000 AGXX40 KNHC 300511 MIMATS MARINE WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 130 AM SAT SEP 30 2006 MARINE WEATHER DISCUSSION FOR GULF OF MEXICO...CARIBBEAN SEA AND SOUTHWEST NORTH ATLC S OF 31N W OF 55W. A LONGWAVE TROUGH OVER THE ERN CONUS CONTINUES TO SHIFT SLOWLY EWD TONIGHT. HEIGHTS DON'T APPEAR TO BE FALLING ANY FURTHER OVER THE NRN GULF. A LARGE MID LEVEL RIDGE COVERS THE CENTRAL ATLC HOLDING SATATIONARY NEAR 35N53W. A EQUALLY LARGE UPPER TROUGH COVERS THE NE ATLC AND ENERGY IS MOVING SWD ALONG 30W TO 40W WELL NE OF THE AREA. ON THE SURFACE TONIGHT T.S. ISAAC CONTINUES TO LUMBER WNW AT 7 KT CAUGHT UNDER THE UPPER RIDGE WITH LIGHT STIRRING CURRENTS. A COLD FRONT EXTENDS FROM 31N75W ACROSS CENTRAL FL THEN BACK ACROSS THE N CENTRAL GULF. THE FRONT IS MOVING ESE. TRPCL WAVES WERE ALONG 56W..67W AND 90W MOVING W 10 TO 15 KT. LATER DAY 1 THE LONGWAVE TROUGH AXIS WILL BE ALONG 80W WITH MOST OF THE ENERGY SHIFTING EWD IN THE TROUGH. THE BLOCKING RIDGE OVER THE ATLC REMAINS STATIONARY. THE STRONG SHORTWAVE OVER THE NE ATLC CONTINUES SWD ALONG 35N BETWEEN 30W AND 40W. ON THE SURFACE LATER DAY 1 T.S. ISAAC IS FORECAST TO BECOME A CAT ONE HRCN NEAR 31N59W STILL MOVING SLOWLY NW. THE COLD FRONT OVER THE GULF WILL MOVE ESE TO S FL AND THE WRN BAHAMAS AND STALL. WEAK HIGH PRES FOLLOWING THE FRONT MOVES TO THE NE GULF WITH LIGHT WINDS. CARIB WINDS TO 20 KT CONTINUE OVER THE CENTRAL PORTION. ATLC WINDS MOSTLY LIGHT. FOR DAY 2 THE WESTERLIES BECOME MORE ZONAL W OF 90W FORCING THE LONGWAVE TROUGH TO MOVE EWD TO 75W. THE MID ATLC RIDGE BEGINS TO BUILD BACK TO THE SW AS THE TROUGH TRIES TO RIDE OVER THE TOP OF THE RIDGE. STRONG SURGE ALOFT CONTINUES OVER THE ERN ATLC AS ENERGY DROPS TO 30N34W. ON THE SURFACE DAY 2 LOW PRESSURE FORMS WITH THIS STRONG IMPULSE OVER THE ERN ATLC AND NLY WINDS INCREASE N OF 27N E OF 40W. OTHERWISE THE ATLC REMAINS FAIRLY QUIET WITH LIGHT TO MODERATE WINDS. WEAK FRONTAL TROUGHING EXTENDS FROM THE CENTRAL BAHAMAS NE TO 31N70W WITH HIGH PRES OVER THE GULF WILL PRODUCE MODERATE NE WINDS OVER THE SE GULF. CARIB WINDS CHANGE LITTLE. OUTLOOK PERIOD... FOR DAY 3 THE STRONG MID LEVEL TROUGH MOVES SLOWLY EWD TO 70W AS MID LEVEL HEIGHTS BEGIN RISING ALONG 90W. THE MID ATLC RIDGE HOLDS FIRM NEAR 34N50W BLOCKED BY THE STRONG TROUGH OVER THE ERN ATLC. ON THE SURFACE DAY 3 HIGH PRESSURE BEGINS TO STRENGTHEN OVER MID OCEAN E OF 60W WHICH WILL INCREASE THE NE AND E TRADES N OF 18N. THE TROUGH OVER THE BAHAMAS SLIDES E TO NEAR 70W AS HIGH PRES OVER THE GULF MOVES NE. WINDS BETWEEN 70W AND 90W CONTINUE NE TO 20 KT. CARIB WINDS CHANGE LITTLE. DAY 4 FINDS THE STRONG MID LEVEL TROUGH OFF THE E COAST FINALLY LIFTING OUT OVER THE MID ATLC RIDGE. MID LEVEL HIGH PRESSURE BUILDS ALONG 90W WITH A CENTER NEAR 32N92W. A STRONG CUTOFF LOW FORMS OVER THE ERN ATLC NEAR 32N27W. ON THE SURFACE DAY 4 THE GFS MODEL SHOWS THE PRES GRADIENT TIGHTENING BETWEEN 70W AND 90W WITH INCREASING NE WINDS TO 20 KT WITH GUSTS TO 25 KT. THE ATLC RIDGE WILL MAINTAIN ELY TRADES TO 20 KT FROM 17N TO 24N E OF 65W. CARIB WINDS REMAIN LIGHT TO MODERATE. FINALLY FOR DAY 5 WEAK MID LEVEL TROUGHING LIFTS NWD ALONG 70W WHILE THE RIDGE OVER THE NRN GULF DRIFTS NWD ALONG 90W. THE MID ATLC RIDGE WEAKENS SOME AND DRIFTS S TO NEAR 28N52W. THE ERN ATLC CUTOFF LOW MOVES NNE TO NEAR 35N26W. ON THE SURFACE DAY 5 THE ATLC RIDGE STRENGTHENS SLIGHTLY WITH A CENTER 1023 MB NEAR 32N42W. THIS WILL INCREASE ELY TRADES TO 20 KT FROM 17N TO 25N E OF 65W. WEAK TROUGHING CONTINUES OVER THE ERN BAHAMAS WITH HIGH PRESSURE OVER THE SE CONUS RESULTING IN A CONTINUATION OF BRISK NE WINDS TO 20 KT BETWEEN 70W AND 95W. EXTREME NW CARIB WINDS COULD ALSO INCREASE SOME TO 20 KT. WARNINGS... ATLANTIC... NONE. CARIBBEAN... NONE. GULF OF MEXICO... NONE. FORECASTER RRG