000 AGXX40 KNHC 150731 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 330 AM EDT THU APR 15 2010 MARINE WEATHER DISCUSSION FOR GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W SW N ATLC AND TROPICAL ATLC... THE NORTHERN STREAM TROUGH OVER THE NW ATLC IS BECOMING MORE AMPLIFIED AND HAS PUSHED S OF 31N. THE LEADING EDGE OF THIS TROUGH IS PICKING UP LINGERING SHORTWAVE ENERGY BETWEEN 20N AND 30N TO THE N OF THE LESSER ANTILLES. THIS LINGERING ENERGY IS REFLECTED AT THE SURFACE AS A TROUGH EXTENDING N FROM A 1011 MB LOW PRES SYSTEM NEAR 20N63W TO 31N58W. THE 0154 UTC ASCAT PASS SUGGESTS THE LOW IS MIGRATING NE THROUGH THE TROPICAL N ATLC ZONE. THE MODELS AGREE ON CONTINUING TO MOVE THE LOW NE AS A SURFACE WAVE ALONG THE BOUNDARY...BUT VARY WITH THE STRENGTH OF THE WAVE AND THE TIMING AT WHICH THE WAVE LIFTS NORTHEASTWARD AND BECOMES INGESTED IN THE ANCHOR LOW ASSOCIATED WITH THE AMPLIFYING NORTHERN STREAM TROUGH. THE 0000 UTC ECMWF HAS INITIALIZED THE SURFACE LOW POSITION CLOSEST TO THE ANALYSIS. IT CARRIES A WEAKER SURFACE LOW/WAVE THAN THE GFS AND DIMINISHES THE WAVE ALONG THE BOUNDARY SLIGHTLY FASTER THAN THE GFS. CONSIDERING THE SPEED AT WHICH THE SUPPORTING MID LEVEL ENERGY IS EXPECTED TO BE SWEPT INTO THE LEADING EDGE OF THE DEEP LAYER TROUGH...CONFIDENCE IS HIGHER IN THE WEAKER/FASTER ECMWF SOLUTION OVER THE GFS. AS THE TROUGH SHIFTS EASTWARD...DEEP HIGH PRES OVER THE CENTRAL APPALACHIANS AND MID ATLANTIC U.S. STATES WILL WEAKEN AND MOVE INTO NW WATERS. THE E TO W ORIENTED SURFACE RIDGE WILL MOVE S OF 30N ON FRI AND ALONG 27N SAT WITH THE SURFACE HIGH SHIFTING E OF AREA ON SUN. THE MODELS ARE IN REASONABLE AGREEMENT ON CARRYING A WEAK COLD FRONT INTO NW WATERS ON SUN AS A NEW DEEP LAYER TROUGH DEEPENS OVER THE E COAST. MOST OF THE MODELS ALSO SHOW A WEAK SOUTHERN STREAM SYSTEM PASSING THROUGH THE SOUTHERN GULF OF MEXICO OR NW CARIBBEAN INTO THE LEADING EDGE OF THIS TROUGH...WITH THE SURFACE SYSTEM PASSING E THROUGH THE CENTRAL OR NORTHERN BAHAMAS SUN/MON. THE MODELS ARE ALL OVER THE PLACE WITH THIS SOUTHERN STREAM ENERGY...SO THE FORECAST HEDGES TOWARD THE MODEL CONSENSUS WHICH IS SLOWER AND MORE SOUTHERLY THAN THE GFS WITH THE TRACK OF THE SURFACE WAVE AND CONSIDERABLY WEAKER. CARIBBEAN... THE PRES GRADIENT BETWEEN STRONG HIGH PRES N OF THE AREA AND BROAD LOW PRES OVER THE SOUTHERN AND EASTERN CARIBBEAN HAS BROUGHT STRONG E WINDS TO THE NW CARIBBEAN. THE 0154 UTC ASCAT PASS SHOWED NE WINDS TO 30 KT IN THE WINDWARD PASSAGE WHILE THE 0336 UTC ASCAT PASS...SEVERAL SHIP OBSERVATIONS...AND AN ALTIMETER PASS OVER THE PAST FEW HOURS SHOW WINDS IN THE 20 TO 25 KT RANGE AND SEAS TO 9 FT IN THE CARIBBEAN N OF 17N W OF 78W. THIS PATTERN IS EXPECTED TO CONTINUE INTO FRI WITH WINDS DIMINISHING AS THE HIGH PRES SYSTEM SHIFTS SE. BY THE WEEKEND...THE FORECAST BECOMES MORE DEPENDENT ON THE EVOLUTION OF THE SOUTHERN STREAM ENERGY MOVING IN FROM THE NE. AS MENTIONED IN THE ATLC SECTION...THE GFS IS MORE NORTHERLY AND CONSIDERABLY STRONGER WITH THE SURFACE REFLECTION OF THIS ENERGY...SO THE FORECAST IS CLOSER TO THE WEAKER AND MORE SOUTHERLY CONSENSUS...TRACKING THE WAVE THROUGH THE FAR NW CARIBBEAN SUN. THE FORECAST IN THE EASTERN CARIBBEAN IS TIED TO THE EVOLUTION OF THE WAVE ALONG THE TROUGH OVER THE CENTRAL N ATLC. THE FORECAST ALLOWS WINDS TO BUILD TO 20 KT IN THE N FACING PASSAGES OVERNIGHT TONIGHT AS HIGH PRES MOVES IN BEHIND THE TROUGH. WINDS WILL REMAIN STRONG HERE INTO SAT BEFORE THE HIGH PRES SYSTEM APPROACHES THE AREA...DROPPING WINDS A NOTCH AND TURNING THEM MORE EASTERLY SUN AND MON. GULF OF MEXICO... ASCAT PASS FROM 0338 UTC AND MORE RECENT SURFACE OBSERVATIONS SHOW E WINDS ACROSS THE CENTRAL AND SE GULF TO 30 KT. THESE STRONG WINDS ARE ON THE S EDGE OF A STRONG HIGH PRES RIDGE THAT WILL SHIFT SE INTO THE SW N ATLC FRI AND CONTINUE SE THROUGH THE WEEKEND. THE STRONG WINDS WILL DIMINISH OVER THE FAR EASTERN GULF AS THE SURFACE RIDGE MOVES SOUTHWARD INTO THE AREA LATE FRI INTO SAT...BUT WINDS WILL REMAIN STRONG OVER THE CENTRAL GULF AS TROUGHING DEVELOPS IN THE SW GULF AND MAINTAINS THE PRES GRADIENT BETWEEN IT AND THE RIDGE. THE MODELS ARE IN REASONABLE AGREEMENT ON CARRYING A WEAK COLD FRONT TO THE GULF COASTAL PLAIN ON SUN WITH LITTLE FANFARE. CONFIDENCE DROPS OFF SIGNIFICANTLY IN THE FORECAST OVER THE WEEKEND WHEN SOUTHERN STREAM ENERGY IS EXPECTED TO PASS EASTWARD ACROSS THE SOUTHERN GULF IN THE LEADING EDGE OF THE BROAD TROUGH SUPPORTING THE COLD FRONT. AS MENTIONED IN THE ATLC SECTION...THE GFS IS MORE NORTHERLY AND CONSIDERABLY STRONGER WITH THE SURFACE REFLECTION OF THIS ENERGY...SO THE FORECAST IS CLOSER TO THE WEAKER AND MORE SOUTHERLY CONSENSUS. WARNINGS... ATLC... .NONE. CARIBBEAN... .NONE. GULF OF MEXICO... .NONE. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ FORECASTER SCHAUER