000 AXPZ20 KNHC 132125 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 2205 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2100 UTC. ...SPECIAL FEATURES... AN ACTIVE TROPICAL WAVE IS ANALYZED ALONG 105W/106W N OF 10N. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED ON EITHER SIDE OF THE WAVE AXIS MAINLY FROM 10N TO 17N BETWEEN 104W AND 110W. THE WAVE LIES UNDER A REGION OF STRONG UPPER-LEVEL DIVERGENCE WHICH SHOULD ASSIST THE DEVELOPMENT OF DEEP CONVECTION. ENVIRONMENTAL CONDITIONS ARE FAVORABLE FOR A TROPICAL CYCLONE TO FORM FROM THIS SYSTEM OVER THE WEEKEND WELL OFFSHORE THE COAST OF MEXICO. THE LATEST NHC TROPICAL WEATHER OUTLOOK GIVES THIS SYSTEM A MEDIUM CHANCE OF BECOMING A TROPICAL CYCLONE AS IT MOVES W-NW AROUND 10 KT. ...TROPICAL WAVES... A TROPICAL WAVE OVER WESTERN PANAMA IS ENHANCING CONVECTION ACROSS THE EASTERN PORTION OF THE MONSOON TROUGH PARTICULARLY FROM 04N TO 07N E OF 85W TO THE COAST OF COLOMBIA WHERE SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED. A WEAK TROPICAL WAVE IS ANALYZED ALONG 123W/124W FROM 08N-16N. IT WAS MOVING W AROUND 15 KT. NO SIGNIFICANT DEEP CONVECTION WAS ASSOCIATED WITH THIS WAVE. A TROPICAL WAVE WAS ANALYZED ALONG 137/138W FROM 08N-16N. THIS WAVE IS MOVING W AROUND 10 KT. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS WITHIN 240 NM E OF THE WAVE FROM 07N-12N. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... MONSOON TROUGH AXIS EXTENDS FROM 07N78W TO 10N94W TO 08N110W TO 09N121W. ITCZ AXIS STRETCHES FROM 09N124W TO 08N136W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS SEEN FROM 04N TO 07N E OF 85W TO THE COAST OF COLOMBIA. SCATTERED MODERATE CONVECTION IS FROM 05N TO 07N BETWEEN 108W AND 116W...FROM 03N TO 05N BETWEEN 121W AND 124W AND WITHIN 140 NM S OF ITCZ AXIS BETWEEN 127W AND 131W. ...DISCUSSION... A 1011 MB LOW PRESSURE SYSTEM IS LOCATED NEAR 19N138W. THE SYSTEM IS PRODUCING SCATTERED LOW TOPPED SHOWERS MAINLY WITHIN 50 NM SW QUADRANT. THE LOW CONTINUES TO MOVE 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 AS IT MOVES W OF AREA. A RECENT SCATTEROMETER PASS INDICATES A BROAD CLOSED LOW- LEVEL CIRCULATION WITH 20 TO 25 KT WINDS WITHIN 150 NM IN THE NE QUADRANT LIKELY DUE TO THE PRES GRADIENT BETWEEN THE LOW PRES AND A SURFACE RIDGE TO THE N. THIS RIDGE NOW DOMINATES THE N WATERS AND STRETCHES FROM 32N132W TO 20N110W. THE PRESSURE GRADIENT BETWEEN THIS RIDGE AND TROUGHING IN THE VICINITY OF THE GULF OF CALIFORNIA IS SUPPORTING MODERATE TO LOCALLY FRESH NW WINDS 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. CROSS-EQUATORIAL S-SE SWELL ACROSS MUCH OF THE REGION WILL GRADUALLY SUBSIDE THROUGH EARLY SAT MORNING. COMBINED SEAS TO 9 FT RANGE CAN BE FOUND ACROSS THE AREA S OF 06N BETWEEN 100W AND 125W. 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 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. $$ GR