Area Forecast Discussion
Issued by NWS Spokane, WA
Issued by NWS Spokane, WA
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778 FXUS66 KOTX 172345 AFDOTX Area Forecast Discussion National Weather Service Spokane WA 445 PM PDT Tue Sep 17 2024 .SYNOPSIS... Some light rain will persist at times over north Idaho and the eastern third of Washington through early Wednesday. Conditions will trend drier toward the end of the work week, then precipitation chances return for the weekend. && .DISCUSSION... Tonight through Thursday: Upper level longwave trof lingers over a good portion of the Western US through this interval. At least two synoptic scale low pressure systems are nested inside it and rotating around the upper level longwave`s edges. The showery bands of precipitation extending outward from one such low centered to our southeast over Southern Idaho/Northeast Nevada is allowing for considerable cloud cover and narrow bands of precipitation over far Eastern Washington and North Idaho to linger on into tonight. As this low, and its associated showers and cloud cover, treks to the northeast the clouds and showers will be relegated to smaller portions of North Idaho Wednesday and then eventually a drier forecast with clearing skies Wednesday night and Thursday. Friday through Tuesday: The upper level flow pattern is still rather progressive as a more zonal north/northwest flow drapped atop the large longwave trof Friday allows for drier air from the northwest void of significant shortwaves to linger into the weekend, although sometime late Saturday there is greater likelihood of at least one frontal feature or more, with increased moisture streaming into them, dropping through from the northwest. With this in mind a increase in cloud cover along with some minor pops and light QPF return to mark late Saturday and beyond coupled with forecast temperatures generally quite near or slightly below normal. Some patchy morning frost and fog appear in very small isolated well sheltered locations of Northeast Washington and the Idaho Panhandle. /Pelatti && .AVIATION... 00Z TAFS: Scattered showers will rotate north up into SE Washington, and the Idaho Panhandle tonight. Showers that form over TAF sites may result in brief visibility reductions to MVFR. With a moist boundary layer and middle to high level clouds thinning overnight, a handful of model soundings are showing a marginal VFR developing around KGEG, KSFF, KCOE, KDEW around 12Z Wednesday morning. FORECAST CONFIDENCE AND/OR ALTERNATE SCENARIOS: Moderate confidence of increasing showers for southeast Washington and north Idaho tonight. There is low confidence for stratus development around KGEG, KSFF, KCOE, KDEW early Wednesday morning. && .PRELIMINARY POINT TEMPS/POPS... Spokane 73 49 76 49 76 47 / 40 20 10 0 0 0 Coeur d`Alene 71 48 72 48 75 48 / 60 40 20 0 0 0 Pullman 65 45 69 43 73 45 / 60 30 20 0 0 0 Lewiston 74 54 76 53 79 53 / 60 20 10 0 0 0 Colville 77 38 78 39 76 38 / 20 20 10 0 0 0 Sandpoint 70 46 72 45 73 44 / 50 50 20 0 0 0 Kellogg 66 49 67 50 72 49 / 70 60 30 10 0 0 Moses Lake 79 48 79 46 78 46 / 0 10 0 0 0 0 Wenatchee 78 55 80 53 79 53 / 0 0 0 0 0 0 Omak 83 51 82 51 81 48 / 10 10 0 0 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. && $$