Freezing Rain, Flooding, and Avalanches – Oh My!

I apologize for not posting as much as I would like recently! I’ve been very busy tweaking the site and preparing for WeatherTogether’s booth at WeatherFest, which is part of the American Meteorological Society’s (AMS) annual conference. As luck would have it, the AMS conference is in Seattle this winter, so it definitely made sense to do something there!

WeatherFest is an open-floor exhibit featuring a variety of different local weather organizations and booths. I’ll be working alongside Brie Hawkins of Little Bear Creek Weather, a very popular local weather page based out of Woodinville, WA that has a site on WeatherTogether. Many other local organizations will also be there as well; the Northwest Avalanche Center, State Climatology Office, and local Seattle National Weather Service office are just a few. For a full list of booths, click here.

WeatherFest takes place at ballroom 6E in the Washington State Convention Center from noon to 4 pm next Sunday, January 22. All ages are welcome and there is no cost! We’ll have some cool weather experiments, posters, and pictures set up, and we’ll talk about WeatherTogether’s niche in tapping into local weather expertise. I hope to see some of you there, I’d really enjoy meeting our readers!

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Models still show a drastic pattern change beginning tomorrow as a warm front breaks through the cold dome of high pressure that has sat over us for much of January and returns us to the warm and wet southwesterly flow we all know and love. The picture below shows high cirrocumulus clouds moving in ahead a front being shoved to our north by a ridge of high pressure over the region. I took the picture below picture near Centralia this morning on the bus ride down to Portland.

Temperatures are still quite cool across the region – we are currently in the 30s in most locations across Western Washington and in the 20s for Western Oregon. As the radiosonde sounding below shows, there is still a massive inversion at the lowest elevations. At the surface, temperatures are still well below freezing, but less than 1 km above the surface, temperatures are in the 50s! This is leading to poor air quality for the Puget Sound Region (Thurston, Pierce, and Snohomish Counties currently have stage 1 burn bans), and, more importantly, will lead to a major ice storm for the Columbia River Gorge Tuesday and even into Wednesday, with substantial freezing rain around the Portland metro area as well.

Forecast:

Previous models were showing today being a transition day for the Pacific Northwest, but newer models show the majority of the energy from the incoming system being directed to our North. Seattle will warm up to the mid 40s, but Portland looks to stay below freezing for yet ANOTHER day due to cold easterly flow through the Columbia River Gorge and the heaps of snow still on the ground from last week’s epic snowstorm.

Our first shot of rain comes in early Tuesday morning as a weakening warm front makes landfall.

Most of Western Washington will be warm enough for plain ol’ rain, but the Columbia River Gorge and parts of NW Oregon/SW Washington will see freezing rain.

After this front, a much stronger and wetter front powered by a 200 knot jet stream makes landfall Tuesday evening.  This system is strong enough that it should quickly scour out any remaining cold air away from the Columbia River Gorge. However, this air will be very slow to move out of the Western/Central gorge, meaning places like the east Portland/Vancouver metro area could get a much more significant shot of freezing rain, with the potential for a major ice storm in the Upper Hood River/Wind River Valleys. The Portland National Weather Service recently issued a Winter Storm Watch for much of NW Oregon and SW Washington to cover this potential… we’ll see if they upgrade it during the day shift today.

Even though we’ll see freezing rain in the Columbia River Gorge, freezing levels will skyrocket to 8,000 feet as this system has tapped into some subtropical moisture. With rain falling on top of fresh snow and building unstable new storm layers, expect widespread wet and wind slab avalanches throughout the mountains. Avoid the backcountry, and be prepared for delays due to avalanche control if you plan on crossing the passes. Speaking of the passes, they will also likely see hefty amounts of freezing rain Tuesday and Wednesday as cold air east of the Cascades rushes through the passes and insulates them from the warmth above. Long story short – get your pass travel done today!

Models have trended slightly lower with rain totals for the Portland metro area, but still drop a ton of rain over us. Expect widespread 1.5-2.5 inch rain totals from Tuesday through Thursday afternoon (bulk of this will come Tuesday night/Wednesday morning), with 3-7+ inches likely for the Coast/Mountains. Urban areas with lots of snow/ice cover like the Portland metro area will experience lots of ponding and localized flooding, and I expect more than a few rivers flowing off the Cascades and Olympics will flood. The Skokomish is a given; that river floods all the time. If you want to escape the rain, go to Sequim. The Olympic Rain Shadow will be in full force over the NE Olympic Peninsula.

Finally, we’ll also have to deal with high winds and surf from this Tuesday night/Wednesday system on the coast. Gale warnings are in place from Cape Flattery to the California/Oregon border, and high wind watches are in effect for the Washington and Oregon Coasts.

One more thing – it will feel positively tropical out there on Wednesday for many of you as highs surge into the low-mid 50s, especially for those in Portland who have failed to reach freezing 4 out of the past 5 days! It’s good to prepare for that too. 😉

Charlie