000 AXPZ20 KNHC 192148 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC TUE APR 19 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2145 UTC. ...INTERTROPICAL CONVERGENCE ZONE... A LOW LEVEL TROUGH EXTENDS W OFF THE COAST OF COSTA RICA AT 06N126W TO 13N127W WHERE SCATTEROMETER WINDS INDICATE AN ITCZ FORMS AND CONTINUES SW TO 05N122W...THEN TURNS NW TO 06N128W WHERE THE ITCZ IS INTERRUPTED BY AN EMBEDDED SURFACE. THE ITCZ RESUMES AT 06N127W AND EXTENDS SW TO BEYOND 03N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED WITHIN 120 NM EITHER SIDE OF OF LINES FROM 08N83W TO 06N93W AND FROM 06N95W TO 06N107W TO 10N117W...AND ALSO WITHIN 90 NM EITHER SIDE OF A FROM 04N117W TO 06N125W THE EMBEDDED SURFACE TROUGH EXTENDS N FROM 06N126W TO 13N127W. SCATTERED MODERATE CONVECTION IS ENHANCED WELL E OF THE TROUGH AXIS WITHIN 120 NM OF LINE FROM 06N122W TO 13N122W. ...DISCUSSION... N OF 15N E OF 120W... A WEAK SURFACE RIDGE EXTENDS FROM NEAR 20N120W TO BEYOND 15N100W. A SURFACE HIGH WILL LIKELY DEVELOP ALONG THE RIDGE NEAR 23N BRIEFLY TONIGHT. SEVERAL WEAK TROUGHS WILL SWEEP E ACROSS THE WATERS N OF THE RIDGE ON WED AND THU AND LOSE IDENTITY OVER THE NORTHERN BAJA PENINSULA. THE GRADIENT WILL TIGHTEN EARLY FRI SUPPORTING FRESH SOUTHERLY FLOW N OF 29.5N AND CONTINUING INTO FRI NIGHT. GUIDANCE SUGGESTS FRESH TO LOCALLY STRONG NORTHERLY DRAINAGE FLOW ACROSS THE GULF OF TEHUANTEPEC LATE FRI NIGHT. S OF 15N E OF 110W... NOCTURNAL PULSES OF FRESH ENE WINDS ARE EXPECTED ACROSS...AND JUST DOWNSTREAM OF THE GULF OF PAPAGAYO LATE TONIGHT...AND AGAIN LATE WED NIGHT. MOSTLY MODERATE N WINDS ARE EXPECTED ACROSS AND DOWNSTREAM OF THE GULF OF PANAMA EACH NIGHT THROUGH THU NIGHT. LONG PERIOD CROSS-EQUATORIAL SOUTHERLY SWELL IN THE FORM OF 7-8 FT SEAS WILL SPREAD N ACROSS THE EQUATOR BETWEEN 100-110W FROM LATE WED INTO EARLY THU. ELSEWHERE FROM THE EQUATOR TO 32N E OF 140W... A COLD FRONT EXTENDS FROM 32N127W TO 23N131W THEN HAS STALLED AND IS DISSIPATING SW TO 19N140W. A SECONDARY SURGE...ACCOMPANIED BY A 15-20 KT SW-W-NW WIND SHIFT...IS NOTED FROM 32N132W TO 27N134W. COMBINED SEAS OF 8-13 FT ARE CURRENTLY OBSERVED W OF A LINE FROM 32N125W TO 19N140W PRIMARILY DUE TO MIXING LONG PERIOD S AND NW SWELL. THESE NW SWELLS WILL PROPAGATE S WITH SEAS OF 6- 8 FT EXPECTED WITHIN 270 NM NW OF LINE FROM 18N126W TO 14N133W ON WED...AND WITHIN 240 NM NW OF LINE FROM 10N125W TO 09N140W ON THU. ALTHOUGH NE TRADES ARE EXPECTED TO REMAIN IN THE 15-20 KT RANGE ACROSS THE TROPICS...COMBINED SEAS OF 7-9 FT ARE OBSERVED WITHIN 300 NM N OF LINE FROM 10N119W TO 07N136W IN MIXED S AND NW SWELL. THE AFFECTED AREA WILL SHRINK TO WITHIN 120 NM N OF LINE FROM 11N122W TO 11N125W ON WED...THEN THE AREA WILL MERGE ON THU. $$ NELSON