Big Picture:

The extended dry spell we've been experiencing is finally about to come to an end, at least temporarily. A storm will arrive on Tuesday with the main impacts expected across Washington and Northern Idaho, with lighter impacts for Oregon.

Snow and rain will begin across the Cascades on Tuesday morning with snow picking up on Tuesday afternoon as snow levels lower. Snow will then pick up across the Inland Northwest on Tuesday afternoon and evening. Most of the snow will taper off across the PNW by Wednesday morning, except for the Idaho Panhandle where snow showers will linger into midday Wednesday.

Forecast for Western Washington:

Dry conditions will persist for one more day on Monday with highs in the upper 30s at mid-mountain elevations.

Rain and snow will then begin early Tuesday morning with snow levels starting out in the 4,000-5,000 foot range. However, a cold front will move through during the morning hours with snow levels dropping to 3,000-4,000 feet across the North Cascades by late morning, and around Paradise/Crystal/White Pass by early afternoon. 

The heaviest snow is then expected during the afternoon with lighter snow showers persisting through Tuesday night. Snow levels should also dip below 3,000 feet on Tuesday night before snow tapers off.

I'm expecting snow totals of 5-10 inches for Alpental and Stevens with possibly higher amounts at Baker depending on the exact rain/snow line behind the cold front. Further south, Crystal and White Pass should pick up 3-8 inches.

Warm air overrunning colder low-level air along the eastern slopes of the Cascades will result in freezing rain east of the Cascade crest, so heads up if you are traveling in this area where icy roads could be an issue.

Conditions will dry out on Wednesday and Thursday as high pressure builds in from the south, and temperatures will also warm up significantly with highs reaching the mid 40s at ski resort mid-mountains on Thanksgiving Day.

On Friday-Saturday, the next storm will arrive from the northwest with colder air and lowering snow levels expected during this timeframe. Snow levels could start out around mid-mountain or so at most ski resorts but will lower heading into Friday night and Saturday with a decent snow event possible.

After that, a stronger and colder storm is possible in the late Saturday to Sunday timeframe.

Forecast for Eastern Washington/Northern Idaho:

Cool and dry conditions will prevail for one more day on Monday with highs in the upper 20s to low 30s at ski resort mid-mountain elevations. 

Light snow will then begin on Tuesday afternoon at the leading edge of the storm, followed by heavier snow on Tuesday evening and Tuesday night. Snow levels will remain below ski resort base areas throughout this event.

Snow will taper off across Eastern Washington along with Schweitzer by early Wednesday morning, while snow showers will persist from Silver Mountain to Lookout Pass through about midday Wednesday.

I'm expecting snow totals to range from 4-8 inches at Schweitzer, Silver, and Lookout, and 2-5 inches at 49º North, Mt. Spokane, and Bluewood.

After this storm, high pressure will build into the area from the south on Thursday and Friday, resulting in a very mild Thanksgiving with temperatures warming up significantly. Highs at mid-mountain elevations will reach the upper 30s to low 40s on both Thursday and Friday, so the new snow will not stay fresh for very long.

A weak storm is projected to move through in the Friday night-Saturday timeframe along with a cold front that will result in a return to colder temperatures.

A stronger storm is then possible in the late Saturday to Sunday timeframe.

Forecast for Oregon:

Dry conditions will prevail for one more day with highs in the mid to upper 30s at ski resort mid-mountain elevations.

A storm will then arrive on Tuesday, though it's expected to be a relatively minor snow event with heavier precipitation and colder temperatures further north. Still, a decent amount of liquid-equivalent precipitation is expected and it will signal the end of our unusually long dry spell.

Light rain/snow is possible early in the day on Tuesday, then the main round of rain/snow will arrive on Tuesday afternoon and into Tuesday evening as a cold front moves through.

Snow levels will start out around 5,500-6,500 feet across the Cascades on Tuesday afternoon before lowering to 4,500-5,500 feet on Tuesday evening. Snow levels will be lower in the 2,500-3,500 feet range throughout the event across the Blue Mountains.

Snow totals above 5,500 feet in the Cascades will range from 2-5 inches from Hood to Bachelor to Willamette Pass, with only light accumulations at best below 5,500 feet and for any areas south of Willamette Pass. The Blue and Wallowa Mountains should pick up around 2-5 inches as well with isolated higher amounts possible.

Conditions will dry out from Wednesday to Friday as high pressure builds in from the south, and temperatures will also warm up significantly with highs approaching 50ºF at ski resort mid-mountains in the Cascades on Thanksgiving Day and again on Friday. Across the Blues, highs will reach the mid 40s.

A weak storm is projected to move through in the Friday night-Saturday timeframe along with a cold front that will result in a return to colder temperatures along with lowering snow levels, though precipitation could start as rain initially up to mid-mountain elevations.

A stronger and colder storm is then possible in the late Saturday to Sunday timeframe.

Outlook for Saturday (11/26) to Monday (11/28):

A stronger storm is expected to move into the PNW during the Saturday night to Sunday timeframe. This storm will likely involve cold air and low snow levels with the potential for significant totals across all regions of the Northwest. We're still a good ways out, so confidence is low in the details, but there is reason for optimism.

For now, I would circle Sunday as being the "main event" with the best potential for widespread snow, while we could see lingering snow showers on the backside of the storm persist into Monday as well.

Outlook for November 29 to December 4:

The pattern is trending drier and cooler again during this timeframe. Initially, the storm track is expected to shift further south with additional weak storms (but with low snow levels) possible for the Northwest, likely favoring OR more than WA.

Later on in this period, there are signs that high pressure could start to build off the West Coast again with fewer and weaker storms, but with temps remaining on the cool side. We're still far enough out that this could change, though, so we'll see.

Thanks so much for reading! Next update on Wednesday (11/23).

ALAN SMITH

PS - I took this survey about "Sliding With Respect" and it would be wonderful if you could contribute your thoughts as well. The survey is being run by a group at Fort Lewis College in Durango. Take the survey.