Heavy snow creates mess at Snoqualmie Pass as stormy pattern begins


Heavy snow seen at Snoqualmie Pass just before 7:30 a.m. on Feb. 16, 2018. (Photo: WSDOT)

SEATTLE — We’re barely hours old into a double punch of storms and already have our first impact: Mountain pass travel.

A stormy pattern is just in its infant hours but has already been causing headaches for travelers. The WSDOT closed the eastbound lanes of Snoqualmie Pass for 2 1/2 hours Friday morning due to spin outs and crashes amid heavy snow up there. The pass reopened just before 9 a.m., but chains were required in both directions. Six inches of snow had already fallen in six hours early Friday morning with plenty more on the way.

A Winter Weather Advisory remains in effect for the mountains through 7 p.m. but that’s just for the first storm. A second, more potent storm comes in on its heels Friday night and Saturday for another 1-2 feet of snow likely, prompting a Winter Storm Watch through Saturday night.

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In the lowlands, Friday will be rainy and breezy but it’s the second storm Saturday that is still expected to bring more of a punch. In addition to a renewed round of rain, gusty south winds will pick up around midday and last into the early afternoon. Gusts could reach as high as 35-50 mph, especially around Seattle and the South Sound. The North Sound areas of Skagit and Snohomish County will be on the lesser end of the wind gust range there.

Once that storm passes, the weather pattern is expected to take a radical shift to a much colder period as arctic air entrenched in B.C. begins to blast into Western Washington via the Fraser River Valley. Forecast models show a near 180 degree wind shift in the wind coming from the south to coming from the north Saturday night and will begin to pour in very cold air into the region.

This will have a number of impacts.

First, it will bring strong northeasterly winds across Whatcom County and the San Juan Islands gusting in the 40-50 mph range that will spread south late Saturday night reaching the Puget Sound region early Sunday morning. The northerly winds won’t have as gaudy numbers by the time they reach the Puget Sound region — gusting around 25-40 mph, but since they’ll be blowing from the “wrong” direction for typical strong winds here, they could cause damage.

Second, the boundary between where this advancing cold air meets the warm, southerly air in place is called an “arctic front” and sometimes that boundary can create its own weather. There is already a chance some of the lingering showers from Saturday’s storm Saturday night could find snow levels low enough for a some snow showers in the lowlands, but any moisture triggered by the front would be snow.

As of the late Thursday night forecast period, the computer forecast models still don’t suggest much, if any, snow accumulations — generally an inch or less except for along Whatcom County and around Port Angeles where a few inches could accumulate. But arctic fronts can be finicky so we’ll have to keep an eye on this. Bottom line, at least be on guard for a little snow on Sunday amid the cold northerly winds.

If it does snow, it won’t snow for very long as the front continues to pass to the south and dry and clearing weather will follow quickly behind. By Sunday night, we’re drying out and clearing with strong north winds and frigid temperatures inbound.

This leads to the storms third impact: The strongest cold snap of the season. Lows Sunday night are expected to drop into the teens in the outlying areas to mid 20s in the city with wind chill a factor amid 25-40 mph north winds.

On the literal bright side, Monday should be blazing sunshine with excellent visibility showing off our mountains that just collected 2-3 feet of new snow. But it’ll remain chilly with highs in the 30s. It’ll be windy early but the north winds taper off during the day.

That means another clear, but calmer night on Monday night allowing temperatures to drop another couple degrees from Sunday night’s lows — so more solidly in the teens to low 20s around Seattle. Brrr. Clear and chilly Tuesday again with highs near 40.

Those overnight low forecasts wouldn’t be historic in the general sense of Seattle winters, but it could do something not seen in seven years: Set a new record daily low temperature. The last time a record low was set was on Feb. 25, 2011. Three record lows have been tied and 69 new record highs have been set since.

The record lows for Monday and Tuesday morning are 25 degrees and forecasted lows are below those marks.

We’ll very slowly moderate through the week but stay dry until the

end of the week. Too early to tell if the next chance of showers then will be cold enough for snow or just a chilly rain but the overall pattern looks to remain colder than normal into the start of March and fresh long range forecasts suggest it will be a cool start to spring.

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