000 AGXX40 KNHC 210457 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 130 AM EDT FRI SEP 21 2007 MARINE WEATHER DISCUSSION FOR GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. BROAD FLAT MID LEVEL RIDGE COVERS THE AREA S OF 40N WITH EMBEDDED LOW PRES CENTERS. ONE OVER THE E ATLC NEAR 27N27W ANOTHER IN A BROAD TROUGH NEAR 33N46W AND A THIRD OVER THE NE GULF NEAR 27N83W. ON THE SURFACE TONIGHT WEAK TRPL WAVES WERE ALONG 37W AND 67W MOVING W 10 TO 15 KT WITH VERY LITTLE ACTIVITY. A SURFACE LOW OVER THE NE GULF NEAR 27N83W WAS MOVING WNW WITH PSBL DEVELOPMENT. LATER DAY 1 MID LEVEL RIDGE KEEPING WESTERLIES N OF 40N FOR NOW BUT A STRONG SHORTWAVE MOVING SE OVER THE NRN PLAINS MAY CHANGE THINGS DOWN THE ROAD. ON THE SURFACE LATER DAY 1 ALL EYES ON LOW OVER NE GULF AND PSBL DEVELOPMENT. OTHERWISE GRADIENT WEAK AND WINDS MOSTLY LIGHT TO MODERATE ELSEWHERE. FOR DAY 2 STRONG SHORTWAVE MOVES E IN A STRONG ZONAL FLOW. LARGE MID LEVEL TROUGH OVER MID ATLC DIPS INTO OUR REGION S OT 23N. INVERTED TROUGH STUCK IN RIDGE DRIFTS WWD OVER CENTRAL GULF. ON THE SURFACE DAY 2 LOW IN GULF MOVES TOWARD NEW ORLEANS WITH LITTLE CHANCE OF DEVELOPMENT THAT CLOSE TO LAND. ANOTHER LOW MOVES NW OVER NW CARIB TOWARD YUCATAN CHANNEL. MODERATE ELY TRADES OVER CENTRAL CARIB OTHERWISE LIGHT TO MODERATE ELSEWHERE. OUTLOOK PERIOD... FOR DAY 3 MID LEVEL RIDGE BUILDS OVER ERN CONUS. MID OCEAN TROUGHING BROADENS AND BEGINS TO TAP ENERGY FROM WESTERLIES IN THE FORM OF WEAK SHORTWAVES. INCREASING SWLY FLOW ALOFT BEGINS W OF RIDGE OVER SRN PLAINS. ON THE SURFACE DAY 3 LOW IN NRN GULF SHOULD MOVE INLAND BUT IF IT STAYS OVER WATER IT COULD INTENSIFY. WEAK TROUGH CONTINUES ALONG 50W OVER ATLC WITH LIGHT WINDS. OTHERWISE PRES GRADIENT WEAK AND WINDS MOSTLY LIGHT TO MODERATE. FOR DAY 4 WITH BULGING MID LEVEL RIDGE ALONG 80W INTO CANADA..WESTERLIES TAKE A DIVE ALONG 50W TAPPING INTO COLD AIR FURTHER N. THIS SERVES TO INTERCEPT TROUGH OVER MID ATLC AND WEAKEN IT. ON THE SURFACE DAY 4 WEAK HIGH PRES GENERALLY N OF 20N WITH OLD EMBEDDED TROUGH ALONG 47W N OF 22N. WINDS OVER ATLC LIGHT. GFS MODEL HINTS AT TRPL WAVES ALONG 35W..50W AND 73W. OTHERWISE GRADIENT WEAK AND WINDS MOSTLY LIGHT. FOR DAY 5 LARGE TROUGH IN WESTERLIES BEGINS TO LIFT NE OVER MID ATLC AS BULGING RIDGE SLIDES EWD TO 70W. STRONG ZONAL FLOW ALOFT FOLLOWING RIDGE OVER PLAINS WITH EMBEDDED SHORTAVE OVER UPPER MIDWEST. ON THE SURFACE DAY 5 CONTINENTAL HIGH PRES MERGES WITH ATLC RIDGE WITH MOSTLY LIGHT WINDS N OF 20N. GULF WINDS LIGHT. GFS HINTS AT POSSIBLE DEVELOPMENT OF WAVE ALONG 42W. CARIB WINDS LIGHT TO MODERATE. WARNINGS... ATLANTIC... NONE. CARIBBEAN... NONE. GULF OF MEXICO... NONE. FORECASTER RRG