Area Forecast Discussion
Issued by NWS Pendleton, OR
Issued by NWS Pendleton, OR
793 FXUS66 KPDT 300518 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 1018 PM PDT Fri Aug 29 2025 Updated Aviation Discussion .AVIATION...06Z TAFs...VFR conditions to prevail through the period. However, smoke from regional fires may produce reductions in vsby/cigs at sites RDM/BDN at times, though confidence in time/duration was too low (<25%) to include in the TAF at this time. Winds will be light, 12kts or less, with diurnally driven wind shifts through the period. Lawhorn/82 && .PREV DISCUSSION... /issued 347 PM PDT Fri Aug 29 2025/ .DISCUSSION...High pressure will begin to build into the Pacific Northwest today. As it does, a large area of low pressure of the coast will move eastward and make its closest approach Sunday into Monday before being pushed westward again. Strong high pressure will then build back for much of the upcoming week. There is enough CAPE and moisture today for isolated showers or thunderstorms, mainly over the mountains of eastern Oregon. After these dissipate this evening, dry and unseasonably hot conditions are forecast for the holiday weekend and into next week. A weak short wave could bring a low chance (20-30 percent) of showers around Tuesday or Wednesday mainly in central Oregon and the higher terrain, but models differ on the occurrence. However, the main story remains very hot, and possibly record- breaking heat for some areas especially Monday through Wednesday of next week. High temperatures should climb into the mid to upper 90s, with locations in the Columbia Basin, Foothills of the Blue Mountains, Columbia Gorge and Yakima Valley topping out around or just above 100 degrees. Temperatures will be 10 to 15 and possibly as high as 20 degrees above normal for early September. HeatRisk values will be mostly Moderate on Monday, with some embedded areas of Major. By Tuesday, There is a large swath of Moderate HeatRisk, with many low elevation areas having Major HeatRisk. Wednesday is similar to Tuesday, though the areal coverage of Major HeatRisk spreads a bit and some areas of the Gorge and Basin have Extreme HeatRisk, and Thursday is similar to Wednesday, especially for the Major and Extreme areas. Some potential caveats include cloud cover or smoke that would hold temperatures down, and of course, the shorter days in early September. By Friday, there should be a slight cool down, at least. NBM probabilities of 100+ temperatures in these areas are 60 to 80 percent Monday through Wednesday and the ECMWF EFI generally has values of 0.8 to 0.9 with the Columbia Basin in 0.9 to 0.95. for anomalies. Low RH values of less than 20 percent and in some areas less than 15 percent will prevail due to the very hot temperatures. There will be diurnal breezes each day, but overall, strong winds are not expected. However, with the high pressure, and the low RH values will have to watch for any enhanced conditions that could develop especially if things should become more unstable around midweek. && .PRELIMINARY POINT TEMPS/POPS... PDT 61 94 63 95 / 0 0 0 0 ALW 66 95 68 97 / 0 0 0 0 PSC 61 95 62 96 / 0 0 0 0 YKM 60 95 64 95 / 0 0 0 0 HRI 61 95 63 96 / 0 0 0 0 ELN 57 92 59 93 / 0 0 0 0 RDM 51 90 51 91 / 10 0 0 0 LGD 56 92 58 93 / 20 0 0 0 GCD 55 93 61 95 / 20 0 0 0 DLS 63 94 64 93 / 0 0 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. && $$ SHORT TERM...77 LONG TERM....77 AVIATION...82