000 AGXX40 KNHC 160647 MIMATS MARINE WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 250 AM EDT MON MAY 16 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... DESPITE A VERY COMPLEX PATTERN ALOFT WITH MULTIPLE VORTICES ROTATING ABOUT A 3-4 STANDARD DEVIATION DEEPER THAN NORMAL H5 LOW...THE MODELS SHOW REASONABLY GOOD AGREEMENT ON THE FORECAST SCENARIO. THE BROAD DEEP LAYERED LOW IS EXPECTED TO DROP SOUTH INTO THE CAROLINAS TODAY THROUGH TUE NIGHT BEFORE WEAKENING AND THEN LIFTING BACK TO THE N. THE AFOREMENTIONED VORTICES WILL SEND A SERIES OF SURFACE TROUGHS THROUGH N FLORIDA AND INTO NW WATERS THROUGH EARLY THU MORNING. THERE ARE SOME DIFFERENCES BETWEEN THE MODELS WITH THE TIMING AND STRENGTH OF THESE TROUGHS AS THEY PASS THROUGH THE AREA. CONFIDENCE IS LOW IN ANY ONE SOLUTION...SO A BLEND OF THE GENERALLY RELIABLE GFS AND ECMWF WAS USED FOR THE FORECAST. BOTH THE 00Z GFS AND ECMWF AGREE ON FINALLY BRINGING WINDS BELOW 20 KT WED EVENING AND GENERALLY ALLOW THE SUBTROPICAL RIDGE TO BUILD ALONG 28N THU INTO FRI. FARTHER E...WEAK MID LEVEL ENERGY E OF THE BAHAMAS IS GENERATING TSTMS APPROXIMATELY 120 NM N OF THE TURKS AND CAICOS. THIS ENERGY IS EXPECTED TO LIFT NORTHWARD THROUGH THE EASTERN PORTION OF THE SW N ATLC ZONE THROUGH TUE NIGHT. THE MAIN IMPACT TO THE SENSIBLE WEATHER WILL CONTINUE TO BE AN INCREASE IN SHOWERS NEAR THE SYSTEM. CARIBBEAN SEA AND THE TROPICAL N ATLANTIC ... WHILE THE WEAKENING AND NORTHEASTWARD EJECTION OF THE DEEP LAYERED LOW OVER THE CENTRAL ATLC NEAR 37N48W IS EXPECTED TO ALLOW FOR BUILDING OF THE SUBTROPICAL RIDGE...FRESH TRADE WINDS ARE NOT EXPECTED TO RETURN IN EARNEST TO THE EASTERN AND CENTRAL CARIBBEAN OR THE TROPICAL N ATLC THIS PERIOD. THE PRIMARY CULPRIT IS THE PERSISTENT TROUGHING OVER THE U.S. EAST COAST WHICH IS WEAKENING THE PRES GRADIENT OVER THE AREA. MOISTURE WILL CONTINUE TO POOL ON THE EASTERN SIDE OF THE DEEP LAYER TROUGHING THAT EXTENDS INTO THE CENTRAL CARIBBEAN...MAKING RAINFALL OVER THE EASTERN CARIBBEAN THE PRIMARY SENSIBLE WEATHER CONCERN FOR THE NEXT FEW DAYS UNDER THIS SOMEWHAT STAGNANT PATTERN. THE SURFACE TROUGHING TO THE N IS EXPECTED TO BEGIN TO DIMINISH ON WED AND THE SUBTROPICAL RIDGE WILL BUILD FROM THE CENTRAL ATLC TOWARD THE NE CARIBBEAN. THE RIDGE WILL TURN MORE ZONAL...BUILDING ALONG 28N THU AND FRI. THIS WILL ALLOW WINDS TO TURN MORE EASTERLY IN THE EASTERN CARIBBEAN AND FINALLY PUSH THE CENTRAL CARIBBEAN SURFACE TROUGH EASTWARD. MEANWHILE...A LOW AMPLITUDE TROPICAL WAVE NEAR 43W S OF ABOUT 08N IS FORECAST TO MOVE THROUGH THE TROPICAL N ATLC ZONE TUE-WED AND LIFT SLIGHTLY N AS IT MOVES INTO THE EASTERN CARIBBEAN BY THU. WINDS ARE NOT EXPECTED TO BE AT OR ABOVE 20 KT BY THU AFTERNOON THROUGH FRI BECAUSE THE MORE ZONAL RIDGING TO THE N WILL PREVENT A SHARP PRES GRADIENT OVER THE CARIBBEAN. THE GFS IS THE ONLY MODEL TO SHOW WINDS THAT STRONG AT THAT TIME AND KEEPS THEM CLOSE TO THE COAST OF HISPANIOLA. WILL KEEP THE FORECAST ON THE WEAKER SIDE. GULF OF MEXICO... WHILE THE COLD FRONT THAT HAD BEEN OVER THE EASTERN GULF YESTERDAY HAS MOVED E OF THE AREA...PERSISTENT TROUGHING IS EXPECTED OVER THE EASTERN GULF THROUGH WED AS A SERIES OF REINFORCING TROUGHS DROP IN FROM THE NORTH ON ITS HEELS. AS MENTIONED IN THE SW N ATLC SECTION...CONFIDENCE IS LOW IN ANY ONE SOLUTION WITH THESE FEATURES AND A BLEND OF THE GFS AND ECMWF WAS USED FOR THEIR FORECAST. HIGH PRES IS FINALLY EXPECTED TO DROP INTO THE NW GULF BEHIND THE EASTERN GULF TROUGHING ON TUE AND GRADUALLY MOVE EASTWARD ALLOWING SE RETURN FLOW TO INCREASE TO 20 KT IN THE WESTERN GULF BY THE WED EARLY MORNING HOURS AS THE GRADIENT BUILDS BETWEEN THIS RIDGING AND TROUGHING OVER THE SOUTHERN HIGH PLAINS. THE 00Z ECMWF AND GFS AGREE ON THIS TIMING AND ON SHIFTING THE EASTERN GULF TROUGHING NORTHWARD WED AND THU AND REPLACING IT WITH THIS HIGH PRES WHICH WILL SHIFT INTO THE NE GULF THU AND FRI. FRESH RETURN FLOW WILL PERSIST IN THE WESTERN GULF TUE NIGHT THROUGH WED AND POSSIBLY INCREASE TO FRESH TO STRONG ON FRI AS A COLD FRONT MOVES INTO CENTRAL TX. THE MODELS ARE IN RELATIVELY GOOD AGREEMENT ON THIS SCENARIO. WARNINGS.. ATLC... .NONE. CARIBBEAN... .NONE. GULF OF MEXICO... .NONE. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ FORECASTER SCHAUER