Massive Snowstorm in Southern OR/Northern CA, Seattle Weekend Snow Chances Slim

While we’ve been cool and dry here in Western Washington over the past few days, areas of Southern Oregon and Northern California have been getting absolutely pummeled with snow! With modified arctic air already in place, a system that was still strengthening as it made landfall stormed ashore the Oregon/California border last night and dropped over a foot of snow over much of Southern OR/Northern CA, both east and west of the Cascade crest. The water vapor satellite image below shows the evolution of the storm from 11 AM yesterday (1/3/2017) to 10 AM today.

Tim Morar of Klamath Falls in Southern Oregon (4,320′) witnessed the heaviest snowstorm he’s ever seen since he’s lived in the area. Snow steadily increased through Tuesday, giving him exactly 4.00″ inches by 5 pm. After dark, the snow started to increase in intensity, particularly between 7-9 pm. At 9 pm, he measured 10 inches, the most in a day since 12/13/2015 (7.50″) and the last 8-inch day in Klamath Falls since 11/23/2010 (thanks Tim for these statistics).

By midnight, 12.40″ inches had fallen at Tim’s place for the day alone!

Heavy snow continued after midnight, and Tim woke up to another 6″ inches on Wednesday morning! 50% of your seasonal average in just 26 hours… nicely done Tim. 🙂

Here are some more pictures Tim took last night/this morning of all the snow in his neighborhood. I can’t even imagine what this kind of snow would do to Seattle or Portland.

[foogallery id=”6435″]

Medford officially had 8.3″ during Monday, which is the second-highest daily total in the city’s history behind an 11-inch day on December 11, 1919. Initial forecasts for the Rogue Valley called for 2-3 inches, but when the snow started coming down in buckets, the NWS upped their forecasts to 6-8 inches. Again, thanks Tim for pointing me to these statistics.

Things have been far more boring for us further to the north. Temperatures are in the 20s to low 30s for most folks this morning, with clear skies and northeasterly winds.

Winds have lessened over the area, and the wind advisory that was over San Juan County and Western Whatcom County for brisk northeasterly winds originating from the Fraser River Valley expired at 9 AM this morning.  There are still gale warnings until 1 PM this afternoon for the Strait of Juan de Fuca, northern inland waters around the San Juan Islands, and the coast, but the observations I’ve looked at have shown that winds in these locations are below gale criteria (sustained 34-47 knots).

Easterly winds are still blowing at a pretty good rate through the western exit region of the Columbia River Gorge. Portland was seeing sustained winds of 28 mph with gusts to 36 around 10 this morning, and Crown Point is up to its usual antics with winds “only” gusting in the mid 50s after notching 75 mph gust around 5 am.

This cool and dry weather with weakening offshore flow will continue today as a strong ridge of high pressure remains parked in the Gulf of Alaska. This high will slowly move to the WSW throughout the day, and on Thursday, a large trough of low pressure will drop over the NE Pacific. If this trough dropped right over us, we would see another shot of cold air and snow, but because it is far enough offshore, it actually helps direct warm and moist SW flow into our area as air spins counterclockwise around the area of low pressure.

By 4 pm Saturday, the trough is “cut off” from the main flow and is just sitting there in the Eastern Pacific, directing moist southerly flow into our area. A weak series of systems will be embedded in this flow, with the first of these being a warm front impacting us Saturday afternoon/evening.

Valid 04:00 pm PST, Sat 07 Jan 2017 – 84hr FcstUnfortunately for those hoping for a brief shot of snow Saturday, the models show us warming rapidly before the bulk of the moisture arrives. The below picture shows temperatures at 925 mb (2,500 feet) near 5-7 degrees C through much of the Puget Sound region, and the moisture hasn’t even arrived yet! Portland remains cooler at the surface due to cold easterly winds rushing through the Columbia River Gorge and insulating them from the warmth aloft.

I am really pessimistic about snow in Seattle with this setup. In the above model, temperatures aloft are too warm and the storm is too dry for us to see any accumulations. Another, heavier shot of precipitation comes in Sunday morning, but by that time, any cold air at the surface will have already been scoured out. As such, I am predicting plain old rain for the weekend for Western Washington.

The exception is Hood Canal. Hood Canal commonly sees “cold air damming” ahead of these warm fronts, where easterly flow ahead of the front results in cold air accumulating up against the Olympic Mountains and locally cooler temperatures near Hood Canal, particularly the southwestern portion of it. Areas near Hood Canal could see a couple inches of snow Saturday night/Sunday morning before transitioning to rain.

I am also concerned about Portland and the Columbia River Gorge in this scenario. The first round of precipitation Saturday could be in the form of snow, but things will switch over to freezing rain Sunday morning as temperatures warm aloft but cold, easterly flow continues to pour westward through the Columbia River Gorge. There are still differences in the timing and amount of precipitation here, but those in the Portland metro area should prepare for a chance of moderate-to-heavy freezing rain for much of Sunday. We’re not looking at a historical “ice storm” here, but even small amounts of freezing rain can be very destructive.

For my fellow Seattlites, this chance may have slipped away, but here’s to another brush or two with snow through the rest of January and February. Winter is far from over – we have a long way to go.

Thanks for reading,
Charlie