000 AXPZ20 KNHC 110956 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC SAT APR 11 2009 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0930 UTC. ...ITCZ... THE INTERTROPICAL CONVERGENCE ZONE LIES ALONG A LINE FROM 04N77W TO 04N89W TO 08N93W TO 04N119W TO 05N133W TO 07N140W. SCATTERED MODERATE CONVECTION IS FROM 04N TO 07N BETWEEN 90W AND 97W. SCATTERED MODERATE CONVECTION IS WITHIN 30 NM OF 03.5N129.5W. ...DISCUSSION... GALE WARNING FOR THE FAR NORTHERN GULF OF CALIFORNIA... RECENT SATELLITE IMAGERY INDICATES THAT THE SURFACE TROUGH... PREVIOUSLY W OF THE BAJA CALIFORNIA COAST AT 11/0000 UTC...HAS MOVED ACROSS BAJA CALIFORNIA AND INTO THE N GULF OF CALIFORNIA. THE WESTERLY COMPONENT OF THE LOW LEVEL FLOW W OF THE SURFACE TROUGH IS DOWNSLOPING INTO THE NORTHERN GULF OF CALIFORNIA. SHEAR VORTICITY GENERATED AT THE NORTHERN PERIPHERY OF THIS TROUGH IS DEEPENING A SURFACE LOW AT THE SOUTHERN EXTENT OF THE MID-LEVEL VORTICITY MAXIMUM THAT CONTINUES DIGGING SOUTHWARD. THIS LOW IS ANALYZED AS A 1008 MB SURFACE LOW NEAR 31N114W AT 11/0600 UTC. IN TURN...THE SURFACE PRESSURE GRADIENT CONTINUES TO STEEPEN IN THE VICINITY OF THE SURFACE LOW...FURTHER INCREASING SW TO W WINDS IN THE N GULF OF CALIFORNIA. DEEP LAYER DRY AIR WRAPPING CYCLONICALLY AROUND THE MID-LEVEL VORTICITY MAXIMUM IS ALSO LIKELY BEING FORCED TO THE SURFACE BY SURFACE PRESSURE FALLS...FURTHER ENHANCING A GALE WIND EVENT IN THE N GULF OF CALIFORNIA N OF 30.5N. THE HIGH RESOLUTION QUIKSCAT PASS AROUND 11/0200 UTC INDICATED SW TO W SURFACE WINDS OF 35 TO 45 KT IN THIS REGION. THIS IS WHERE A SHORT-DURATION GALE WARNING IS IN EFFECT. AS THE SURFACE LOW DRIFTS INLAND AND INTO THE SW CONUS DURING THE NEXT SEVERAL HOURS...THE PRESSURE GRADIENT IN THE WARNING AREA WILL SLACKEN...WITH THE THREAT FOR GALE FORCE WINDS ENDING BY 11/1200 UTC. SINCE THE GFS IS UNDER-FORECASTING OBSERVED WINDS IN THIS AREA...MAXIMUM WAVE HEIGHTS IN THE N GULF OF CALIFORNIA ARE LIKELY AROUND 9 FT...WHICH IS ABOVE WAVEWATCH GUIDANCE. OTHER GAP WIND AREAS... TRADE WINDS OVER THE CARIBBEAN REGION ARE FORECAST TO EXTEND INTO THE GULF OF PAPAGAYO DURING THE NEXT FEW DAYS...WHEN SURFACE WINDS ARE EXPECTED TO OCCASIONALLY REACH 20 KT. TRADES... A BROAD AREA OF TRADE WINDS IS BEING ENHANCED ON THE SOUTHERN PERIPHERY OF A BROAD SURFACE RIDGE OVER THE NW QUARTER OF THE DISCUSSION AREA...ANCHORED BY A 1028 MB SURFACE HIGH NEAR 32N140W. NE WINDS TO 20 KT ARE PRESENT FROM 07N TO 21N W OF 122W BASED ON THE QUIKSCAT PASS AROUND 11/0345 UTC AND THE ASCAT PASS AROUND 11/0600 UTC. COMPUTER MODEL GUIDANCE INDICATES THIS AREA OF WINDS SLOWLY SINKING SOUTHWARD DURING THE NEXT FEW DAYS AS A SURFACE RIDGE N OF THE DISCUSSION AREA SLOWLY TRANSLATES EAST-SOUTHEASTWARD. SATELLITE IMAGERY AND SCATTEROMETER DATA INDICATE AN INVERTED SURFACE TROUGH EXTENDING FROM 15N113W TO 08N119W LOCALLY ENHANCING THESE WINDS. ENHANCED BOUNDARY LAYER MOISTURE CONVERGENCE IS SUPPORTING SCATTERED SHOWERS WITHIN 90 NM EITHER SIDE OF THE SURFACE TROUGH. ALSO...RELATIVELY LOWER SURFACE PRESSURE OVER MEXICO DURING THE NEXT FEW DAYS...COMBINED WITH LOCAL TOPOGRAPHICAL EFFECTS...WILL LOCALLY ENHANCE NORTHWESTERLY WINDS NEAR THE W COAST OF MEXICO FROM 17N TO 21N. WINDS WILL LOCALLY REACH 20 KT IN THIS AREA...AS RECENT ASCAT AND QUIKSCAT PASSES CONFIRM. ALSO...A SURFACE TROUGH IS EMBEDDED WITHIN THE ITCZ AXIS. THIS SURFACE TROUGH EXTENDS FROM 05N130W TO 01N131W...AND IS ENHANCING THE SCATTERED MODERATE CONVECTION WITHIN 30 NM OF 03.5N129.5W. WIND WAVES RESULTING FROM THE PERSISTENT TRADE WINDS WILL REACH 8 TO 9 FT...WITH A LARGE AREA OF SEAS OF 8 TO 10 FT IN MERGING SW AND NW SWELL AFFECTING MUCH OF THE DISCUSSION AREA DURING THE NEXT FEW DAYS. ELSEWHERE... A SHORTWAVE TROUGH CURRENTLY OVER THE E PACIFIC REGION CONTINUES TO DIVE SOUTHWARD WHILE DEEPENING...AS A VIGOROUS MID/UPPER-LEVEL JET FORCES IT TO DIG SOUTHWARD. A SURFACE TROUGH ASSOCIATED WITH THE SURFACE LOW OVER THE N GULF OF CALIFORNIA EXTENDS FROM 27N113W TO 20N124W...AND IS MOVING SOUTHWARD ACROSS THE NORTHEASTERN WATERS. NW WINDS UP TO 30 KT ARE N OF THE TROUGH...WITH GALES N OF 30N. WAVEWATCH GUIDANCE INDICATES SEAS UP TO 12 FT N OF THE TROUGH...WITH THE ASSOCIATED NORTHWESTERLY SWELL AFFECTING THE NE DISCUSSION AREA THROUGH THE WEEKEND. BY EARLY NEXT WEEK...A WEAKENING COLD FRONT WILL APPROACH THE NE DISCUSSION AREA...WITH INCREASED N WINDS AND BUILDING SEAS IN NW SWELL ENTERING THE DISCUSSION AREA BY EARLY TUESDAY. $$ COHEN