000
AGXX40 KNHC 240705
MIMATS

MARINE WEATHER DISCUSSION 
NWS NATIONAL HURRICANE CENTER MIAMI FL
305 AM EDT SUN APR 24 2011

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

SW N ATLC...
THE 0116 UTC ASCAT PASS SHOWS THE CENTER OF THE LOW PRES SYSTEM 
OVER THE SE PORTION OF THE SW N ATLC OFFSHORE ZONE HAS BECOME 
MORE ELONGATED BUT REMAINS CLOSED. THE ASCAT PASS ALSO SHOWED 
WINDS REACHING 25 KT FROM 120 NM TO 210 NM N QUADRANT OF THE 
LOW. THE 00Z MODEL THAT IS BEST INITIALIZED COMPARED TO THE 
ASCAT PASS APPEARS TO BE THE GFS. THE GFS HOLDS ONTO 25 KT WINDS 
WITH THE SYSTEM OVERNIGHT TONIGHT WHILE THE UKMET AND ECMWF DROP 
WINDS TO 20 KT BY SUNSET. ALL OF THESE MODELS AGREE ON OPENING 
UP THE CIRCULATION TO A TROUGH TODAY. GIVEN THE WELL-DEFINED 
CIRCULATION STILL EVIDENT ON SATELLITE IMAGERY AS OF 0600 UTC 
AND THE AGREEMENT IN THE MODELS FOR HIGH PRES TO BUILD OVER THE 
NE PORTION OF THE ZONE INCREASING THE PRES GRADIENT...WILL STICK 
CLOSE TO THE STRONGER GFS FORECAST HERE AND ITS CORRESPONDING 
WAVE WATCH WHICH IS HIGHER THAN THE UKMET OR ECMWF WAVE MODELS 
INTO MON. THE MODELS DO AGREE ON CARRYING THE REMNANT TROUGH 
INTO THE STRAITS OF FLORIDA LATE MON/EARLY TUE WITH THE MAIN 
IMPACT W OF THE BAHAMAS BEING AN INCREASED CHANCE OF 
PRECIPITATION. 

THE SUBTROPICAL HIGH WILL MOVE SOUTHWESTWARD OVER THE NEXT 48 
HOURS...SETTLING E OF BERMUDA AND STRENGTHENING TUE AND WED 
BEFORE BEING NUDGED SLIGHTLY TO THE E THU NIGHT AS A COLD FRONT 
MOVES OFF THE N FL COAST. THE GFS IS ON THE FAST SIDE OF THE 
GUIDANCE WITH THIS FRONT ONCE IT REACHES THE SW N ATLC ZONE 
WHILE THE ECMWF IS ON THE SLOW END. A COMPROMISE BETWEEN THE GFS 
AND ECMWF SEEMS BEST FOR NOW AND IS IN LINE WITH THE MODEL 
CONSENSUS.


CARIBBEAN AND TROPICAL N ATLC...
THE LOW PRES SYSTEM OVER THE SW N ATLC WEAKENED THE TRADE WINDS 
IN THE CARIBBEAN AND TROPICAL ATLC MUCH OF THE LAST WEEK...BUT 
THE AFOREMENTIONED DISSIPATION OF THAT LOW AND BUILDING OF THE 
SUBTROPICAL HIGH WILL ALLOW FOR MODERATE TO FRESH TRADES TO 
RETURN TO MUCH OF THE AREA BEGINNING MON. SW RETURN FLOW WILL 
ALSO ACT TO INCREASE WINDS OVER THE NW CARIBBEAN INCLUDING THE 
GULF OF HONDURAS BY TUE NIGHT AS A COLD FRONT APPROACHES THE 
TEXAS COAST AND INCREASES THE E TO W PRES GRADIENT OVER THE NW 
CARIBBEAN BETWEEN THIS FRONT AND THE SUBTROPICAL HIGH. THE 00Z 
ECMWF...UKMET...AND GFS ARE ALL IN REASONABLE AGREEMENT WITH THE 
TIMING AS THE FRONT MOVES OFF THE TX COAST WED MORNING...BUT THE 
GFS BECOMES SLIGHTLY FASTER THAN THE ECMWF AND UKMET AS THE 
FRONT MOVES INTO THE CENTRAL AND NE GULF ON THU. A BLEND OF THE 
ECMWF AND GFS WAS USED FOR THE FORECAST ON THU HERE TO KEEP IN 
LINE WITH THE MODEL CONSENSUS. THIS CAUSES THE PRES GRADIENT TO 
SLACKEN BY THU NIGHT OVER THE NW CARIBBEAN AS THE FRONT MOVES 
INTO THE SE GULF OF MEXICO.


GULF OF MEXICO...
THE MODELS SHOW THE FRESH EASTERLY WINDS THROUGH THE STRAITS OF 
FLORIDA OBSERVED IN THE 0256 UTC ASCAT PASS AND SEVERAL SURFACE 
OBSERVATIONS DIMINISHING MON AS THE REMNANTS OF THE LOW PRES 
SYSTEM CURRENTLY MOVING THROUGH THE SW N ATLC ZONE MOVE INTO THE 
AREA AND DISTURB THE STRONG N TO S PRES GRADIENT CURRENTLY IN 
PLACE. AS MENTIONED IN THE SW N ATLC SECTION...THE 00Z GFS IS 
THE PREFERRED SOLUTION WITH THESE REMNANTS. THE MAIN IMPACT OF 
THIS REMNANT TROUGH WILL BE AN INCREASE IN AVAILABLE MOISTURE 
AND PRECIPITATION CHANCES MON AND TUE OVER THE STRAITS OF FL AND 
THE FL PENINSULA. THE TROUGH IS EXPECTED TO DISSIPATE WED AND 
THE SUBTROPICAL HIGH WILL BUILD BRIEFLY WESTWARD OVER THE 
EASTERN GULF AHEAD OF A COLD FRONT. THE MODELS AGREE ON TAKING 
THE FRONT OFFSHORE OF THE TX COAST WED MORNING. 
CURRENTLY...FRESH SE RETURN FLOW COVERS MUCH OF THE WESTERN AND 
MIDDLE GULF AND IS EXPECTED TO CONTINUE UNTIL TUE WHEN THE COLD 
FRONT APPROACHES THE TX COAST AND BRIEFLY INCREASES THE PRES 
GRADIENT...ALLOWING WINDS TO INCREASE A NOTCH TUE NIGHT IN THE 
NW GULF. FRESH TO STRONG N WINDS ARE EXPECTED BEHIND THE FRONT 
WED. THE 00Z ECMWF...UKMET...AND GFS ARE ALL IN REASONABLE 
AGREEMENT WITH THE TIMING AS THE FRONT MOVES OFF THE TX COAST 
WED MORNING...BUT THE GFS BECOMES SLIGHTLY FASTER THAN THE ECMWF 
AND UKMET AS THE FRONT MOVES INTO THE CENTRAL AND NE GULF ON 
THU. A BLEND OF THE ECMWF AND GFS WAS USED FOR THE FORECAST ON 
THU HERE TO KEEP IN LINE WITH THE MODEL CONSENSUS. 


WARNINGS..

ATLC...
.NONE.

CARIBBEAN...
.NONE.

GULF OF MEXICO...
.NONE.

FOR ADDITIONAL INFORMATION PLEASE VISIT 
HTTP://WWW.HURRICANES.GOV/MARINE

$$
FORECASTER SCHAUER