000 AXPZ20 KNHC 230404 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC THU OCT 23 2008 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0345 UTC. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 9N84W 8N90W 11N100W 10N110W 10N120W 10N130W 9N140W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 120 NM S OF THE AXIS BETWEEN 118W-124W... AND 60 NM S OF THE AXIS BETWEEN 109W-111W. ...DISCUSSION... NW-N WINDS OF 20 KT ARE CURRENTLY ESTIMATED THROUGH THE GULF OF TEHUANTEPEC BASED ON A QUIKSCAT PASS FROM AROUND 0030 UTC. SEAS HAVE SUBSIDED TO 8 FT IN THAT LOCATION. MODELS ARE IN PRETTY GOOD AGREEMENT THAT THESE WINDS WILL DIMINISH FURTHER THROUGH THU...HOWEVER HIGH PRES PRESSING SWD OVER THE INTERIOR OF MEXICO WILL INCREASE THE PRES GRADIENT ALONG GULF OF TEHUANTEPEC BRINGING ANOTHER ROUND OF GALE FORCE WINDS INTO THE GULF OF TEHUANTEPEC BEGINNING THU EVENING. THIS EVENT IS EXPECTED TO LAST THROUGH FRI NIGHT...AND POSSIBLY INTO SAT MORNING. A WEAK 1011 MB SURFACE LOW IS JUST N OF THE ITCZ NEAR 11.5N104W MOVING NW 10 KT. CONVECTION HAS INCREASED WITHIN 150 NM OF THE LOW IN THE W SEMICIRCLE. LATEST SATELLITE IMAGERY IMAGERY INDICATES THAT CLOUDINESS ASSOCIATED WITH THE LOW HAS BECOME SYMMETRICAL IN APPEARANCE. SOME SLIGHT DEVELOPMENT OF THE LOW IS EXPECTED OVER THE NEXT 12-24 HOURS BEFORE UPPER LEVEL WINDS DISRUPT ITS CHANCES OF ANY MORE DEVELOPMENT. BROAD MID/UPPER RIDGING EXTENDS FROM THE CARIBBEAN SEA W TO NEAR 109W FROM 10N TO 22N. THIS IS PROVIDING UPPER DIFFLUENCE WHICH IS ENHANCING CONVECTION OVER AND WITHIN 180 NM W SEMICIRCLE OF THE LOW. BROAD UPPER ANTICYCLONE IS CENTERED JUST N OF THE ITCZ NEAR 13N135W WITH ITS ASSOCIATED ENVELOPE OF RIDGING COVERING THE AREA S OF 21N W OF 120W. AN UPPER TROUGH IS RAPIDLY MOVING SE OVER THE SW UNITED STATES...AND EXTENDING SW TO ACROSS SOUTHERN BAJA CALIFORNIA ...AND SSW TO 14N117W. EXTENSIVE MID/UPPER LEVEL MOISTURE IS PREVALENT TO THE SE OF TROUGH TO 99W. THIS TROUGH IS FORECAST TO MOVE EASTWARD AS IT SHARPENS AND REACH THE CENTRAL UNITED STATES THROUGH THE END OF THE WEEK. A WELL PRONOUNCED UPPER LEVEL ANTICYCLONE IS LOCATED WELL N OF THE REGION OVER NORTHERN CALIFORNIA...AND IS SHIFTING E WITH TIME. AT THE SURFACE...A RIDGE EXTENDS FROM A 1027 MB HIGH WELL N OF THE AREA NEAR 39N133W SSE 28N130W TO 24N122W TO 20N116W. THE HIGH IS FORECAST TO SHIFT E TOWARDS CALIFORNIA OVER THE NEXT 48 HOURS AS A STRONG STRONG DEEP LAYERED TROUGH MOVES INTO THE NW SECTION OVERNIGHT INTO EARLY THU. A CUT-OFF LOW WILL DEVELOP ON THIS TROUGH AND DROP S ALONG 140W THU AND FRI THEN LIFT NE ACROSS THE FAR NW CORNER OF THE AREA SAT AND SUN. THE ASSOCIATED SURFACE COLD FRONT IS EXPECTED TO ENTER THE FAR NW PORTION OF THE AREA EARLY ON THU IN A WEAKENED STATE. WAVEWATCH MODEL GUIDANCE INDICATES THAT A LARGE SWELL TRAIN WITH SEAS UP TO 10 FT WILL MOVE SE INTO THE NW PORTION ON FRI...WITH YET ANOTHER SWELL TRAIN CONSISTING OF HIGHER SEAS PERHAPS UP TO 11 FT MOVING INTO THE NW PORTION LATE THU THROUGH EARLY FRI...THEN SUBSIDE TO 8 FT LATER FRI INTO EARLY SAT. ANOTHER SURGE OF LARGE SWELLS...POSSIBLY MAXING UP TO 12 FT...IS EXPECTED IN THE NW PORTION OF THE AREA LATER ON SAT AND SUBSIDE SOME BEFORE SPREADING EASTWARD TO THE N CENTRAL PORTION ON SUN. MID/UPPER LEVEL RIDGING N OF 24N W OF 128W PRECEDES THE ABOVE MENTIONED TROUGH CURRENTLY W OF THE AREA. AN INCREASING PRES GRADIENT OVER THE FAR SW UNITED STATES RESULTING AS STRONG HIGH PRES BUILDS S AND SE OVER THE GREAT PLAINS WED AND THU AND INTERACTS WITH LOWER PRES IN THE VICINITY OF THE GULF OF CALIFORNIA IS BRINGING 25-30 KT AND GUSTY NW WINDS TO THE NORTHERN GULF OF CALIFORNIA. THESE WINDS SHOULD DIMINISH TO 20 KT N OF 87N IN ABOUT 48 HOURS. LONG PERIOD CROSS-EQUATORIAL SOUTHERLY SWELLS (ABOUT 8-10 FT) WILL CONTINUE TO EXIST OVER MUCH OF THE SOUTHERN PORTION OF THE AREA THROUGH FRI BEFORE SUBSIDING TO 8-9 IN 24 TO 48 HOURS. $$ AGUIRRE