000 AXPZ20 KNHC 092205 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC THU APR 09 2009 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2145 UTC. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 9N85W 3N100W 2N110W 4N123W 2N131W 3N140W. NO SIGNIFICANT CONVECTION IS NOTED. ...DISCUSSION... LATEST WATER VAPOR IMAGERY IMAGERY SHOWS A SHARPENING SHORTWAVE TROUGH PRESSING SEWD INTO THE N/CENTRAL PORTION OF THE AREA N OF 23N BETWEEN 123W AND 134W DUE TO A VIGOROUS MID/UPPER LEVEL JET STREAM ARCING SEWD INTO THE AREA INTO THE AREA BEHIND IT ...AND ROUNDING ITS BASE. THE ASSOCIATED SURFACE COLD FRONT CURRENTLY JUST N OF THE AREA LIES ALONG 32N BETWEEN 130W AND 140W AS ANALYZED ON THE 1800 UTC SURFACE ANALYSIS AND VIVIDLY DISPLAYED IN VISIBLE SATELLITE IMAGERY. GLOBAL MODEL GUIDANCE SUGGESTS THAT A SURFACE LOW WILL DEVELOP OFF THE SRN CALIFORNIA COAST ON FRI NEAR 33N118W 1007 MB AND MOVE SE MOVING INLAND THE SRN CALIFORNIA COAST FRI NIGHT INTO SAT PUSHING THE FRONT SE THROUGH THE NE WATERS TONIGHT INTO FRI MORNING. THE FRONT WILL BE PRECEDED AND FOLLOWED BY STRONG WINDS...BUT WEAKEN FROM 30N115W TO 25N118W BY SAT AFTERNOON. THE DEVELOPMENT OF THE LOW IN COMBINATION WITH HIGH PRES RIDGING TO THE WILL SERVE TO STRENGTHEN THE SURFACE PRESSURE GRADIENT NEAR THE FRONT LEADING TO NW WINDS OF 25-30 KT WITH THE POTENTIAL FOR GALE FORCE WINDS FROM 30N-32N E OF 130W WHERE LOW LEVEL INSTABILITY WILL INCREASE. LATEST WAVEWATCH GUIDANCE DEPICTS MAXIMUM COMBINED WAVE HEIGHTS BUILDING TO 16 FT OVER THE FAR NE WATERS BY FRI NIGHT BEHIND THE FRONT...BUT SUBSIDING TO 10 FT DURING SAT. A SWATH OF MODERATE SUBSIDENCE PROTRUDES INTO THE AREA IN CONFLUENT FLOW PATTERN BEHIND THE TROUGH...AND EXTENDS FROM 22N-27N BETWEEN 127W-136W AND WITHIN 90 NM EITHER SIDE OF LINE FROM 25N135W TO 27N140W. THE ABOVE MENTIONED JET STREAM ENTERS THE REGION THROUGH 24N140W...AND EXTENDS TO 22N135W TO 23N130W AND NE TO 27N120W TO ALONG 26N130W ROUNDING THE BASE OF THE UPPER TROUGH NE TO ACROSS CENTRAL BAJA CALIFORNIA AND TO ACROSS CENTRAL MEXICO. THIS JET CONTINUES TO TRANSPORT AMPLE MID AND HIGH LEVEL MOISTURE IN THE FORM OF BROKEN CLOUDS ENE TO ACROSS NRN AND CENTRAL BAJA CALIFORNIA AND CENTRAL MEXICO. MAXIMUM WINDS WITHIN THE JET CORE ARE 70-120 KT. OVER THE FAR ERN PORTION OF THE AREA...THE JET RIDGE NE ACROSS MID/UPPER LEVEL RIDGING THAT EXTENDS FROM FROM NW MEXICO N TO THE WRN U.S. THIS RIDGE IS ADVANCING EWD AHEAD OF THE SHORTWAVE TROUGH MENTIONED ABOVE. A MID/UPPER LEVEL TROUGH EXTENDS FROM 18N113W SW TO 9N119W TO 1N125W. TO THE E AND SE OF THIS TROUGH...BROAD UPPER RIDGING WITH AN ASSOCIATED ANTICYCLONE NEAR 2N107W IS MAINTAINING RATHER DRY AND STABLE CONDITIONS OVER THE SE PORTION OF THE AREA. AT THE SURFACE...A SURFACE RIDGE EXTENDS THROUGH 27N140W TO 24N128W TO 19N110W. LATEST VISIBLE SATELLITE IMAGERY SHOWS THREE INVERTED TROUGHS WITH THE FIRST ALONG 7N113W TO 12N115W...THE SECOND...BEING THE MOST DISTINCT AS IT WAS NICELY REVEALED IN A QUIKSCAT PASS FROM NEAR 1400 UTC THIS MORNING...EXTENDS FROM 2N123W TO 8N124W AND THE THIRD ALONG 134W FROM 8N TO 12N. ALL TROUGHS ARE MOVING W ABOUT 15 KT. THE FIRST TROUGH HAS SCATTERED MODERATE CONVECTION WITHIN 30 NM OF 13N113W DUE TO INFLUENCE OF THE MID/UPPER LEVEL TROUGH JUST TO ITS W. THE SECOND TROUGH HAS ISOLATED WEAK CONVECTION WITHIN 30 NM OF ITS AXIS FROM 4N TO 7N. THE THIRD TROUGH ONLY HAS ISOLATED SHOWERS WITHIN 60 NM OF ITS AXIS. THE COMBINATION OF THESE TROUGH WITH THE SURFACE RIDGE TO THE N IS RESULTING IN NE TRADES OF 20 KT FROM 5N TO 19N W OF 120W WITH SEAS TO 8 FT IN WIND WAVES AND 8-10 FT IN NW SWELL FROM 12N TO 19N. THESE CONDITIONS ARE EXPECTED TO CHANGE LITTLE OVER THE NEXT 48 HRS. NW WINDS TO 20 KT WITHIN 90 NM OF THE BAJA CALIFORNIA COAST ARE BEING GENERATED BY SURFACE PRESSURE FALLS OVER MEXICO COMBINING WITH LOCAL TOPOGRAPHICAL EFFECTS...HOWEVER THESE WINDS ARE EXPECTED TO PERIODICALLY DIMINISH AND INCREASE DURING THE NEXT 48 HRS IN RESPONSE TO FLUCTUATING PRESSURES OVER MEXICO. SMALL PATCHES OF SCATTERED TO BROKEN STRATOCUMULUS CLOUDS MOVING SSW WITH POSSIBLE ISOLATED SHOWERS ARE PRESENT FROM 20N TO 27N W OF 124W. THEY ARE BEING STEERED BY THE NE FLOW AROUND THE SRN PERIPHERY OF THE SURFACE RIDGE. GAP WINDS... INCREASING TRADE WINDS OVER THE WRN CARIBBEAN CONTINUE TO SURGE INTO THE ERN PACIFIC BY WAY OF THE GULF OF PAPAGAYO AS NE-E 20-25 KT WINDS. THESE WINDS ARE FORECAST TO SUBSIDE IN ABOUT 24-30 HRS. N WINDS TO 20 KT THROUGH THE GULF OF PANAMA ARE EXPECTED TO DIMINISH IN 18 HRS. ALSO...SW TO 20 KT WINDS OVER THE NRN GULF OF CALIFORNIA N OF 29N ARE EXPECTED TO BECOME MORE S TO SW IN 48 HRS IN RESPONSE TO THE APPROACHING COLD FRONT DESCRIBED IN THE FIRST PARAGRAPH. $$ AGUIRRE