000 AGXX40 KNHC 300501 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 130 AM EDT MON APR 30 2007 MARINE WEATHER DISCUSSION FOR GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. A STRONG SHORTWAVE IN THE NRN BRANCH IS OVER THE WRN ATLC TONIGHT AND BEGINNING TO LIFT NE. A SMALLER SCALE SHORTWAVE IS IN THE SRN BRANCH EXITING THE SRN ROCKIES. MID LEVEL RIDGES WERE ALONG 40W AND 95W. ON THE SURFACE TONIGHT A WEAKENING COLD FRONT WAS OVER THE SW ATLC FROM 31N62W TO 25N75W. THE FRONT SEPARATES A WEAK POLAR AIRMASS CENTERED BACK OVER SRN LA AND THE ATLC RIDGE OVER MID OCEAN. MODERATE ELY TRADES EXIST S OF 23N OVER THE ATLC E OF 60W AND IN THE CARIB E OF 78W TONIGHT. SE WINDS OVER THE WRN GULF ARE SLOWLY INCREASING TO 15 KT TONIGHT AS THE HIGH MOVES SLOWLY E. LATER DAY 1 MID LEVEL HEIGHTS BEGIN TO RISE W OF 55W AS THE STRONG TROUGH IN THE NRN BRANCH LIFTS NE ALONG 60W. THE SHORTWAVE IN THE SRN BRANCH IS FORECAST TO CLOSE OFF AS IT MOVES SLOWLY E TO NEAR 100W. MID LEVEL RIDGING CONTINUES ALONG 40W AND 90W. ON THE SURFACE LATER DAY 1 THE ATLC FRONT GRADUALLY DISSIPATES NEAR 65W AS THE OLD POLAR AIR IS MODIFIED BY THE WARM ATLC WATERS. CENTER OF THE AIRMASS EXTENDS FROM THE N CENTRAL GULF OVER N FL TO NEAR 30N78W. WINDS OVER THE REGION REMAIN ABOUT THE SAME. FOR DAY 2 THE MID LEVEL FLOW BECOMES MORE WLY N OF 30N AS THE STRONG SHORTWAVE LIFTS NE OFF THE CANADIAN MARITIMES. THE SHORTWAVE IN THE SRN BRANCH DRIFTS E TO NEAR 96W. THE OPEN RIDGE ALONG 90W WEAKENS AS IT MOVES SLOWLY E. ON THE SURFACE DAY 2..THE FIRST DAY OF MAY..THE MODIFIED POLAR AIRMASS BEGINS TO MERGE WITH THE ATLC RIDGE ALONG 30N. SOME WEAKENING OF THE MAIN PORTION OF THE ATLC RIDGE CENTER DAY 2 WITH ELY TRADES DECREASING SOME..OTHERWISE LITTLE CHANGE ELSEWHERE. OUTLOOK PERIOD... FOR DAY 3 ANOTHER STRONG SHORTWAVE MOVES SE OFF THE NEW ENGLAND COAST TIGHTENING THE MID LEVEL FLOW N OF 31N. THE SHORTWAVE IN THE SRN BRANCH DRIFTS E TO NEAR 92W BUT WEAKENS SOME DUE TO A MID LEVEL RIDGE BUILDING OVER THE PLAINS. SOME VORTICITY MOVES SE IN THE SRN BRANCH INTO THE SE GULF AND NW CARIB DAY 3 WHICH COULD INCREASE SOME CONVECTION IN THAT AREA. A WEAK SHORTWAVE IN THE SRN BRANCH MOVES E ALONG 50W. ON THE SURFACE DAY 3 THE ATLC RIDGE AXIS REMAINS ALONG 30N EXTENDING W ACROSS THE NRN GULF. SE WINDS TO 15 KT W OF 95W WILL CONTINUE. CARIB WINDS REMAIN MODERATE E OF 77W WHILE ATLC TRADES MOSTLY 15 TO 20 KT. FOR DAY 4 A BROAD UPPER TROUGH BEGINS TO FORM OVER THE NE CONUS AND CANADIAN MARITIMES. WHILE IT'S FLOW DOESN'T DIRECTLY AFFECT OUR REGION..WEAK VORTICITY IN THE NRN BRANCH IS SENT AROUND THE SRN PERIMETER INTO OUR REGION. THE SHORTWAVE IN THE SRN BRANCH REMAINS STATIONARY OVER THE SRN PLAINS CAUGHT UNDER THE STRONG MID LEVEL RIDGE OVER THE PLAINS. WEAK VORTICITY CONTINUES TO BLEED OUT OF THE SYSTEM AND IS ADVECTED EWD. ONE NEAR 45W..ANOTHER NEAR 70W AND A THIRD NEAR 85W. ON THE SURFACE DAY 4 A LITTLE BROADER SELY FLOW SHAPES UP OVER THE GULF AS SURFACE PRES FALLS OVER THE SRN PLAINS. OTHERWISE THE ATLC RIDGE SHIFTS S TO NEAR 28N WITH ELY TRADES MOSTLY 15 TO 20 KT. FOR DAY 5 THE BIG UPPER TROUGH OVER THE NE GETS A NEW SUPPLY OF COLD AIR AND BEGINS CHARGING SWD OVER THE WRN ATLC. WHILE STILL N OF OUR REGION..IT WILL TIGHTEN THE MID LEVEL FLOW OVER OUR AREA BETWEEN 55W AND 80W. THE OLD SHORTWAVE IN THE SRN BRANCH WEAKENS FURTHER ALONG 93W STILL CAUGHT UNDER THE MID LEVEL RIDGE NOW ALONG 90W. WEAK SHORTWAVES IN THE SRN BRANCH MOVE TO NEAR 43W..58W AND 80W. ON THE SURFACE DAY 5 THE GFS MODEL SHOWS WEAK LOW PRES AT THE SURACE DEVELOPING JUST E OF THE BAHAMAS ASSOCIATED WITH THE WEAK SHORTWAVE ALONG 80W. WILL SEE IF ANYTHING COMES OF IT. RETURN SELY FLOW W OF 90W REMAINS MODERATE WITH LOW PRES OVER THE SRN PLAINS CONTINUING. CARIB TRADES PICK UP A BIT BUT MAINLY IN THE S CENTRAL PORTION WHERE THEY ARE USUALLY IN THE 20 KT RANGE. ATLC TRADES REMAIN ABOUT THE SAME 15 TO 20 KT. WARNINGS... ATLANTIC... NONE. CARIBBEAN... NONE. GULF OF MEXICO... NONE. FORECASTER RRG