000 FXUS66 KPDT 052251 AAA AFDPDT AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE PENDLETON OR 350 PM PDT SUN JUL 5 2009 UPDATED AVIATION DISCUSSION .SHORT TERM...TONIGHT THROUGH WEDNESDAY. ACTIVE WEATHER OCCURRING WITH A SEVERE THUNDERSTORM IN PROGRESS AT THE TIME OF THE PRODUCT. QUICKLY MID LEVEL MOISTURE OVER THE EASTERN CWA WAS COMBINING WITH DAYTIME HEATING TO PRODUCE THUNDERSTORMS OVER THE BLUE/WALLOWA AREAS THAT SHOULD PERSIST INTO THE EVENING. NEXT STORM SYSTEM TO AFFECT THE AREA WAS OFF THE PACNW COAST THAT WILL MOVE INLAND OVERNIGHT. AHEAD OF THIS SYSTEM THE MODELS WERE SHOWING AN AREA OF SHOWERS AND TSRA THAT IS EXPECTED TO DEVELOP OVER OR NEAR CENTRAL OREGON AFTER 00Z AND MIGRATE NNE INTO PORTIONS OF THE BASIN AFTER 06Z. THEN TRAVEL INTO THE EASTERN CWA AFTER 12Z AND HAVE ADJUSTED THE ZONES TO REFLECT THIS TIMING. COLD FRONT WILL RACE ACROSS THE AREA WITH BREEZY WINDS TOMORROW. SIGNIFICANT COOLER AFTERNOON HIGH TEMPS WILL OCCUR MONDAY. MID LEVEL LOW PRESSURE WILL LINGER OVER OR NEAR VANCOUVER ISLAND FROM TUESDAY TO WEDNESDAY WITH UNSETTLED WEATHER CONTINUING ALONG WITH BELOW NORMAL TEMPS. .LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY...WEDNESDAY NIGHT AN UPPER LEVEL LOW WILL BE NEAR VANCOUVER ISLAND WITH A TROUGH EXTENDING INTO MANITOBA. WEDNESDAY NIGHT THROUGH FRIDAY THE LOW WILL SLOWLY RETROGRADE INTO THE EASTERN PACIFIC AND FILL. A WEAK WAVE WILL ROTATE AROUND THE LOW INTO EASTERN OREGON WEDNESDAY NIGHT AND THURSDAY. THIS WAVE WILL TRIGGER A FEW SHOWERS OVER THE CASCADES AND NORTHEAST OREGON MOUNTAINS WHILE THE TROUGH WILL KEEP LOWER TEMPERATURES OVER ALL OF EASTERN WASHINGTON AND OREGON. FRIDAY THROUGH SUNDAY AN UPPER LEVEL RIDGE WILL BUILD OVER MONTANA WHILE THE LOW OFFSHORE CONTINUES TO FILL. MOUNTAIN SHOWERS WILL END AND TEMPERATURES INCREASE DUE TO THE BUILDING RIDGE. COONFIELD && .AVIATION...0Z TAFS...VFR CONDITIONS WILL BE PREVALENT FOR THE NEXT 24 HOURS. MID AND HIGH CLOUDS WILL INCREASE TONIGHT AHEAD OF A COLD FRONT. ISOLATED THUNDERSTORMS HAVE DEVELOPED THIS AFTERNOON IN THE UNSTABLE AIR OVER NORTHEASTERN OREGON AND MAY AFFECT KRDM...KPDT AND KALW UNTIL 12Z. THE THUNDERSTORMS OVER THE MOUNTAINS ARE MOVING NORTH AND MAY MOVE OVER KPDT. AT THIS TIME IT LOOKS LIKE THE THUNDERSTORMS MAY REMAIN EAST OF KALW SO WILL LEAVE OUT OF THE TAF. THE FRONT WILL CROSS THE CASCADES THIS EVENING AND MAY TRIGGER ISOLATED THUNDERSTORMS OVER ALL OF EASTERN WASHINGTON AND OREGON TONIGHT. PROBABILITY WILL NOT BE ENOUGH TO INCLUDE TS IN TAFS EXCEPT KPDT...BUT DO EXPECT SOME SHOWER ACTIVITY NEAR ALL TAF LOCATIONS. LOW LEVELS REMAIN VERY DRY SO CONVECTIVE ACTIVITY WILL BE HIGH BASED...ABOVE 8-12 KFT. WINDS WILL BE 10 TO 20 KTS WITH GUSTS TO 25 KTS AT KDLS. GUSTS WILL DECREASE AT KDLS OVERNIGHT...THEN REDEVELOP AFTER 18Z. WINDS WILL BE BRIEFLY GUSTY AT ALL OTHER TAF LOCATIONS THIS EVENING. THUNDERSTORM ACTIVITY MAY GENERATE BRIEF GUSTY WINDS TO 35 KTS. WINDS WILL ALSO INCREASE BRIEFLY TO 10-20 KT WITH GUSTS TO 30 KT WITH THE FRONTAL PASSAGE 03-06Z KDLS...KYKM...AND KRDM AND 05-09Z KPSC...KALW...AND KPDT. 76 && .FIRE WEATHER...RED FLAG WARNINGS HAVE BEEN ISSUED FOR THE GRASSLAND AREAS OF SOUTH CENTRAL WASHINGTON AND CENTRAL AND NORTH CENTRAL OREGON. THIS INCLUDES THE COLUMBIA BASIN...EASTERN COLUMBIA RIVER GORGE...THE WARM SPRINGS RESERVATION AREA...AND PRINEVILLE DISTRICT. ALTHOUGH WINDS ARE NOT EXPECTED TO INCREASE SIGNIFICANTLY THIS AFTERNOON AND EVENING IN THE COLUMBIA BASIN...THE COMBINATION OF WINDS AND VERY LOW HUMIDITIES ARE A CONCERN. THE FRONT MOVING THROUGH TONIGHT WILL RESULT IN NUMEROUS CLOUD-TO-GROUND STRIKES OVER THE WARNING AREA FOR ADDITIONAL CONCERNS FOR CRITICAL FIRE WEATHER CONDITIONS. THERE WILL BE ABUNDANT LIGHTNING IN OUR MOUNTAIN ZONES...YET THE FUELS IN THE HIGHER ELEVATIONS ARE NOT QUITE AS DRY AS THE GRASSY AREAS. JOHNSON && .PRELIMINARY POINT TEMPS/POPS... PDT 62 80 54 78 / 30 30 10 20 ALW 65 83 56 80 / 30 30 10 20 PSC 64 86 57 83 / 30 30 10 10 YKM 61 80 53 79 / 30 30 10 10 HRI 62 84 54 81 / 30 20 10 10 ELN 62 79 53 75 / 30 30 10 10 RDM 49 77 42 74 / 30 20 10 20 LGD 58 78 49 74 / 30 30 10 20 GCD 54 78 46 74 / 20 20 10 20 DLS 62 76 54 75 / 30 20 10 10 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...RED FLAG WARNING FROM 8 PM THIS EVENING TO 11 AM PDT MONDAY FOR ORZ610-630. RED FLAG WARNING UNTIL 11 AM PDT MONDAY FOR ORZ609-631. HEAT ADVISORY UNTIL 8 PM PDT THIS EVENING FOR ORZ044. WA...RED FLAG WARNING UNTIL 11 AM PDT MONDAY FOR WAZ609-631-675. HEAT ADVISORY UNTIL 8 PM PDT THIS EVENING FOR WAZ028. && THREAT INDEX MONDAY : YELLOW TUESDAY : GREEN WEDNESDAY : GREEN GREEN: NONE OR LIMITED NEED FOR WATCHES, WARNINGS, OR ADVISORIES. YELLOW: A FEW WATCHES, WARNINGS, OR ADVISORIES POSSIBLE OR IN EFFECT. RED: NUMEROUS WATCHES, WARNINGS, OR ADVISORIES POSSIBLE OR IN EFFECT. FOR ADDITIONAL WEATHER INFORMATION, CHECK OUR WEB SITE AT... WWW.WEATHER.GOV/PENDLETON $$ 97/76/76