Scientific Forecaster Discussion
000 FXUS66 KPDT 170526 AFDPDT Area Forecast Discussion National Weather Service Pendleton OR 1022 PM PDT Mon Oct 16 2017 .SHORT TERM...Clear skies over the forecast area this evening. Clouds associated with approaching frontal boundary still off to the northwest. Will see increasing clouds across the Washington Cascades and eventually into the northern Columbia basin late. Further south should remain clear overnight. Highs today were 5-10 degrees warmer than Sunday so expect a milder night with lows in the 30s to lower 40s for most locations. Cold front moves slowly across the region Tuesday. Best area of rain will be over the Washington Cascades. Much less over the Blues with downslope flow likely keeping the Columbia basin dry. Main impact will be increasing winds. Strong westerly winds aloft will move through during the day and expect mixing down off the Cascades. Afternoon winds will likely be in the 20-40 mph range. Blowing dust possible in the basin. 94 .AVIATION...06z tafs. Clear skies overnight with winds less than 10kt. Increasing clouds Tue with a frontal passage during the day. Ceilings bkn 050-100. Westerly winds increasing late morning through the afternoon becoming 15-30kt. && .PREV DISCUSSION... /issued 500 PM PDT Mon Oct 16 2017/ SHORT TERM...Tonight through Wednesday night...The flat upper level ridge over the Pacific Northwest will flatten further tonight as a disturbance moves towards the region for the Gulf of Alaska. This disturbance will swing across British Columbia and Washington Tuesday. As such, will see mainly fair and dry conditions over much of the area tonight. Will see clouds increase overnight over south- central Washington. Also should see some light precip begin to move into the Washington Cascade east slopes, mainly after midnight. The system Tuesday will push a cold front across the area. The main impact with this frontal passage will be increasing winds across the area, especially the Columbia Basin. Winds in the Basin and adjacent valleys will generally run 20 to 30 mph. Could see winds locally of 30 to 35 mph with gusts around 45 mph in the Yakima valley and the Lower Basin in Washington, as well as the Kittitas valley. Thus will issue wind advisories for these areas. Winds in the Columbia Basin could cause some patchy blowing dust Tuesday afternoon and early Tuesday evening. The bulk of the precip with this system will occur along the Washington Cascade east slopes. The Blue Mountains could see decent chances of precip Tuesday evening. A warm front will bring precip to portions of the area, especially the Washington Cascade east slopes, Wednesday. The precip will persist over the Washington Cascade east slopes Wednesday night, but will largely end elsewhere. Low temps will generally be below seasonal again tonight. Otherwise temps will be above seasonal Tuesday through Wednesday night. Snow levels will run 5500 feet or higher through the period. 90 LONG TERM...Thursday through Monday...Longwave upper trough approaches the coast Thursday and pushes a cold front into CWA Thursday afternoon bringing rain through Thursday night. Friday will be windy and rainy while the cold front sweeps through the region and moves into Idaho by daybreak Friday morning. The upper trough moves across the forecast area during the day on Friday resulting in unsettled conditions over the eastern Oregon mountains during the day on Friday. Friday night the region will be between weather systems with rain shadowing at lower elevations due to a ridge of high pressure building over the pacific Northwest ahead of a wet warm front that moves into central and north central Oregon Saturday morning. The warm front and attendant rain spreads over the rest of the forecast area Saturday afternoon. Rain totals on Saturday will be around 0.25-0.35 inches at lower elevations and near 0.50 inch of rain in the mountains. Snow levels lower to 4500 feet in the Blue Mountains on Friday. The warm front at associated rain/mountain snow remains over the forecast area Saturday night and Sunday for additional precipitation. Polan && .PRELIMINARY POINT TEMPS/POPS... PDT 41 68 44 68 / 0 10 20 20 ALW 46 69 50 68 / 0 20 30 30 PSC 36 70 41 67 / 0 10 10 20 YKM 33 69 38 63 / 0 20 10 20 HRI 34 71 42 69 / 0 10 10 20 ELN 34 65 37 59 / 0 20 10 30 RDM 34 72 38 72 / 0 0 10 10 LGD 34 70 44 69 / 0 10 20 20 GCD 35 70 40 70 / 0 0 10 10 DLS 40 67 46 68 / 0 20 20 20 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...None. WA...Wind Advisory from noon to 8 PM PDT Tuesday for WAZ027-028. Wind Advisory from 2 PM to 8 PM PDT Tuesday for WAZ026.