000 AXPZ20 KNHC 122203 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC TUE FEB 12 2013 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2115 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... MONSOON TROUGH AXIS EXTENDS 02N81W TO 05N88W TO 05.5N101W... WHERE IT TRANSITIONS TO ITCZ AXIS...CONTINUING TO 07N123W TO 04N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION NOTED WITHIN 120 NM S OF TROUGH BETWEEN 88W AND 94W. SCATTERED MODERATE ISOLATED STRONG CONVECTION NOTED WITHIN 120 NM N AND 90 NM S OF ITCZ BETWEEN 123W AND 130W. ...DISCUSSION... A STRONG 80-120 KT SUBTROPICAL JET REMAINS IN PLACE FROM 17N140W E-NE ACROSS THE S HALF OF THE BAJA CALIFORNIA PENINSULA AND INTO NRN MEXICO...AND LOCATED S OF TWO SEPARATE TROUGHS EXTENDING FROM THE NE PACIFIC INTO N PORTIONS OF THE AREA. THE JET IS FORECAST TO WEAKEN TONIGHT AND WED AND SHIFT NORTHEASTWARD AS RIDGING BUILDS OVER THE NORTH CENTRAL PORTION OF THE FORECAST AREA. TO THE EAST...A STRONG AND ELONGATED SHORTWAVE TROUGH LIES IN THE SOUTHWESTERN SIDE OF A MEAN UPPER TROUGH CENTERED OVER THE INTERIOR WESTERN UNITED STATES...AND IS CURRENTLY ENTERING NW MEXICO AS A NEW SHORTWAVE SYSTEM ON THE BACKSIDE OF THE MEAN TROUGH IS DROPPING S INTO THE NE FORECAST WATERS. BOTH SYSTEMS WILL MERGE WITH THE MEAN TROUGH BY THU. WEAK SURFACE TROUGHING IN NE WATERS AND ALONG THE BAJA PENINSULA HAS STRENGTHENED IN THE PAST 12 HOURS TO INCREASE THE PRESSURE GRADIENT OVER THE GULF OF CALIFORNIA. PARTIAL ASCAT PASSES FROM 17-1800 UTC SHOWED 20-25 KT N-NW WINDS ACROSS N AND CENTRAL PORTIONS OF THE GULF S OF 29N WHICH ARE EXPECTED TO EXPAND N AND S THROUGH THE ENTIRE GULF TONIGHT...WITH WIND GUSTS TO 30 KT POSSIBLE OVERNIGHT. THESE FRESH TO STRONG WINDS ARE EXPECTED TO CONTINUE THROUGH MIDDAY THU BEFORE DIMINISHING...WITH SEAS BUILDING 8-9 FT ACROSS S PORTIONS TONIGHT THROUGH WED NIGHT. AN UPPER LOW LIES JUST W OF THE AREA NEAR 26N145W AND REFLECTS A 1020 MB LOW AT THE SURFACE NEAR 26.5N145.5W. NW SWELL FROM THIS SYSTEM THAT MOVED INTO THE NW WATERS A FEW DAYS AGO IS MAKING ITS WAY SOUTHEASTWARD...WITH PERIODS ON THE LEADING EDGE OF THE SWELL TRAIN IN THE 19-21 SECOND RANGE. THE LEADING EDGE OF THE SWELL IS CURRENTLY NEAR MANZANILLO MEXICO AND WILL LIE ALONG 95W S OF 13N BY WED MORNING BEFORE MIXING WITH LONG PERIOD SW SWELL E OF 95W. THE SURFACE LOW WILL MOVE SW AND GRADUALLY DISSIPATE...BUT THE PRESSURE GRADIENT BETWEEN THE LINGERING TROUGHING AND THE SUBTROPICAL RIDGE WILL KEEP FRESH TO STRONG WINDS OVER THE NW CORNER OF THE FORECAST AREA INTO WED MORNING. SOME SCATTERED SHOWERS AND THUNDERSTORMS ARE CURRENTLY JUST W OF THE AREA AND E OF THE LOW N OF 25N. THESE CONDITIONS WILL HUG NW WATERS THIS EVENING BEFORE SHIFTING SW AND DIMINISHING. AFTERNOON SCATTEROMETER PASSES SHOWED FRESH TO LOCALLY STRONG TRADE WINDS OVER THE WATERS N OF THE ITCZ FROM 09N TO 20N W OF 125W AND FROM 10N TO 17N BETWEEN 113W AND 125W AS THE SUBTROPICAL RIDGE BUILT BETWEEN THE AFOREMENTIONED TROUGHING OVER THE BAJA PENINSULA AND TROUGHING OVER NW WATERS. LOOK FOR TRADES TO REMAIN UNCHANGED FOR THE NEXT 24 HOURS AND THEN SHIFT WEST-SOUTHWESTWARD BY EARLY THU. GAP WINDS... GULF OF PAPAGAYO...THE PRESSURE GRADIENT BETWEEN THE MONSOON TROUGH TO THE S AND RIDGING OVER THE NW CARIBBEAN REMAINS MODERATE THIS AFTERNOON. HOWEVER...TRADE WINDS HAVE WEAKENED ACROSS THE SW CARIBBEAN TODAY...WHICH HAS RESULTED IN A SLIGHTLY DIMINISHED NE TRADE WIND FLOW THROUGH CENTRAL AMERICA AND INTO THE GULF OF PAPAGAYO. AFTERNOON SCATTEROMETER PASSES ACROSS THIS REGION SUGGEST NE WINDS HAVE DIMINISHED TO NEAR 20 KT...AND A FURTHER WEAKENING TREND IS EXPECTED TONIGHT AS THE ATLC HIGH RIDGE WEAKENS ACROSS THE W CARIBBEAN. $$ STRIPLING