An active and progressive weather pattern has taken hold across the Pacific Northwest as a strong trans-Pacific jet stream is now pointed at the region. Our next weather feature is a warm front that is rapidly approaching the forecast area, and has a moist subtropical connection. Precipitation will likely start as snow across most of the forecast area then transition to rain through the course of the day as southwest winds increase. We are calling for 1-3 inches of snow in Spokane, the Palouse, across the West Plains, and the Okanogan Valley. Both Lookout and Stevens Passes could see 1 to 2 feet of snow. For Northcentral Washington today, expect a 70% chance of morning snow showers changing over to rain by afternoon with highs today in the lower 40’s.
Tonight through Tuesday, unsettled weather will continue as the upper trough of low pressure approaches the coast. Rain is likely tonight with a 60% chance of precipitation while on Tuesday, expect mostly cloudy skies with a 40% chance of rain with afternoon high temperatures in the lower to mid-40’s.
A cold front will push across Tuesday night bringing increased wind Tuesday night and Wednesday with west winds 10-20 mph, highs Wednesday in the mid 30’s. Colder temperatures will move in as well, but not atypical for early January.
Partly cloudy skies for Thursday with a 30% chance of snow developing late in the day into the evening hours with highs in the mid 30’s.
Weather models are all in good agreement of a fairly robust winter storm to drop down into the region on Friday. Temperatures will be cold enough for snow down into the valleys, except possibly a rain/snow mix south of areas from Moses Lake to Ritzville. A preliminary estimate just based off the aforementioned liquid amounts and snow ratios would give a general 3 to 6 inches of snowfall on Friday. This range is on the conservative side as well. There looks to be at least some down-sloping off of the northern Cascade Mountains that will reduce the amount of precipitation that can be expected in the western basin from Moses Lake to Ritzville and to the Okanogan Valley where 3 inches figures to be closer to the upper estimate for these areas. This is especially so for Moses Lake to Ritzville where snow ratios will be less with temperatures a bit warmer. So, Wenatchee Valley weather for Friday calling for an 80% chance of snow, heavy at times, with highs once again in the mid 30’s.
The uncertainty increases for impacts over the weekend into early next week. We will see partly cloudy skies both Saturday and Sunday with afternoon high temperatures on Saturday in the mid to upper 30’s cooling back to the lower 30’s on Sunday.