Significant Rain, Lowland Snow, and Major Mountain Snow Expected From Wednesday to Friday

 FastCast—Wednesday, Jan. 5 to Friday, Jan. 7:

Another round of localized roadway icing is possible overnight Tuesday into Wednesday morning due to temperatures near freezing. Use caution on roads, especially bridges, shaded areas, and side streets.

An impactful weather system with significant rain, potential lowland snow, and major mountain snow will impact Western Washington from midday Wednesday to early Friday. The storm will begin with potential lowland snow as a warm front moves north into the region. Lowland snow is most likely in areas cooled by Fraser River outflow and easterly winds. A Winter Storm Watch is in effect for Whatcom and San Juan Counties and the Cascade Foothills. Snow totals of 2-6 inches are possible in these areas before a changeover to rain by Thursday morning. This probability exists for the Hood Canal Area as well, further exacerbating the ongoing closure of 47 miles of US-101. Light snow accumulations of a trace to around an inch are possible in the rest of the lowlands, but this snow will melt quickly on roads due to the warmer temperatures. Snow is most likely Wednesday evening through very early Thursday morning. Significant lowland rain is expected with this system. Expect rain totals of 2-4 inches in the lowlands by Friday. Urban flooding and standing water are possible, with river flooding possible from King County southward. The mountains will also get dumped on yet again. 1-3 feet of snow are expected at the passes, with brief freezing rain possible at Snoqualmie Pass. Continue reading the blog below for more information about this storm.

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An active couple days is ahead for Western Washington, featuring localized lowland snow, significant rain, and more major mountain snow. Let’s begin with the lowland snow potential.

Below is the Euro model forecast for snowfall.

This forecast shows what is most likely…snowfall of 2-6 inches in Whatcom & San Juan Counties and the Cascade Foothills and the Hood Canal area. The Interior Lowlands will receive a trace to 1 inch, with more slightly possible from Snohomish County northward.

It is important to note that most snow that falls in the lowlands won’t stick to most surfaces due to warmer ground temperatures (33-35°). Snow that does stick will likely only stick on grassy, non-road surfaces.

The UW WRF model is a bit snowier for most of the region, representing a colder scenario. 

This forecast shows 1-3 inches south of Seattle, 2-4” north of Seattle, and 4-8 inches in the favored areas. I expect that this situation is too snowy, but it shows the upper end of potential snow. 

In both of these forecasts, the passes receive a whopping 2-3 feet of snow, with up to 4-5 feet at higher elevations. Expect mountain pass closures and very difficult travel conditions.

This storm will also bring significant rain totals to Western Washington. The warm front will increase temperatures from the mid 30s to the upper 40s early Thursday morning. By midday Thursday, the entire region should have transitioned to rain (except the mountains). Below is the UW WRF rain forecast through 4 PM Friday.

This forecast shows significant totals of 1.5 to 3 inches across the Lowlands, with a small Olympic rain shadow. 3-5 inches are possible for areas from Olympia south and west, with 5-10 inches possible on the South/Central Coast and coast mountains.

The NAM model is below, showing a similar situation.

The NAM shows more rain north of Seattle than the UW forecast does. An Olympic rain shadow is still prevalent in this forecast.

Most of this rain will fall within a 48-hour period from midday Wednesday to midday Friday. Due to the short amount of time that significant rain amounts will fall, urban flooding, small stream flooding, and standing water is possible around Western Washington.

Bottom line: significant rainfall totals of 1-3 inches from Olympia northward and 3-5 inches on the coast and south of Olympia are expected. Flooding/bankfull stage on area rivers (mainly from King County southward) is expected from Friday to Saturday. Due to this, a Flood Watch has been issued. (Posted below).

A lot of active weather is expected by Friday! Stay tuned to local meteorologists on Twitter for more information!

Snow Showers Possible Overnight Monday Into Tuesday

 FastCast—Monday, Jan. 3 to Tuesday, Jan. 4:

It has been an active start to 2022, which will continue in the coming days. As of 7:20 PM Monday, temperatures across the Puget Sound area have fallen to 30-34 degrees. With showers moving in, precipitation will likely fall as snow or brief rain/snow mix. Generally, expect accumulation of a trace to half inch. The Cascade Foothills and Hood Canal Area will receive up to 1-3 inches due to their higher elevation and exposure to easterly winds. Additionally, remaining snow and slush on area roads (mainly side streets in the metro area) will likely freeze overnight, with low temperatures near freezing. This is especially likely in the foothills and along Hood Canal, where road conditions remain hazardous. Be careful driving Monday night and Tuesday morning. Expect temperatures to warm into the mid 30s to low 40s on Tuesday, with rain showers likely at times. A more impactful system, with heavy rain, potential lowland snow in places, and heavy mountain snow is expected from late Wednesday to early Friday.

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Continue reading the full blog below!

Localized showers have been moving through Western Washington today, bringing rain, mix, or snow. This will be the theme overnight Monday to Tuesday morning, with showers changing to all rain by midday Tuesday. With temperatures generally in the 30-34° range Monday evening, most precipitation around Puget Sound will fall as snow. 

Showers today have shown that snow can fall (sometimes mixed with rain) with temperatures as warm as 36 degrees, likely lowering temperatures in the process. A particularly impactful snow shower moved through parts of Puyallup, Bonney Lake, Buckley, and Enumclaw Monday evening. Below is a photo from Bonney Lake Weather showing accumulating snow on roads during the heavy snow shower.

This heavy snow shower caused some difficult road conditions and limited visibility as it moved through SE King County and East Pierce County this evening.

More localized snow showers are expected overnight Monday into Tuesday morning. Below is the UW WRF model showing snowfall (not necessarily what accumulates) through Tuesday.

This model generally did pretty good with predicting Sunday night’s areas of snow. Notice light accumulations of a trace to 1 inch in parts of the lowlands and 1 to 4 inches in parts of the Cascade Foothills and Hood Canal Area through Tuesday.

Additionally, the mountains will continue to get hammered with snow and blowing snow. At one point on Monday morning, Snoqualmie, Stevens, and White Passes were all closed simultaneously. 

As of 9 PM Monday, Snoqualmie Pass has opened after an 18 hour closure, Stevens Pass is open, and White Pass remains closed due to snow slides and “extreme” weather conditions. Below is Denny Creek (west of Snoqualmie summit) at 9:15 PM Monday. Chains are required except 4WD/AWD on Snoqualmie, Stevens, and Blewett Passes as of Monday evening.

You’ll find snowy conditions on I-90 from Issaquah onward in most places across the state. The passes will receive an additional 2 to 4 feet  of snow by the end of the week. (A power outage has been impacting the Snoqualmie Summit areas all day Monday and is ongoing at the time of writing this blog). 

Stay tuned as a more impactful system with heavy rain, potential lowland snow (in places), and heavy mountain snow will impact the region late Wednesday through Friday.

Major Weather Shift: Heavy Rain, Strong Winds, and Mountain Snow Arrive Sunday

 FastCast—Sunday, Jan. 2 to Monday, Jan. 3:

Happy New Year! 2022 will begin with a return to mostly “normal” weather in the Pacific Northwest. A system moving in on Sunday will bring much warmer temperatures (but temperatures will re-freeze in the upper 20s to low 30s Sunday morning) with temperatures reaching the upper 30s to low 40s. This, combined with expected rain, will make some significant progress melting remaining snow. Expect southerly winds to increase overnight into the morning. Wind Advisories are in effect for different areas. The North/Central Coast and Interior Lowlands will get southerly gusts up to 50 mph. The Foothills and Port Townsend area will have E-SE winds gusting up to 55 mph. The North Sound and South Washington Coast will have very strong gusts of 55-65 mph. A cold front will move in Sunday afternoon and evening, bringing 0.5-1.5 inches of rain. This will cause urban flooding and standing water, especially in areas with clogged storm drains. To top it off, the mountains will receive 1-2 feet of snow, keeping mountain pass travel difficult. Chances of lowland/foothill snow are possible on Sunday night and Monday afternoon/night with colder temperatures and easterly winds. Stay tuned for more information on this!

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Continue reading the full blog below!

After days in the freezer, Western Washington is transitioning back to typical weather, with rain, strong winds, and mountain snow. Lowland temperatures will warm into the upper 30s to low 40s on Sunday, after a brief freeze overnight Saturday into Sunday (lows in the upper 20s to low 30s). 

The biggest weather impact will be strong winds around the region. Below is the HRRR forecast for wind gusts at 7 PM Sunday, around the time of cold frontal passage.

Generally, expect gusts up to 50 mph in the metro area and the North/Central Coast, up to 55 mph in the Foothills and Eastern Strait areas (E-SE winds), and the strongest gusts of 55-65 mph in the North Sound and on the South Coast.

These winds will produce tree damage and potential power outages around the region. 

Rain will be heaviest with frontal passage in the evening. Rain totals through Monday evening from the HRRR model are below.

Expect rain totals of 0.5-1 inches in the Lowlands, except less in the Olympic rain shadow and more from Olympia southward.

This rain, which will be heavy at times, combined with warming temperatures will cause rapid snowmelt. High temperatures for Sunday are below (from the Euro model).

Expect highs in the upper 30s to low 40s in the lowlands and in the mid 40s on the coast. Expect the combination of rain and warmer temperatures to bring areas of urban flooding and lots of standing water on area roadways. Be sure to clear clogged storm drains if possible.

There will still be snow…but a much more uncertain forecast. Below is the Euro model forecast for snowfall (not accumulation) through Monday evening.

The passes will receive 1-2 feet of snow, and the higher elevations will receive 3-4 feet. You’ll notice that in this map, the lowlands receive some snowfall, a trace to 3 inches according to the Euro model. In the wake of the cold front (Monday afternoon/evening), temperatures will cool to the mid 30s, and with higher precipitation rates, brief snow is possible.

Some forecasts have shown a potential for metro area snow in the wake of the cold front on Sunday night/early Monday. Light easterly winds and temperatures cooling into the 30s make this complex situation possible. This is still very uncertain and may not happen, but be prepared for a fast transition to wet snow on Sunday night in some parts of the lowlands.

Stay tuned on Twitter to our local meteorologists for more information on what weather is upcoming!