000
AGXX40 KNHC 020713
MIMATS

MARINE WEATHER DISCUSSION       
NWS NATIONAL HURRICANE CENTER MIAMI FL
315 AM EDT SEP 02 2011

UPDATED TROPICAL N ATLC AND WARNINGS SECTION FOR FORECAST AND
WARNING CONDITIONS REGARDING TROPICAL STORM KATIA

MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA 
AND TROPICAL N ATLC...AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W.

GULF OF MEXICO...
T.D. THIRTEEN IS FORECAST TO SLOWLY MIGRATE NORTHWARD INTO S 
CENTRAL LOUISIANA THROUGH SUN NIGHT. THE 00Z GFS IS THE CLOSEST 
OF THE GLOBAL MODELS TO THE OFFICIAL FORECAST TRACK UNTIL SUN 
AFTERNOON WHEN THE GFS TURNS THE SYSTEM BACK TO THE SW ONLY TO 
LOOP THE SYSTEM BACK TO THE NE MON AS IT BEGINS TO BE PICKED UP 
BY THE DEEP LAYER TROUGH. ON MON...ALL OF THE MODELS ARE 50-100 
NM SE OF THE OFFICIAL FORECAST...WITH THE GFS BACK TO BEING 
CLOSEST TO THE OFFICIAL FORECAST. THE GFS WILL BE ADJUSTED 
TOWARD THE OFFICIAL FORECAST FOR THIS PACKAGE.
  
CARIBBEAN SEA AND TROPICAL N ATLC S OF 22N W OF 55W...
THE 00Z GFS IS SLOWER THAN THE OTHER MODELS AND THE OFFICIAL 
FORECAST CARRYING KATIA INTO THE TROPICAL N ATLC ZONE TODAY. 
HOWEVER...IT IS CLOSER TO THE INTENSITY AND THE LATITUDE OF THE 
OFFICIAL FORECAST THAN THE OTHER MODELS...WITH THE ECMWF A CLOSE 
SECOND TRACK-WISE BY SUN EVENING. ADJUSTMENTS WILL BE MADE TO 
THE GFS TOWARD THE OFFICIAL KATIA FORECAST HERE. IT WILL ALSO BE 
THE MODEL OF CHOICE OVER THE CARIBBEAN WHERE WINDS AND SEAS WILL 
REMAIN RELATIVELY SUBDUED.

SW ATLC S OF 31N W OF 55W...
THE 00Z GFS CONTINUES TO BE CLOSEST TO THE OFFICIAL KATIA 
FORECAST TRACK AND INTENSITY AS THE SYSTEM TRAVELS NW OF THE 
TROPICAL N ATLC ZONE INTO THE SW N ATLC...WITH THE ECMWF A CLOSE 
SECOND TRACK-WISE. BOTH MODELS SLOW KATIA DOWN MORE THAN THE 
OFFICIAL FORECAST BY TUE EVENING...WITH BOTH MODELS ABOUT 120 NM 
FARTHER E AT THAT TIME. A SPED UP VERSION OF THE GFS WILL BE 
USED NEAR THE END OF THE PERIOD TO ADJUST MORE TO THE OFFICIAL 
FORECAST. PRIOR TO THE ARRIVAL OF KATIA...THE GFS ALLOWS THE LOW 
PRES SYSTEM CURRENTLY W OF BERMUDA TO LINGER OVER N WATERS 
LONGER THAN THE OTHER MODELS. CONFIDENCE IS SOMEWHAT LOW IN THIS 
LINGERING AS A DEEP LAYER TROUGH IS EXPECTED TO AMPLIFY OVER THE 
WESTERN ATLC FRI AND HELP PICK THE SYSTEM UP. A BLEND OF THE GFS 
AND FASTER ECMWF WILL BE USED HERE.


WARNINGS...

GULF OF MEXICO...
.NONE.

CARIBBEAN...
.NONE.

TROPICAL N ATLC...
.AMZ087...HURRICANE WARNING N OF 17N E OF 60W.

SW N ATLC...
.NONE.
          
FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
FORECASTER SCHAUER