000 AGXX40 KNHC 080503 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 130 AM EDT SUN APR 8 2007 MARINE WEATHER DISCUSSION FOR GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. A LARGE COLD CYCLONIC CIRCULATION DOMINATES THE ERN CONUS TONIGHT. THE CIRCULATION HAS TIGHTENED THE MID LEVEL HEIGTH FIELD RESULTING IN A STRONG WSW FLOW W OF 70W. A WEAK SHORTWAVE IS NOTED IN THE FLOW OVER CENTRAL TX BUT WILL WEAKEN AS IT MOVES THROUGH CONFLUENT FLOW FURTHER E. MID LEVEL RIDGING CENTERED OVER THE CARIB EXTENDS NNE TO 45W. ON THE SURFACE TONIGHT A WEAKENING COLD FRONT EXTENDS SW FROM 31N57W TO 20N72W. A SECONDARY FRONT EXTENDS FROM 31N68W TO THE NRN BAHAMAS. A WEAK TROUGH WAS OVER THE NW GULF. POLAR AIR LIES OVER THE SRN PLAINS EXTENDING SE OVER FL. LATER DAY 1 LITTLE CHANGE TO THE OVERALL MID LEVEL PATTERN WITH THE TX SHORTWAVE MOVING TO NEAR 90W. ON THE SURFACE LATER DAY 1 WEAK LOW PRES TRIES TO FORM OVER THE NW GULF BUT THE MID LEVEL DYNAMICS LEAVES IT BEHIND. WINDS OVER THE NW GULF REMAIN 20 TO 25 KT WHERE SOME GRADIENT PERSISTS. THE SUBTROPIC RIDGE 1024 MB NEAR 31N40W EXTENDS SW AND MAINTAINS NE AND E TRADES TO 20 KT E OF 75W OVER THE CARIB AND ATLC S OF 20N. FOR DAY 2 WHILE THE LARGE CYCLONIC VORTEX LIFTS NE OFF THE CANADIAN MARITIMES..A NEW SHORTWAVE IN THE NRN BRANCH DIVES SE OVER THE MO VALLEY. MID LEVEL FLOW S OF 35N REMAINS ZONAL BUT STRONG. THE SHORTWAVE MOVES QUICKLY TO 60W AND WEAKENS. ON THE SURFACE DAY 2 A WEAK WARM FRONT FORMS OVER THE NW GULF AS THE FLOW BECOMES MORE SLY IN RESPONSE TO POLAR AIR MASS MOVING EWD TOWARD THE SE COAST. A WEAKENING COLD FRONT OVER THE ATLC MOVES TO NEAR 31N53W 20N65W. TRADES WEAKEN AS THE ATLC RIDGE OVER MID OCEAN WEAKENS. OUTLOOK PERIOD... FOR DAY 3 THE OVERALL WLY FLOW ALOFT CONTINUES QUITE STRONG WITH NRN BRANCH SHORTWAVES MOVING RAPIDLY EWD AS WELL AS SRN BRANCH ONES. ANOTHER SHORTWAVE IN THE SRN BRANCH MOVES TO 90W. A FLAT MID LEVEL RIDGE HOLDS ON OVER THE CARIB E TO 50W. ON THE SURFACE DAY 3 THE STRONG ZONAL FLOW ALOFT OVER THE ROCKIES LOWERS SURFACE PRESSURES OVER THE PLAINS AND SLY WINDS OVER THE GULF INCREASE TO 20 KT. THE GFS MODEL SHOWS WEAK LOW PRES MOVING E OVER THE GULF TO THE NE GULF IN RESPONSE TO THE SHORTWAVE ALOFT. WEAKENING HIGH PRES PREVAILS ALONG 27N OVER THE ATLC WITH TRADES S OF 17N TO 20 KT E OF 80W. FOR DAY 4 A NEW STRONG SHORTWAVE DROPS ESE INTO THE N CENTRAL PLAINS LOWERING MID LEVEL HEIGHTS W OF 85W. THE GULF SHORTWAVE MOVES E TO NEAR 72W BUT STRUGGLES IN THE STRONG CONFLUENT FLOW. ON THE SURFACE DAY 4 THE GFS MODEL DEVELOPS THE NE GULF LOW TO 1007 MB AS IT MOVES ENE TO 32N72W. MODEL WINDS OF 30 TO 35 KT LOOKS TOO STRONG. SLY WINDS OVER THE GULF REMAIN TO 20 KT AS LOW PRES MOVES E TOWARD THE TN VALLEY. OTHERWISE WEAK RIDGING SLIDES EWD ALONG 25N MAINTAINING LIGHT TO MODERATE TRADES S OF 20N E OF 80W. FOR DAY 5 IT IS EVIDENT THE STRONG SHORTWAVE OVER THE N CENTRAL PLAINS JUST DOESN'T HAVE MUCH COLD AIR WITH IT AS IT MOVES ENE TOWARD THE ERN GREATLAKES. MID LEVEL FLOW W OF 90W TURNS MORE SWLY AS A NEW SHORTWAVE MOVES OUT OF THE CENTRAL ROCKIES. A FLAT MID LEVEL RIDGE CENTERED OVER THE CARIB REMAINS STATIONARY WARMING WITH THE APPROACHING SUMMER PATTERN. ON THE SURFACE DAY 5 THE GFS MODEL CLINGS TO A 1009 MB LOW NEAR 33N62W WITH WINDS OF 25 KT EVEN THOUGH THE SHORTWAVE WEAKENS. STILL A LITTLE OVERDONE. SLY WINDS OVER THE GULF WEAKEN AS LOW PRES MOVES OFF THE MID ATLC COAST. ATLC RIDGING REMAINS WEAK ALONG 24N WITH LITTLE CHANGE TO THE ELY TRADES. WARNINGS... ATLANTIC... NONE. CARIBBEAN... NONE. GULF OF MEXICO... NONE. FORECASTER RRG