Precipitation across the region yesterday has left a moist boundary layer in its wake this morning. This moist low level air mass will remain trapped under a strengthening inversion layer over the next couple of days as a transient upper level ridge builds and passes before being pushed out by the next weak storm system due on Friday. This is a weather recipe for a damp and murky period for many locations around Northcentral Washington at the very least each overnight and morning period will feature extensive low clouds and patchy fog around the Columbia Basin and Wenatchee Valley.
For today, our weather will feature patchy morning fog with partly cloudy skies by afternoon with afternoon high temperatures in the mid 40’s. Overnight low temperatures will hover near or a bit below freezing with poor radiational cooling potential while daytime highs will be impacted by the stubbornness of the thin, mid-level clouds.
Thursday will begin with some patchy morning fog as well with mostly cloudy skies and highs in the upper 40’s. Thursday night the next incoming weather system will begin to spread a chance of rain and mountain snow into the Cascades and Eastern Washington with a 30% chance of rain in the Wenatchee Valley.
Friday through the upcoming weekend, weather models continue to show an upper level trough passage on Friday with mid-level westerly flow favoring the Cascade crest and Idaho Panhandle for the highest precipitation chances. Models have trended slightly wetter with light rain also likely for Eastern Washington with a 40% chance of rain for the Okanogan Valley, Wenatchee area, Columbia Basin and Lewiston area. High temperatures Friday will be mild into the lower 50’s. A warm front passes Saturday but the bulk of the moisture remains north of the Canadian border. Expect mostly cloudy skies with highs in the upper 40’s. On Sunday a weakening frontal boundary will sag south over the area with a 40% chance of rain and highs in the lower 50’s.
Just a slight chance for scattered showers on Monday and Tuesday with mostly cloudy skies and afternoon high temperatures in the upper 40’s to lower 50’s.