000 AXPZ20 KNHC 130332 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC WED FEB 13 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0215 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... MONSOON TROUGH AXIS EXTENDS 00N85W TO 06N95W TO 05N102W...WHERE IT TRANSITIONS TO ITCZ...CONTINUING TO 07N126W TO 05N132W TO 05N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION NOTED WITHIN 120 NM S OF TROUGH BETWEEN 89W AND 94W. SCATTERED MODERATE ISOLATED STRONG CONVECTION NOTED WITHIN 150 NM N AND 270 NM S OF ITCZ BETWEEN 124W AND 131W. ...DISCUSSION... A DEEP LAYERED TROUGH REMAINS NEARLY STATIONARY JUST W OF THE AREA. SOUTHEAST OF THIS TROUGH...A STRONG 80-120 KT SUBTROPICAL JET PERSISTS FROM JUST OFF THE EQUATOR SOUTH OF THE HAWAIIAN ISLANDS THROUGH 15N140W E-NE ACROSS THE S TIP OF THE BAJA CALIFORNIA PENINSULA AND ACROSS NRN MEXICO...TRANSPORTING TROPICAL UPPER LEVEL MOISTURE. 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 LONG WAVE TROUGH IS CENTERED OVER THE INTERIOR WESTERN UNITED STATES...AND EXTENDS SW THROUGH THE SOUTHWESTERN STATES OF THE U.S. AND ACROSS FAR N BAJA CALIFORNIA. THE WEST PORTIONS OF THIS TROUGH ARE DROPPING SLOWLY S INTO THE NE FORECAST WATERS...WITH MEAN TROUGH AXIS FORECAST TO BECOME STATIONARY ALONG ABOUT 30N THERE WED. SURFACE TROUGHING ALONG THE SIERRA MADRE OCCIDENTALES HAS STRENGTHENED TODAY AS DEEP LAYERED LOW PRESSURE AND A COLD FRONT HAVE MOVED INTO THE NW GULF OF MEXICO REGION. THIS HAS ACTED TO INCREASE THE PRESSURE GRADIENT BETWEEN THE TROUGH AND A STRONG HIGH PRESSURE RIDGE TO THE NW...AFFECTING WINDS THROUGH THE GULF OF CALIFORNIA. PARTIAL ASCAT PASSES FROM 17-1800 UTC THIS AFTERNOON SHOWED 20-25 KT N-NW WINDS ACROSS CENTRAL PORTIONS OF THE GULF S OF 29N...WHILE A 1944 UTC OSCAT PASS ALSO SHOWED SIMILAR WINDS THROUGH CENTRAL AND S PORTIONS. THESE WINDS ARE EXPECTED TO EXPAND N AND S THROUGH THE ENTIRE GULF TONIGHT...WITH FREQUENT WIND GUSTS TO 30 KT POSSIBLE OVERNIGHT. THESE FRESH TO STRONG WINDS ARE EXPECTED TO CONTINUE THROUGH MIDDAY THU BEFORE DIMINISHING...WITH SEAS BUILDING 8-10 FT ACROSS S PORTIONS TONIGHT THROUGH WED NIGHT. AN UPPER LOW LIES JUST W OF THE AREA EMBEDDED WITHIN THE DEEP LAYERED TROUGH MENTIONED ABOVE...CENTERED NEAR 25N145.5W AND REFLECTS A 1019 MB LOW AT THE SURFACE NEAR 26N146W. 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 WILL REACH 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 22.5N. 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 BETWEEN 122W AND 135W AND FROM 10N TO 17N BETWEEN 113W AND 122W AS THE SUBTROPICAL RIDGE DOMINATES BETWEEN THE AFOREMENTIONED TROUGHING OVER W MEXICO AND TROUGHING OVER NW WATERS. LOOK FOR THE TRADES TO REMAIN UNCHANGED FOR THE NEXT 24 HOURS AND THEN SHIFT WEST-SOUTHWESTWARD BY EARLY THU. A SIGNIFICANT PERTURBATION HAS DEVELOPED ALONG THE ITCZ ALONG 127W AND IS ENHANCING THE TRADES JUST NORTH OF THIS WAVE. AS THIS PERTURBATION SHIFTS W DURING THE NEXT 2 DAYS...AND DIRECTLY S OF THE HIGH ACROSS THE NE PACIFIC...WINDS ACROSS THE N SEMICIRCLE OF THIS FEATURE ARE FORECAST TO INCREASE TO 25-30 KT...AND SEAS BUILDING 10-15 FT. GAP WINDS... GULF OF PAPAGAYO...THE PRESSURE GRADIENT BETWEEN THE MONSOON TROUGH TO THE S AND RIDGING OVER THE NW CARIBBEAN WAS WEAKENED SUFFICIENTLY THIS AFTERNOON AND EVENING TO ALLOW WIND FLOW THROUGH CENTRAL AMERICA AND INTO THE GULF OF PAPAGAYO TO DIMINISH. 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