000 AGXX40 KNHC 210747 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 400 AM EDT THU MAY 21 2009 MARINE WEATHER DISCUSSION FOR THE GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. GULF OF MEXICO AND SW N ATLC... GALES ARE BEGINNING TO SHRINK IN AREA OVER BOTH THE SW N ATLC AND NE GULF OF MEXICO. CHECKING SURFACE OBSERVATIONS OVER THE LAST FEW HOURS...GALES HAVE SUBSIDED AT SGOF1...THE 35 METER TOWER OFFSHORE OF TYNDALL AFB JUST SOUTH OF APALACHICOLA FLORIDA. HOWEVER...SHIP PCUI NEAR 27N86.5W REPORTED 33 KT AT 0600 UTC WITHIN 60 NM N OF THE ELONGATED 1006 MB LOW. THIS SHIP IS CLOSE TO THE REGION OF GALES IDENTIFIED BY THE 2340 UTC QUIKSCAT PASS. THIS PASS ALSO SUGGESTS THE AREA OF GALE FORCE WINDS DRIFTING W WITH THE LOW CENTER. ON THE ATLC COAST OF FL...BUOYS 41010 AND 41012 OFF NE FL REPORT WINDS AROUND 25 KT. HOWEVER...THE REPORT FROM SHIP A8NH4 SHOWS 37 KT NEAR 29.488.2 AT 0600 UTC. THE 0206 AND 0246 UTC ASCAT PASSES CONFIRM THE WIND FIELD SHRINKING FURTHER OVER THE LAST FEW HOURS SINCE THE 2340 QUIKSCAT PASS. GALES SHOULD SUBSIDE IN BOTH THE ATLC AND THE GULF BY AFTERNOON. THE MODELS ARE IN REASONABLE AGREEMENT WEAKENING THE WINDS WITH THE SYSTEM AND CARRYING THE LOW CENTER TOWARD THE LOUISIANA COAST. THE BIGGER QUESTION IN THIS REGION LIES WITH THE ZONAL SHEAR AXIS ACROSS THE BAHAMAS WHERE MOST OF THE MODELS AGREE ON DEVELOPING A SURFACE TROUGH OR LOW. THE NOGAPS IS THE MOST AGGRESSIVE SOLUTION WHILE THE UKMET IS THE WEAKEST. UPPER LEVEL DIFFLUENCE SHOULD SUPPORT CONVECTION IN THIS REGION OF LOW LEVEL MOISTURE CONVERGENCE. MOST OF THE MODELS...INCLUDING THE GFS AND ECMWF...AGREE ON DRAWING SOME OF THE MID LEVEL VORTICITY FROM THE TROPICAL WAVE OVER VENEZUELA NORTHWARD INTO THIS TROUGH. THE GFS DOES SO MORE RAPIDLY THAN THE ECMWF. FORECAST USES A BLEND OF THE STRONGER/FASTER GFS AND WEAKER/SLOWER ECMWF SOLUTIONS WHICH YIELDED A SLOW W MOVING TROUGH OVER THE BAHAMAS THROUGH SAT BEFORE THE TROUGH IS DRAWN NE AS THE HIGH PRESSURE SYSTEM TO ITS N CURRENTLY OFF THE MID ATL COAST DRIFTS E AND WEAKENS EARLY NEXT WEEK. CARIBBEAN AND TROPICAL ATLC... THE TROPICAL WAVE PASSING THROUGH VENEZUELA AND THE SOUTHERN CARIBBEAN HAS BROUGHT A SURGE OF EASTERLY FLOW BEHIND IT WITH AN UNKNOWN SHIFT REPORT NEAR 14N71W AND SHIP A8JH7 NEAR 16N70W SHOWING WINDS AROUND 25 KT AT 0600 UTC. DIFFERENCES IN THE MODEL FORECASTS HERE HINGE ON THE TIMING AND STRENGTH OF THE AFOREMENTIONED LOW TO MID LEVEL VORTICITY MOVING NORTHWARD FROM THE WAVE INTO THE SHEAR AXIS OVER THE BAHAMAS. AGAIN...A BLEND OF THE GFS AND ECMWF WAS USED. OVER THE TROPICAL ATLC...TRADE WINDS ARE SLOW TO RETURN TO 20 KT AND HIGHER AS THE SUBTROPICAL HIGH CONTINUES TO BE WEAKENED BY THE PERSISTENT DEEP LAYER LOW OVER THE N CENTRAL ATLC. WARNINGS ATLC... .GALE WARNING N OF 29N W OF 78W...AMZ080. CARIBBEAN... .NONE. GULF OF MEXICO... .GALE WARNING N OF 29N E OF 88W...GMZ086 AND GMZ084.. FORECASTER SCHAUER CLARK. TROPICAL PREDICTION CENTER.