Weekend storm looms with wind, snow

Weekend storm looms with wind, snow
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You can consider Friday the calm before the next storm as a new round of snow is heading our way for the weekend.

Like Thursday's snow, this storm looks like it could have a profound impact on the region, only this time it could cause greater problems, including the potential of a major windstorm in the Cascade foothills, and a big mess of snow and freezing rain in the lowlands.

It's the last thing drivers on Friday wanted to hear, likely already exhausted with the challenges of ice-covered roads and snowy hills.

Most schools in the area didn't hesitate to close for the day, with most of them making the decision Thursday afternoon (see complete school closure list).

Metro Transit again suspended dozens of routes because of dangerous driving conditions in many areas. (Full list of suspended routes.)

Dozens of bus routes were disrupted by the snow and by collisions on Thursday, leaving many commuters waiting in the freezing cold at stops for buses that often never arrived. Metro officials said Friday that they would be focusing on core service until road conditions improve.

There were no major collisions reported Friday morning, but emergency officials were busy responding to spinouts.

And emergency officials will be busy once again this weekend as another major storm heads our way.

Quick Overview

  • The foothills could see east winds of 50-70 mph, gusting to 70-90 mph Saturday morning through Sunday. A HIGH WIND WARNING is in effect here. Widespread and potentially prolonged power outages are a concern in this region, combined with below-freezing temperatures.
  • The Seattle-Tacoma-Bellevue Metro area could see 3-8" of snow Saturday evening into Sunday. Gusty winds in parts of this region could get to 50-60 mph.
  • The Hood Canal area could see 6-18" of snow
  • Southwest Interior might get 4-10" of snow
  • Everett north to border could get about 4-6", but has higher uncertainty
  • Some areas, especially south, could also get freezing rain and icing problems
  • Storm calms down Sunday evening

What's Happening?

Unlike the past few storms that have come from the chilly north, this storm is coming in from the west, and it looks pretty wet -- and much warmer than we've seen lately. So we have a much greater moisture source.

In the meantime, we'll not only have some arctic air here in Western Washington, but even more in Eastern Washington, where temperatures have been in the single digits and teens for several days. That air is very dense, and thus has higher pressure.

First, The Wind

As the strong low pressure of the storm approaches, we will have a massive difference in pressure between Eastern Washington and Western Washington. The Cascade Mountains block the wind from blowing across much of the region, but the gaps in the Cascades act like a hole in balloon, allowing air to race through into western Washington to try and equalize the lower pressure approaching offshore.

That means starting Saturday morning, a roaring east wind for those who live on the western end of those gaps. Cities here include North Bend, Gold Bar, Enumclaw, Cumberland, and Snoqualmie Ridge. If you've lived out there for any period of time, you know if you get the east wind. A HIGH WIND WARNING is in effect from Saturday morning through Sunday evening for this area.

How strong? Forecasting models as of Friday morning indicate sustained winds could be as strong as 50-70 mph with gusts of 70-90 mph. That would be hurricane force. Again, this is starting Saturday morning, but could last into Sunday. If this verifies, it would be the strongest one since December 2003.

During that storm, power was knocked out to thousands for several days. People here need to be prepared for a prolonged power outage and, with temperatures still in the 20s, dangerously low wind chills to near zero, especially if you lose power. With a severe snow event expected to occur in the lowlands late Saturday into Sunday, travel may be difficult to get to areas that do still have power farther west.

But you also need to be aware of the dangers of some alternate heating sources. We've seen carbon monoxide kill several people in the region during prolonged power outages as people use gas grills indoors, or run their car in their garage for heat. All of those can put out carbon monoxide, which can be deadly.

These high winds look localized to the cities along the Cascade foothills, however the winds will funnel out into parts of the lowlands, where winds could gust into the 40-60 mph range, especially along the I-405 and SR 167 corridors south from Bellevue south. Lower wind speeds, but still gusty, are expected along the I-5 corridor between Seattle and Fife. Note that areas north of Seattle and western Pierce and Thurston County would not be expecting problematic winds.

On the other hand we could also see strong east winds along the central coast and northwestern tip of the Olympic Peninsula as the air rushes out to sea. Wind would taper off as the front passes on Sunday.

Next, The Snow

While the strong wind is only for parts of the region, the snow will be much more widespread. As that storm arrives Saturday evening or perhaps into Sunday night, all that moisture will fall into the cold, arctic air in place, making for a heavy snow overnight Saturday into Sunday across a large swath of the region. We then may undergo a transition into freezing rain or sleet or even just rain as we get into Sunday. A WINTER STORM WATCH is in effect for most of the region, except for the Cascade Foothills (note, this watch was expanded Friday morning to now cover the Everett-to-Bellingham corridor). And remember, this is concurrent with the possibly damaging winds out east.

But this storm's effects will be highly variable -- even more than Thursday, so it presents a hefty challenge to try and get too specific, but here is our best forecast for now:

As of now, forecasting models suggest the brunt of the storm will head into northern Oregon and southwestern Washington. Areas south of Olympia could see as much as 4-10" of snow with this storm before changing to rain or freezing rain.

The greatest snow totals will be along the Kitsap Peninsula and the Highway 101 corridor between Shelton and Quilcene along the eastern slopes of the Olympic Mountains. The strong east winds blowing out of the Cascades will run into the mountains, where the moisture will be wrung out in a heavy, relentless snow. These areas could see 6-18" of snow, possibly even higher amounts in isolated spots. This is on top of the snow that's still on the ground over there. Residents here need to prepare for incredible snow.

On the other hand, over where the winds are roaring out east in the foothills, snow totals will be less due to the dry, east wind. Snow totals here could be almost nothing to 3".

This puts the greater Seattle-Tacoma-Bellevue metro area in a transition zone between the not much to the east and massive totals out west. So snow totals will be highly variable. The more wind you have, the less snow you'll see, and the farther west you go should be snowier than east.

But the farther north you go would be less snowier than south. That could mean, roughly speaking, Downtown Seattle gets 3-6", while Renton and Bellevue get 2-4". Again, these are just rough guesstimates and highly dependent on the wind and the storm's track. Plus, local elevation could affect totals. Just be prepared for anywhere from 2-8" for now.

In a change from Thursday night's forecast, it appears the north end, from Everett north to Bellingham, could see a decent amount of snow as well, but this is more uncertain as it'll depend on how much moisture makes it this far north. We'll put 2-6" as a potential total here. This area has the greatest chance of weathering this storm the best, which is good since parts of this area got hit particularly hard earlier this week. With wind and freezing rain not as likely here, chances of power outages are small, but it's good to prepared just in case.

One exception to the lower wind and snow forecast is the areas west of Port Angeles, where higher totals of 6-15" are possible as the strong winds near the outflow of the Strait run into the edges of the Olympics.

Then, The Warm Air Arrives

As I mentioned earlier, this storm is a warmer storm, so as we get through the event, late Saturday night and into Sunday, warmer air will begin to mix in and start scouring out the arctic air in place, changing the snow to perhaps a rain or sleet. However, with that frigid east wind blowing in from Eastern Washington, that could create some areas of still-freezing air near the ground -- a recipe for freezing rain.

This looked more dire and widespread with the Thursday night models than it does as of Friday morning (this morning limits freezing rain to southwestern Washington and along the coast) but the ingredients are in place for at least the potential for more of a widespread freezing rain problem.

That would be the icing on the cake (and everything else) to make this storm truly a headache, as that could cause a thick glaze of ice to form on just about everything, possibly knocking over trees and power lines due to the added weight of the ice.

A worst case scenario is a widespread freezing rain event on top of a several-inch snow event with winds still roaring to 40-60 mph across parts of the region -- a recipe for power outages in the midst of freezing weather, especially in the foothills and in Southwestern Washington. So use today's calm weather, maybe once we get into Friday afternoon and the roads improve, to get yourself at least prepared for the possibility.

Trying to gauge exact timelines for the interactions between these three scenarios of wind, how much snow will fall before the changeover, and how long it'll take to change over (or in some places -- especially north -- *if* there's a changeover), is next to impossible, and these times will vary widely across the region with our complex topography likely making conditions highly variable. We could see a prolonged snow in some areas, while others get a quicker change to rain and limited snow totals.

But the bottom line: This weekend could be messy and residents face multiple weather-related challenges. We'll of course, be monitoring the situation through the weekend as small changes in the storm's track and development could require big changes to the forecast.

Some lingering rain showers, possibly back to snow showers above 500 feet, linger for Monday, then we get a dry break for Monday afternoon into Tuesday with highs getting back into the upper 30s/low 40s.

Another storm moves in on Christmas Eve Wednesday, but this one looks much tamer. If we've scoured out the arctic air as expected, this would likely mean rain at times, although perhaps some snow up near Bellingham. Showers taper off Wednesday night for Santa, and then Christmas Day looks like just a few rain showers mixed with sunbreaks, with highs back up into the low-mid 40s.