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AGXX40 KNHC 211751
MIMATS

MARINE WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
151 PM EDT THU AUG 21 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. NWPS/MWW3 BLEND USED FOR WAVE PARAMETERS. HIGH CONFIDENCE.

A RIDGE EXTENDS FROM FL BAY TO THE MS DELTA WITH A HIGH PRES CENTER ALONG THE RIDGE NEAR 28N87W. THIS FEATURE CONTINUES TO MAINTAIN CONTROL OF THE WEATHER PATTERN OVER THE AREA.THE HIGH WILL GRADUALLY SHIFT NW ALONG THE RIDGE TO THE N-CENTRAL GULF TODAY AND TONIGHT...THEN SHIFT FURTHER NW OVER INTERIOR LA ON FRI...WITH A RIDGE EXTENDING SE TO THE SE GULF WATERS. THE HIGH WILL SHIFT SE ALONG THE RIDGE AND BACK OVER THE NE GULF OVER THE WEEKEND AND CONTINUE EARLY NEXT WEEK AS THE RIDGE BECOMES ALIGNED FROM SW LA TO FL BAY.

VARIABLE 5-10 KT WINDS EXPECTED OVER THE NE GULF WATERS TILL FRI WHEN THEY BECOME NE AT 5-10 KT. THE LIGHT AND VARIABLE CONDITIONS WILL DEVELOP AGAIN ON FRI NIGHT AND SAT...THEN BECOME NE ACROSS THE NE PORTION EARLY MON...AND INTO TUE BY THEN THE GRADIENT MAY BE TIGHTENING AS A TROPICAL LOW...POSSIBLY A TROPICAL CYCLONE... CONTINUES NW OVER OR VERY NEAR THE BAHAMAS.

S OF 23N...EXPECT AN EVENING ENHANCEMENT OF 15-20 KT NE WINDS ALONG THE W COAST OF THE YUCATAN PENINSULA EACH EVENING SETTING UP AN INVERTED TROUGH OVER THE EASTERN BAY OF CAMPECHE DURING THE LATE NIGHT HOURS. THE TROUGH WILL SHIFT W ACROSS THE CENTRAL BAY OF CAMPECHE DURING EACH MORNING...AND LOSE IDENTITY DURING THE EARLY AFTERNOON HOURS ACROSS THE CENTRAL BAY OF CAMPECHE.


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

MODEL PREFERENCE: LATEST GFS BLENDED WITH PREVIOUS OFFICIAL
...WEIGHTED MORE TOWARDS THE GFS. NWPS/MWW3/PREVIOUS OFFICIAL BLEND USED FOR WAVE PARAMETERS. AVERAGE CONFIDENCE W PORTION...LOW CONFIDENCE E PORTION.

FRESH TO LOCALLY STRONG EASTERLY TRADES WILL CONTINUE ACROSS THE S-CENTRAL CARIBBEAN THROUGH EARLY FRI. THE TROPICAL LOW PRES NEAR 15N56W 1009 MB HAS CHANGED LITTLE IN ORGANIZATION DURING THE PAST SEVERAL HOURS...PARTIALLY DUE TO AN EASTERLY WAVE MERGING WITH THE CIRCULATION AND SOME DRY AIR INTRUDING INTO THE SYSTEM.NHC GUIDANCE FAVORS THE LOW TRACKING NORTHWESTERLY...WITH GOOD POTENTIAL FOR TROPICAL CYCLONE FORMATION. EVEN IF THE LOW DOES NOT DEVELOP SIGNIFICANTLY...THERE IS STRONG GRADIENT NE OF THE LOW LEVEL CIRCULATION...ROUGHLY FROM 15N-21N BETWEEN 52W-60W...WHERE E 20-25 KT WINDS ARE CURRENTLY SUPPORTED AS NOTED IN THE 1308 ASCAT PASS FROM THIS MORNING. EXPECT THE GRADIENT TO GRADUALLY TIGHTEN TONIGHT INTO FRI SUPPORTING AN INCREASE TO AT LEAST 20-30 KT BY LATE FRI NIGHT. RECON WILL INVESTIGATE THE AREA TODAY AND GET A BETTER HANDLE OF THE AFFECTED AREA. THERE IS SOME POSSIBILITY OF A MINIMUM GALE WARNING BEING POSTED OVER THE N...OR NE...SEMICIRCLE EVEN IF TROPICAL CYCLONE FORMATION DOES NOT OCCUR.

FOR THIS FORECAST WILL MAITAIN CLOSE CONTINUITY WITH PREVIOUS FORECAST REGARDING FORECAST TRACK OF THE TROPICAL LOW. THE LOW WILL REACH TO NEAR 15N61W BY EARLY THIS EVENING...NEAR 16N66W EARLY ON FRI...THEN TO VICINITY NE HISPANIOLA LATE FRI NIGHT...TO NEAR THE WINDWARD PASSAGE AT SUNSET SAT...WITH THE LOW THEN MOVING NW THROUGH THE BAHAMA CHAIN THROUGH MON NIGHT. EXACT TRACK AND INTERACTION WITH THE LARGER ISLANDS WILL OF COURSE PLAY A MAJOR PART IN THE ORGANIZATION OR WEAKENING OF THIS TROPICAL LOW...AND MARINERS SHOULD EXPECT FREQUENT ADJUSTMENTS TO THE NDFD GRIDS...TEXT AND MARINE GRAPHICS OVER THE NEXT WEEK. IN ANY EVENT EXPECT AT LEAST FRESH TO STRONG WINDS WITHIN 540 NM N AND NE OF THESE ESTIMATED POSITIONS.


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

MODEL PREFERENCE: LATEST GFS BLENDED WITH PREVIOUS OFFICIAL WHICH WAS MOSTLY GFS. NWPS USED FOR WAVE PARAMETERS. LOW-MED CONFIDENCE DUE TO TROPICAL LOW.

PLEASE ALSO REFER TO CARIBBEAN AND TROPICAL ATLC SECTION FOR DETAILS ON THE TROPICAL LOW. SIMILARLY TO THE GULF OF MEXICO... A RIDGE NEAR 27N IS THE DOMINATE WEATHER FEATURE PRESENTLY CONTROLING THE WIN D REGIME THROUGHOUT. THE RIDGE IS FORECAST BY THE MODELS TO GRADUALLY SHIFT N TO NEAR 30N ON SUN...AND RETREAT EASTWARD MON AND TUE AS STRONGER RIDGING BUILDS SSW ALONG THE U.S. SE COAST. A TROPICAL LOW...POSSIBLY A TROPICAL CYCLONE...IS EXPECTED TO MOVE NW ACROSS THE CARIBBEAN AND INTO THE ATLC NEAR HISPANIOLA ON SAT...THEN CONTINUE NW ACROSS OR VERY NEAR THE BAHAMA ISLANDS THROUGH MON BEFORE TURNING NE WHILE INCREASING ITS FORWARD SPEED. SW 10-15 KT WINDS WILL CONTINUE N OF THE RIDGE THROUGH THE REST OF THIS AFTERNOON AND TONIGHT BEFORE DIMINISHING TO 5-10 KT ON FRI. EASTERLY TRADES FROM THE RIDGE AXIS S TO ALONG 25N ARE EXPECTED TO CONTINUE INITIALLY AT 5-10 KT. TO THE S OF 25N MODERATE 10-15 KT TRADES ARE EXPECTED W OF 65W...EXCEPT FOR 15-20 KT CONDITIONS ALONG THE N COAST OF HISPANIOLA. EXPECT EASTERLY 20-25 KT WINDS ACROSS THE WATERS S OF 23N E OF 65W THROUGH TONIGHT
...INCREASING TO 20-30 KT LATE FRI. MUCH UNCERTAINTY...BUT EXPECT AT A MINIMUM A LARGE AREA OF ENHANCED 20-25 KT WINDS TO SHIFT W ACROSS THE WATERS S OF 24N E OF THE BAHAMAS TODAY THROUGH FRI...THEN MOVE THROUGH THE SOUTHERN BAHAMAS ON SAT...THE CENTRAL BAHAMAS ON SUN...AND THE NORTHERN BAHAMAS ON SUN WITH POSSIBLE TROPICAL CYCLONE FORMATION THROUGHOUT THE ENTIRE PERIOD. GUIDANCE FROM THE NHC/WPC MEDIUM RANGE COORDINATION WILL BE USED FOR THE FORECAST OF THE LOW...HOWEVER CAN ANTICIPATE MORE CHANGES ARE VERY POSSIBLE TO THE NDFD GRIDS...TEXT AND MARINE GRAPHICS OVER THE NEXT FEW DAYS WITH RESPECT TO THE AFOREMENTIONED TROPICAL LOW.

$$


.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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