Area Forecast Discussion
Issued by NWS Pendleton, OR
Issued by NWS Pendleton, OR
719 FXUS66 KPDT 111805 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 1005 AM PST Thu Dec 11 2025 .Updated for Aviation... .AVIATION... 18Z TAFS...VFR conditions are expected at all TAF sits, with MVFR or lower possible at DLS though confidence is below average (<40 percent). Lingering gusty winds 20 to 25 kts will gradually decrease to 10 kts or less at all TAF sites. && .PREV DISCUSSION... /issued 344 AM PST Thu Dec 11 2025/ DISCUSSION... Key Messages: 1. Flooding concerns persist due to continued mountain rain. *Flood Warnings & Advisories Active* 2. Windy conditions linger through the morning. *High Wind Warning & Advisories Active* 3. Above normal temperatures until next system early next week. Current radar and infrared satellite imagery showing light to moderate returns along the Washington Cascades under partly to mostly cloudy skies. This is in response to an upper level shortwave and cold front that will stall over the Washington/Oregon border today before lifting north this evening. A strong Atmospheric River (AR) has been associated with this system, which has dumped 2 to 6 inches of rainfall over the Washington Cascades and 1 to 4 inches of rain over the northern Blue Mountains over the last 48 hours. Even lower elevations of the Columbia Basin and Blue Mountain foothills have received 0.25-0.75" over the last 48 hours, with some stations earlier in the week breaking daily precipitation records. The AR will be losing strength through the day today before being cut off later this evening. An additional inch of rain will be possible today across higher terrain of the Cascade and northern Blue Mountains, with around 0.25" for lower slopes of the Cascades, and 0.02-0.10" along the east slopes of the Cascades (Kittitas/Simcoe Highlands) and the northern Blue Mountain foothills. Due to the rainfall earlier in the week, flooding concerns are ongoing along the Yakima and Naches Rivers as several reaches are currently in moderate flood stage. These include the Naches River at Naches and the Yakima River at Horlick and Parker, with the reach near Kiona forecast to reach moderate flood stage during the early morning hours on Friday. Other reaches are currently in minor flood stage, including the Naches River near Cliffdell and the Yakima River at Easton and Umtanum. The upstream reaches have crested and are beginning to slowly decline in river level, however, the Yakima River at Umtanum, Parker, and Kiona are continuing to rise. The reaches near Umtanum and Parker are forecast to crest later today, with Kiona cresting Friday afternoon through Saturday morning at 15.59 feet, 4 feet higher than its current level (11.66 feet as of 1:15 AM). The incoming cold front pushing into the region has allowed a pressure gradient to develop across the Columbia Basin. The RAP, GFS, NAM, and SREF all advertise a gradient of 9 to 12 mb between Portland (PDX) and Spokane (GEG), which relates to sustained southwest winds of 20 to 40 mph and wind gusts of of between 55 to 70 mph. These higher wind values are focused across the Lower Columbia Basin of Washington which includes the Tri-Cities area. Gusts of 67 mph have already been observed this morning, with the potential of these high winds lingering through the early morning. Thus, a High Wind Warning is currently active until 7 AM. Elevated winds are also occurring across other portions of the Columbia Basin and Blue Mountain foothills as gusts of 50-55 mph have been observed this morning and will also linger through the early morning hours. As a result of the windy conditions, a Wind Advisory is currently active through 7 AM for North-Central Oregon, Lower Columbia Basin of Oregon, Yakima Valley, and the northern/southern Blue Mountains. The cold front will be retreating north tonight and departs east into the weekend as an upper level ridge builds offshore and passes over the area on Saturday. This will keep conditions dry and temperatures well above normal as highs peak in the mid-to upper 50s across the Columbia Basin and in the low 60s over Central Oregon. Ensembles are in fairly good agreement regarding the next system early in the week bringing widespread rainfall and slightly cooler temperatures. Mid-week high temperatures are still expected to be 5 to 10 degrees above normal for this time of year across the Columbia Basin, with snow levels likely dropping to between 3000-5000 feet on Tuesday and Wednesday. This will provide some significant snowfall across the Cascade and northern Blue Mountains above 4000. Ensembles do struggle with the strength and timing of the system, with 23% of members hinting at less snowfall over the Cascades and 22% suggesting more. The remaining 55% of members are aligning with the current forecast of 10-20 inches of snowfall over the Cascade passes Tuesday through Wednesday and 5-15 inches over the northern Blue Mountains. Confidence in these amounts is currently low (10-30%) as uncertainty resides primarily in overall system strength. Stay Tuned. 75 AVIATION...12Z TAFs...Currently, all sites are in VFR. However, KDLS may see MVFR conditions this morning into afternoon hours from low clouds with the influence of the ongoing atmospheric river. KYKM/KALW could also have light rain develop in the morning hours as well, but chances are low (<30%). Other than that, the main concern for most sites will be gusty winds up to 20-30kts or higher through later this morning. An Airport Weather Warning for KPSC will remain through 6AM this morning due to winds gusts potentially exceeding to 40-50kts. With KBDN seeing gusts at 25kts around this early morning, there is a slight chance that KRDM might see some gusts along with KBDN (30% chance). Feaster/97 && .PRELIMINARY POINT TEMPS/POPS... PDT 59 43 60 39 / 30 20 0 0 ALW 59 49 59 44 / 50 30 10 10 PSC 62 44 59 39 / 20 10 0 0 YKM 57 42 57 37 / 30 20 0 0 HRI 61 44 59 38 / 20 10 0 0 ELN 51 40 53 36 / 60 30 10 10 RDM 58 30 60 29 / 0 0 0 0 LGD 54 41 57 36 / 40 20 10 0 GCD 55 36 57 35 / 0 0 0 0 DLS 61 47 59 41 / 60 30 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...None. WA...Flood Watch through Friday morning for WAZ026-027-521>523. && $$ SHORT TERM...75 LONG TERM....75 AVIATION...77