000 AXPZ20 KNHC 220251 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC MON OCT 22 2012 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS. BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0230 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH IS ALONG 12N86W TO 13N92W TO 11N105W TO 08N125W TO 10N133W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 10N136W TO 11N140W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION WITHIN 120 NM S OF THE TROUGH AXIS BETWEEN 95W AND 104W...WITHIN 240 NM N OF THE TROUGH AXIS BETWEEN 97W AND 102W...AND ALSO FROM 08N TO 12N BETWEEN 105W AND 110W. SCATTERED MODERATE CONVECTION IS WITHIN 90 NM S OF THE TROUGH AXIS BETWEEN 113W AND 118W...AND WITHIN 90 NM EITHER SIDE OF THE TROUGH AXIS BETWEEN 120W AND 125W. ...DISCUSSION... THE AXIS OF THE SUBTROPICAL JET EXTENDS FROM 13N145W AND CUTS NE INTO THE AREA NEAR 17N140W...THEN SPILLS EASTWARD TO SOUTHERN BAJA CALIFORNIA. SATELLITE DERIVED WINDS IN ASSOCIATION WITH THIS JET WERE IN THE 90-110 KT RANGE. THIS JET IS ADVECTING SOME UPPER LEVEL MOISTURE OVER THE AREA FROM 10N TO 26N BETWEEN 129W AND 140W. OTHERWISE THE UPPER LEVELS APPEAR MAINLY DRY N OF 15N BETWEEN 110W AND 125W SUPPRESSING CONVECTION. AN ELONGATED UPPER ANTICYCLONE IS E OF THIS JET WITH A MEAN CENTER NEAR 17N118W. WEAK UPPER DIFFLUENCE ON THE S AND W SIDES OF THE ANTICYCLONE IS SUPPORTING CONVECTION ALONG THE MONSOON TROUGH AND ITCZ AS IS DESCRIBED IN THE SECTION ABOVE. THE EASTERN PORTION OF THE DISCUSSION WATERS IS DOMINATED BY A QUASI-STATIONARY ELONGATED UPPER ANTICYCLONE OVER SE MEXICO NEAR 19N98W WITH A RIDGE EXTENDING N TO A CREST OVER CENTRAL TEXAS. THE ENVELOPE OF ANTICYCLONIC FLOW EXTENDS S OVER THE DISCUSSION AREA N OF 06N TO THE E OF 110W. THIS UPPER LEVEL EASTERLY FLOW IS ADVECTING DEBRIS MOISTURE WESTWARD FROM THE MONSOON TROUGH CONVECTION NOTED E OF 110W. A WEAK SURFACE TROUGH EXTENDS FROM 15N126W TO 10N135W WITH SCATTERED SHOWERS POSSIBLE WITHIN 120 NM W OF THE TROUGH AXIS. RECENT SCATTEROMETER PASSES INDICATED ONLY 5 TO 15 KT IN THE VICINITY OF THE TROUGH. THIS FEATURE WILL MOVE W OF THE AREA BY 48 HOURS WITH LITTLE FANFARE. OTHERWISE...A BROAD SURFACE RIDGE COVERS THE SUBTROPICS N OF THE MONSOON TROUGH. SCATTEROMETER DATA ALSO INDICATED TRADE WINDS OF 5 TO 15 KT ELSEWHERE N OF THE MONSOON TROUGH...WITH THE EXCEPTION OF A FEW POCKETS OF 15 TO 20 KT WINDS NEAR AREAS OF CONVECTION ASSOCIATED WITH THE MONSOON TROUGH. A WEAK COLD FRONT IS FORECAST TO SKIRT ACROSS 30N MON AND TUE WITH WINDS REMAINING 20 KT OR LESS BOTH AHEAD OF AND BEHIND IT IN THE FAR NORTHERN WATERS. THE WAVEWATCH MODEL GUIDANCE KEEPS SEAS LESS THAN 8 FT THROUGH 48 HOURS WHILE THE ECMWF WAVE AND UKMET WAVE MODELS HAVE AN AREA OF 8 TO 9 FT NW SWELL BREACHING 30N BY 48 HOURS. GAP WINDS...AN AFTERNOON HIGH RESOLUTION ASCAT PASS INDICATED N TO NE 20 TO 25 KT WINDS PULSING IN THE GULF OF TEHUANTEPEC. ALSO...OBSERVATIONS AT IXTEPEC IN OAXACA MEXICO REPORTED GUSTS TO 25 KT. A SHIP WITH CALL-SIGN A8IY2 JUST SW OF THE GULF RECENTLY REPORTED 20 KT NE WINDS. THESE FRESH TO STRONG WINDS ARE EXPECTED TO CONTINUE TO PULSE THROUGH THE NEXT 48 HOURS WITH THE STRONGEST DRAINAGE FLOW OCCURRING DURING THE FAVORABLE LATE NIGHT HOURS UNTIL JUST AFTER SUNRISE EACH DAY. THE GFS NWP GUIDANCE CONTINUES TO SUGGEST THAT THIS NORTHERLY FLOW WILL HELP TRIGGER LOW PRESSURE DEVELOPMENT WITHIN THE MONSOON TROUGH NEAR 10N98W BY TUE. THE GFS REMAINS THE AGGRESSIVE OUTLIER IN ITS SOLUTION WHILE OTHER NWP MODELS FAVOR A WEAKER BROAD LOW CLOSER TO CENTRAL AMERICA WHICH DRIFTS TO THE E AS A POSSIBLE DEVELOPING TROPICAL CYCLONE IN THE CARIBBEAN EXERTS GREATER INFLUENCE ON THE OVERALL PATTERN. THIS MORE CONSERVATIVE SOLUTION...IN THE PACIFIC...IS FAVORED AT THIS TIME AND LOW PRES IS NOT REFLECTED IN 12 UTC FORECAST WIND WAVE CHARTS THROUGH 48 HOURS. A BLEND OF THE GFS...ECMWF AND THE PREVIOUS FORECAST WAS USED IN THE GRIDDED WIND FIELDS. ASSOCIATED WAVE HEIGHTS FOLLOW A BLEND OF THE WAVEWATCH AND ECMWF WAVE MODELS WITH HEIGHTS CAPPED AT 11 FT THROUGH THE FORECAST PERIOD. $$ LEWITSKY