000 AXPZ20 KNHC 282143 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC SAT JUL 28 2012 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... TROPICAL WAVE EXTENDS FROM 15N138W TO 10N140W MOVING W AT 10 TO 15 KT. A WELL DEFINED MID LEVEL CYCLONIC CIRCULATION REMAINS EVIDENT IN SATELLITE IMAGERY AND TOTAL PRECIPITABLE WATER ANIMATIONS...WITH THE BEST MOISTURE CONVERGENCE LOCATED TO THE E OF THE AXIS. SCATTERED SHOWERS ARE OCCURRING FROM 04N TO 15N W OF 135W ALTHOUGH NO DEEP CONVECTION IS PRESENT. THIS WAVE WILL MOVE W OF THE DISCUSSION AREA TONIGHT. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH IS ALONG 08N78W TO 08N94W TO 11N119W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 10N121W TO 08N130W TO 11N138W. SCATTERED MODERATE TO STRONG CONVECTION IS WITHIN 180-270 NM S OF THE MONSOON TROUGH E OF 89W. SIMILAR CONVECTION IS WITHIN 150 NM S OF THE MONSOON TROUGH BETWEEN 89W AND 95W...AND ALSO WITHIN 180 NM N OF THE MONSOON TROUGH BETWEEN 89W AND 100W. SCATTERED MODERATE CONVECTION IS FROM 05N TO 08N BETWEEN 96W AND 102W...AND ALSO FROM 05N TO 08N BETWEEN 120W AND 125W. ...DISCUSSION... A TROUGH-RIDGE-TROUGH PATTERN PREVAILS IN THE MIDDLE TO UPPER LEVELS N OF 20N W OF 118W. N OF 20N E OF 118W...A BLOCKING MIDDLE TO UPPER LEVEL RIDGE PERSISTS OVER NW MEXICO AND THE DESERT SW OF THE UNITED STATES. THIS NARROW UPPER RIDGE EXTENDS SW FROM THE PARENT ANTICYCLONE NEAR 35N106W TO 17N122W TO 15N136W...WITH NE-E UPPER FLOW GENERALLY PREVAILING S OF THIS RIDGE ACROSS THE DEEP TROPICS. A TUTT LOW OVER THE SW GULF OF MEXICO EXTENDS WEAK INVERTED TROUGHING S-SW ACROSS SE MEXICO AND THE CHIVELA PASS TO NEAR 13N97W. 1028 MB HIGH PRES IS CENTERED NEAR 36N135W WITH A RIDGE ENTERING THE DISCUSSION WATERS NEAR 32N128W WITH A SE TERMINUS NEAR 21N111W. AN AREA OF 20-25 KT TRADES EXISTS FROM 14N TO 21N W OF 130W BETWEEN THIS RIDGE AND THE TROPICAL WAVE MENTIONED ABOVE. THESE WINDS WILL PERSIST THROUGH MON AFTERNOON EVEN ONCE THE TROPICAL WAVE EXITS W OF 140W TONIGHT AS A SURFACE TROUGH... CURRENTLY FROM 15N117W TO 09N121W...MOVES THROUGH THE SOUTHERN PORTION OF THE RIDGE HELPING TO MAINTAIN A TIGHT PRES GRADIENT. A SMALL AREA OF CROSS-EQUATORIAL SOUTHERLY SWELL COVERS THE WATERS S OF 02N BETWEEN 84W AND 88W. THIS SWELL IS FORECAST TO DECAY TO LESS THAN 8 FT TONIGHT. A LOW LEVEL WIND SURGE ASSOCIATED WITH THE REMNANTS OF AN OLD TROPICAL WAVE HAS MOVED ACROSS THE SW CARIBBEAN AND CENTRAL AMERICA DURING THE PAST 24-48 HOURS AND IS AIDING EXCELLENT MOISTURE CONVERGENCE ALONG THE MONSOON TROUGH E OF 100W WITH A LARGE AREA OF ACTIVE CONVECTION...AS IS MENTIONED IN THE CONVECTION SECTION ABOVE. THESE CONDITIONS HAVE ALSO PRODUCED AN ELONGATED PLUME OF NE TO E WINDS 20 TO 30 KT THROUGH AND DOWNWIND/SW OF THE GULF OF PAPAGAYO TO 93W. THESE WINDS WILL CONTINUE THROUGH ABOUT 18 HOURS BEFORE A WEAK AREA OF LOW PRES BEGINS TO DEVELOP NEAR 08N93W BY SUN AFTERNOON WITH 20 TO 25 KT WINDS EXPECTED IN THE N SEMICIRCLE OF THE LOW. THE LOW WILL THEN MOVE WESTWARD TO NEAR 08N97W BY MON AFTERNOON WITH FRESH TO STRONG WINDS PERSISTING IN THE NW SEMICIRCLE. A LATE MORNING ASCAT SCATTEROMETER PASS INDICATE 20-30 KT NORTHERLY WINDS IN AND DOWNWIND/SW OF THE GULF OF TEHUANTEPEC. THESE WINDS ARE SPILLING THROUGH THE CHIVELA PASS WITH THE REGION UNDER A TIGHT PRES GRADIENT BETWEEN A SURFACE TROUGH IN THE SW GULF OF MEXICO AND HIGH PRES OVER INLAND MEXICO W OF THE TROUGH. EXPECT THESE CONDITIONS TO PERSIST THROUGH THE NEXT 24-48 HOURS. NORTHERLY SWELL IS EXPECTED TO SEEP INTO THE FAR N CENTRAL WATERS N OF 28N BETWEEN 120W AND 126W BY LATE SUN NIGHT THROUGH MON AFTERNOON. THIS SWELL WILL BE GENERATED BY FRESH TO STRONG WINDS OFF OF THE CALIFORNIA COAST N OF THE AREA BETWEEN STRONG NE PACIFIC HIGH PRES AND THERMAL LOW PRES/TROUGHING OVER INTERIOR CALIFORNIA. $$ LEWITSKY