000 AXPZ20 KNHC 151545 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC SUN MAR 15 2015 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1230 UTC. ...SPECIAL FEATURES... GULF OF TEHUANTEPEC GALE WARNING...THE 0818 UTC RAPIDSCAT PASS OVER THE GULF OF TEHUANTEPEC SHOWED 20-25 KT N WINDS. THESE WINDS SHOULD PERSIST THROUGH THIS MORNING WITH THE ASSISTANCE OF DRAINAGE FLOW OFF THE MOUNTAINS AND INTENSIFY THROUGH THIS EVENING AS HIGH PRESSURE BUILDS OVER THE WESTERN GULF OF MEXICO. THE RIDGE AXIS WILL BUILD OVER NORTHEASTERN MEXICO TONIGHT JUST AS A NW TO SE TROUGH BUILDS OVER THE SOUTHWESTERN GULF TO THE BAY OF CAMPECHE. THIS SET UP WILL ALLOW N WINDS TO FUNNEL THROUGH CHIVELA PASS. WINDS WILL INCREASE TO GALE FORCE IN THE GULF OF TEHUANTEPEC BY THIS EVENING AND REMAIN AT MINIMAL GALE STRENGTH THROUGH THE END OF THE FORECAST PERIOD TUE MORNING. SEAS WILL HOVER IN THE 7-9 FT RANGE TODAY THROUGH SUN AND BUILD AS HIGH AS 13 FT UNDER THE GALE CONDITIONS BY MON MORNING. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH WAS ANALYZED FROM 08N84W TO 05N97W TO 08N105W...THEN CONTINUES FROM 08N113W TO 05N135W. THE ITCZ AXIS WAS ANALYZED FROM 05N135W TO 04N140W. SCATTERED MODERATE CONVECTION WAS WITHIN 120 NM EITHER SIDE OF THE AXIS BETWEEN 91W AND 100W. ISOLATED MODERATE CONVECTION WAS WITHIN 150 NM S OF THE AXIS BETWEEN 120W AND 128W. ...DISCUSSION... A WEAKENING DEEP LAYER TROUGH IS CHARGING EASTWARD THROUGH NW WATERS. A SOUTHWESTERLY JET ON THE LEADING EDGE OF THIS UPPER TROUGH IS PROPELLING MOISTURE ALOFT INTO THE FORECAST AREA. SATELLITE IMAGERY SHOWS AN AREA OF MULTI-LAYERED CLOUDS WITH SOME EMBEDDED SHOWERS W OF A LINE FROM 32N124W TO 06N140W. A COLD FRONT AT THE SURFACE STRETCHES FROM 32N131W TO 16N138W. THE DEEP LAYERED TROUGH SHOULD WEAKEN THROUGH THE END OF THE FORECAST PERIOD TUE MORNING...WITH THE COLD FRONT EXPECTED TO DISSIPATE ON MON. THE 0712 UTC ASCAT PASS SHOWED 20-25 KT NORTHERLY WINDS AHEAD OF THE FRONT WHERE THE PRESSURE GRADIENT BETWEEN THE ITCZ/MONSOON TROUGH TO THE S AND A RAPIDLY WEAKENING RIDGE AXIS JUST E OF THE FRONT WAS STRONG. WINDS TO ADVISORY CONDITIONS MAY LINGER NEAR THE FRONT INTO THE DAY TODAY OVER FAR W WATERS AS THE RIDGE AXIS DISSIPATES. NW SWELL IN THE 8 TO 10 FT RANGE WILL IMPACT MUCH OF THE AREA W OF 130W THROUGH TUE MORNING. THE 1017 MB HIGH PRESSURE CENTER NEAR 32N125W EXTENDS A RIDGE AXIS AHEAD OF THE AFOREMENTIONED COLD FRONT TO 17N135W. THIS WEAK RIDGE WILL DISSIPATE BY TONIGHT AS THE COLD FRONT ADVANCES EASTWARD...WITH THE HIGH PRESSURE BEHIND THE COLD FRONT BECOMING DOMINANT TONIGHT. THIS NEW RIDGE WILL ALSO BE WEAK...SUPPORTING ONLY GENTLE TO MODERATE TRADES. AN UPPER LOW CENTERED NEAR THE SOUTHERN GULF OF CALIFORNIA IS IN THE PROCESS OF CUTTING OFF FROM THE NORTHERN STREAM. PACIFIC MOISTURE IS FEEDING INTO THE LEADING EDGE OF THIS TROUGH WHERE POSITIVE VERTICAL MOTION IN THE REAR RIGHT QUADRANT OF THE UPPER JET ON THE EASTERN SIDE OF THE LOW IS ENHANCING CONVECTION. NUMEROUS MODERATE TO SCATTERED STRONG CONVECTION LIES WITHIN 360 NM E OF THE SURFACE TROUGH FROM 19N104W TO 09N108W. MOISTURE IS BEING PULLED NORTHWARD INTO CENTRAL MEXICO WHERE WIDESPREAD SHOWERS ARE FOUND FROM SOUTHERN TEXAS TO THE PACIFIC COAST PRIMARILY BETWEEN ACAPULCO AND MANZANILLO...WITH ISOLATED TO SCATTERED THUNDERSTORMS FOUND S AND W OF MEXICO CITY. THE UPPER LOW IS EXPECTED TO SHIFT SLIGHTLY NORTHWARD ALONG THE GULF OF CALIFORNIA MON BEFORE TURNING NEGATIVE TILT MON NIGHT AND HEADING NE INTO NORTHWESTERN MEXICO AS IT BECOMES CAUGHT IN THE LEADING EDGE OF THE PROGRESSIVE UPPER TROUGH CURRENTLY OVER NW WATERS. THE PLUME OF LOW-LEVEL MOISTURE SHOULD SHIFT NORTHWARD ALONG THE COAST OVER THE NEXT TWO DAY. AT THE SURFACE...THE TROUGH IS EXPECTED TO SLOWLY MOVE NW. THE PRESSURE GRADIENT SHOULD BUILD BETWEEN THE TROUGH AND THE RIDGING OVER NE MEXICO THAT IS HELPING TO DRIVE THE TEHUANTEPEC WINDS. AN AREA OF FRESH TO STRONG E-NE WINDS WITH SEAS TO 9 FT IS EXPECTED TO PERSIST ALONG THE CENTRAL MEXICAN COAST IN THE VICINITY OF MANZANILLO LATE THIS AFTERNOON THROUGH MON MORNING. GAP WINDS... GULF OF PAPAGAYO...BUILDING HIGH PRESSURE CENTERED OVER THE LOWER MISSISSIPPI VALLEY AND NORTHERN GULF WILL MAINTAIN A MODERATE PRESSURE GRADIENT BETWEEN THIS RIDGING TO THE N AND THE MONSOON TROUGH TO THE S. FRESH TO STRONG E-NE WINDS ARE EXPECTED TO CONTINUE IN THE LATE NIGHT AND EARLY MORNING HOURS FROM THE GULF OF PAPAGAYO AREA DOWNWIND TO AROUND 90W THROUGH AT LEAST MON MORNING. $$ SCHAUER