000 AXPZ20 KNHC 211513 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC THU MAY 21 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 1300 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE ITCZ AXIS WAS ANALYZED FROM 09N95W TO 11N110W TO 11N114W. A TROUGH WAS ANALYZED FROM 13N114W TO 04N119W. THE MONSOON TROUGH AXIS WAS ANALYZED FROM 07N118W TO 06N125W TO LOW PRES NEAR 08N134W 1010 MB TO LOW PRES NEAR 08N137W 1009 MB TO 04N140W. SCATTERED MODERATE TO STRONG CONVECTION WAS FROM 00N-10N BETWEEN 115W-139W AND ELSEWHERE FROM 09N-12N BETWEEN 112W-118W. ...DISCUSSION... A 1022 MB SUBTROPICAL HIGH NEAR 31N137W EXTENDS A RIDGE AXIS THROUGH 1018 MB HIGH PRESSURE NEAR 27N114W TO 15N105W. PRIMARILY MODERATE TO FRESH TRADE WINDS LIE BETWEEN THE RIDGE AXIS AND MONSOON TROUGH...WITH FRESH TO STRONG WINDS FOUND ON THE NW SIDE OF THE SURFACE TROUGH ANALYZED FROM 13N114W TO 04N119W. THIS TROUGH IS FORECAST TO MOVE W AROUND 5-10 KT OVER THE NEXT TWO DAYS...CARRYING THE STRONGEST WINDS W WITH IT. ABUNDANT DEEP CONVECTION LIES FROM THIS TROUGH WESTWARD PRIMARILY S OF THE MONSOON TROUGH AXIS. THIS CONVECTION WAS DESCRIBED ABOVE. AT THE MOMENT...THE LOW PRESSURE CENTERS ALONG THE MONSOON TROUGH APPEAR TO BE TRANSIENT. MODEL GUIDANCE SUGGESTS DEVELOPMENT OF ONE OR TWO LOW PRESSURE CENTERS W OF 120W BY SAT MORNING...BUT CONFIDENCE IS LOW IN THE DETAILS AT THIS TIME. CONDITIONS APPEAR CONDUCIVE FOR THIS AREA TO REMAIN CONVECTIVELY ACTIVE UNDER UPPER LEVEL DIVERGENCE MAINLY FOUND S OF 15N W OF 115W ASSOCIATED WITH A BROAD ANTICYCLONE ALOFT. N OF 15N E OF 120W...A PAIR OF UPPER LEVEL IMPULSES ARE PIVOTING EASTWARD THROUGH THE BASE OF A SHARP UPPER TROUGH EXTENDING FROM OFF CENTRAL CALIFORNIA TO ROUGHLY 25N118W. THE FIRST IMPULSE WILL MOVE INTO SOUTHERN CALIFORNIA AND THE NORTHERN COAST OF BAJA CALIFORNIA NORTE LATER TODAY AND THE SECOND IMPULSE WILL REACH THE COAST FRI MORNING. THIS PATTERN HAS BEEN REINFORCING LOW PRESSURE CENTERED OVER THE SOUTHWESTERN UNITED STATES. EXPECT A MODEST AMOUNT OF 20 TO 25 KT SW WINDS OVER THE FAR NORTHERN GULF OF CALIFORNIA TODAY THROUGH FRI MORNING IN RESPONSE TO TIGHTENED PRESSURE GRADIENT BETWEEN THE TROUGHING TO THE N AND THE SUBTROPICAL RIDGE TO THE SW...WITH WINDS THEN DIMINISHING BY LATE FRI AS THE UPPER SUPPORT LIFTS NE AND THE LOW PRESSURE WEAKENS. S OF 15N E OF 110W...AN UPPER LEVEL CYCLONIC CIRCULATION CENTERED JUST SE OF THE GALAPAGOS ISLANDS WILL REMAIN RELATIVELY STATIONARY THROUGH SAT MORNING. A 50 KT UPPER JET ALONG THE W COAST OF S AMERICA JUST S OF THE EQUATOR WILL CREEP NORTHWARD THROUGH SAT MORNING. SCATTERED MODERATE TO STRONG CONVECTION CURRENTLY WITHIN 60 NM OF THE COAST OF COLOMBIA FROM 03N TO 07N MAY BRIEFLY BECOME ENHANCED LATE TODAY AS THE LEFT FRONT QUADRANT OF THIS JET PASSES THROUGH...BUT WILL LIKELY BREAK DOWN BY FRI EVENING UNDER THIS STRONG SOUTHERLY SHEAR. A WEAK UPPER RIDGE ALONG 10N E OF 90W IS ENHANCING CONVECTION NEAR THE COAST OF COSTA RICA. THIS RIDGE AXIS WILL SHIFT NE INTO THE SW CARIBBEAN THROUGH SAT MORNING. LONG PERIOD SOUTH-SOUTHWESTERLY SWELL PRODUCING WAVE HEIGHTS TO 10 FT AND PERIODS OF 17-19 SECONDS WILL MOVE ACROSS THE EQUATOR TODAY THROUGH FRI AND BEGIN TO SUBSIDE FRI NIGHT...WITH SEAS REMAINING OVER 8 FT S OF A LINE FROM 03.4S82W TO 04N103W TO 03.4S120W BY SAT MORNING. 4 TO 6 FT OF SWELL WILL REACH THE COASTLINES OF CENTRAL AMERICA AND SOUTHERN MEXICO LATE FRI AND SAT. THESE LONG PERIOD SWELLS WILL GENERATE LARGE AND DANGEROUS SURF CONDITIONS ALONG THESE COASTLINES THROUGH THE UPCOMING WEEKEND. $$ SCHAUER