FXUS66 KPDT 032253 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 253 PM PST Tue Feb 3 2026 .KEY MESSAGES... - A dry period through Friday however Fog will create visibility issues each morning - A pattern change by the weekend could bring rains and mountain snow && .DISCUSSION... Fog has been the primary challenge Today and will return over the next couple of overnights and mornings, primarily to the Kittitas and Yakima Valleys, and much of the Foothills of the Northern Blue Mountains. Even as visibility improved across the areas to above a mile from the dense quarter mile or less earlier the stratus remains anchored over the aforementioned areas including the entire Lower Columbia basin. It will be just a matter of time given the stagnant pattern that the boundary layer cools sufficiently for visibility to begin dropping once again for most of these microclimates. HREF data showed probabilities around 60% for one quarter mile or lower visibility based on rolling 4 hour increments through the next couple of days. NBM’s Forecast High Temperatures are in the ball park of the 25th to 10th percentiles which seem reasonable given the fog and stratus expected. Advisories on fog for select forecast zones will be considered toward the end of this shift depending on forecaster confidence , and would lean toward the areas around Walla Walla deteriorating earliest as ALW still reports less than a quarter mile at noon. By Sunday the GFS AR IVT shows about a 250-400 kg/ms AR dropping south across central WA, the remnants of a much more robust one that would dissipate across BC. Ran showers and high snow levels, above pass, will be the most probable early on however by late Sunday into Monday colder air will lead to snow levels below 4kft, which could spell some snow accums for White and Santiam passes. Russell/71 && .AVIATION /00Z TAFS THROUGH 00Z THURSDAY/... Fog and low stratus will bring periods of MVFR or lower conditions across most sites through the period. Sites DLS/PDT/YKM/ALW/PSC will be stuck under the stratus layer for most of the period. Some clearing of CIGs may take place at site PSC this afternoon, but low stratus is expected to redevelop during the mid to late evening time period and persist through tomorrow. CIGs are expected to remain mostly at MVFR or lower heights through the period. Confidence is mod-high (50-80%) that these sites will also see lowered vsby impacts throughout the period as the associated fog layer moves around the lower elevations. That said, confidence is low (20-30%) on exact timing of the vsby impacts. Site RDM/BDN are expected to remain clear and dry through the period. Winds will be light, 12kts or less, through the period. Lawhorn/82 && .Preliminary Point Temps/PoPs... PDT 33 48 32 47 / 0 0 0 0 ALW 38 49 36 48 / 0 0 0 0 PSC 35 48 33 49 / 0 0 0 0 YKM 35 49 33 50 / 0 0 0 0 HRI 34 47 33 47 / 0 0 0 0 ELN 34 46 30 47 / 0 0 0 0 RDM 30 61 26 57 / 0 0 0 0 LGD 36 56 36 57 / 0 0 0 0 GCD 34 60 33 59 / 0 0 0 0 DLS 38 51 36 50 / 0 0 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... WA...None. OR...Air Quality Alert until 10 AM PST Thursday for ORZ506-509. && $$ DISCUSSION...71 AVIATION...82