000 AXPZ20 KNHC 121605 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC THU MAY 12 2016 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 1500 UTC. ...INTERTROPICAL CONVERGENCE ZONE... THE EPAC MONSOON TROUGH EXTENDS W FROM COASTAL CENTRAL AMERICA NEAR 10N87W TO LOW PRES 1011 MB NEAR 08N96W TO 11.5N106W TO LOW PRES 1009 MB NEAR 11N111W TO 07N124W...WHERE IT TRANSITIONS TO ITCZ...CONTINUING ON TO BEYOND 04.5N140W. WIDELY SCATTERED TO SCATTERED MODERATE TO STRONG CONVECTION IS NOTED WITHIN 240 NM N AND 330 NM S OF TROUGH BETWEEN 99W AND 109W. WIDELY SCATTERED MODERATE CONVECTION IS NOTED WITHIN 90 NM N OF ITCZ BETWEEN 121W AND 135W. WIDELY SCATTERED MODERATE TO STRONG CONVECTION IS NOTED WITHIN 120 NM OF LOW PRES NEAR 08N96W. SCATTERED MODERATE TO STRONG CONVECTION IS NOTED WITHIN 120 NM N AND 150 NM S SEMICIRCLES OF LOW PRES NEAR 11N111W. ...DISCUSSION... N OF 15N E OF 120W... A NEARLY N TO S ALIGNED SURFACE TROUGH WILL DEVELOP ACROSS THE BAJA CALIFORNIA PENINSULA DURING THE AFTERNOON AND EARLY EVENING HOURS FOR THE NEXT FEW DAYS AS A RESULT OF DAYTIME HEATING. THIS WILL ENHANCE THE MODERATE NWLY WINDFLOW PRESENTLY OCCURRING ALONG THE PACIFIC COASTAL WATERS OF THE BAJA PENINSULA... INCREASING WINDS TO AROUND 20 KT WITHIN 90 NM OF THE COAST THROUGH THE EVENING HOURS. THE PRESSURE GRADIENT IS EXPECTED TO TIGHTEN ON FRI NIGHT WITH MODERATE TO FRESH NW FLOW DEVELOPING ACROSS THE EPAC WATERS FROM 27-32N E OF 120W THROUGH SUN MORNING. THE GRADIENT WILL FURTHER TIGHTEN ON SUN AFTERNOON WITH FRESH NW FLOW ACROSS THE WATERS FROM 27-32N AS THE RIDGE ACROSS THE REGION BUILDS SE. COMPUTER MODEL GUIDANCE ALSO SUGGESTS THAT SOUTHERLY FLOW WILL INCREASE TO 20 TO 25 KT ACROSS THE GULF OF CALIFORNIA WATERS FROM 29.5N TO 31N W OF 113W ON SAT NIGHT. A NW TO SE SURFACE RIDGE WILL MEANDER ACROSS THE TROPICAL WATERS ROUGHLY FROM NEAR 23N120W TO BEYOND 15N100W THROUGH THE UPCOMING WEEKEND. MODERATE-FRESH N-NE FLOW...SEAS 5-7 FT...IS EXPECTED S OF 17N BETWEEN 105-120W IN RESPONSE TO A TROPICAL LOW PRESSURE SYSTEM S OF THE AREA. OTHERWISE...LIGHT TO GENTLE ANTICYCLONIC FLOW AROUND THE QUASI-STATIONARY RIDGE IS EXPECTED ELSEWHERE ACROSS THE OPEN EPAC WATERS THROUGH THE WEEKEND. STRONG NORTHERLY DRAINAGE FLOW WILL DEVELOP LATE TONIGHT ACROSS AND JUST DOWNWIND OF THE GULF OF TEHUANTEPEC AND PERSIST INTO FRI MORNING. A MORE SIGNIFICANT EVENT IS EXPECTED ON FRI NIGHT INTO SAT MORNING AS WINDS INCREASE TO 25-30 KT AND SEAS BUILD TO 9 OR 10 FT NEAR 15N95W. COMBINED SEAS OF 3-6 FT ARE CURRENTLY OBSERVED ACROSS THE OPEN PAC WATERS W OF 100W IN MIXING LONG-PERIOD CROSS EQUATORIAL S SWELL AND LONG PERIOD NW SWELL. S OF 15N E OF 110W... MODERATE TO FRESH EASTERLY NOCTURNAL DRAINAGE FLOW IS EXPECTED ACROSS THE GULF OF PAPAGAYO REGION EACH NIGHT INTO EARLY NEXT WEEK. ELSEWHERE FROM THE EQUATOR TO 32N E OF 140W... A TROPICAL LOW NEAR 11N111W IS ESTIMATED AT 1009 MB. THE LOW HAS BEEN MOVING SLOWLY WESTWARD FOR THE PAST FEW DAYS BUT IS FORECAST TO BEGIN TO MOVE MORE STEADILY DURING THE NEXT FEW DAYS AS A TYPICAL EASTERLY WAVE. MODERATE TO FRESH N TO NE WINDS ARE EXPECTED TO CONTINUE WITHIN 200-300 NM OVER THE NW SEMICIRCLE OF THE LOW WITH SEAS 7-8 FT. THE PRESSURE GRADIENT SHOULD TIGHTEN A LITTLE ON FRI NIGHT AS THE LOW BEGINS TO MOVE S OF THE RIDGE... SUPPORTING STRONG N-NE WINDS ACROSS THE NW SEMICIRCLE OF THE LOW CENTER. A 1020 MB SURFACE HIGH AT 30N127W WILL SHIFT A LITTLE S TO NEAR 28N128W ON FRI. FRESH NE WINDS ARE NOTED ELSEWHERE ACROSS THE TROPICS BETWEEN THE RIDGE AND THE ITCZ...ALL TO THE W OF 110W...WHERE SEAS OF 6-8 FT PREVAIL. LITTLE CHANGE EXPECTED THROUGH THE WEEKEND ACROSS THE WATERS W OF THE PREVIOUSLY DESCRIBED TROPICAL LOW. A COLD FRONT EXTENDS FROM 302N137W TO 26N140W AND IS PRECEDED BY MODERATE TO FRESH SOUTHERLY FLOW. THE SURFACE HIGH WILL BLOCK THE EASTWARD PROGRESSION OF THE COLD FRONT WHICH WILL STALL FROM ABOUT 32N132W TO 26N140W ON FRI. $$ STRIPLING