000 AXPZ20 KNHC 170309 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC TUE FEB 17 2009 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 0300 UTC. ...ITCZ... THE INTERTROPICAL CONVERGENCE ZONE LIES ALONG A LINE FROM 03N78W TO 01N90W TO 02N105W TO 03N125W TO 02N140W. NO SIGNIFICANT CONVECTION. ...DISCUSSION... A NEARLY VERTICALLY-STACKED DEEP LOW CONTINUES APPROACHING THE NW CALIFORNIA COAST. THE ATTENDANT LARGE AMPLITUDE DEEP TROUGH EXTENDS INTO THE NORTHERN PORTION OF THE DISCUSSION AREA...WITH A 100-110 KT UPPER LEVEL JET ROTATING AROUND THE BASE OF THE UPPER TROUGH INTO THE SW CONUS. AN ASSOCIATED SURFACE TROUGH EXTENDS SOUTHWARD INTO THE DISCUSSION AREA FROM 30N116W TO 25N121W. W OF THE SURFACE TROUGH TO 123W...W TO NW WINDS TO 20 KT ARE OCCURRING...WITH LIGHTER SW TO W WINDS E OF THE TROUGH. THE SURFACE TROUGH WILL CONTINUE TO DISSIPATE WHILE SLOWLY DRIFTING EASTWARD DURING THE NEXT SEVERAL HOURS AS IT ENCOUNTERS A SURFACE RIDGE WITH AN AXIS EXTENDING FROM 24N112W TO 21N126W...AND THE UPPER JET DEPARTS THE REGION. IN THE MEANTIME...THE UPPER JET CONTINUES TO ADVECT COPIOUS AMOUNTS OF MID/UPPER-LEVEL MOISTURE INTO THE CENTRAL BAJA CALIFORNIA. FARTHER TO THE S... SUBSIDENCE...DEEP LAYER DRY AIR...AND STABLE ATMOSPHERIC CONDITIONS ASSOCIATED WITH AN UPPER RIDGE S OF 18N BETWEEN 84W-113W ARE RESULTING IN FAIR WEATHER ACROSS SOUTHEASTERN PORTIONS OF THE DISCUSSION AREA. A PROGRESSIVE UPPER PATTERN IS FORECAST TO CONTINUE INTO MIDWEEK AS ANOTHER DEEP LOW APPROACHES THE NORTHERN PORTION OF THE DISCUSSION AREA. AN ASSOCIATED COLD FRONT WILL ENTER THE NORTHWEST WATERS BY LATE TUESDAY. THIS FRONT WILL BE REINFORCED BY LATE WED...WHEN IT WILL BE ACCOMPANIED BY SW TO W WINDS OF 20 TO 30 KT. THESE CONDITIONS WILL BE PRIMARILY CONFINED TO LOCATIONS NW OF A LINE FROM 30N125W TO 24N140W. THE LATEST COMPUTER MODEL GUIDANCE IS TRENDING UPWARDS WITH REGARD TO THESE WIND SPEEDS. THE POTENTIAL FOR GALE FORCE WINDS IN THE FAR NW PORTION OF THE DISCUSSION AREA WEDNESDAY NIGHT AND THURSDAY MORNING...ALBEIT LOW...CANNOT BE COMPLETELY RULED OUT AS THE LOW NORTH OF THE AREA DEEPENS. ONE INHIBITING FACTOR FOR GALES WILL BE WARM AIR ADVECTION OVER COOLER WATERS LIMITING LOW LEVEL MIXING AHEAD OF THE FRONT. THE DEEP LOW WILL STALL NORTH OF THE AREA FROM THURSDAY THROUGH SUNDAY...WITH A SERIES OF EMBEDDED DEEP LOWS PIVOTING AROUND EACH OTHER DURING THIS PERIOD. CORRESPONDINGLY...SURFACE WINDS OF 20 TO 25 KT WILL PERIODICALLY IMPACT FAR NW PORTIONS OF THE DISCUSSION AREA LATE THIS WEEK AND THIS WEEKEND. BY LATE THIS WEEKEND...AN UPPER LEVEL JET DIVING SOUTHEASTWARD TOWARD THE DEEP LOW WILL EJECT THE LOW NORTHEASTWARD...PULLING THE STRONGER WINDS N OF THE DISCUSSION AREA BY EARLY NEXT WEEK. MEANWHILE...SURFACE RIDGING S AND E OF THE FRONTS WILL MAINTAIN EASTERLY TRADE WINDS GENERALLY UNDER 20 KT FOR MUCH OF THIS WEEK. GAP WINDS... IN THE WAKE OF THE DEEP LOW CURRENTLY APPROACHING THE NW CALIFORNIA COAST...STRONG SURFACE HIGH PRESSURE IS FORECAST TO BUILD OVER THE GREAT BASIN OF THE CONUS BY MIDWEEK...STEEPENING THE SURFACE PRESSURE GRADIENT OVER THE SW CONUS. IN TURN... NORTHWESTERLY WINDS ARE FORECAST TO INCREASE IN THE GULF OF CALIFORNIA BY LATE WEDNESDAY...WITH STRONG WINDS CONTINUING THERE THROUGH EARLY FRIDAY. HOWEVER...THE FORECAST PRESSURE GRADIENT DOES NOT APPEAR STRONG ENOUGH TO SUPPORT A GALE EVENT IN THE GULF OF CALIFORNIA AT THIS TIME. THE ABSENCE OF ANY STRONG FRONTAL PASSAGE ALSO PRECLUDES A GALE THREAT THERE. ADDITIONALLY...SURFACE RIDGING IN MEXICO IN THE WAKE OF A COLD FRONT CURRENTLY IN THE GULF OF MEXICO WILL INDUCE A BRIEF PERIOD OF 20-KT WINDS IN THE GULF OF TEHUANTEPEC DURING THE NEXT DAY...WITH ANOTHER PERIOD OF STRONGER WINDS THERE LATE THIS WEEK. ALSO...TRADE WIND FLOW IN THE CARIBBEAN WILL LIKELY FUNNEL INTO THE GULFS OF PAPAGAYO AND PANAMA... MAINTAINING PERIODS OF STRONGER WINDS THERE DURING THE NEXT FEW DAYS. $$ COHEN