000 AXPZ20 KNHC 172125 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC WED JUL 17 2013 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. ...TROPICAL WAVES... A TROPICAL WAVE EXTENDS FROM 19N107W TO 13N108W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS NOTED MAINLY AHEAD OF THE WAVE AXIS FROM 14N TO 17N BETWEEN 107W AND 112W. ISOLATED MODERATE TO STRONG CONVECTION IS SEEN ELSEWHERE FROM 10N TO 19W BETWEEN 105W AND 112W. THE WAVE COINCIDES WITH A BULGE OF MOISTURE PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. GLOBAL MODELS ARE IN FAIR AGREEMENT INDICATING THE WAVE WILL DAMPEN OUT AS IT TRACKS FARTHER WEST THROUGH THE NEXT COUPLE OF DAYS. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... MONSOON TROUGH EXTENDS FROM 09N84W TO 09N92W TO 11N101W. ITCZ CONTINUES FROM 11N101W TO 13N110W TO 11N120W TO 13N134W THEN RESUMES AT 09N137W TO BEYOND 08N140W. A CLUSTER OF MODERATE TO STRONG CONVECTION IS JUST SOUTH OF WESTERN PANAMA COVERING FROM 05N TO 08N BETWEEN 80W AND 84W. SIMILAR CONVECTION IS NOTED FROM 06N TO 08N BETWEEN 85W AND 87W. ISOLATED MODERATE CONVECTION IS FROM 06N TO 10N BETWEEN 117W AND 130W. SCATTERED MODERATE CONVECTION CAN BE FOUND FROM 07N TO 12N W OF 130W. ...DISCUSSION... ALOFT...AN ANTICYCLONE LOCATED WEST OF AREA NEAR 12N145W EXTENDS A RIDGE NE ACROSS THE WEST-CENTRAL WATERS TO ABOUT 23N129W. MODERATE TO STRONG SUBSIDENCE AND IMPLIED DRY AIR MASS COVERS MOST OF THE AREA N OF 16N W OF 122W. AN UPPER TROUGH EXTENDS FROM AN UPPER LOW CENTERED NEAR 25N124W TO 15N130W. THE UPPER LOW AND TROUGH WILL LARGELY LOSE DEFINITION AND DAMPEN OUT OVER THE NEXT 24 HOURS AHEAD OF AN AMPLIFYING UPPER TROUGH ALONG 145W NE OF HAWAII WHICH IS ALREADY PRODUCING MODERATE SW FLOW ACROSS THE NW CORNER OF THE AREA. A RIDGE DOMINATES WESTERN MEXICO... THE BAJA CALIFORNIA PENINSULA AND THE WATERS N OF 18N E OF 120W. MODERATE TO STRONG SOUTHERLY WINDS ARE NOTED BETWEEN THE UPPER LOW AND THE ANTICYCLONE. A SMALL AREA OF UPPER DIFFLUENCE ASSOCIATED WITH THIS RIDGE SUPPORTS THE CONVECTION RELATED TO THE TROPICAL WAVE. AN INVERTED TROUGH EXTENDS FROM 17N116W TO 10N113W. EASTERLY WINDS ALOFT DOMINATE MUCH OF THE AREA N OF 05N E OF 110W. UPPER DIFFLUENCE IS SUPPORTING THE AFOREMENTIONED CLUSTER OF MODERATE TO STRONG CONVECTION LOCATED JUST SOUTH OF WESTERN PANAMA. THE MAIN MARINE IMPACT WILL BE THE BRIEF POTENTIAL FOR NE WINDS OF 20 TO 25 KT AND SEAS TO 8 FT AHEAD OF A SURFACE TROUGH THAT CURRENTLY EXTENDS FROM 15N132W TO 10N136W. THE MOST RECENT ASCAT PASS SHOWED NE WINDS OF 15-20 KT AHEAD OF THE TROUGH AXIS. SCATTERED MODERATE CONVECTION IS NOTED WITHIN AROUND 50 NM EITHER SIDE OF TROUGH AXIS. PRES GRADIENT BETWEEN THE TROUGH AND HIGH PRES TO THE NORTH WILL BRING AN INCREASE IN THE AERIAL EXTENT OF THE FRESH TO STRONG NE WINDS LATER TONIGHT INTO THU. THESE MARINE CONDITIONS WILL SHIFT W OF 140W ALONG WITH THE TROUGH THU NIGHT. A SURGE OF TRADE WINDS OVER THE CARIBBEAN SEA WILL PUSH GAP WINDS TO 20 KT TONIGHT AND LATE FRI THROUGH THE GULF PAPAGAYO. THIS ALONG WITH SOME ASSISTANCE FROM A TROPICAL WAVE MOVING INTO THE WESTERN CARIBBEAN AND SOUTHERN CENTRAL AMERICA OVER THE NEXT 48 HOURS WILL ALLOW A WEAK SURFACE LOW PRES AREA TO FROM ALONG THE MONSOON TROUGH OFF THE COAST OF COSTA RICA THROUGH FRI. GLOBAL MODELS CARRY THE LOW WESTWARD...REACHING 95W BY EARLY SAT WITH A EXPECTED MSLP AROUND 1009 MB. THE MAIN IMPACT WILL BE INCREASED SHOWERS AND THUNDERSTORMS OVER THE WATERS E OF 100W...MAINLY ALONG THE COASTLINES DURING THE LATE NIGHT AND EARLY MORNING HOURS. AN UPPER LOW ANOMALOUSLY MOVING WESTWARD FROM THE SOUTHERN PLAINS INTO NEW MEXICO THIS AFTERNOON IS EXPECTED TO EVENTUALLY PUSH SW INTO THE GULF OF CALIFORNIA FRI INTO SAT. THIS WILL ENHANCE SURFACE TROUGHING OVER THE GULF AND BAJA...AND ITS INTERACTION WITH RIDGING TO THE WEST TO ALLOW FRESH NW WINDS OFF THE NORTHERN COAST OF BAJA BY LATE THU...WITH SEAS BUILDING TO 8 FT. THE UPPER LOW WILL WEAKEN FRI AND SAT ALLOWING WINDS AND SEAS TO DIMINISH. LONG PERIOD CROSS EQUATORIAL SOUTHWESTERLY SWELLS RESULTING IN COMBINED SEAS TO 9 FT DOMINATE THE FORECAST WATERS S OF LINE FROM 00N94W TO 08N105W TO 08N114W TO 00N126W. A SET OF LONG PERIOD SW SWELLS...WAVE PERIOD OF 19 TO 21 SECONDS...IS NOW REACHING MOST OF THE MEXICAN COAST AND WILL AFFECT PARTS OF THE COAST OF CENTRAL AMERICA LATER TONIGHT...BRINGING ROUGH SURF CONDITIONS AND DANGEROUS RIP CURRENTS TO THOSE COASTS. $$ GR