000 AXPZ20 KNHC 140953 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC FRI SEP 14 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0945 UTC. ...SPECIAL FEATURES... TROPICAL STORM KRISTY CENTERED NEAR 20.0N 112.0W AT 0900 UTC MOVING WNW OR 295 DEG AT 9 KT. MAXIMUM SUSTAINED WINDS HAVE INCREASED TO 50 KT WITH GUSTS TO 60 KT AND MINIMUM PRESSURE OF 998 MB. THE SYSTEM APPEARS A LITTLE BETTER ORGANIZED THE PAST FEW HOURS WITH THE CENTER NO LONGER EXPOSED...BUT UNDER THE NW EDGE OF THE DEEPEST CONVECTION. SCATTERED MODERATE TO STRONG CONVECTION IS OBSERVED WITHIN 90 NM EITHER SIDE OF A LINE FROM 17N108W TO 21N111W. KRISTY IS FORECAST TO TRACK IN A GENERAL NW DIRECTION OVER COOLER SEA SURFACE TEMPERATURES DURING THE NEXT 48 HRS CAUSING KRISTY TO UNDERGO GRADUAL WEAKENING. SOUTHERLY SWELL WILL MIX WITH NW SWELLS RESULTING IN COMBINED SEAS TO 7 FT REACHING THE PACIFIC COAST THE BAJA CALIFORNIA PENINSULA TO THE N OF 24N. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP1/WTPZ21 KNHC FOR MORE DETAILS. TROPICAL LOW PRESSURE IS ANALYZED WITHIN THE MONSOON TROUGH NEAR 15N119W AN ESTIMATED AT 1009 MB. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED WITHIN 45 NM OVER THE E AND WITHIN 120 NM OVER THE W SEMICIRCLES OF CENTER. CURRENTLY NE TO E SURFACE WINDS ARE AT 20 TO 25 KT WITHIN 150 NM OVER THE N QUADRANT...WITH SEAS 6 TO 8 FT. THIS SYSTEM HAS THE POTENTIAL TO DEVELOP INTO A TROPICAL CYCLONE FORMATION AS IT TRACKS WSW TO NEAR 14N122W LATE SAT...AND NEAR 14N123W LATE SUN. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS W ALONG 10N FROM THE NW COAST OF COLOMBIA ACROSS COSTA RICA THEN TURNS SW TO THE TROPICAL PACIFIC NEAR 07N96W...THEN EXTENDS WNW TO NEAR 09N110W WHERE IT LOSES IDENTITY. THE MONSOON TROUGH RESUMES SW OF TROPICAL CYCLONE KRISTY NEAR 17N115W AND CONTINUES SW THROUGH EMBEDDED LOW PRESSURE CENTERS AT 15N119W AND 14.5N132W...THEN CONTINUES SW TO BEYOND 12N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED WITHIN 30 NM OF 05N78W...WITHIN 240 NM EITHER SIDE OF A LINE FROM 06N92W TO 11N97W...WITHIN 90 NM EITHER SIDE OF A LINE FROM 05N107W TO 08N113W...WITHIN 90 NM OF 12N120W...AND WITHIN 90 NM OF 13N136W. ...DISCUSSION... A LONGWAVE UPPER RIDGE DOMINATES THE EASTERN N PACIFIC STEMMING FROM AN UPPER ANTICYCLONE CENTERED AT 19N125W AND RIDGING NNE THROUGH 32N125W AND ACROSS THE NW COAST OF CALIFORNIA. AN UPPER RIDGE ALSO EXTENDS SW TO A CREST AT 12N145W. AN UPPER SHORTWAVE TROUGH IS APPROACHING THE NW PORTION WITH EMBEDDED UPPER CYCLONES NOTED AT 32N142W AND 27N145W...AND SETTING UP A SOUTHERLY JET AT 60 TO 100 KT OVER THE NW PORTION WITHIN 180 NM OF LINE FROM 23N140W TO BEYOND 32N135W...WITH A THIN LINE OF UPPER MOISTURE NOTED N OF 30N WITHIN THIS JETLET. WEAK UPPER DIFFLUENCE OVER THE TROPICS IS ENHANCING CONVECTION ALONG THE MONSOON TROUGH BETWEEN 117W AND 140W. SOME OF THE DEBRIS MOISTURE IS ADVECTED SW TO NEAR 04N140W...AND SOME OF THE MOISTURE IS ALSO ADVECTED NW ACROSS THE UPPER RIDGE AXIS BETWEEN 130W AND 145W...THEN TURNING NE TO NEAR 21N130W WHERE IT SEEMS TO EVAPORATE IN THE VERY DRY THAT IS INDICATED OVER THE DISCUSSION AREA N OF 20N BETWEEN 115W AND 134W. THE UPPER ANTICYCLONE IS EXPECTED TO SHIFT N TO NEAR 28N120W LATE SUN SETTING UP A BLOCK THAT WILL ONLY ALLOW THE APPROACHING UPPER TROUGH TO SHIFT ONLY SLIGHTLY EASTWARD. IMMEDIATELY TO THE E OF THE LARGE UPPER RIDGE IS A DEEP LAYERED CYCLONE OVER W-CENTRAL NEW MEXICO WITH AN UPPER TROUGH EXTENDING S TO BASE OVER N-CENTRAL OLD MEXICO AT 28N106W. UPPER DIFFLUENCE ALONG AND E OF THIS TROUGH HAS ENHANCED CONVECTION OVER INTERIOR OLD MEXICO AND OVER TROPICAL CYCLONE KRISTY. THE DEBRIS MOISTURE TO THE N OF 20N IS SPREADING SE OVER THE WESTERN GULF OF MEXICO WHILE THE MOISTURE S OF 20N IS ADVECTED SW IN A 600 NM WIDE PLUME WITH MEAN AXIS FROM 20N105W TO 08N115W. A BROAD INVERTED UPPER TROUGH IS NOTED OVER THE DEEP TROPICAL PACIFIC TO THE S OF 17N BETWEEN 90W AND 100W...AND IS SHIFTING WESTWARD WITH TIME. AN UPPER ANTICYCLONE IS OVER COLOMBIA AT 08N76W WITH AN UPPER RIDGE EXTENDING NW ACROSS CENTRAL AMERICA TO A CREST AT 17N90W. THESE TWO UPPER FEATURES COMBINE TO SET UP AN AREA OF UPPER DIFFLUENCE OVER CENTRAL AMERICA AND THE TROPICAL PACIFIC TO THE E OF 92W. ALTHOUGH ONLY A FEW CONVECTIVE CLUSTERS ARE CURRENTLY ENHANCED...A BROAD AREA OF DENSE DEBRIS MOISTURE IS NOTED TO THE N OF 05N E OF 92W. DRY UPPER AIR W OF THE UPPER TROUGH IS SUPPRESSING CONVECTION OVER THE TROPICAL PACIFIC S OF 16N BETWEEN 98W AND 105W. ELSEWHERE AT THE SURFACE...A RIDGE EXTENDS FROM 32N135W TO 25N118W. A SURFACE RIDGE ORIENTATED FROM NE TO SW OVER THE GULF OF MEXICO IS CAUSING NORTHERLY WINDS TO PULSE AT 20 TO 25 KT WITH SEAS TO 8 FT...INTO AND JUST DOWNSTREAM OF THE GULF OF TEHUANTEPEC WITH LITTLE CHANGE EXPECTED THROUGH SUN. NE TO E WINDS ARE EXPECTED TO PULSE AT 15 TO 20 KT THROUGH THE GULF OF PAPAGAYO WITH MAX SEAS OF 7 FT JUST DOWNSTREAM OF THE GULF THROUGH SUN. THE STRONGEST GAP WINDS ARE EXPECTED TO OCCUR DURING THE LATE NIGHT HOURS THROUGH A FEW HOURS AFTER SUNRISE. $$ NELSON