AFDPDT AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PENDLETON OR 1042 AM PDT WED APR 20 2022 UPDATED AVIATION DISCUSSION .SHORT TERM...TODAY AND TONIGHT...THE TRANSITORY RIDGE OF HIGH PRESSURE PASSING OVER THE REGION OVERNIGHT IS MOVING OFF TO THE EAST AS A DEEP UPPER LEVEL LOW OFF THE COAST APPROACHES THE COAST. THIS LOW IS PUSHING A DECAYING COLD FRONT INTO WESTERN OREGON THIS MORNING AND THEN WILL SPREAD ACROSS THE FORECAST AREA THIS AFTERNOON AS SHOWERS AND SOME POSSIBLE THUNDERSTORMS. THE THUNDERSTORM POTENTIAL WILL MAINLY BE CONFINED TO CENTRAL OREGON AND THE SOUTHERN BLUE MOUNTAINS THROUGH THIS EVENING. THE REMNANTS OF THE FRONT WILL MOVE EAST OF THE FORECAST AREA LATE TONIGHT BUT SHOWERS WILL LINGER ACROSS THE FORECAST AREA AS WE REMAIN UNDER A SOUTHWEST FLOW WITH THE LOW OFF THE OREGON COAST. WILL ALSO SEE SOME BREEZY CONDITIONS ACROSS CENTRAL AND NORTHEAST OREGON AS SOUTHERLY WINDS INCREASE AHEAD OF THE FRONT. .AVIATION...18Z TAFS...INCREASING CLOUDS WITH LOWERING CIGS TO AROUND 030-060 AND THE ONSET OF SHOWERS TODAY AS A FRONT MOVES INTO THE REGION AND A SLIGHT CHANCE OF THUNDERSTORMS POSSIBLE, MAINLY OVER CENTRAL OREGON THROUGH THIS EVENING. VIS MAY REDUCE TO 6SM WITH RAIN AND POSSIBLE MIST/FOG, BUT REMAIN VFR LATE THIS AFTERNOON THROUGH EARLY TONIGHT. WINDS WILL BE UNDER 10 KTS THIS MORNING BUT INCREASING SOUTH WINDS AT RDM AND BDN BECOMING 10-20KTS WITH HIGHER GUSTS THIS AFTERNOON AND EVENING. && .PREV DISCUSSION... /ISSUED 430 AM PDT WED APR 20 2022/ SHORT TERM...A TRANSITORY UPPER RIDGE THIS MORNING WILL GIVE WAY TO ANOTHER UPPER TROUGH THAT WILL MOVE INTO THE REGION BY THIS AFTERNOON AND EVENING. IT WILL BRING MOISTURE AND AN INCREASING CHANCE OF SHOWERS BY THIS AFTERNOON AND EVENING. THERE WILL ALSO BE SOME INSTABILITY THAT WILL BE TRANSPORTED INTO THE FORECAST AREA IN A SOUTHWEST FLOW ALOFT. THIS INSTABILITY COMBINED WITH SURFACE HEATING AND MOISTURE WILL BE ENOUGH FOR ISOLATED THUNDERSTORMS THAT WILL BEGIN ALONG THE CASCADE EAST SLOPES AND SPREAD NORTHEAST ACROSS NORTH CENTRAL OR INTO THE NORTHEAST MOUNTAINS. THE HREF ENSEMBLE PAINTBALL IS SHOWING QUITE A BIT OF BLOTCHES OF 40+ DBZ WITH MUCAPE > 50 J/KG WIND AND PRECIPITATION OVER THESE AREAS BY THIS AFTERNOON WHICH INCREASES CONFIDENCE OF THUNDERSTORMS. HOWEVER, AM ONLY EXPECTING A SLIGHT CHANCE. SPC CONVECTIVE OUTLOOK FOR TODAY HAS MOST OF THE FORECAST AREA UNDER A GENERAL RISK OF THUNDERSTORMS FOR TODAY. THIS SOUTHWEST FLOW WILL PERSIST OVERNIGHT AND ON THURSDAY, IN WHICH ANOTHER ROUND OF THUNDERSTORMS FOR THURSDAY AFTERNOON AND EARLY EVENING ARE EXPECTED AS THE SOUTHWEST FLOW ALOFT AND INSTABILITY REMAINS. SPC HAS A GENERAL THUNDERSTORM RISK OVER THE CWA AGAIN ON THURSDAY. IN FACT THUNDERSTORM COVERAGE FOR THURSDAY WILL BE GREATER WITH EVEN GREATER HREF ENSEMBLE PAINTBALL DEPICTION OF THUNDERSTORM POTENTIAL OVER MOST OF THE CWA ON THURSDAY. SHOWERS AND THUNDERSTORMS WILL DECREASE QUICKLY AFTER ABOUT 06Z FRIDAY (THURSDAY EVENING) AS THE UPPER TROUGH MOVES EASTWARD AND THE FLOW ALOFT BECOMES NORTHWEST. HOWEVER, SOME UPSLOPE SHOWERS WILL REMAIN IN THE MOUNTAINS ON FRIDAY. AFTER THAT AN UPPER RIDGE WILL BUILD INTO THE REGION FRIDAY NIGHT AND EARLY SATURDAY WITH DRIER AND MORE STABLE CONDITIONS. IT WILL BE LOCALLY BREEZY TO WINDY THIS AFTERNOON, ESPECIALLY OVER CENTRAL OR, WHICH WILL DIMINISH LATE THIS EVENING. AFTER THAT WINDS WILL BE LIGHT UNTIL THURSDAY WHEN IT WILL BECOME LOCALLY BREEZY AGAIN, BUT THIS TIME OVER THE LOWER COLUMBIA BASIN AREAS. HOWEVER, THESE WINDS WILL DIMINISH AND BECOME LIGHT AGAIN BY LATE THURSDAY EVENING. WINDS WILL THEN REMAIN LIGHT THROUGH THE REST OF THE SHORT TERM FORECAST PERIOD. TEMPERATURES WILL BE WARMER FOR THE NEXT FEW DAYS AND NEAR NORMAL, COMPARED TO RECENT DAYS WHEN TEMPERATURES WERE COOLER THAN NORMAL. 88 LONG TERM...SATURDAY THROUGH TUESDAY. MAINLY DRY AND WARMER SATURDAY AND SUNDAY AS A RIDGE MOVES THROUGH THE REGION. SOME LINGERING MOISTURE AND INSTABILITY OVER EXTREME NORTHEAST OREGON AND DAYTIME HEATING, MIGHT SEE A SLIGHT CHANCE OF SHOWERS FOR THAT AREA ON SATURDAY AFTERNOON. THE NEXT SYSTEM IS EXPECTED TO REACH THE CASCADES BY LATE SUNDAY AND THEN MOVE THROUGH LATE MONDAY AND MONDAY NIGHT WITH A STRONGER SYSTEM TUESDAY. THIS WILL BRING A CHANCE OF SHOWERS MONDAY NIGHT AND MORE WIDESPREAD PRECIPITATION TUESDAY. SNOW LEVELS ARE STILL 5500 TO 7000 FEET, SO RAIN, EXCEPT FOR THE HIGHEST PEAKS MONDAY NIGHT,BUT THEN LOWER TO 4000 TO 5500 FEET FOR TUESDAY WITH MORE OF A RAIN/SNOW MIX. TEMPERATURES SHOULD WARM TO NEAR SEASONAL NORMALS THROUGH THE WEEKEND AND MONDAY, THEN SLIGHTLY COOLER WITH THE SYSTEM ON TUESDAY. GOOD AGREEMENT AMONG THE MODELS AND ENSEMBLES THROUGH MOST OF THE EXTENDED PERIOD. SOME TIMING DIFFERENCES START TO SHOW UP WITH THE SYSTEM LATE MONDAY/TUESDAY. 93 A && .PRELIMINARY POINT TEMPS/POPS... PDT 61 38 57 34 / 30 80 40 20 ALW 64 42 59 37 / 20 80 50 20 PSC 63 44 63 38 / 20 70 20 10 YKM 53 37 59 32 / 60 70 30 10 HRI 63 41 61 37 / 30 80 30 10 ELN 51 37 56 33 / 40 70 40 10 RDM 56 34 54 30 / 60 70 30 20 LGD 53 38 51 31 / 30 80 70 20 GCD 53 38 53 30 / 60 80 50 20 DLS 56 42 61 39 / 80 70 50 20 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...NONE. WA...NONE. &&