000 AXPZ20 KNHC 130931 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0815 UTC. ...SPECIAL FEATURES... AN ACTIVE TROPICAL WAVE WAS ANALYZED ALONG 101W N OF 10N. SCATTERED MODERATE TO STRONG CONVECTION ASSOCIATED WITH THE WAVE WAS N OF 12N BETWEEN 92W-103W...EXCEPT OVER THE GULF OF TEHUANTEPEC. THE ASCAT-B PASS FROM 0326 UTC SHOWED 20-25 KT SE WINDS WITHIN 180 E OF THE WAVE FROM 12N-15N. THE NUMERICAL GUIDANCE IS TOO WEAK HERE INITIALLY. 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 COULD BECOME 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 79W N OF 08N. 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 WAS WITHIN 150 NM S OF THE AXIS E OF 84W. A WEAK TROPICAL WAVE WAS ANALYZED ALONG 121W FROM 8N-17N. IT WAS MOVING W AROUND 15 KT. NO SIGNIFICANT DEEP CONVECTION WAS ASSOCIATED WITH THIS WAVE. A TROPICAL WAVE WAS ANALYZED ALONG 134W FROM 06N-16N. THIS WAVE WAS MOVING W AROUND 10 KT. SCATTERED MODERATE CONVECTION WAS WITHIN 240 NM E OF THE WAVE FROM 07N-12N. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH AXIS WAS ANALYZED FROM 08N78W TO 10N102W TO 09N118W. THE ITCZ AXIS WAS ANALYZED FROM 08N121W TO 08N140W. SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION WAS WITHIN 150 NM S OF THE AXIS E OF 84W. SCATTERED MODERATE CONVECTION WAS WITHIN 180 NM S OF THE AXIS BETWEEN 93W-110W. ...DISCUSSION... A 1010 MB LOW PRESSURE SYSTEM WAS ANALYZED NEAR 19N136W. DEEP CONVECTION ASSOCIATED WITH THIS SYSTEM WANED SIGNIFICANTLY OVER THE PAST 24 HOURS AND IS NOW ABSENT NEAR THE CENTER. THE LOW HAS MOVED OVER COOLER WATER AND CONTINUES TO LIE IN A REGION OF NW SHEAR. THIS LOW IS FORECAST TO OPEN UP TO A TROUGH LATER TODAY. THE ASCAT PASSES FROM 0556 UTC AND 0650 UTC SHOWED A BROAD...CLOSED LOW-LEVEL CIRCULATION WITH 20 TO 25 KT WINDS WITHIN 45 NM N SEMICIRCLE...EXCEPT 120 NM N QUADRANT. THESE WINDS ARE FORECAST TO DIMINISH TODAY AS THE SYSTEM CONTINUES TO WEAKEN. A SURFACE TROUGH ACROSS N CENTRAL WATERS FROM 32N130W TO 30N137W 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 THROUGH EARLY SAT. GAP WINDS... GULF OF TEHUANTEPEC...THE 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. A FRESH TO STRONG N-NE BREEZE SHOULD CONTINUE HERE UNTIL JUST AFTER SUNRISE WITH THE ASSISTANCE OF NOCTURNAL DRAINAGE FLOW. A FRESH TO STRONG N-NE BREEZE WILL RETURN EARLY FRI MORNING AND DISSIPATE JUST AFTER SUNRISE. SOUTHERLY SWELL COUPLED WITH THE GAP WIND GENERATED SWELL WILL BUILD SEAS TO 8-10 FT THIS MORNING. GULF OF PAPAGAYO...THE SAME PATTERN DESCRIBED IN THE GULF OF TEHUANTEPEC SECTION IS FORCING FRESH TO STRONG E-NE WINDS THROUGH THE GULF OF PAPAGAYO THIS MORNING WITH SEAS TO 8 FT. THESE WINDS WILL DIMINISH AFTER SUNRISE THIS MORNING AS THE TROPICAL WAVE CONTINUES W AWAY FROM THE AREA...WEAKENING THE PRESSURE GRADIENT. $$ SCHAUER