000 AXPZ20 KNHC 171005 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC SUN MAY 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0900 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM 09N87W TO 06.5N101W TO 11N110W TO 08.5N115W...WHERE IT BREAKS...THEN RESUMES FROM 10N123W TO LOW PRES 1010 MB NEAR 09N125.5W TO LOW PRES 1010 MB NEAR 09N138.5W TO BEYOND 08N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION NOTED WITHIN 150 NM N AND S OF TROUGH TO 00N BETWEEN 91W AND 105W. SCATTERED MODERATE TO STRONG CONVECTION NOTED FROM 03N TO 14.5N BETWEEN 115W AND 128W...AND WITHIN 180 NM N OF TROUGH BETWEEN 132W AND 140W. SCATTERED MODERATE TO STRONG CONVECTION NOTED FROM 00N TO 05N E OF 87W TO W COAST OF COLOMBIA. SCATTERED MODERATE ISOLATED STRONG CONVECTION NOTED WITHIN 120 NM OF THE COAST OF COSTA RICA FROM 08N TO 11N. SCATTERED MODERATE ISOLATED STRONG CONVECTION NOTED FROM 10N TO COAST BETWEEN 91W AND 99W. ...DISCUSSION... THE SUBTROPICAL RIDGE EXTENDS FROM A 1030 MB HIGH NEAR 38N150W TO A COLD FRONT SINKING SE INTO THE AREA ALONG 30N140W TO 35N133W...WITH THE RIDGE THEN BRIDGING ACROSS THE FRONT AND INTO THE AREA THROUGH 29N129W TO 22N113W. THE COLD FRONT WILL STRETCH FROM 32N130W TO 29N133W TO 28N140W BY THIS AFTERNOON THEN DISSIPATE THROUGH MONDAY AS IT SINKS SLIGHTLY SE. WINDS NEAR THE FRONT ARE EXPECTED TO REMAIN BELOW 20 KT AND SEAS ONLY REACHING 5-7 FT IN NW SWELL BEHIND THE FRONT. THE HIGH IS FORECAST TO WEAKEN AS IT SHIFTS SE BEHIND THE FRONT AND SETTLES NEAR 33N145W BY MONDAY NIGHT. THIS SHOULD KEEP THE PRESSURE GRADIENT RELATIVELY CONSTANT AND MAINTAIN THE AREA OF FRESH TRADES FOUND BETWEEN THE MONSOON TROUGH AND 20N...AND W OF 120W. MEAN TROUGHING ALOFT OVER NW MEXICO AND THE SW UNITED STATES WILL CONTINUE THROUGH THE PERIOD...WITH LITTLE CHANGE TO THE OVERALL PATTERN. SUFFICIENT PRES GRADIENT EXISTS BETWEEN THE SUBTROPICAL HIGH AND LOW PRES ACROSS BAJA CALIFORNIA AND NW MEXICO TO PRODUCE NWLY WINDS AROUND 15-20 KT ALONG MOST OF THE PACIFIC COASTAL WATERS OF THE BAJA PENINSULA. THE GRADIENT WILL TIGHTEN SLIGHTLY BY MONDAY AFTERNOON OR EVENING TO PROMOTE 20 KT WINDS ALONG MUCH OF THE NEAR AND OFFSHORE COASTAL WATERS THERE THROUGH WED...WITH SEAS BRIEFLY BUILDING TO 7-8 FT N OF PUNTA EUGENIA...AND 6-7 FT ALONG THE SOUTHERN HALF. A BROAD ANTICYCLONE ALOFT CENTERED NEAR 11N115W EXTENDS A RIDGE AXIS W TO 140W AND ANOTHER RIDGE AXIS EASTWARD TO NEAR 100W. THIS CONTINUES TO PROVIDE A FAVORABLE ENVIRONMENT FOR ACTIVE CONVECTION DESCRIBED ABOVE. CONVECTION UNDER THE RIDGE WILL DIMINISH SOMEWHAT DURING THE NEXT 24-36 HOURS AS THE RIDGE FLATTENS AND BECOMES CONFINED TO S OF 20N. HOWEVER...E OF 100W AN UPPER LEVEL TROUGH WILL DIG S-SW ACROSS CENTRAL AMERICA AND INTO THE TROPICS OF 10N...AND DESTABILIZE THE ATMOSPHERE FOR CONTINUED ACTIVE CONVECTION THERE THROUGH TONIGHT BEFORE UPPER CONDITIONS STABILIZE MODESTLY MONDAY. GAP WINDS... GULF OF PAPAGAYO...THE PRESSURE GRADIENT BETWEEN RIDGING OVER THE NW CARIBBEAN AND TROUGHING TO THE SW IS SUPPORT A STRONG E TO SE BREEZE IN THE GULF OF PAPAGAYO TO 89W THIS MORNING...AS DEPICTED BY OVERNIGHT ASCAT PASSES. THESE WINDS WILL DIMINISH AFTER SUNRISE AND DIMINISH TO AROUND 15 KT BY AFTERNOON...THEN INCREASE AGAIN TO 20-25 KT EARLY MON MORNING ONLY TO DIMINISH AGAIN AFTER SUNRISE MON. LOOKING AHEAD...ANOTHER STRONG SOUTHERN HEMISPHERIC SW SWELL WILL MOVE INTO THE REGIONAL WATERS LATE IN THE WEEK AND RAISE SEAS TO 8 FT AND GREATER ALONG THE EQUATORIAL WATERS BY THURSDAY MORNING...BEFORE THIS PULSE OF LONG PERIOD SWELL REACHES THE COASTLINES OF CENTRAL AMERICA BY LATE FRIDAY. $$ STRIPLING