000
AGXX40 KNHC 050643
MIMATS

MARINE WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
243 AM EDT THU SEP 5 2013

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 INTO PREVIOUS PACKAGE WITH
MEDIUM CONFIDENCE.

A BROAD AREA OF LOW PRESSURE...DEPICTED AS AN INVERTED TROUGH 
ORIENTATED FROM NW TO SE WITH A LOW PRESSURE APPEARING 
INTERMITTENTLY ALONG THE TROUGH AXIS...IS NOW EXPECTED TO 
PERSIST ACROSS THE SW GULF WATERS THROUGH THE PERIOD...WITHOUT 
DISAPPEARING DURING THE NIGHT HOURS AS IT HAS BEEN OVER THE 
PAST FEW DAYS. THE GRADIENT E OF THE LOW WILL SUPPORT E WINDS AT 
15-20 KT ACROSS THE S-CENTRAL WATERS NE OF THE TROUGH AXIS 
TODAY...THEN EXPECT E WINDS AT 10-15 KT ACROSS THE SOUTHERN 
WATERS THROUGH THE REMAINDER OF THE PERIOD. WEAK RIDGING WILL 
CONTINUE ACROSS THE NORTHERN GULF WATERS THROUGH THE PERIOD.   


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

MODEL PREFERENCE: LATEST GFS BLENDED INTO PREVIOUS PACKAGE.
MEDIUM CONFIDENCE. 

TS GABRIELLE JUST S OF PUERTO RICO IS FORECAST TO MOVE NW 
PASSING THROUGH THE MONA PASSAGE TODAY. THE TS FORCE WIND FIELD 
IS WITHIN 60 NM OF THE CENTER...SO EXPECT THE SEAS TO MAX AT 14 
FT AS THE MOSTLY SOUTHERLY WIND WAVES MEET NE SWELL IN THE MONA 
PASSAGE. ALL GABRIELLE CONDITIONS WILL LIFT N OF THE CARIBBEAN 
LATE TONIGHT. A TROPICAL WAVE OVER THE NW CARIBBEAN WILL MOVE W 
OF THE AREA AROUND MIDDAY FRI WITH ONLY THE SLIGHEST ENHANCEMENT 
OF CONVECTION...AND VERY LITTLE WIND/WAVE EFFECTS. A SECOND 
TROPICAL WAVE IS JUST NOW ENTERING THE E CARIBBEAN. EXPECT THE 
NORTHERN EXTENT OF THIS WAVE TO TRANSITION INTO A BROAD TROUGH 
EXTENDING NE FROM THE CIRCULATION ASSOCIATED WITH TROPICAL 
CYCLONE GABRIELLE. THE SOUTHERN SEGMENT OF THE TROPICAL WAVE 
WILL CONTINUE W THROUGH THE E CARIBBEAN TODAY AND FRI...AND 
CONTINUE W THROUGH THE CENTRAL CARIBBEAN ON SAT AND SUN...AND 
THEN THROUGH THE W CARIBBEAN ON MON AND TUE. THIS WAVE WILL BE 
ACCOMPANIED BY ONLY THE SLIGHEST WIND SHIFT AND LIKELY BE 
DIFFICULT TO LOCATE UNTIL THE EFFECTS OF GABRIELLE LIFT N OF THE 
AREA. A THIRD TROPICAL WAVE WILL REMAIN WELL E OF 55W THROUGH 
THE END OF THE PERIOD.


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

MODEL PREFERENCE: LATEST GFS BLENDED INTO PREVIOUS PACKAGE WITH
LOW-MEDIUM CONFIDENCE.

TS GABRIELLE IS FORECAST TO MOVE N THROUGH THE MONA PASSAGE 
TODAY AND CONTINUE NW THROUGH SAT. BY THEN THE NORTHERN SEGMENT 
OF A TROPICAL WAVE CURRENTLY S OF 21N BETWEEN 62-63W IS EXPECTED 
TO TRANSITION INTO A BROAD TROUGH EXTENDING NE FROM THE  
CIRCULATION ASSOCIATED WITH TROPICAL CYCLONE GABRIELLE. THIS NE-
SE TROUGH WILL AMPLIFY OVER THE WEEKEND AND BECOME THE STEERING  
FOR GABRIELLE FOR THE REMAINDER OF THE PERIOD. EVEN IF GABRIELLE 
WERE TO WEAKEN AS IT PASSES HISPANIOLA THE TROUGH WILL BE THE 
SIGNIFICANT MARINE PROBLEM AS THE GRADIENT SE OF THE TROUGH WILL 
SUPPORT SE WINDS AT LEAST 20-25 KT THROUGH THE PERIOD. IT IS 
POSSIBLE THAT SMALL CYCLONES MAY FORM ALONG THIS TROUGH LATE IN 
THE PERIOD. 

FURTHER N...A WEAK COLD FRONT WILL DIP INTO THE N-CENTRAL WATERS 
TODAY SEPARATING THE E-W RIDGE WITH A WEAK HIGH FORMING W OF THE 
FRONT NEAR 30N78W THIS AFTERNOON. THE FRONT WILL WEAKEN TO A 
TROUGH ON FRI...AND SHIFT E EVENTUALLY CONTRIBUTING TO THE 
DEEPENING TROUGH AMPLIFYING NE FROM GABRIELLE.   
 
$$

.WARNINGS...ANY CHANGES IMPACTING COASTAL NWS OFFICES WILL BE
COORDINATED THROUGH AWIPS 12 PLANET CHAT OR BY TELEPHONE:

.GULF OF MEXICO...
GMZ011...NONE.
GMZ013...NONE.
GMZ015...NONE.
GMZ017...NONE.
GMZ019...NONE.
GMZ021...NONE.
GMZ023...NONE.
GMZ025...NONE.

.CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN
55W AND 64W...
AMZ011...NONE.
AMZ013...NONE.
AMZ015...NONE.
AMZ017...NONE.
AMZ019...NONE.
AMZ021...NONE.
AMZ023...TS WARNING.
AMZ025...NONE.
AMZ027...NONE.
AMZ029...NONE.
AMZ031...NONE.
AMZ033...NONE.
AMZ035...NONE.
AMZ037...NONE.
AMZ039...NONE.

.SW N ATLANTIC INCLUDING THE BAHAMAS...
AMZ111...NONE.
AMZ113...NONE.
AMZ115...NONE.
AMZ117...NONE.
AMZ119...NONE.
AMZ121...GALE CONDITIONS EXPECTED FRI NIGHT INTO SAT NIGHT. 
AMZ123...NONE.
AMZ125...TS WARNING. GALE CONDITIONS EXPECTED FRI NIGHT INTO SAT.
AMZ127...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.HURRICANES.GOV/MARINE

$$
.FORECASTER NELSON. NATIONAL HURRICANE CENTER.