000 AXPZ20 KNHC 210235 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0200 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH IS CURRENTLY NOT EVIDENT ACROSS THE REGION. THE ITCZ AXIS EXTENDS FROM 09N87W TO 09N100W TO 10N110W...AND FROM 07N120W TO 09N130W TO 07N135W. SCATTERED MODERATE CONVECTION IS NOTED WITHIN 120 NM S OF AXIS E OF 100W. SCATTERED MODERATE TO ISOLATED STRONG IS NOTED WITHIN 150 NM N AND 180 NM S OF AXIS W OF 110W. ...DISCUSSION... N OF 15N E OF 120W...A PAIR OF UPPER LEVEL IMPULSES WILL CONTINUE TO MOVE EASTWARD ACROSS THE AREA N OF 20N THROUGH TONIGHT...INTO SOUTHERN CALIFORNIA AND THE NORTHERN COAST OF BAJA CALIFORNIA NORTE. THIS PATTERN HAS BEEN REINFORCING LOW PRESSURE CENTERED OVER SOUTHERN CALIFORNIA AS WELL AS KEEPING HIGH PRESSURE WEST OF THE AREA NEAR 28N123W FAIRLY WEAK. EXPECT A BRIEF PERIOD OF 20 TO 25 KT SW WINDS OVER THE FAR NORTHERN GULF OF CALIFORNIA TONIGHT IN RESPONSE TO THE LOW PRESSURE IN THE AREA. THIS WILL DIMINISH THROUGH THU AS THE UPPER SUPPORT LIFTS NE AND THE LOW PRESSURE WEAKENS. MEANWHILE SHIP OBSERVATIONS AND SCATTEROMETER SATELLITE DATA INDICATE ONLY MODERATE NORTHERLY FLOW ALONG THE COAST OF BAJA CALIFORNIA DUE TO THE WEAKENED HIGH PRESSURE E OF THE AREA. LOOKING AHEAD...DEEP LAYER RIDGING WEST OF THE AREA WILL BUILD IN THE WAKE OF THE EXITING UPPER TROUGH...ALLOWING THE SURFACE HIGH PRESSURE TO BUILD AND ALLOWING NORTHERLY WINDS ALONG THE BAJA COAST TO INCREASE SLIGHTLY. SEAS ARE CURRENTLY 4 TO 6 FT OFF BAJA CALIFORNIA AND WILL BUILD TO 5 TO 7 FT THROUGH THE WEEKEND. S OF 15N E OF 110W...AN UPPER LEVEL CYCLONIC CIRCULATION THAT WAS NEAR 06N97W YESTERDAY HAS SHIFTED SOUTH TO NEAR THE GALAPAGOS ISLANDS TODAY. THIS CONTINUES TO ENHANCE CONVECTION ALONG THE ITCZ SOUTH OF 10N AND EAST OF 95W. THE SHARP UPPER TROUGHING ALONG 95W WILL WEAKEN AND BE REPLACED BY UPPER RIDGING ORIENTED E-W ALONG 10N BY LATE FRI. AREAS OF SHOWERS AND THUNDERSTORMS WILL PERSIST HOWEVER ESPECIALLY ALONG THE CENTRAL AMERICAN COAST DURING THE MORNINGS...AND CLOSER TO 100W WHERE DIVERGENCE ALOFT ON THE WESTERN PERIPHERY OF THE UPPER RIDGE WILL ENHANCE CONVECTION. LOW LEVEL FLOW WILL REMAIN WEAK AND DISORGANIZED IN THE DEEP TROPICS EAST OF 120W...EXCEPT FOR PULSES OF 15 TO 20 KT GAP WINDS INTO THE GULF OF PAPAGAYO DURING THE OVERNIGHT HOURS. LOOKING AHEAD...GLOBAL MODELS HINT OF BROAD BUT WEAK LOW PRESSURE AREAS FORMING ALONG 08N-10N BETWEEN 90W AND 110W BY EARLY NEXT WEEK. LONG PERIOD SOUTHERLY SWELL WITH WAVE HEIGHTS TO 9 FT AND PERIODS OF 15 TO 17 SECONDS WILL MOVE ACROSS THE EQUATOR MAINLY W OF THE GALAPAGOS THU INTO FRI...DECAYING TO BELOW 8 FT BY LATE FRI BUT DELIVERING 5 TO 6 FT TO THE COASTLINES OF CENTRAL AMERICA AND SOUTHERN MEXICO LATE FRI AND SAT. THESE LONG PERIOD SWELLS ARE FORECAST TO POSSIBLY GENERATE LARGE AND DANGEROUS SURF CONDITIONS ALONG THESE COASTLINES THROUGH THE UPCOMING WEEKEND. ELSEWHERE... A SERIES OF UPPER IMPULSES ARE PIVOTING EASTWARD AT THE BASE OF A SHARP UPPER TROUGH EXTENDING FROM OFF NORTHERN CALIFORNIA TO ROUGHLY 25N130W. THIS HAS BEEN KEEPING 1018 MB SURFACE HIGH PRES CENTERED NEAR 28N123W FAIRLY WEAK. THE RIDGE WILL BUILD NORTH OF THE AREA THU AND FRI BEHIND THE EXITING UPPER TROUGH. THIS WILL ALLOW LOW LEVEL CONVERGENCE OF 15 TO 20 KT TRADE WIND FLOW SOUTH OF THE RIDGE IS ENOUGH TO SUPPORT CLUSTERS OF SHOWERS AND THUNDERSTORMS FARTHER SOUTH ALONG THE ITCZ...MAINLY AROUND A PAIR OF TROUGH/LOW PRESSURE AREAS ANALYZED NEAR 115W AND NEAR 135W. LOOKING AHEAD TO SAT AND SUN...GLOBAL MODELS INDICATE SOME SLOW AND MODEST DEVELOPMENT OF BOTH OF THESE TROUGHS OVER THE NEXT SEVERAL DAYS...WITH INCREASED TRADE WIND FLOW AND SEAS TO 8 FT BETWEEN THE TROUGHS AND THE STRONGER RIDGE TO THE NORTH. $$ CHRISTENSEN