000 AXPZ20 KNHC 200249 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC SAT JUN 20 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 0315 UTC. ...TROPICAL WAVES... A TROPICAL WAVE AXIS IS ALONG 88W N OF 09N TO ACROSS EASTERN EL SALVADOR AND CENTRAL HONDURAS MOVING W AT 10-15 KT. ONLY ISOLATED WEAK TSTMS ARE WITHIN 30-60 NM OF THE WAVE. A TROPICAL WAVE AXIS IS ALONG 99W FROM 09N-15N MOVING W NEAR 13 KT. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE WITHIN 120 NM W OF THE WAVE FROM 09N-12N. THIS CONVECTION REMAINS UNDER FAVORABLE DIFFLUENCE ALOFT. IN ADDITION...THIS WAVE IS MOVING THROUGH A FAVORABLE BACKGROUND ENVIRONMENT GENERATED BY A KELVIN WAVE MOVING THROUGH ITS VICINITY. A TROPICAL WAVE EXTENDS FROM 12N123W TO 04N124W MOVING W NEAR 15 KT. ISOLATED MODERATE CONVECTION IS WITHIN 60 NM OF THE AXIS. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 60 NM E OF THE WAVE FROM 08N-10N. ANOTHER TROPICAL WAVE EXTENDS FROM 15N135W TO 07N137W... ...SCATTERED MODERATE CONVECTION IS WITHIN 30 NM OF 14N136W. THIS ACTIVITY IS BEING FURTHER FUELED BY A SHARP UPPER TROUGH AXIS JUST TO THE W OF THE SURFACE TROUGH. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... SCATTEROMETER DATA INDICATES THAT THE MONSOON TROUGH EXTENDS FROM NW COLOMBIA W TO 08N79W TO 08N90W TO 08N103W. THE SCATTEROMETER DATA THEN INDICATES THAT THE ITCZ BEGINS AT 08N103W...AND CONTINUES TO 09N110W TO 06N121W TO 03N130W TO 02N140W. SCATTERED MODERATE TO STRONG CONVECTION EXISTS WITHIN 120 NM N OF ITCZ BETWEEN 95W-99W...AND WITHIN 180 NM S OF THE TROUGH AND ITCZ BETWEEN 101W-105W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 120 NM OF THE ITCZ BETWEEN 94W-99W. ...DISCUSSION... UPPER LEVELS...TWO UPPER ANTICYCLONES PRETTY MUCH DOMINATE THE FLOW PATTERN WITH THE FIRST ONE NEAR 27N128W MOVING SLOWLY NE...AND THE SECOND ONE JUST INLAND OVER THE BORDER OF SOUTHERN CALIFORNIA AND NORTHERN BAJA CALIFORNIA BORDER. AN UPPER LEVEL TROUGH EXTENDS ACROSS NW MEXICO AND SOUTHERN BAJA CALIFORNIA INTO THE EPAC TO TO NEAR 21N115W. MODERATE TO STRONG SUBSIDENCE IS PROVIDING A RATHER DRY AND STABLE ATMOSPHERE AS OBSERVED ON WATER VAPOR IMAGERY ACROSS MUCH OF THE AREA N OF 18N. A SHARP NEGATIVELY-TILTED UPPER TROUGH AXIS ENTERS THE FAR WESTERN PART OF THE AREA FROM AN UPPER LOW W OF THE 140W AT 18N145W. THE TROUGH REACHES SE TO NEAR 13N135W. TROPICAL MOISTURE FROM DEEP TROPICAL CONVECTION IS SLOWLY BEING ADVECTED NORTHWARD DUE TO SLY FLOW ALOFT FROM 08N-16N BETWEEN 118W-130W. NLY FLOW IS OVER SE MEXICO...THE GULF OF TEHUANTEPEC AND THE REMAINDER OF THE AREA N OF 10N BETWEEN 85W AND 115W DUE TO THE PRESENCE OF AN ANTICYCLONE OVER WESTERN MEXICO NEAR 21N103W...AND A BROAD MID/UPPER LOW SITUATED JUST N OF THE YUCATAN PENINSULA. AT THE SURFACE...HIGH PRES OF 1025 MB IS CENTERED N OF THE AREA NEAR 42N132W WITH A RIDGE STRETCHING SEWD INTO THE FORECAST REGION TO NEAR 21N113W. HIGH PRES COVERS THE AREA N OF 19N W OF 116W. THE PRES GRADIENT BETWEEN THE RIDGE AND LOWER PRES IN THE VICINITY OF THE ITCZ IS MAINTAINING MODERATE TO LOCALLY FRESH NE- E TRADES OVER THE WESTERN WATERS N OF THE ITCZ FROM 10N-16N BETWEEN 127W-136W. SCATTEROMETER DATA CONFIRMED THE PRESENCE OF THESE WINDS. THE HIGH PRES IS FORECAST TO WEAKEN OVER THE 24-48 HRS AS A WEAK COLD FRONT APPROACHES THE FAR NW CORNER OF THE AREA. SE SWELLS MIXED WITH LONG PERIOD CROSS-EQUATORIAL SW SWELLS ARE PRODUCING AN AREA OF 8-9 FT SEAS S OF LINE FROM 00N133W TO 02N124W TO 02N113W. THIS AREA OF SEAS WILL GRADUALLY SHRINK THROUGH THE NEXT 48 HOURS WITH SEAS TO 8 FT IN MIXED SE AND SW SWELLS EXPECTED AT THAT TIME S OF 02N BETWEEN 131W-137W. GAP WINDS... GULF OF PAPAGAYO...PULSING WINDS OF 20-25 KT ARE EXPECTED ACROSS THE GULF BEGINNING LATE TONIGHT WITH THE ADDITIONAL ASSISTANCE OF THE NOCTURNAL DRAINAGE FLOW AND SOME ADDED ENHANCEMENT FROM THE EASTERLY GRADIENT FLOW ACROSS THE SW CARIBBEAN. SEAS ARE FORECAST TO BUILD TO 9 FT. THE RESULTANT ENE SWELLS WILL PROPAGATE W REACHING 98W BY EARLY SAT EVENING. THESE PULSING WINDS ARE FORECAST TO PERSIST THROUGH SUN. $$ AGUIRRE