000 AXPZ20 KNHC 170234 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC TUE MAR 17 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0115 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH AXIS WAS ANALYZED FROM 10N85W TO LOW PRES NEAR 05N92W 1009 MB TO 03N106W TO 11N118W TO LOW PRES NEAR 10N122W 1010 MB TO 07N127W. ITCZ AXIS FROM 07N127W TO 06N140W. SCATTERED MODERATE CONVECTION WAS S OF THE AXIS TO 03N BETWEEN 82W AND 87W AS WELL AS FROM 07N TO 10N BETWEEN 113W AND 124W. ...DISCUSSION... A WEAKENING UPPER LEVEL TROUGH IS CHARGING EASTWARD THROUGH CENTRAL 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 WITHIN 360 NM E OF A LINE FROM 32N128W TO 17N130W. A BATCH OF NW SWELL ATTRIBUTABLE TO THIS TROUGH STILL MAINTAINS AN AREA OF SEAS TO 9 FT S OF 11N W OF 126W. THIS DAMPENING SWELL SHOULD SEE SEAS SUBSIDE BELOW 8 FT OVERNIGHT TONIGHT. THE UPPER TROUGH WILL PUSH INTO NE WATERS TUE AND RECEIVE REINFORCING SHORTWAVE ENERGY IN ITS BACK EDGE BY WED WHICH WILL DEEPEN AND SLOW THE TROUGH ALOFT. THE 1020 MB HIGH PRESSURE CENTER NEAR 31N138W EXTENDS A RIDGE AXIS NE THROUGH 32N137W AND SW THROUGH 30N140W. THE HIGH SHOULD STRENGTHEN AND IT MOVES NE TO 35N132W BY TUE AFTERNOON WHERE IT WILL REMAIN THROUGH THE END OF THE FORECAST PERIOD WED EVENING AS IT CONTINUES TO STRENGTHEN. THE STRENGTHENING SUBTROPICAL HIGH WILL TRIGGER A RETURN OF MODERATE TO FRESH TRADE WINDS OVER WATERS W OF 120W BY WED AFTERNOON. AN UPPER LOW IS CENTERED NEAR THE SOUTHERN GULF OF CALIFORNIA. PACIFIC MOISTURE IS FEEDING INTO THE LEADING EDGE OF THE SUPPORTING TROUGH WHERE POSITIVE VERTICAL MOTION IN THE REAR RIGHT QUADRANT OF THE UPPER JET ON THE EASTERN SIDE OF THE LOW IS ENHANCING CONVECTION. SCATTERED MODERATE CONVECTION WAS FROM 16N-20N BETWEEN 101W-104W AND SCATTERED SHOWERS WERE FOUND N OF THIS AREA OVER MUCH OF CENTRAL MEXICO BETWEEN 100W-107W. THERE ARE ALSO ISOLATED THUNDERSTORMS NEAR THE UPPER LOW CENTER OVER THE SOUTHERN BAJA CALIFORNIA PENINSULA AND ALONG THE W SLOPES OF THE SIERRA MADRE OCCIDENTAL FROM 25N-28N ACCORDING TO LIGHTNING STRIKE DATA. THE UPPER LOW WILL TURN NEGATIVE TILT TONIGHT AND SHIFT NE INTO NORTHWESTERN MEXICO BEFORE PUSHING INTO TEXAS WED. THE PLUME OF LOW-LEVEL MOISTURE DIRECTED INTO MEXICO WILL WANE THROUGH TUE...WITH THE BULK OF THE PRECIPITATION MOVING N OUT OF MEXICO BY WED MORNING. GAP WINDS... GULF OF TEHUANTEPEC...THE GRADIENT BETWEEN 1021 MB HIGH PRES OVER THE N CENTRAL GULF OF MEXICO AND THE MONSOON TROUGH TO THE S IS STRONG ENOUGH TO SUPPORT NEAR GALE FORCE N WINDS IN THE GULF OF TEHUANTEPEC THIS EVENING WITH SEAS TO 11 FT. HIGH PRES OVER THE GULF OF MEXICO WILL GRADUALLY WEAKEN OVER THE NEXT DAY OR SO...DIMINISHING THE PRES GRADIENT AND THE WINDS IN THE GULF OF TEHUANTEPEC. DRAINAGE FLOW OFF THE MOUNTAINOUS TERRAIN WILL HELP MAINTAIN 30 KT N WINDS THROUGH SUNRISE TUE. WINDS SHOULD DIP BELOW THE ADVISORY CRITERIA OF 20-25 KT BY TUE EVENING...AND SEAS WILL SUBSIDE BELOW 8 FT. GULF OF PAPAGAYO...HIGH PRES OVER THE GULF OF MEXICO WILL REMAIN STATIONARY BUT GRADUALLY WEAKEN THROUGH WED EVENING. THE PRES GRADIENT BETWEEN THIS RIDGING TO THE N AND THE MONSOON TROUGH TO THE S WILL BE ENHANCED BY NOCTURNAL DRAINAGE FLOW TO ALLOW FRESH TO STRONG E-NE WINDS IN THE GULF OF PAPAGAYO DURING THE OVERNIGHT AND EARLY MORNING HOURS THROUGH THE END OF THE FORECAST PERIOD WED EVENING. $$ SCHAUER