000 AGXX40 KNHC 200456 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 130 AM EDT THU APR 20 2006 MARINE WEATHER DISCUSSION FOR GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. A LARGE UPPER VORTEX CENTERED NEAR 40N65W DOMINATED THE CIRCULATION W OF 50W N OF 20N TONIGHT. AN OPEN RIDGE WAS OVER THE CENTRAL GULF. ON THE SURFACE A WEAK COLD FRONT WAS OVER THE CENTRAL ATLC NEAR 31N54W AND EXTENDED TO THE SRN BAHAMAS. SE WINDS OVER THE WRN GULF WERE NEAR 20 KT TONIGHT. A SHORTWAVE TROUGH IS EXPECTED TO DROP SWD AROUND THE UPPER VORTEX DAY 1 LOWERING HEIGHTS BETWEEN 60W AND 70W. THIS WILL HELP SUPPORT THE COLD FRONT AS IT MOVES SLOWLY EWD. ONLY SW WINDS AHEAD OF THE FRONT WILL BE A PROBLEM DAY 1. GRADIENT AGAINST THE ATLC RIDGE WILL PRODUCE 20 TO 25 KT WINDS. CARIB WINDS MOSTLY LIGHT TO MODERATE. WRN GULF WINDS REMAIN SE TO 20 KT DAY 1. THE UPPER VORTEX IS FORECAST TO TRACK EWD DAY 2 WITH IT'S AXIS ALONG 60W. THE UPPER OPEN RIDGE MVOES TO THE SE COAST WHILE A NEW STRONG VORTEX MOVES THE MS VALLEY. THE ATLC COLD FRONT WEAKENS DAY 2 AS IT MOVES TO 55W. A WEAK POLAR AIRMASS FOLLOWS NEAR 30N70W. GULF WINDS DECREASE AS A WEAK FRONT APPROACHES THE TX COAST. CARIB WINDS INCREASE TO 20 KT DAY 2 AS THE POLAR AIRMASS MOVES SWD. OUTLOOK PERIOD... A PROGRESSIVE PATTERN CONTINUES DAY 3 AS LARGE VORTICIES ROLL EWD. THE EASTERN VORTEX MOVES TO 55W WHILE THE SECOND ONE'S AXIS MVOES TO 85W. ON THE SURFACE THE ATLC FRONT MOVES E OF 55W DAY 3 WITH WEAKENING WINDS. THE POLAR HIGH MOVES LITTLE. GULF WINDS REMAIN LIGHT WHILE CARIB WINDS REMAIN ELY 20 TO 25 KT. WHILE THE FIRST VORTEX MOVES TO 50W THE SECOND UPPER TROUGH MOVES TO 75W DAY 4. WEAK SURFACE TROUGHING DEVELOPS OVER THE BAHAMAS AS A RESULT OF THE UPPER TROUGH. SE WINDS INCREASE TO 20 KT OVER THE ATLC S OF 25N BETWEEN 65W AND 72W. LITTLE CHANGE ELSEWHERE. PROGRESSIVE EWD MOVEMENT CONTINUES DAY 5 WITH FIRST UPPER TROUGH LEAVING THE AREA AND THE SECOND TROUGH MOVING TO 65W. ON THE SURFACE A WEAK TROUGH REMAINS OVER THE CENTRAL BAHAMAS. THE OLD POLAR HIGH MOVES SLOWLY E TO NEAR 33N59W. GULF WINDS INCREASE OVER THE SRN PORTION TO 20 KT. CARIB WINDS REMAIN ABOUT THE SAME WITH 20 KT WINDS MAINLY S OF 17N E OF 80W. WARNINGS... ATLANTIC... NONE. CARIBBEAN... NONE. GULF OF MEXICO... NONE. FORECASTER RRG