000 AXPZ20 KNHC 201016 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC WED MAY 20 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 0315 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A MONSOONAL CIRCULATION IS NOT CURRENTLY EVIDENT ACROSS THE REGION. THE ITCZ AXIS EXTENDS FROM 08N89W TO 11N108W...THEN RESUMES FROM 08N113W TO 09N131W. SCATTERED MODERATE TO STRONG CONVECTION NOTED FROM 01.5N TO 10N BETWEEN 77W AND 97W. SCATTERED MODERATE TO STRONG CONVECTION NOTED WITHIN 180 NM N AND 360 NM S OF AXIS BETWEEN 97W AND 108W...AND WITHIN 180 NM N AND 240 NM S OF AXIS BETWEEN 108W AND 131W. NUMEROUS MODERATE TO STRONG CONVECTION NOTED FROM 05N TO 09N BETWEEN 135W AND 139W ASSOCIATED WITH 1009 MB LOW PRES NEAR 07.5N135.5W. ...DISCUSSION... E OF 120W... A WEAKENING 1020 MB SURFACE HIGH WAS CENTERED NEAR 29N125W WITH RIDGE AXIS EXTENDING SE TO NEAR 20N112W. THE PRESSURE GRADIENT BETWEEN THE HIGH AND LOWER PRESSURE ALONG BAJA CALIFORNIA AND NW MEXICO WAS SUPPORTING NW TO N WINDS 15-20 KT ALONG THE COAST AND OFFSHORE WATERS FROM SOUTHERN CALIFORNIA ALONG THE COAST OF BAJA CALIFORNIA TO SAN JUANICO...AND OUTWARD 120-150 NM OFFSHORE...BASED ON RECENT SCATTEROMETER DATA. SEAS WERE GENERALLY 5-7 FT THERE IN MIXED NW SWELL. THE HIGH IS EXPECTED TO WEAKEN FURTHER AND SINK SLIGHTLY S THROUGH FRI...WHICH WILL LIKELY ONLY PRODUCE WINDS TO NEAR 20 KT DURING THE NEXT FEW AFTERNOONS ALONG THE BAJA W COAST. A STRENGTHENING HIGH PRESSURE RIDGE WILL BUILD INTO THE REGION FROM THE NW FRI AFTERNOON THROUGH THE WEEKEND TO BRING A RETURN TO STRONG AFTERNOON WINDS TO 25 KT ACROSS THE COASTAL WATERS OF THE FULL LENGTH OF THE PENINSULA. LOOK FOR INCREASING SEAS TO 6-8 FT S OF PUNTA EUGENIA BEGINNING SAT. FARTHER SOUTH...AN UPPER LEVEL LOW PRES CIRCULATION CENTERED NEAR 06N96W IS SUPPORTING A BROAD AREA OF HEAVY SHOWERS AND THUNDERSTORMS FROM 01.5N TO 10N BETWEEN 77W AND 97W. THIS LEVEL FEATURE WILL WEAKEN TO AN OPEN TROUGH AND SHIFT S ACROSS THE EQUATOR DURING THE 48 HOURS...WITH CONVECTION THERE EXPECTED TO SLOWLY DIMINISH IN AREAL COVERAGE THROUGH FRI MORNING. GAP WIND FLOW ACROSS AND DOWNWIND OF THE GULF OF PAPAGAYO HAS INCREASED TO NEAR 20 KT OVERNIGHT...AND IS EXPECTED TO DIMINISH BY THIS AFTERNOON TO 10-15 KT. NOCTURNAL WINDS THERE ARE NOT EXPECTED TO REACH 20 KT TONIGHT OR THU NIGHT...BUT WILL INCREASE TO NEAR 20 KT FRI NIGHT AND THEN TO 20-25 KT DURING THE LATE NIGHT DURING THE WEEKEND. W OF 120W... A SERIES OF EASTERLY WAVES ARE CURRENTLY MOVING WESTWARD ACROSS THE DEEP TROPICS THIS MORNING...ONE ALONG 113-114W...AND A PAIR OF WEAKER WAVE BEGINNING TO MERGE BETWEEN 129W AND 137W. A 1009 MB SURFACE LOW HAS RECENTLY DEVELOPED NEAR 07.5N135.5W...WITH AN EXPLOSIVE GROWTH OF CONVECTION DEVELOPING FROM 05N TO 09N BETWEEN 135W AND 139W. ABUNDANT TROPICAL MOISTURE RESIDES ACROSS THE AREA...WHILE UPPER LEVEL RIDGING W OF 110W IS PROVIDING A GENERALLY FAVORABLE ENVIRONMENT FOR ACTIVE CONVECTION IN THE VICINITY OF THESE WAVES. THE RIDGE ASSOCIATED WITH THE WEAK HIGH NEAR 29N125W IS PRODUCING A ZONE OF FRESH NE TO E TRADES ACROSS THIS REGION...FROM 09N TO 20N W OF 115W...WHERE SEAS ARE 6-8 FT. LOOK FOR THESE WAVES TO SHIFT SLOWLY WESTWARD OVER THE NEXT FEW DAYS...WITH ACTIVE CONVECTION CONTINUING TO PULSE SURROUNDING THEM BETWEEN 125W AND 145W. A NEW PULSE OF STRONG SOUTHWESTERLY SWELL WILL MOVE ACROSS THE EQUATOR AND INTO THE AREA WATERS TONIGHT...WITH WAVE HEIGHTS OF 8 TO 9 FT AND PERIODS OF 15 TO 18 SECONDS...MAINLY W OF THE GALAPAGOS...THEN REACH THE COASTLINES OF CENTRAL AMERICA AND SOUTHERN MEXICO LATE FRI AND SAT...BUILDING TO 4-5 FT BY SUN. THESE LONG PERIOD SWELLS WILL GENERATE LARGE AND DANGEROUS SURF ALONG THESE COASTLINES AND OUTER REEFS THROUGH THE UPCOMING WEEKEND. $$ STRIPLING