000
AGXX40 KNHC 040712
MIMATS

MARINE WEATHER DISCUSSION  
NWS NATIONAL HURRICANE CENTER MIAMI FL
315 AM EDT FRI MAY 04 2012

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

GULF OF MEXICO...
A QUIET PERIOD IS ON TAP FOR THE GULF OF MEXICO WITH WINDS 
EXPECTED TO REMAIN AT 15 KT OR LOWER AND SEAS NO HIGHER THAN 5 
FT THROUGH TUE. THE MID LEVEL TROUGH OVER THE EASTERN GULF THAT 
HAS POOLED MOISTURE INTO THE CENTRAL GULF COAST IS EXPECTED TO 
WEAKEN AS IT MOVES EASTWARD ACROSS FL TODAY INTO EARLY SAT. 
THUNDERSTORM ACTIVITY IS SHIFTING EASTWARD FROM THE OFFSHORE TO 
THE COASTAL WATERS. THE NEXT THREAT OF ORGANIZED PRECIPITATION 
COMES LATE SUN OVER THE NE GULF AHEAD OF A BACKDOOR COLD FRONT 
DROPPING INTO NE FL. A DEEP LAYER TROUGH WILL BUILD OVER THE 
MISSISSIPPI VALLEY MON AND SHIFT EASTWARD TUE...KEEPING THE 
THREAT OF PRECIPITATION GOING OVER THE NE GULF ON ITS LEADING 
EDGE. THE COLD FRONT ASSOCIATED WITH THIS TROUGH WILL NOT REACH 
THE GULF THROUGH THE END OF THE PERIOD TUE. THE 00Z GFS WAS 
BLENDED WITH THE PREVIOUS FORECAST FOR THE GRIDS. 

CARIBBEAN SEA...
TROUGHING OVER THE CENTRAL ATLC HAS DISRUPTED THE SUBTROPICAL 
RIDGING OVER THE CARIBBEAN AND LESSENED THE PRES GRADIENT 
YIELDING LIGHT TO MODERATE WINDS AND SEAS 6 FT OR LESS. THESE 
CONDITIONS ARE EXPECTED TO CONTINUE THROUGH THE END OF THE 
PERIOD ON TUE. THERE IS SOME DISAGREEMENT BETWEEN THE 00Z GFS 
AND THE OTHER MODELS ON THE STRENGTH OF A TROUGHING EXPECTED 
OVER THE EASTERN CARIBBEAN MON AND TUE WITH THE GFS SPORTING A 
DEEPER TROUGH AND BRIEFLY GENERATING 20 KT SOUTHERLY WINDS JUST 
W OF THE LESSER ANTILLES ON MON. WHILE OVERALL THE GFS FORECAST 
LOOKS ACCEPTABLE...SOME CHANGES WERE MADE TO DIMINISH THE 
STRENGTH OF THE TROUGHING AND THE WINDS ON MON/TUE TOWARD THE 
MODEL CONSENSUS IN THE E CARIBBEAN. AT ANY RATE...SUN THROUGH 
TUE LOOKS TO BE A WET PERIOD FOR THE LESSER ANTILLES AHEAD OF 
THIS TROUGH.

ATLC...
FOR THE TROPICAL N ATLC...PLEASE SEE THE DISCUSSION OF THE 
TROUGHING EXPECTED IN THE EASTERN CARIBBEAN LATER IN THE PERIOD 
IN THE SECTION ABOVE. FARTHER N...THE MOST SIGNIFICANT MODEL 
DIFFERENCES LIE WITH THE COLD FRONT EXPECTED TO SWEEP S INTO THE 
SW N ATLC ZONE WITH A LOW PRES SYSTEM ALONG THE FRONT SUN NIGHT. 
THE 00Z GFS AND ECMWF AGREE ON A WEAKER LOW THAN THE UKMET AND 
CMC HANGING AROUND INTO TUE. THE CMC ALLOWS THIS LOW TO MIGRATE 
NORTHWARD BY TUE TOWARD THE LEADING EDGE OF THE NEXT TROUGH. 
THIS SOLUTION SEEMS TO BE AN OUTLIER. THE GFS AND ECMWF ARE 
GENERALLY IN AGREEMENT ON WEAKENING THE LOW...BUT DIFFER WITH 
THE FRONTAL TIMING. THE GFS IS SLIGHTLY FASTER TO SWING THE COLD 
FRONT SOUTHWARD THAN THE UKMET/ECMWF SOLUTION. THE ECMWF WAS 
BLENDED INTO THE FORECAST BEGINNING SUN NIGHT TO ADJUST TOWARD 
THE MODEL CONSENSUS. 

NOTE... EFFECTIVE APR 3, 2012 AT 1800 UTC THE OFFSHORE WATERS 
FORECAST ZONES CHANGED FOR THE CARIBBEAN AND SW N ATLANTIC AND 
THE GULF OF MEXICO. ISSUANCE TIME FOR THE GULF OF MEXICO 
OFFSHORE WATERS FORECASTS IS REFERENCED TO THE EASTERN TIME 
ZONE. FOR DETAILS SEE WWW.NHC.NOAA.GOV/ABOUTTAFBPROD.SHTML#OWF

GRIDDED MARINE OUTPUT IS AVAILABLE AT 
WWW.NHC.NOAA.GOV/TAFB/GRIDDED_MARINE (LOWER CASE).

GULF OF MEXICO...
.NONE.

CARIBBEAN SEA...
.NONE.

ATLANTIC...
.NONE.

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

$$
FORECASTER SCHAUER