000 AGXX40 KNHC 300458 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 130 AM EDT MON JUL 30 2007 MARINE WEATHER DISCUSSION FOR GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. UPPER TROUGH ALONG 73W TONIGHT EXTENDS S TO 25N..UNUSUAL FOR THIS TIME OF YEAR. TROUGH BLOCKED BY A RIDGE ALONG 50W. ALSO MID LEVEL RIDGING COVERS THE PLAINS TONIGHT HELPING DIVERT THE WESTERLIES SE INTO THE TROUGH WITH WEAK VORTICITY IMPULSES THAT CONTINUE TO CAUSE FLARE UPS OF CONVECTION S OF 30N W OF 65W. ON THE SURFACE TONIGHT TRPL WAVES REMAIN WEAK. ONE ALONG 46W CAUSING THE ITCZ TO BOW UP WITH CONVECTION. ANOTHER ONE IN THE LESSER ANTILLES WITH NO CONVECTION NOTED. THE ATLC RIDGE IS WEAK TONIGHT WITH A CENTER NEAR 33N56W AND AN AXIS EXTENDING WSW TO THE FL STRAITS AND INTO THE NW GULF. WINDS OF 20 KT ARE MAINLY OVER THE CARIB S OF 17N AND IN NE TRADES OVER THE ATLC E OF 55W. LATER DAY 1 UPPER TROUGH BEGINS TO WEAKEN WITH MID LEVEL HEIGHTS SLOWLY RISING W OF 70W. SIGNS OF WEAKENING OF THE ATLC MID LEVEL RIDGE WITH INVERTED TROUGHING DEVELOPING ALONG 45W S OF 30N. MID LEVEL RIDGE OVER PLAINS REMAINS IN PLACE. ON THE SURFACE LATER DAY 1 BASICALLY LITTLE CHANGE EXCEPT FOR LOWERING PRESSURES OVER THE SE WHICH WILL INCREASE SW WINDS OVER THE NE GULF AND SW ATLC N OF 28N W OF 65W TO 20 KT. FOR DAY 2 NEVER COUNT AN UPPER TROUGH OUT OF THE PICTURE AS LONG AS IT GETS A NWLY JET FEED OF COLD AIR. THE GFS MODEL SHOWS THIS OCCURING SINCE THE MID LEVEL RIDGE OVER THE PLAINS EXTENDS WELL INTO CANADA..IT IS ABLE TO TAP SOME COLDER AIR OVER CENTRAL CANADA AND SEND IT SE INTO THE OLD TROUGH REGUVENATING IT FOR YET ANOTHER DAY. OTHERWISE THE MID ATLC RIDGE SLIDES E TO ALONG 35W. ON THE SURFACE DAY 2 THE ATLC RIDGE STRENGTHENS SOME OVER MID OCEAN WITH IT'S AXIS EXTENDING WSW TO THE FL STRAITS AND INTO THE CENTRAL GULF. GFS MODEL SHOWS THAT TRPL WAVE ALONG 10N WEAKENING AS IT MOVES SLOWLY WWD. WINDS OVER THE CARIB DECREASE SOME WITH WEAKENING GRADIENT. GULF WINDS REMAIN LIGHT. OUTLOOK PERIOD... FOR DAY 3 WHILE THE MAIN PORTION OF THE UPPER TROUGH LIFTS NE..THE SRN PORTION HANGS BACK WITH THE ADDITIONAL POCKET OF COLD AIR OVER N FL. THE PLAINS MID LEVEL RIDGE WHILE STILL IN PLACE HAS LOST IT'S AMPLITUDE DUE TO INCREASING WESTERLIES OVER THE NRN PLAINS. THE MID LEVEL BLOCKING RIDGE OVER THE ERN ATLC REMAINS ALONG 35W. ON THE SURFACE DAY 3..THE FIRST DAY OF AUGUST..THE ATLC RIDGE REMAINS ABOUT THE SAME EXTENDING WSW TO THE WRN BAHAMAS. GFS STILL HOLDS ON TO A WEAK CIRCULATION WITH A TRPL WAVE ALONG 52W. LITTLE CHANGE WITH WINDS OVER THE REGION. FOR DAY 4 A WEAK LEFT OVER MID LEVEL TROUGH HANGS BACK ALONG THE SE COAST JUST ENOUGH TO AID WEAK SURFACE LOW DEVELOPMENT. THE STRONG BLOCKING RIDGE OVER THE ERN ATLC REMAINS IN PLACE BUT NOW EXTENDS WSW TO SRN FL. A MID LEVEL RIDGE HOLDS OVER THE WRN CENTRAL PLAINS. ON THE SURFACE DAY 4 THE MAIN FEATURE REMAINS THE ATLC RIDGE WITH LITTLE CHANGE TO IT'S ORIENTATION..THUS LITTLE CHANGE TO WINDS. GFS SHOWS A WEAK TROUGH DROPPING S INTO THE NE GULF WITH WINDS TO 20 KT OVER THE ATLC WATERS N OF 28N W OF 70W. FOR DAY 5 GFS MODEL SHOWS THE MID LEVEL RIDGE WORKING SLOWLY WWD ALONG 27N AS HEIGHTS FALL OVER THE EXTREME ERN ATLC ALONG 30N. THE MODEL ALSO SHOWS INVERTED TROUGHS ON THE S SIDE OF THE RIDGE MIGRATING WWD. THESE ARE ASSOCIATED WITH TRPL WAVES AND INDICATE THEY ARE GETTING STRONGER. ON THE SURFACE DAY 5 THE ATLC RIDGE AXIS SHIFTS NWD TO 27N WITH ELY TRADES TO 20 KT BETWEEN 17N AND 25N EXTENDING W TO THE BAHAMAS. GULF WINDS REMAIN LIGHT WHILE CARIB WINDS INCREASE AGAIN TO 25 KT OVER CENTRAL SECTIONS DUE TO THE RIDGE BUILDING WWD. WARNINGS... ATLANTIC... NONE. CARIBBEAN... NONE. GULF OF MEXICO... NONE. FORECASTER RRG