000 AXPZ20 KNHC 081548 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC WED APR 08 2009 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1530 UTC. ...ITCZ... THE INTERTROPICAL CONVERGENCE ZONE LIES ALONG A LINE FROM 08N83W TO 04N100W TO 00N125W TO 01N140W. SCATTERED MODERATE WITHIN 90NM S OF THE AXIS BETWEEN 83W AND 86W. ...DISCUSSION... GAP WINDS... A HIGH RESOLUTION QUIKSCAT PASS FROM 1248 UTC INDICATED THAT THE STRONG GAP WIND EVENT WAS RAPIDLY WEAKENING IN THE GULF OF TEHUANTEPEC WITH AN ISOLATED AREA OF MARGINAL GALE FORCE WINDS ...35 KT...NOTED. SATELLITE IMAGERY CONTINUES TO INDICATE COOLING SEA SURFACE TEMPERATURES DUE TO UPWELLING AND THIS HAS STABILIZED LOW LEVEL LAPSE RATES AND ALLOWED WINDS TO DROP OFF QUICKLY. WINDS SHOULD DROP BELOW GALE FORCE THIS AFTERNOON AND BELOW 20 KT WITHIN 24 HOURS. AS THE WINDS HAVE DROPPED OFF..SEA HEIGHTS HAVE SUBSIDED TO 10-12 FT IN THE AREA. THIS AREA OF SWELL IS EXPECTED TO PROPAGATE SOUTHWARD INTO THE EQUATORIAL EAST PACIFIC...BUT NOT QUITE REACH THE AREA OF THE GALAPAGOS ISLANDS. TO PUT THIS RECENT HURRICANE FORCE GAP WIND EVENT IN PERSPECTIVE THE LAST SUCH OCCURRENCE OF HURRICANE FORCE WINDS SO LATE IN THE SEASON OCCURRED ON MARCH 30-31 2003. THUS THIS EVENT REPRESENTS THE LATEST DATE FOR HURRICANE FORCE WINDS IN THE GULF OF TEHUANTEPEC SINCE THE ADVENT OF QUIKSCAT IN 1999. INCREASING TRADE WINDS OVER THE CARIBBEAN HAVE EXTENDED INTO THE GULFS OF PAPAGAYO AND PANAMA. A HIGH RESOLUTION QUIKSCAT PASS FROM 1106 UTC SHOWED NLY WINDS OF 20-25 KT IN THE GULF OF PANAMA...BUT MISSED THE GULF OF PAPAGAYO. THESE WINDS ARE EXPECTED TO PERSIST IN THE GULF OF PAPAGAYO DURING THE NEXT FEW DAYS...BUT DIMINISH TO LESS THAN 20 KT IN THE GULF OF PANAMA WITHIN 24 HOURS. ALSO...SW TO W WINDS TO 20 KT ARE DOWNSLOPING OFF THE BAJA CALIFORNIA MOUNTAINS INTO THE NORTHERN GULF OF CALIFORNIA AS A 110-120 KT MID/UPPER-LEVEL JET MAXIMUM SOUTH OF A CLOSED UPPER LOW NEAR 40N123W PROPAGATES EASTWARD WITH THE UPPER LOW. ELSEWHERE... THE SURFACE TROUGH THAT WAS OVER THE NW DISCUSSION AREA HAS DISSIPATED. WAVEWATCH GUIDANCE SUGGESTS THAT LONG PERIOD NW SWELL...UP TO 16 SECONDS AND CONTAINING SEAS UP TO 11 FT IS MOVING SOUTHEASTWARD ACROSS THE NW DISCUSSION AREA. AS THIS SWELL DEPARTS ITS SOURCE REGION...MAXIMUM SEAS WILL SUBSIDE...THOUGH NORTHWESTERLY SWELL OF 8 TO 10 FT WILL OVERTAKE A LARGE PART OF THE DISCUSSION AREA THROUGH LATE THIS WEEK. FARTHER TO THE S...TRADES ARE BEING ENHANCED ON THE SOUTHERN PERIPHERY OF A BROAD SURFACE RIDGE OVER THE NW QUARTER OF THE DISCUSSION AREA...WHERE NE WINDS OF 20 KT ARE PRESENT. SATELLITE IMAGERY AND SCATTEROMETER DATA INDICATE AN INVERTED TROUGH IS LOCALLY ENHANCING THESE WINDS...THE TROUGH EXTENDED FROM 10N114W TO 01N113W. THE AXIS OF THE SUBTROPICAL JET STREAM STRETCHES ALONG A LINE FROM 22N140W TO 25N125W TO SOUTHERN BAJA CALIFORNIA. THIS JET IS ADVECTING ABUNDANT MID TO UPPER LEVEL MOISTURE EASTWARD ACROSS THE DISCUSSION AREA. SE OF THIS JET...ATMOSPHERIC STABILITY AND DEEP LAYERED DRY AIR IN THE VICINITY OF AN UPPER RIDGE OVER THE SE PORTION OF THE DISCUSSION AREA IS SUPPORTING FAIR WEATHER CONDITIONS THERE. LOOKING FURTHER AHEAD...A SHORTWAVE TROUGH CURRENTLY OVER THE GULF OF ALASKA WILL DIVE SOUTHWARD WHILE DEEPENING...AS A VIGOROUS MID/UPPER-LEVEL JET FORCES IT TO DIG SOUTHWARD. COMPUTER MODEL GUIDANCE IS IN GOOD AGREEMENT THAT AN ASSOCIATED SURFACE COLD FRONT WILL APPROACH THE NORTHEASTERN WATERS BY FRIDAY...WITH STRONG WINDS ON EITHER SIDE OF THE FRONT. GUIDANCE ALSO INDICATES THAT A SURFACE LOW WILL DEVELOP NEAR THE CALIFORNIA COAST BEFORE REDEVELOPING INLAND LATE FRIDAY. THIS WILL SERVE TO STRENGTHEN THE SURFACE PRESSURE GRADIENT NEAR THE FRONT...WITH THE POTENTIAL FOR GALE FORCE WINDS NW OF THE COLD FRONT WHERE LOW LEVEL INSTABILITY WILL BE INCREASED. WAVEWATCH GUIDANCE INDICATES SEAS BUILDING TO 14 FT BY FRI NIGHT IN THE WAKE OF THE FRONT. $$ COBB