The first fall-like weather system of the season arrives this afternoon near the Cascades and then tonight across Eastern. A deep area of low pressure off the Central British Columbia coast will send a moist frontal boundary across the Inland Northwest. Initially, the frontal boundary shows little movement but eventually reaches the East Slopes of the Cascades this afternoon producing several hours of light to moderate rain into the evening. Weather for Northcentral Washington today calling for cloudy skies, a 40% chance of light rain showers with afternoon high temperatures today in the upper 60’s to lower 70’s. By tonight, thee Wenatchee Valley could see between .05-.25 of total precipitation.
On Thursday, a westerly post frontal air mass dominates our weather as the large low- pressure system slowly moves to the northeast. We can expect mostly cloudy skies tomorrow with breezy conditions developing, highs in the lower 70’s.
In the wake of the first weather system we’re seeing today, another similar wave of moisture moves into the area on Friday. Currently the timing looks to put the front through the Inland NW during the morning hours with a good likelihood for rain in most areas. Wenatchee Valley weather for Friday calling for cloudy skies, an 80% chance of rain and windy out of the west 10-20 mph and gusty, highs in the mid to upper 60’s. The typical rain-shadowed areas of the Columbia Basin may not see much if any rain. This has big implications for the afternoon weather. Winds behind this front will be strong with gusts up to 45 mph. This could cause some blowing dust issues in the Basin, depending on how much if any rain they get. This will bear watching as the event draws closer.
By Saturday, strong high pressure will develop over California and it wants to amplify into the Pacific Northwest, but, the jet stream over the Northwest is very strong and well established, and as such, wins the battle initially. This allows a third weaker system to move into the area from the Pacific bringing Northcentral Washington cloudy skies Saturday, a 60% chance of showers with afternoon high temperatures in the upper 60’s to lower 70’s.
On Sunday, the ridging from the south starts to push the jet stream north of our area. But there`s still enough of a moisture plume in the jet stream to bring us some scattered showers with highs warming into the lower and mid 70’s.
Next week the weather pattern switches from zonal to *very* amplified, with a huge ridge of high pressure in the West and a deep low pressure over the Great Lakes. So, Monday and Tuesday will be much drier and much quieter. We will see mostly sunny skies each day with afternoon high temperatures climbing into the upper 70’s to lower 80’s.