Area Forecast Discussion
Issued by NWS Pendleton, OR
Issued by NWS Pendleton, OR
698 FXUS66 KPDT 200547 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 1047 PM PDT Sat Jul 19 2025 Updated Aviation Discussion AVIATION...06Z TAFs...Mostly VFR conditions to prevail through the period. Smoke from regional fires has collected along the foothills of the Blue Mountains this evening, resulting in site ALW reporting a bkn-ovc CIG between 2.5kft to 3kft. This CIG is expected to dissipate in the next few hours. Otherwise, few-sct CIGS AOA 10kft-25kft AGL will impact sites through the period. Breezy winds between 10-15kts with gusts to 20-25kts at site PDT will weaken overnight, with light winds prevailing through the period. Winds between 10-15kts with gusts around 21kts will continue at site DLS, then increase 15-20kts with gusts around 25kts after 19Z. Otherwise, winds will be 12kts or less at all other sites through the period. Lawhorn/82 PREV DISCUSSION... /issued 227 PM PDT Sat Jul 19 2025/ DISCUSSION...Tonight through Saturday... Key Messages: 1. Heightened fire weather conditions through this evening. 2. Slight chance (~20%) of thunderstorms Monday and Tuesday. 3. Fire weather concerns return Wednesday through Friday. Current radar and visible satellite imagery shows dry conditions as mid-to high level clouds stream in across the Lower Columbia Basin from the northwest. These are associated with a weak upper level trough that will give way to a stronger system that approaches Sunday, before passing through the Pacific Northwest Monday into Tuesday morning. A surface low pressure has dropped into southeastern Washington this morning, which has allowed a pressure gradient to develop along the Cascades. This pressure gradient has allowed for breezy winds to occur through the Gorge, Lower Columbia Basin of Oregon, Blue Mountain foothills, and the Kittitas Valley as gusts of between 25 and 35 mph are currently being observed. Even though conditions are cooler than on Friday, humidities are nearing critical fire weather thresholds in the aforementioned areas as values hover around 20%. Conditions will improve this evening as overnight humidity recoveries will increase into the good to excellent range (>55%) for much of the region, but lower lying areas of the Gorge, Blue Mountain foothills, Hanford area, and the Yakima Valley may only experience moderate (40-50%) recoveries into Sunday morning. The approaching upper level trough will dig along the coast on Sunday, tapping into additional moisture from lower latitudes as afternoon humidities improve slightly on Sunday ahead of a much more substantial increase on Monday. The pressure gradient will also relax on Sunday to allow for lower wind speeds, but still breezy through the afternoon and early evening for the Gorge and Simcoe Highlands. The incoming system will dig along the coast on Sunday and begin to erode the upper level ridge located to our east on Monday. This will bring a slight chance (15-25%) of showers across the eastern mountains and portions of the John Day Basin Sunday evening after 5 PM. These chances will trend upward (40-55%) overnight and into Monday morning, extending across much of the area with higher chances (30-40%) along the eastern mountains, Blue Mountain foothills, and the east slopes of the Washington Cascades. Rain chances will push north and east after 5 PM, with only a slight chance (15-25%) of showers lingering across the east slopes of the Washington Cascades and Wallowa County. Rain amounts late Sunday through Monday are expected to reach around a wetting rain (0.10") along the Blue Mountain foothills and Kittitas Valley, with higher amounts of 0.15-0.25" along the east slopes of the Washington Cascades and east of the northern Blue Mountains. Ensemble members are also picking up on the potential (15-25% chance) for isolated thunderstorms to develop across Central/Eastern Oregon and the east slopes of the Washington Cascades as the system passes and interacts with the upper level ridge. Best storm chances will align with the peak heating of the day, between 2 PM and 5 PM. Main storm concerns revolve around gusty and erratic winds associated with any developing cells, as well as new fire starts outside the rain core. The system exits the area to the east on Tuesday, with a slight chance (15-25%) of afternoon showers and isolated thunderstorms lingering along the east slopes of the Washington Cascades. 58% of ensemble clusters are showing a cut-off low developing offshore of the northern California coast on Wednesday, which would attribute to drier and warmer conditions across our area. This low pressure looks to slowly track north Thursday before passing through southern and central Oregon Friday, with 67% of ensemble members in agreement. This will bring a period of warm, dry, and breezy conditions across the area Wednesday through Friday. At this time, critical Red Flag conditions are not forecast to be met, but some areas in the Kittitas Valley and the east slopes of the Oregon Cascades do approach these values Thursday and Friday. 75 && .PRELIMINARY POINT TEMPS/POPS... PDT 60 84 60 84 / 0 10 20 30 ALW 63 83 64 83 / 0 0 20 40 PSC 58 85 61 84 / 0 0 10 20 YKM 58 85 60 81 / 0 10 10 40 HRI 60 86 62 86 / 0 0 10 20 ELN 57 84 58 79 / 0 10 10 40 RDM 48 84 50 79 / 0 10 10 20 LGD 57 82 58 78 / 0 10 30 50 GCD 54 85 57 80 / 0 10 30 50 DLS 61 82 62 84 / 0 10 10 20 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. && $$ SHORT TERM...75 LONG TERM....75 AVIATION...82