000 AXPZ20 KNHC 112155 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC TUE AUG 11 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 FEATURE... A 1009 MB LOW PRES IS LOCATED NEAR 16.5N131W. LATEST VISIBLE SATELLITE IMAGERY INDICATES THAT THE LOW LEVEL CENTER IS TOTALLY EXPOSED AND THE DEEP CONVECTION HAS ALSO DIMINISHED COMPARED WITH THIS MORNING. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS CURRENTLY NOTED WITHIN 120 NM SE SEMICIRCLE. ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BECOME INCREASINGLY UNFAVORABLE OVER THE NEXT 48 HOURS WHILE IT MOVES WESTWARD AT AROUND 10 KT. THIS SYSTEM COULD OPEN UP INTO A TROUGH BY THU. AN EARLIER ASCAT PASS SHOWED FRESH TO STRONG WINDS IN THE 20-25 KT RANGE WITHIN 120 NM NE QUADRANT OF LOW CENTER. ...TROPICAL WAVES... A TROPICAL WAVE IS ALONG 91W N OF 06N. THIS SYSTEM IS PRODUCING AN AREA OF DISORGANIZED CLOUDINESS AND SHOWERS. AN AREA OF LOW PRES IS FORECAST TO FORM IN ASSOCIATION WITH THIS WAVE LATER THIS WEEK. ENVIRONMENTAL CONDITIONS SHOULD SUPPORT GRADUAL DEVELOPMENT OF THE LOW BY THE WEEKEND WHILE IT MOVES W-NW AT 10- 15 KT. THIS WAVE SHOWS UP VERY WELL ON THE TPW ANIMATION AS A SURGE OF MOISTENED AIR. A WEAK TROPICAL WAVE IS ALONG 113W FROM 10N TO 18N. MOISTURE IS LIMITED IN ASSOCIATION WITH THIS FEATURE AS DEPICTED IN THE TPW PRODUCT. SOME LOW-LEVEL INVERTED-V PATTERN IS NOTED IN VISIBLE SATELLITE IMAGERY. A TROPICAL WAVE IS ALONG 129W FROM 05N TO 12N. SOME LOW-LEVEL INVERTED-V SIGNATURE IS ALSO NOTED IN VISIBLE SATELLITE IMAGERY. SCATTERED MODERATE CONVECTION IS FROM 05N TO 09N BETWEEN 128W AND 131W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM 10N92W TO 09N108W TO 08N116W. THE ITCZ AXIS CONTINUES FROM 08N116W TO 10N127W TO 08N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED FROM 06N TO 08.5N BETWEEN 97W AND 102W. SIMILAR CONVECTION IS WITHIN 120 NM S OF TROUGH BETWEEN 107W AND 109W. SCATTERED MODERATE CONVECTION IS FROM 05N TO 08N BETWEEN 111W AND 123W. ...DISCUSSION... A SURFACE RIDGE DOMINATES THE N WATERS ANCHORED ON A 1018 MB HIGH PRES LOCATED NEAR 28N127W. THE PRESSURE GRADIENT BETWEEN THIS RIDGE AND THE LOW PRES SITUATED 16.5N131W IS PRODUCING AN AREA OF MODERATE TO FRESH WINDS FROM 18N TO 21N BETWEEN 130W AND 134W. THESE WINDS ARE FORECAST TO PERSIST AND MOVE IN TANDEM WITH THE LOW PRES OVER THE NEXT COUPLE OF DAYS. LONG PERIOD CROSS-EQUATORIAL SWELL HAS REACHED MOST OF THE COAST OF MEXICO AND CENTRAL AMERICA. COMBINED SEAS IN THE 8-10 FT RANGE IN MIXED SE AND S SWELL CAN BE FOUND ACROSS MUCH OF THE AREA S OF 06N BETWEEN 81W AND 110W...EXCEPT IN THE LEE OF THE GALAPAGOS ISLANDS...S OF 02N BETWEEN 110W AND 120W AND S OF 03N W OF 135W. THIS SWELL EVENT WILL CONTINUE TO PROPAGATE N OVER EASTERN WATERS TO NEAR 09N BY EARLY WED BEFORE SUBSIDING...WITH SEAS TO 8 FT CONFINED PRIMARILY W OF THE GALAPAGOS ISLANDS BY EARLY THU. GAP WINDS... GULF OF TEHUANTEPEC...A TROPICAL WAVE WILL PASS S OF THE GULF OF TEHUANTEPEC...INCREASING THE TROUGHING THERE. THIS WILL INCREASE THE PRESSURE GRADIENT ACROSS SOUTHERN MEXICO AND ALLOW N WINDS TO FUNNEL THROUGH CHIVELA PASS BEGINNING OVERNIGHT TONIGHT. EXPECT FRESH TO STRONG NORTHERLY WINDS WITH THE ASSISTANCE OF NOCTURNAL DRAINAGE FLOW BOTH WED AND THU MORNINGS. SOUTHERLY SWELL COUPLED WITH THE GAP WIND GENERATED SWELL WILL QUICKLY BUILD SEAS TO 8-9 FT BY LATE WED...WITH SEAS EXPECTED TO REMAIN AT OR ABOVE 8 FT THROUGH LATE THU. GULF OF PAPAGAYO...THE SAME PATTERN DESCRIBED IN THE GULF OF TEHUANTEPEC SECTION ABOVE WILL FORCE FRESH TO STRONG E-NE WINDS THROUGH THE GULF OF PAPAGAYO BY EARLY WED. THESE WINDS WILL PULSE...BECOMING STRONGEST IN THE MORNING HOURS WITH THE BENEFIT OF NOCTURNAL DRAINAGE FLOW BOTH WED AND THU MORNINGS. SEAS WILL ALSO QUICKLY BUILD TO 9 FT HERE WED WHEN COMBINED WITH S SWELL...AND REMAIN IN THE 7-9 FT RANGE DOWNSTREAM OF PAPAGAYO THROUGH THE END OF THE FORECAST PERIOD. $$ GR