497 FXUS66 KOTX 152306 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 406 PM PDT Thu Sep 15 2022 .SYNOPSIS... The Inland Northwest will remain in a cool, unsettled pattern through the week. A cold front Friday will result in breezy winds across much of the region. Expected daytime temperatures in the 60s and morning lows in the 40s and a few 30s. Morning lows will dip further early next week with some frost possible for the mountain valleys. && .DISCUSSION... Tonight: The afternoon satellite and radar picture has quite a broad area of convection across northeast Oregon and central Idaho. Some storm cells beginning to develop along the eastern slopes of the Cascades, though these seem to be moving at a relatively good pace so the threat for flooding is much less today than the past few days. The instability is pretty minimal, 100-200 J/kg with a mean flow of 10-15 knots. The moisture profile is markedly drier than we saw the past few days, but residual moisture around did give us localized valley fog this morning. So, speaking of afternoon and evening convection -- The threat should minimize as we lose daylight and the storms will continue tracking northeast along the Cascade slopes into the north-central mountains. Overnight fog development again in the northern valleys is a possibility as we're still seeing those cooler overnight temperatures and higher dewpoints. Friday: The upper level pattern shows a cold front passage during the afternoon hours Friday which will bring another push of cooler air and gusty west winds. A line from Stevens Pass through the Palouse will be the focus of the stronger winds. A cross Cascade tight pressure gradient and well stacked baroclinic zone will usher the cold advection through the Pacific Northwest. Gusts in the afternoon of 20-30 mph will be common from Wenatchee to Moses Lake to the Palouse during the afternoon hours. Now, knowing the locations that have and haven't seen rainfall in the last few days, this area happens to be one that hasn't seen a ton of rainfall. So, gusty winds plus rather dry ground surface, this could spell blowing dust. Confidence is growing that we could see some blowing dust across the Columbia Basin into the Palouse (Highway 2 corridor as well) tomorrow afternoon. Saturday and Sunday: The upper level pattern gives us a glance at Fall weather this weekend. As has been advertised for several days now a deepening Low will dig down the west coast this weekend and bring cooler temperatures and another shot at precipitation, though not widespread or heavy rain. The ensemble models are still differing among the cluster analysis. The more favorable solution which continues to grow in confidence and buy-in from other ensembles would shift the Low farther south and cut it off from the mean flow, leaving Washington and Idaho in a deformation zone. This would help our daytime temperatures on Sunday warm several degrees over the cool start on Saturday. However, the other option which has been losing confidence would be a much cooler solution. Regardless, temperatures will be about 5-8F degrees cooler than normal this weekend, which for all those Fall-loving folks should be a welcome weather change. /Dewey Monday through Thursday: Both the ECMWF and GFS ensemble means suggest the upper level low heading south from the Gulf of Alaska will reach the coast of California by Monday, bringing a chance of precipitation for the Northern Mountains, SE Washington, and the Idaho Panhandle. Best chances for precipitation on Monday with around a 60-70% chance will be in the Idaho Panhandle. The low will remain on the coast of California and weaken into Tuesday. Meanwhile, models are showing a shortwave trough swooping over a strong ridge of high pressure in the Gulf of Alaska Monday night, diving into West-Central Canada. This would strengthen a northerly pressure gradient, resulting in dry northerly winds down the Okanogan Valley and Purcell Trench. Incoming dry air would shoo away mid- level cloud cover, which would enable more radiative cooling and cause a noticeable drop in nighttime temperatures, especially Tuesday night. Model guidance is pointing toward temperatures becoming considerably colder by Wednesday morning with heat having radiated away from the surface more efficiently the night before. Frost is not out of the question, particularly in the sheltered mountain valleys. Temperatures will remain right around seasonal average with daytime highs generally in the upper 60s and 70s through Thursday. /Fewkes && .AVIATION... 00Z TAFs: Some clearing of skies today and lifting of low stratus and fog has brought airfields into VFR status. Lingering haze can be seen on satellite and has reduced some visibility into the 5-6 mile range. This should improve with tomomrrow's cold front, bringing gusty west winds to EAT, MWH, PUW, and less so to GEG and COE. /Dewey && .PRELIMINARY POINT TEMPS/POPS... Spokane 49 71 43 67 46 70 / 0 0 0 0 20 30 Coeur d'Alene 48 70 43 68 45 71 / 0 10 0 0 10 20 Pullman 42 67 37 67 41 66 / 0 0 0 0 30 40 Lewiston 54 76 49 74 52 73 / 0 0 0 0 30 40 Colville 41 72 35 67 36 70 / 10 30 30 0 10 20 Sandpoint 45 67 41 65 41 69 / 0 10 20 0 10 20 Kellogg 51 67 45 68 51 68 / 0 10 0 0 10 20 Moses Lake 46 74 42 68 48 72 / 0 0 0 0 30 30 Wenatchee 54 70 49 65 52 69 / 0 0 0 0 20 20 Omak 51 74 43 69 47 73 / 10 20 0 0 10 10 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. && $$