000 AXPZ20 KNHC 182121 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC THU JUL 18 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 18N109W TO 12N110W MOVING W AT NEAR 10 KT. THE 1724 UTC ASCAT PASS SHOWED THE WIND SHIFT ASSOCIATED WITH THE WAVE. AN INVERTED V LOW LEVEL SIGNATURE IS NOTED ON VISIBLE SATELLITE IMAGERY. THE WAVE COINCIDES WITH A BULGE OF MOISTURE PRESENT IN TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS OBSERVED MAINLY AHEAD OF THE WAVE AXIS COVERING THE AREA FROM 13N TO 17N BETWEEN 110W AND 115W. GLOBAL MODELS SUGGEST THAT THE WAVE WILL GRADUALLY LOSE ITS SURFACE IDENTITY AS IT TRACKS WESTWARD THROUGH THE NEXT COUPLE OF DAYS. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... MONSOON TROUGH AXIS EXTENDS FROM 09N84W TO 07N100W TO 12N115W TO 09N126W. ITCZ AXIS CONTINUES FROM 09N126W TO 13N138W. NUMEROUS MODERATE TO ISOLATED STRONG CONVECTION CAN BE FOUND N OF 05N E OF 82W. SCATTERED MODERATE TO STRONG CONVECTION IS FROM 08N TO 11N BETWEEN 95W AND 99W...AND FROM 10N TO 12N BETWEEN 106W AND 110W. SCATTERED MODERATE CONVECTION IS NOTED FROM 07N TO 12N BETWEEN 120W AND 124W. ...DISCUSSION... ALOFT...AN ANTICYCLONE LOCATED WEST OF AREA NEAR 12N145W EXTENDS A RIDGE E-NE TO NEAR 15N130W. A WEAK UPPER LOW IS AT 24N125W. A TROUGH AXIS EXTENDS FROM THE LOW SSW TO NEAR 15N128W. SATELLITE WATER VAPOR IMAGERY SHOWS MODERATE TO STRONG SUBSIDENCE INDUCING A DRY AND VERY STABLE ATMOSPHERIC ENVIRONMENT W OF A LINE FROM 30N123W TO 20N125W TO 15N130W TO 18N140W. THE UPPER LOW WILL LIFT N AND AND BECOME DIFFUSE IN THE UPPER SW FLOW AHEAD OF A BROAD UPPER TROUGH LOCATED NW OF THE DISCUSSION AREA. A HIGHLY AMPLIFIED UPPER LEVEL RIDGE IS PRESENT OVER MUCH OF THE WESTERN U.S. AND STRETCHES SSW TO THE EASTERN PORTION OF THE FORECAST REGION N OF 18N AND E OF 120W...AND ALSO SEWD TO SE MEXICO. A WELL DEFINED DEEP LAYER LOW HAS MOVED FROM NEW MEXICO INTO NORTHERN MEXICO AND IS GENERATING SOME SHOWER AND TSTM ACTIVITY. ANOTHER MID TO UPPER LEVEL LOW IS SPINNING NEAR LOS MOCHIS SINALOA. AN INVERTED TROUGH EXTENDS FROM 17N119W TO 11N119W. ANOTHER INVERTED TROUGH IS NOTED ALONG 107W FROM 12N TO 16N. ELY WINDS ALOFT DOMINATE MUCH OF THE AREA N OF 05N E AND E OF ABOUT 120W...AND ARE TRANSPORTING DEBRIS CLOUDINESS FROM CONVECTION ALONG AND NEAR THE TROPICAL WAVE AND THE MONSOON TROUGH BETWEEN 108W AND 125W. A DIFFLUENT PATTERN ALOFT IS HELPING TO INDUCE THE CONVECTION N OF 05N E OF 82W...INCLUDING PARTS OF PANAMA. AT THE SURFACE...A RIDGE EXTENDS FROM A 1027 MB HIGH N OF THE AREA AT 35N138W SE TO 22N120W...WHILE A SURFACE TROUGH CONTINUES TO MOVE WWD ACROSS THE WEST-CENTRAL WATERS AND NOW EXTENDS FROM 16N137W TO 10N141W. NE WINDS OF 20-25 KT AND SEAS TO 9 FT ARE NOTED BETWEEN THE TROUGH AND THE RIDGE TO THE NORTH MAINLY FROM 14N TO 18N W OF 132W. AN ALTIMETER PASS CONFIRMED THE PRESENCE OF THE 9 FT SEAS. WINDS AND SEAS ARE FORECAST TO DIMINISH LATER TONIGHT INTO FRI AS THE TROUGH MOVES WEST OF AREA. THE MOST RECENT ASCAT PASS ALONG WITH A COUPLE OF SHIP OBSERVATIONS SHOWED NW WINDS OF 20 KT W OF BAJA CALIFORNIA TO ABOUT 120W N OF 26N WITH SEAS TO NEAR 8 FT. THESE MARINE CONDITIONS ARE FORECAST TO PERSIST TONIGHT AND WILL GRADUALLY DIMINISH ON FRI. A SURGE OF TRADE WINDS OVER THE CARIBBEAN SEA WILL PUSH GAP WINDS TO 20 KT THROUGH THE GULF PAPAGAYO AGAIN FRI MORNING. LONG PERIOD CROSS EQUATORIAL SOUTHWESTERLY SWELLS RESULTING IN COMBINED SEAS TO 8 FT DOMINATE THE FORECAST WATERS S OF LINE FROM 00N102W TO 05N112W TO 05N117W TO 00N130W. A SET OF LONG PERIOD SW SWELLS...WAVE PERIOD OF 18 TO 19 SECONDS...CONTINUES TO IMPACT MOST OF THE COASTS OF MEXICO AND CENTRAL AMERICA PRODUCING ROUGH SURF CONDITIONS AND DANGEROUS RIP CURRENTS TO THOSE COASTS. $$ GR