000 AXPZ20 KNHC 180936 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC MON MAY 18 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0830 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... LIGHT WINDS DOMINATE THE CLIMATOLOGICAL REGION OF THE ITCZ/MONSOON TROUGH IN THE NORTH EASTERN PACIFIC...AND NO MONSOON TROUGH IS EVIDENT TONIGHT. THE ITCZ AXIS WAS ANALYZED FROM 04N101W TO 05N105W TO 03N112W TO 05N119W TO 03.5N137W. SCATTERED MODERATE ISOLATED STRONG CONVECTION NOTED FROM 03.5N TO 11N E OF 91W TO THE COASTS OF COSTA RICA...PANAMA...AND COLOMBIA. ISOLATED TO SCATTERED MODERATE TO STRONG CONVECTION NOTED FROM 07N TO 13.5N BETWEEN 104W AND 124W. SCATTERED MODERATE ISOLATED STRONG CONVECTION NOTED WITHIN 120 NM EITHER SIDE OF ITCZ FROM 101W TO 130W. ...DISCUSSION... A WEAKENING 1021 MB HIGH WAS CENTERED NEAR 26.5N128W AND EXTENDS A RIDGE AXIS EASTWARD TO THE W COAST OF BAJA CALIFORNIA NORTE. THE PRESSURE GRADIENT BETWEEN THE HIGH RIDGE AND LOWER PRESSURE TO THE SOUTH ASSOCIATED WITH THE ITCZ IS GENERATING MODERATE TO FRESH TRADES MAINLY BETWEEN 09N-20N W OF 120W. THE FRESH TRADES ARE HELPING TO MAINTAIN AREAS OF SEAS AS HIGH AS 9 FT FROM 07N- 16N W OF 134W...AS WELL AS WITHIN 75 NM EITHER SIDE OF LINE FROM 16N123W TO 10N131W...WHERE NE WINDS AROUND 20 KT PREVAILED. A PAIR OF TROUGHS OR EASTERLY WAVES WERE LOCATED ACROSS THIS AREA...ALONG ABOUT 121-122W AND 126-127W. THE AREA OF FRESH TRADES AND 8 FT SEAS WILL GENERALLY SHIFT W AT 5-10 KT WITH THESE TWO TROUGH OVER THE NEXT FEW DAYS. A COLD FRONT WAS ANALYZED NW OF THE HIGH...EXTENDING FROM 1017 MB LOW PRESSURE N OF THE AREA NEAR 35N130W THROUGH 30N129W TO 25N140W. THIS COLD FRONT WILL CONTINUE TO WEAKEN AS IT DRIFTS SLOWLY SE THROUGH EARLY TUE BEFORE DISSIPATING. WINDS OVER FORECAST WATERS ARE NOT EXPECTED TO REACH 20 KT NEAR THE FRONT AND SEAS TO 8 FT SHOULD REMAIN CONFINED N OF 31N BEHIND THE FRONT. THIS WEAK HIGH PRESSURE WILL REMAIN OVER THE NORTHERN WATERS WHICH WILL KEEP THE PRESSURE GRADIENT RELATIVELY CONSTANT AND MAINTAIN THE AREA OF MODERATE TO FRESH TRADES FROM 10N-20N W OF 120W. THE PRESSURE GRADIENT BETWEEN THE EASTERN RIDGE AND LOWER PRESSURE ACROSS BAJA CALIFORNIA AND NW MEXICO IS PRODUCING A MODERATE NORTHWESTERLY BREEZE ALONG MOST OF THE PACIFIC COASTAL WATERS OF THE BAJA CALIFORNIA PENINSULA. THE PRESSURE GRADIENT IS EXPECTED TO TIGHTEN SLIGHTLY THIS AFTERNOON AND AGAIN TUE AFTERNOON AS AN UPPER TROUGH SWINGS THROUGH THE BAJA CALIFORNIA PENINSULA AND INCREASES SURFACE TROUGHING. THIS SHOULD ALLOW WINDS TO BRIEFLY REACH AROUND 20 KT ALONG THE PACIFIC WATERS OF THE PENINSULA OUT TO 150 NM...AND GENERALLY N OF 25N DURING THE AFTERNOONS...WITH SEAS BUILDING 7 TO 8 FT. GAP WINDS... GULF OF PAPAGAYO...WINDS WILL CONTINUE TO PULSE OVER THE GULF OF PAPAGAYO THE NEXT COUPLE OF DAYS. WINDS WILL PEAK NEAR 25 KT DURING THE LATE NIGHT AND EARLY MORNING HOURS WITH THE ADDED COMPONENT OF NOCTURNAL DRAINAGE FLOW. WINDS WILL DIMINISH TO 20 KT OR LESS DURING THE AFTERNOON AND EARLY EVENING HOURS. LOOKING AHEAD...ANOTHER STRONG SOUTHERN HEMISPHERIC SW SWELL WILL MOVE INTO THE REGIONAL WATERS LATE IN THE WEEK. SEAS WILL BUILD TO 8 FT AND GREATER ALONG THE EQUATORIAL WATERS BY THU MORNING. THIS PULSE OF LONG PERIOD SWELL IS EXPECTED TO REACH THE COASTLINES OF CENTRAL AMERICA BY LATE FRI. $$ STRIPLING