO WINDS/SEAS WERE REQUIRED WITH THE POTENTIAL TC FROM THE WEEKEND ONWARD. THE NWPS WAS RELIED ON FOR THE SEAS AROUND THE TC WITH THE MWW3 USED MORE FOR THE SURROUNDING WAVE FIELD AS IT WAS BETTER INITIALIZED.

$$


.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 SCHAUER. NATIONAL HURRICANE CENTER.

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