000 AXPZ20 KNHC 041546 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC SAT AUG 04 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1545 UTC. ...TROPICAL WAVES... A TROPICAL WAVE IS N OF 10N ALONG 94W. THE WAVE HAS MOVED AT 10 OVER THE PAST 24 HOURS. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS FLARING N OF 10N WITHIN 240 NM E OF WAVE BUT HAS HAS RECENTLY MOVED AWAY FROM THE COAST OF CENTRAL AMERICA. A TROPICAL WAVE EXTENDS FROM 10N TO 19N ALONG 107W AND HAS MOVED W AT 10 KT OVER THE PAST 24 HOURS. ONLY ISOLATED MODERATE CONVECTION IS OBSERVED FROM 10N TO 19N WITHIN 90 NM E OF THE WAVE. SCATTERED STRONG CONVECTION WITH NUMEROUS LIGHTNING STRIKES IS ENHANCED ALONG THE NORTHERN EXTENT OF THE WAVE WITHIN 90 NM OF 21.5N107W. THE WAVE MOTION IS NOT EXPECTED TO CHANGE OVER THE NEXT DAY OR SO WITH A NE TO E TO SE WIND SHIFT AT 5 TO 10 KT. LOW PRES HAS DEVELOPED AT 14N123W ALONG A TROPICAL WAVE EXTENDING N TO S ALONG 123W FROM 10N TO 18N..AND HAS MOVED W AT 10 KT OVER THE PAST 24 HOURS. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS OBSERVED WITHIN 90 NM OF THE LOW PRES CENTER. THE SYSTEM IS EXPECTED TO MOVE W ABOUT 10 KT OVER THE NEXT 48 HOURS WITH NE TO E TO SE WINDS ENHANCED TO 20 TO 25 KT...SEAS TO 8 FT...MAINLY OVER THE NE SEMICIRCLE. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS W FROM THE NW COAST OF COLOMBIA AT 09N78W TO NEAR 09N90W...THEN TURNS SLIGHTLY NW THROUGH 11N103W...THEN DIPS SW THROUGH 09N115W BEFORE TURNING ABRUPTLY NW AND BECOMING DISTORTED IN THE CYCLONIC CIRCULATION ASSOCIATED WITH A TROPICAL LOW AT 14N123W. LOW LEVEL WINDS INDICATE THAT THE ITCZ FORMS NEAR 11N125W AND CONTINUES SW TO BEYOND 07N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED ELSEWHERE N OF 07N E OF 93W...N OF 07N BETWEEN 97W AND 103W...AND FROM 06N TO 13N BETWEEN 108W AND 123W. ONLY ISOLATED MODERATE TO STRONG CONVECTION IS NOTED ALONG THE ITCZ...WITHIN 30 NM EITHER SIDE OF A LINE FROM 09N130W TO 06N140W. ...DISCUSSION... SEVERAL UPPER CYCLONES ARE NOTED JUST N OF THE AREA. THE WESTERNMOST CYCLONE IS QUASI STATIONARY AT 34N144W WITH A TROUGH EXTENDING SE INTO THE AREA AT 28N133W. ANOTHER UPPER CYCLONE IS AT 35N128W WITH AN UPPER TROUGH EXTENDING SE TO 23N119W THEN TURNS SW TO A BASE AT 14N128W. THE UPPER LEVELS ARE IMPRESSIVELY DRY OVER THE DISCUSSION AREA N OF 20N W OF 117W AND FROM 15N TO 20N BETWEEN 126W AND 140W. AN UPPER ANTICYCLONE IS OVER CENTRAL TEXAS WITH THE W PERIPHERY OF ITS ENVELOPE ALONG 20N102W TO 27N110W TO BEYOND 32N109W. DENSE DEBRIS MOISTURE...ORIGINATING MOSTLY FROM FORMER CONVECTION ALONG WESTERN OLD MEXICO...IS ADVECTED ALONG THE RIDGE PERIPHERY INTO A 240 NM PLUME THAT CONTINUES N ACROSS THE ARIZONA/NEW MEXICO BORDER EVENTUALLY TURNING NE ACROSS THE CENTRAL CONUS. AN UPPER ANTICYCLONE IS OVER THE DEEP TROPICS AT 15N140W WITH A RIDGE EXTENDING E TO A CREST AT 12N130W. THE DEBRIS MOISTURE FROM THE ITCZ RELATED CONVECTION PREVIOUSLY DESCRIBED IS ADVECTED SW TO ALONG 03N BETWEEN 130W AND 145W. AN UPPER ANTICYCLONE IS AT 14N113W WITH A RIDGE EXTENDING E AND W ALONG 14N BETWEEN 105W AND 125W. UPPER DIFFLUENCE FROM THIS RIDGE IS SUPPORTING THE CONVECTION ASSOCIATED WITH THE TROPICAL LOW DEVELOPING ALONG THE TROPICAL WAVE AT 123W...AS WELL AS THE LARGE AREA OF CONVECTION DESCRIBED FROM 06N TO 13N BETWEEN 108W AND 123W. SOME OF THE DEBRIS MOISTURE HAS ADVECTED N TO ALONG 20N NEAR 125W...BUT WILL LIKELY EVAPORATE BEFORE CROSSING THE W COAST OF MEXICO. A SMALL UPPER CYCLONE IS FILLING NEAR 18N109W BUT ENHANCED THE CONVECTION PREVIOUSLY MENTIONED ALONG THE N EXTENT OF THE TROPICAL WAVE ALONG 107W. THE CONVECTION SEEMS TO HAVE MATURED AND IS DECREASING IN BOTH AREAL COVERAGE AND INTENSITY. BROAD UPPER ANTICYCLONIC FLOW IS BECOMING ESTABLISHED OVER THE DEEP TROPICAL PACIFIC TO THE N OF 05N E OF 95W WITH SLIGHT ENHANCEMENT OF CONVECTION WITHIN THE MONSOON TROUGH. THE RESULTANT DEBRIS MOISTURE IS ADVECTED W IN THE ANTICYCLONIC UPPER FLOW. ELSEWHERE AT THE LOW LEVELS...A RIDGE EXTENDS SE INTO THE AREA FROM 30N140W TO 17N123W. NE TRADES AT 15 TO 20 KT ARE STILL ENHANCED SW OF THE RIDGE IN THE AREA FROM 10N TO 13N TO W OF 137W. THE GRADIENT IS EXPECTED TO RELAX TONIGHT WITH THESE TRADES FURTHER WEAKENING. AS THE TROPICAL LOW AND PARENT TROPICAL WAVE CURRENTLY ALONG 123W PROGRESS WESTWARD...THE GRADIENT WILL TIGHTEN INCREASING THE NE TRADES TO 20 KT WITH SEAS BUILDING TO 8 FT...ACROSS THE WATERS FROM 12N TO 17N W OF 130W EARLY NEXT WEEK. CROSS-EQUATORIAL LONG PERIOD S SWELL HAS PROPAGATED N TO ALONG 08N BETWEEN 81W AND 89W AND SHOULD BEGIN TO DIMINISH SOME TONIGHT. SOUTHEASTERLY SWELL HAS ALSO CROSSED THE EQUATOR REACHING ALONG 08N BETWEEN 93W AND 115W...AND TO THE S OF 06N BETWEEN 115W AND 128W. THESE SWELL ARE EXPECTED TO PROPAGATE N TO ABOUT 10N OVER THE NEXT COUPLE OF DAYS. GAPS WINDS...NORTHERLY WINDS ARE EXPECTED TO INCREASE TO 20 TO 25 KT IN THE GULF OF TEHUANTEPEC AROUND SUNRISE ON MON. $$ NELSON