908 FXUS66 KOTX 210931 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 231 AM PDT Tue Aug 21 2018 .SYNOPSIS... Northeast winds will continue to gradually push smoke out of the Idaho Panhandle and eastern Washington today. Lighter winds in north central Washington may do little to improve the East Slopes of the Cascades. Wednesday will feature warm temperatures and light winds. The arrival of a vigorous cold front on Thursday will produce breezy west winds. Much cooler and cleaner air is expected by Friday into the weekend. There may even be a decent chance for showers Sunday and Monday. && .DISCUSSION... Today: The Inland NW will remain under broad northeast flow sandwiched between an area of low pressure over Oregon/southern Idaho and ridge of high pressure leaning onshore into Central British Columbia. The big difference for today versus Monday will be a decreasing pressure gradient and waning of wind speeds from north to south. The windiest locations today will be across the open Columbia Basin where northeast winds of 10-15 mph will be common accompanied by gusts 20-25 mph. These winds will be common through midday then decrease to 10 mph by the early evening. The air mass will warm a few degrees but confidence is below average how this will equate at the surface given the persistent smoke layers aloft and forecast continued to undercut model guidance for this reasoning with the largest cuts in the Cascades where smoke is quite thick. I don't think we will see much more improvement in air quality from where we start the day as we lose the northeast winds but continued light northeast push suggest it shouldn't get any worse either and current observations indicate hazardous conditions still in the East Slopes of the Cascades and unhealthy conditions elsewhere. Tonight through Wednesday night: Low pressure to our south will eject to the east and high pressure will briefly strengthen over the region. This will result in light winds and stable conditions. Winds will begin to switch around back to the southwest/west Wednesday afternoon and evening and will likely bring smoke that was pushed into Western Oregon/Washington back inland. In addition the stable weather conditions, this is likely to lead to deteriorating air quality once again. Temperatures have the potential to be quite warm on Wednesday with projected model numbers in the upper 80s to mid 90s but given the smoke, forecast once again undercut these numbers. /sb Thursday: Our transition day will be Thursday as a cool Pacific trough moves inland. The GFS and NAM forecast stiff cold advection late in the day and through the night. Look for increasing west or southwest winds in the afternoon across the Columbia Basin, West Plains, and Palouse with sustained winds approaching 15 mph with gusts up to 25 mph by late afternoon. Gusts in the lee of the Cascades will peak in the evening with gusts as high as 30 or 35 mph around Wenatchee, Vantage, Entiat, and Waterville. The winds on Thursday will be a mixed blessing. The westerly direction will begin to usher cleaner air into the Pacific Northwest, but look for fire activity to increase Thursday afternoon and evening given the combination of warm temperatures, gusty winds, and seasonably low humidity. Friday and Saturday: Confidence in a big pattern change continues to grow as the medium range models forecast a persistent cool trough over the Pacific Northwest Friday into early next week. The evening runs of the GFS and Canadian models forecast a shortwave trough Friday that may be deep enough to produce scattered rain showers across northern Washington and the far northern Idaho Panhandle. If the models verify, it won't be big rains, but portions of Okanogan, Ferry, Stevens, Pend Oreille, and Boundary counties will have a shot of some rain. There may be more isolated showers on Saturday for the north Washington Cascades with another shortwave. Perhaps as important as the prospect of some rain for areas with active wildfires will be the persistent influx of cooler air and higher humidity Friday and Saturday courtesy of "cleaner" west winds. Air quality should be much improved. Sunday and Monday: The trough over western Canada and the Pacific Northwest will likely deepen Sunday and Monday. There are differences between the evolution and depth of the trough between the GFS and ECMWF, but there is loose agreement that Sunday and Monday will provide the potential for showers along with much cooler than average temperatures. Keep your fingers crossed. This pattern could give fire fighters the upper hand on the fires that have plagued our region for weeks. /GKoch && .AVIATION... 00Z TAFS: Difficult TAFs with very low confidence. What will the smoke do? We have seen improvement this evening, but have generally trended vis down towards morning as winds are light and smoke will likely sink into the valleys. IFR vis is quite possible for all tafs at some point, except KPUW and KLWS where they are a bit further away from the sources of the smoke. Once you get above the smoke skies will be clear to mostly clear as the best moisture remains towards Missoula. && .PRELIMINARY POINT TEMPS/POPS... Spokane 83 58 85 60 85 54 / 0 0 0 0 0 0 Coeur d'Alene 83 54 85 56 85 52 / 0 0 0 0 0 0 Pullman 83 53 84 55 85 49 / 0 0 0 0 0 0 Lewiston 87 61 90 63 92 58 / 0 0 0 0 0 0 Colville 86 51 86 53 86 49 / 0 0 0 0 0 0 Sandpoint 79 48 83 50 83 47 / 0 0 0 0 0 0 Kellogg 80 51 82 54 82 50 / 0 0 0 0 0 0 Moses Lake 89 57 89 57 91 52 / 0 0 0 0 0 0 Wenatchee 86 63 87 64 88 57 / 0 0 0 0 0 0 Omak 88 60 87 60 88 55 / 0 0 0 0 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. && $$