A sharp upper level ridge of high pressure exists over the coastal northwest this morning with a dry northerly weather flow aloft. This ridge is promoting a subsidence inversion to form over the forecast area. This inversion aloft combined with the normal nocturnal inversion and short daylight period this time of year will bring stagnant conditions with low level stratus and at least patchy morning and overnight freezing fog and afternoon simple fog to much of the Columbia Basin and Wenatchee Valley over the next two days. Clear to partly cloudy conditions will prevail above this inversion on the high terrain around the region. Expect partly cloudy skies today with light, variable wind with afternoon highs in the mid to upper 30’s.
The next storm system will climb over the ridge and crush it temporarily as a transient short wave weather system moves through Tuesday with a 20% chance of rain mixed with snow and afternoon highs in the mid 30’s.
On Wednesday, the wave will pass off to the east with lingering snow showers in Eastern Washington and a return to clouds and fog for Northcentral Washington. Then by Wednesday night, a closed low pressure system moving into the Gulf of Alaska will flatten the ridge and send numerous weather disturbances into the Pacific Northwest. The Wenatchee Valley can expect an 80% chance of rain Wednesday night with mild overnight lows in the lower 30’s. It looks like we will have a good opportunity to receive some much needed snowfall in our mountains. The Cascades could see up to a foot, with much higher amounts along the crest. Periods of mountain snow and valley rain or snow is expected.
We will see a 60% chance of a rain/snow mix Thursday with mild high temperatures in the lower 40’s.
Partly cloudy skies for Friday as the weather system moves away, afternoon high temperatures will remain above normal into the lower 40’s.
By Saturday however, it looks like we transition from a westerly flow to a more northwesterly flow, which will bring in some slightly cooler temps and a 20% chance of snow showers, highs both Saturday and Sunday in the mid to upper 30’s