An active weather period is in store today and tonight as a strong negatively tilted trough of low pressure along with a cold front pass through Northcentral Washington. After strong thunderstorms moved through the Wenatchee Valley this morning, relatively quiet weather conditions are expected through the afternoon as monsoon moisture coming up from the south tracks mainly to our south and east across Central Idaho and Southwest Montana. The main threat of showers as well as potentially a few thunderstorms will be in the Cascades with the approaching upper trough. Away from the Cascades we can expect partly cloudy skies and hot with high temperatures later today in the lower 90’s. By tonight, showers and thunderstorms will be on the increase this as a slug of monsoonal moisture across Eastern Oregon gets pulled north into Eastern Washington. While the storms will be quick moving tonight, the moist atmosphere and strong atmospheric lift should promote locally moderate rain in some Northcentral Washington locations. The fast moving nature of the storms across the Wenatchee Valley and Columbia Basin should limit rain amounts to less than a tenth of an inch for most locations where the Fire Weather Watch will be upgraded to a Red Flag Warning where new fire starts from lightning are possible.
By Wednesday morning, the upper trough axis will be hooking out of the area into Montana and Alberta. The main issue on Wednesday will be winds and dry conditions despite significantly cooler temperatures. Strong cool advection in the wake of the cold front invading the basin through the Cascade gaps will promote solidly breezy and gusty conditions across the region. The strongest wind potential will be in the morning and early afternoon with locations near the Cascades with sustained winds around 20 mph with gusts into the 30 to 40 mph range. High temperatures will be a good 10 to 15 degrees cooler on Wednesday than today with Wenatchee Valley highs on Wednesday only around 83 degrees.
Weather models are in good agreement in advertising a rather progressive summertime flow over the region through the remainder of the week and through next weekend featuring flat short wave ridge of high pressure. Thursday through Monday expect sunny skies with afternoon high temperatures on Thursday and Friday in the lower 90’s with highs on Saturday and Sunday in the upper 80’s.