Area Forecast Discussion
Issued by NWS Pendleton, OR
Issued by NWS Pendleton, OR
341 FXUS66 KPDT 311720 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 1020 AM PDT Sun Aug 31 2025 Updated Aviation Discussion .AVIATION...18z TAFs...VFR conditions expected, with generally sct mid-level cigs around 15 kft and light, terrain-driven winds less than 12 kts, except for DLS which will see gusts up to 25 kts at times this afternoon and early evening. Haze will continue to obscure the horizon for most sites. Evans/74 && .PREV DISCUSSION... /issued 641 AM PDT Sun Aug 31 2025/ MORNING UPDATE...Radar this morning depicts isolated shower activity along the east slopes of the Washington Cascades, spreading from Klickitat County northward. Expectation is that the boundary layer is dry enough that not much should reach the ground from these showers, but did include a low-end (15% chance) for showers to occur across the aforementioned areas just in case. Have seen traces of precip reported in the area, but moisture influx into the area isn`t great, so not expecting anything more than some sprinkles, save for maybe the higher terrain. Evans/74 PREV DISCUSSION... /issued 125 PM PDT Sat Aug 30 2025/ DISCUSSION...A relatively complex synoptic pattern is setting up for the Pacific Northwest for the next week. Satellite imagery currently shows a broad low pressure system circulating just off the coast. Models have this low meandering towards the Olympic Peninsula before retrograding during the week, leaving our forecast area caught between two deep troughs. A quasi-ridge pattern results, which will cause a distinct warm-up through the midweek. So long as this offshore low remains in our area of influence, however, expect mild gap flows and persistent chances for isolated showers and thunderstorms over at least the next several days. Currently, radar shows some light shower and storm activity developing across Union and Wallowa County. CAMs are not too bullish on coverage this afternoon and evening, likely due to the low shear and subsidence aloft as weak ridging forms ahead of this offshore low, but the ingredients still remain for at least isolated activity for the area. Winds remain relatively light, however gap flows are picking up above guidance for The Dalles this afternoon, suggesting a stronger cross-Cascade gradient than what models are picking up on (which makes sense. There is a low offshore after all). Expect mild breezes downslope of the Cascades this afternoon as well as tomorrow, combining with low RHs to make for elevated fire weather concerns. Don`t think winds will be strong nor widespread enough to warrant any headlines, but active incidents (like the Flat Fire) will certainly be affected by these conditions. Favorable ascent then shifts to the central Washington Cascades for tomorrow, albeit only enough to support slight (15-20%) chances for showers and thunderstorms. Focus then shifts to the building heat beyond Labor Day, but before then, this low looks to circulate a secondary trough from SoCal into the region Tuesday night into Wednesday. Models aren`t depicting this system too cleanly as of yet, but will certainly be something to keep an eye on as the days progress. By then, the heat will really start ramping up, with decent probabilities (50-60%) for the lower Columbia Basin to see high temps eclipse 100 degrees, which would flirt with daily records given the time of year. Evans/74 && .PRELIMINARY POINT TEMPS/POPS... PDT 94 61 93 62 / 10 10 0 0 ALW 96 67 95 68 / 10 10 0 0 PSC 95 62 95 61 / 10 10 0 0 YKM 95 62 94 63 / 20 20 0 0 HRI 95 63 95 62 / 10 10 0 0 ELN 93 59 92 59 / 20 20 0 0 RDM 91 50 92 50 / 0 0 0 0 LGD 95 59 96 60 / 10 0 0 0 GCD 95 58 97 60 / 0 10 0 0 DLS 92 63 93 63 / 0 10 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. && $$ SHORT TERM...74 LONG TERM....74 AVIATION...74