000 AXPZ20 KNHC 282207 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC FRI SEP 28 2012 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2100 UTC. ...SPECIAL FEATURE... TROPICAL STORM NORMAN LOCATED NEAR NEAR 24.4N 108.7W 1002 MB AT 2100 UTC SEP 28 MOVING N OR 355 DEG AT 14 KT. MAXIMUM SUSTAINED WINDS HAVE WEAKENED TO 35 KT GUSTS 45 KT WITH MINIMUM PRESSURE 1000 MB. THE SAME MIDDLE TO UPPER LEVEL TROUGH RESPONSIBLE FOR THE DEMISE OF MIRIAM HAS MOVED E TO THE GULF OF CALIFORNIA AND STRONGLY AFFECTED NORMAN THIS AFTERNOON...PRODUCING 25-30 KT OF SW WIND SHEAR ACROSS NORMAN PER THE MOST RECENT UW-CIMSS ANALYSIS. NUMEROUS STRONG CONVECTION WAS OCCURRING WITHIN 30 NM ACROSS SW SEMICIRCLE OF NORMAN...WHILE THE SHEAR HAS DISPLACED SCATTERED MODERATE TO STRONG CONVECTION WITHIN 150 NM ACROSS THE NE QUADRANT. NORMAN WILL MOVE NORTHWARD THIS EVENING AND IS EXPECTED TO MOVE ASHORE ALONG THE W COAST OF MEXICO ALONG N PORTIONS OF THE STATE OF SINALOA. TROPICAL STORM FORCE WINDS AND SEAS 8 TO 13 FT WILL CONTINUE ACROSS THE ENTRANCE INTO THE GULF OF CALIFORNIA S OF NORMAN AND E OF 109W UNTIL LANDFALL...THEN QUICKLY FADE THROUGH SAT MORNING. OTHERWISE...THE MAIN THREAT FROM NORMAN IS CONTINUED HEAVY RAINFALL WELL E AND SE OF NORMAN...ALONG THE W SLOPES AND COASTAL PLAINS OF THE SIERRA MADRE OCCIDENTALES. HEAVY RAINS FROM JALISCO TO SINALOA COULD LEAD TO FLASH FLOODING AND MUDSLIDES. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP4/WTPZ24 KNHC FOR MORE DETAILS. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... MONSOON TROUGH FROM 08N77W TO 10.5N96W TO 13N103W WHERE IT REMAINS FRACTURED...THEN RESUMES FROM NEAR 18N108W TO 10N130W TO 09N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION NOTED WITHIN 150 NM N AND 240 NM S OF TROUGH E OF 103W. SCATTERED MODERATE ISOLATED STRONG CONVECTION NOTED FROM 09N TO 23N BETWEEN 103W AND 108W. CLUSTERS OF SCATTERED MODERATE TO STRONG WITHIN 90 NM S OF TROUGH BETWEEN 108W AND 131W. ...DISCUSSION... POST-TROPICAL REMNANT LOW MIRIAM CONTINUES TO LINGER NEAR 21.5N 116W AND SLOWLY WEAKEN OVER COLD WATER WITHOUT DEEP CONVECTION. FRESH WINDS TO 25 KT ON THE S SIDE OF THIS LOW ARE MIXING WITH SW SWELL TO MAINTAIN SEAS 8 TO 10 FT WITHIN 180 NM OF THE CENTER. THE LOW WILL DRIFT SLOWLY SOUTHWARD THROUGH SUN AND EVENTUALLY DEGENERATE INTO AN OPEN TROUGH BY TUE. A WEAKENING COLD FRONT EXTENDING FROM 40N134W TO 33N150W BISECTS THE SUBTROPICAL HIGH NW OF THE AREA INTO TWO HIGH PRES CELLS... CENTERED NEAR 38N150W AND 31N150W. NW SWELL ASSOCIATED WITH THE WEAK FRONT WILL SWEEP INTO THE NW PORTION OF THE DISCUSSION AREA LATE TONIGHT...BUILDING SEAS TO 9 FT NW OF A LINE FROM 30N130W TO 24N140W BY SAT AFTERNOON. THE SUBTROPICAL HIGH WILL STRENGTHEN SAT AND SHIFT WELL N OF THE AREA W OF OREGON NEAR 43N133W SUN. THIS WEAK RIDGE PATTERN WILL SUPPORT MODERATE N-NE TRADE WINDS OVER MOST OF THE REGION N OF 16N W OF 120W THROUGH THE WEEKEND. WITH NORMAN LIFTING QUICKLY N INTO THE GULF OF CALIFORNIA... FRESH SWLY WINDS OCCURRING ALONG AND S OF THE MONSOON TROUGH HAVE BEGUN TO SUBSIDE THIS AFTERNOON. GFS MODEL GUIDANCE SHOWS THE SW WINDS ASSOCIATED WITH THE MONSOON TROUGH GRADUALLY DIMINISHING BELOW 20 KT THROUGH SAT NIGHT. EXPECT THE TROUGH TO REMAIN CONVECTIVELY ACTIVE FOR THE NEXT COUPLE OF DAYS PARTICULARLY BETWEEN 115W AND 135W WITH MULTIPLE WEAK VORTICES EMBEDDED WITHIN THE CONVERGENCE ZONE. HIGH SEAS 8-10 FT GENERATED BY FRESH SW WINDS BETWEEN 105W-125W WILL SUBSIDE BELOW 8 FT BY SAT AFTERNOON. $$ STRIPLING