117 FXUS66 KOTX 061129 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 429 AM PDT Mon Sep 6 2021 .SYNOPSIS... The region is expected to be dry and warm this Labor Day and will continue through mid week. Locally breezy conditions are also expected today through the Cascade Gap valleys. Changes in the weather pattern are expected mid week with the potential for mountain showers, isolated thunderstorms, and breezy winds. && .DISCUSSION... Monday and Tuesday: Early morning water vapor satellite imagery shows the shortwaves moving through British Columbia along the WA/ID border sending mid and high clouds across northern Washington and northern Idaho. The surface pressure gradient along the Cascades remains tightly packed and as a result breezy to gusty winds through the Cascade Gaps are still evident early this morning. Expecting these winds to slowly subside through mid day. As the ridge begins to build across the west coast, the drying and warming trend will begin to enhance. The low-level moisture from the marine layer that is spilling over the Cascades this morning will quickly erode. Westerly flow aloft today will advect wildfire smoke from the fires in the Cascades eastward, depending on the fire activity. Skies will be mostly clear or see some high cirrus streak across the region. *Return of smoke to the region. Tuesday as the ridge strengthens over the Great Basin, centered to our south- southeast, the flow will turn more southwesterly. This will act to warm temperatures to about 10-12F above seasonal normal through Wednesday. The downside to this flow pattern is this will draw up more wildfire smoke from the ongoing wildfires in Oregon and California. Smoke models all advertise this blanketing of total smoke Tuesday through late week, with some clearing possible late Wednesday and again Thursday but returning Friday. *Thunder potential A shortwave will track along the Oregon coast late Tuesday and bring increasing instability and moisture into the Cascades through Wednesday. Models have continued to hint at this feature moving north through the Cascades and into Canada bringing moisture and limited instability. The more recent model guidance is now hinting at a bit more instability and dynamics with this wave. Lapse rates look a bit more healthy on the east side of the Cascades with a bit more shear available. We have added thunder chances to the forecast with the more recent model updates and feel the potential is there, our confidence just remains a bit low. Timing for precip and thunder chances will be overnight Tuesday into the morning hours on Wednesday from about the Kittitas Valley north through the Okanogan Valley. /Dewey Wednesday through Sunday: Remnants of an upper level low off the California coast eject and pass over Eastern Washington and North Idaho in the provided southwest flow. Enough moisture and instability to keep a small mention of thunder over parts of the Cascades along with some showers. The southwest flow continues but flattens out some and is coupled with a cold front passage Thursday with its influence felt mostly by breezy/gusty westerly winds. Friday and on through the weekend the flow is more a flat progressive zonal type which may allow disturbance passage however efficient shadowing by the Cascades will limit any pops for minor light precip to the vicinity of the Cascade Crest and some parts of the Blue Mountains up into the Central Panhandle Mountains of North Idaho. Of particular concern with this weather pattern is how much smoke/haze may linger in and over the area. Have kept a strong wording of haze Wednesday and into part of Thursday but when upper level flow becomes less from the southwest and more zonal (westerly) it should lose potential to bring up smoke from fires in Northern California and Oregon so haze is not mentioned Thursday night night and over most of the weekend. Forecast temperatures show a general and gradual cooling trend yet remain on the warm side of climo. /Pelatti && .AVIATION... 12Z TAFS: Main aviation concerns for Labor Day will be smoke from area/regional wildfires. The dry and breezy weather pattern has perked up fire activity and smoke production in the Cascades, resulting in smoke being drawn into central and eastern Washington. This will occasionally reduce visibilities to MVFR thresholds. A shift in the weather pattern Monday night into Tuesday has the potential to allow a lot more smoke intrusion from the south into the aviation area, resulting in more widespread haze and visibility reduction. /Dewey && .PRELIMINARY POINT TEMPS/POPS... Spokane 82 51 87 54 87 55 / 0 0 0 0 0 0 Coeur d'Alene 80 50 86 54 87 54 / 0 0 0 0 0 0 Pullman 79 47 87 52 85 51 / 0 0 0 0 0 0 Lewiston 88 56 94 61 93 61 / 0 0 0 0 0 0 Colville 81 45 86 48 86 48 / 0 0 0 0 0 0 Sandpoint 77 45 82 48 82 49 / 0 0 0 0 0 0 Kellogg 78 55 85 59 84 58 / 0 0 0 0 0 10 Moses Lake 83 49 89 56 89 53 / 0 0 0 0 0 0 Wenatchee 84 59 88 65 87 61 / 0 0 0 0 10 0 Omak 85 54 89 58 88 57 / 0 0 0 0 10 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. && $$