000 AXPZ20 KNHC 131558 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC THU AUG 13 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1545 UTC. ...SPECIAL FEATURES... AN ACTIVE TROPICAL WAVE WAS ANALYZED ALONG 104W/105W N OF 10N. SCATTERED MODERATE ISOLATED STRONG CONVECTION WAS NOTED N OF 12N WITHIN 180 NM EITHER SIDE OF AXIS. THIS CONVECTION MERGED INTO A LARGER AREA OF SCATTERED MODERATE TO STRONG CONVECTION WHICH WAS NOTED WITHIN 240 NM N OF THE MONSOON TROUGH BETWEEN 92W AND 100W. THE WAVE LIES UNDER A REGION OF STRONG UPPER-LEVEL DIVERGENCE WHICH SHOULD ASSIST THE DEVELOPMENT OF DEEP CONVECTION. AN AREA OF LOW PRESSURE IS EXPECTED TO DEVELOP ALONG THE WAVE WITHIN THE NEXT 24 HOURS...AND THIS LOW CURRENTLY HAS A MEDIUM CHANCE OF BECOMING A TROPICAL CYCLONE AS IT MOVES NW AROUND 10 KT. ...TROPICAL WAVES... A TROPICAL WAVE HAS ENTERED THE EASTERN NORTH PACIFIC OVER THE GULF OF PANAMA ALONG 81W N OF 09N. THIS WAVE WAS MOVING W AROUND 15 KT. CONVECTION ALONG THE EASTERN PORTION OF THE MONSOON TROUGH IS BEING ENHANCED BY THIS WAVE...WITH SCATTERED MODERATE AND ISOLATED STRONG CONVECTION NOTED FROM 04N TO 07N E OF 82W TO THE COAST OF COLOMBIA. A WEAK TROPICAL WAVE WAS ANALYZED ALONG 122W/123W FROM 09N-17N. IT WAS MOVING W AROUND 15 KT. NO SIGNIFICANT DEEP CONVECTION WAS ASSOCIATED WITH THIS WAVE. A TROPICAL WAVE WAS ANALYZED ALONG 136/137W FROM 08N-16N. THIS WAVE WAS MOVING W AROUND 10 KT. SCATTERED MODERATE ISOLATED STRONG CONVECTION WAS WITHIN 240 NM E OF THE WAVE FROM 07N-12N. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH AXIS WAS ANALYZED FROM 09N84W TO 10N100W TO 08N120W. ITCZ AXIS WAS ANALYZED FROM 08N122W TO 08N140W. SCATTERED MODERATE TO STRONG WAS NOTED WITHIN 240 NM N OF AXIS BETWEEN 92W AND 100W...AND WITHIN 180 NM S OF AXIS BETWEEN 107W AND 111W...AND WITHIN 240 NM EITHER SIDE OF AXIS BETWEEN 120W AND 135W. ...DISCUSSION... A 1011 MB LOW PRESSURE SYSTEM WAS ANALYZED NEAR 19N137W. THE SYSTEM WAS VOID OF ANY DEEP CONVECTION WITH SCATTERED LOW TOPPED SHOWERS OCCURRING WITHIN 75 NM OF THE LOW LEVEL CENTER. THE LOW CONTINUES TO TREK OVER COOLER WATER WITHIN A REGION OF NORTHWEST SHEAR. THIS LOW IS FORECAST TO OPEN UP TO A TROUGH WITHIN THE NEXT 12 HOUR OR SO. EARLIER SCATTEROMETER PASSES R SHOWED A BROAD CLOSED LOW-LEVEL CIRCULATION WITH 20 TO 25 KT WINDS WITHIN 120 NM IN THE N QUADRANT. A SURFACE TROUGH BRUSHED THE N CENTRAL WATERS FROM 32N130W TO 30N135W HAS FORCED THE SUBTROPICAL RIDGE AXIS NORTHEASTWARD OVER THE FORECAST AREA. THE RIDGE STRETCHES FROM 32N126W TO 30N126W TO 10N110W. THE PRESSURE GRADIENT BETWEEN THIS RIDGE AND TROUGHING IN THE VICINITY OF THE GULF OF CALIFORNIA IS SUPPORTING A MODERATE NW BREEZE ON THE PACIFIC COAST OF THE BAJA CALIFORNIA PENINSULA. THESE WINDS SHOULD DIMINISH TO A GENTLE BREEZE DURING THE DAYS AND INCREASE AGAIN IN THE EVENING HOURS FOR THE NEXT FEW DAYS...WITH WINDS INCREASING TO A MODERATE TO FRESH NW BREEZE FRI EVENING AS UPPER-LEVEL NORTHERN STREAM TROUGHING IN THE EASTERN PACIFIC WEAKENS ALLOWING THE SURFACE RIDGE TO INTENSIFY. CROSS-EQUATORIAL S-SE SWELL ACROSS MUCH OF THE AREA WILL GRADUALLY SUBSIDE THROUGH THE END OF THE FORECAST PERIOD EARLY SAT MORNING. COMBINED SEAS TO 9 FT RANGE CAN BE FOUND ACROSS THE AREA S OF 10N BETWEEN 95W AND 105W AND S OF 04N W OF 105W. SEAS WILL GRADUALLY SUBSIDE BELOW 8 FT BY EARLY SAT. GAP WINDS... GULF OF TEHUANTEPEC...ENHANCED PRESSURE GRADIENT BETWEEN A SURFACE RIDGE ACROSS THE GULF OF MEXICO...DISPLACED SOUTHWARD BY A STATIONARY FRONT OVER THE NORTHERN GULF OF MEXICO COAST...AND A TROPICAL WAVE SW OF THE GULF OF TEHUANTEPEC HAS ALLOWED N WINDS TO FUNNEL THROUGH CHIVELA PASS. FRESH N-NE WINDS HAVE DIMINISHED BELOW 20 KT BUT ARE EXPECTED TO RETURN OVERNIGHT TONIGHT INTO FRI MORNING AND DISSIPATE JUST AFTER SUNRISE. SOUTHERLY SWELL COUPLED WITH THE GAP WIND GENERATED SWELL HAS BUILT SEAS TO 8-9 FT. GULF OF PAPAGAYO...THE SAME PATTERN DESCRIBED IN THE GULF OF TEHUANTEPEC SECTION FORCED FRESH NE TO E WINDS THROUGH THE GULF OF PAPAGAYO EARLIER THIS MORNING WITH SEAS TO 8 FT. THESE WINDS HAVE DIMINISHED AS THE TROPICAL WAVE CONTINUES W AWAY FROM THE AREA...WEAKENING THE PRESSURE GRADIENT. $$ COBB