000 AXPZ20 KNHC 230332 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC FRI JAN 23 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 0115 UTC. ...ITCZ... THE INTERTROPICAL CONVERGENCE ZONE LIES ALONG THE AXIS FROM 05N76W TO 03N95W TO 06N115W TO 04N130W TO 05N140W. SCATTERED MODERATE CONVECTION WITHIN 90 NM N OF AXIS BETWEEN 110W AND 112W. ...DISCUSSION... THE PREVIOUS ASCAT PASS FROM 1538 UTC CONFIRMED THE END OF THE GALE EVENT IN THE GULF OF TEHUANTEPEC...WITH THE HIGHEST RETURNS SHOWING WINDS ONLY TO 30 KT. SINCE THEN...THE SHIP OBSERVATION 9VEN5 NEAR 12.6N99.5W AT 0000 UTC REPORTED 13 KT WINDS...SHOWED THAT THE AREA OF 20-30 KT WINDS IS SHRINKING EASTWARD AND THE QUIKSCAT PASS JUST RECEIVED FROM 0049 UTC CONFIRMS THE CONTRACTION OF THE WIND FIELD...WITH WINDS FROM 25-30 KT ONLY WITHIN APPROXIMATELY 75 NM FROM THE COAST. WINDS ARE EXPECTED TO DIMINISH BELOW 20 KT BY FRI AFTERNOON. THE 1538 ASCAT PASS ALSO HAD PARTIAL COVERAGE OF THE GULF OF PAPAGAYO WHERE WINDS WERE STILL SOLIDLY IN THE 20 TO 25 KT RANGE. WINDS HERE ARE EXPECTED TO DIMINISH SLIGHTLY OVER THE NEXT 24 TO 48 HOUR AS THE PRESSURE GRADIENT BETWEEN HIGH PRESSURE OVER CENTRAL AMERICA AND LOW PRESSURE OVER COLUMBIA SLACKENS. LAST SCATTEROMETER OBSERVATIONS OVER THE GULF OF FONSECA...QUIKSCAT AT 1218 UTC...ALSO SHOWED WINDS IN THE 20 TO 25 KT RANGE...BUT WINDS ARE EXPECTED TO DIMINISH HERE MORE RAPIDLY THAN IN THE GULF OF PAPAGAYO AS THE WIND DIRECTION IN THE WESTERN CARIBBEAN BECOMES MORE EASTERLY AND LESS FAVORABLE FOR BLEEDING THROUGH THE GULF OF FONSECA. THE 2310 UTC QUIKSCAT PASS OVER THE GULF OF PANAMA SHOWED WINDS IN THE 20 TO 25 KT RANGE N OF 05.5N BETWEEN 79W AND 80.5W. THESE WINDS SHOULD BE DIMINISHING OVERNIGHT AS HIGH PRESSURE TO THE NORTH WEAKENS. THE REMAINS OF THE DISSIPATING COLD FRONT APPROACHING BAJA CALIFORNIA WILL BE LIFTED N OF THE AREA BY TOMORROW AFTERNOON AS THE DEEP LAYER LOW JUST N OF FAR WESTERN WATERS OVERTAKES THIS SYSTEM. CONVECTION ASSOCIATED WITH THE DIFFLUENCE AREA ON THE LEADING EDGE OF THE UPPER TROUGH SUPPORTING THIS COLD FRONT IS GENERATING ISOLATED MODERATE CONVECTION FROM 09N TO 15N BETWEEN 104W AND 112W AT THE MOMENT WHILE BROKEN MID TO UPPER LEVEL CLOUDS ARE LIKELY BRINGING SOME STRATIFORM PRECIPITATION TO THE BAJA AND MUCH OF NW MEXICO...WITH SOME ISOLATED EMBEDDED CONVECTION POSSIBLE. THE MID TO UPPER LEVEL SUPPORTING TROUGH IS EXPECTED TO BECOME MORE POSITIVELY TILTED...WITH THE LEADING EDGE MOVING INTO NW MEXICO OVERNIGHT TONIGHT WHILE A WEAK UPPER LOW IS PINCHED OFF FARTHER SOUTH. A WEAK SURFACE TROUGH... REFLECTING THE UPPER LOW...IS EXPECTED TO LINGER S OF 15N BETWEEN 114W AND 118W INTO FRI BEFORE DISSIPATING. THE DEEP LAYER LOW N OF THE FORECAST AREA WILL BE SLOW TO MOVE EASTWARD...AMPLIFYING OVER NW WATERS OVER THE NEXT FEW DAYS AS IT IS RELOADED WITH NORTHERN STREAM ENERGY. THE ASSOCIATED COLD FRONT WILL ALSO BE SLOW MOVING. WINDS IN EXCESS OF 25 KT ARE EXPECTED TO REMAIN N OF FORECAST WATERS...BUT SEAS ARE EXPECTED TO BUILD TO THE 16 TO 18 FT RANGE WITH THIS SYSTEM. LONG PERIOD SWELL...ON THE ORDER OF 15 TO 16 SECONDS...WILL MOVE WELL AHEAD OF THE FRONT...REACHING BAJA CALIFORNIA OVERNIGHT FRI NIGHT. HIGH PRESSURE IN ADVANCE OF THIS COLD FRONT IS EXPECTED TO BE SQUEEZED BETWEEN THE FRONT AND CLIMATOLOGICALLY LOW PRESSURE OVER THE GULF OF CALIFORNIA ENHANCED BY A COLD FRONT PASSING SOUTHWARD THROUGH NORTHERN MEXICO ON SAT. THE RESULTING PRESSURE GRADIENT IS EXPECTED TO INCREASE WINDS TO 20 TO 25 KT OVER THE MOUTH OF THE GULF OF CALIFORNIA FRI NIGHT THROUGH SAT. $$ SCHAUER CLARK