Temps in Western WA begin to warm, but not without some potential snow

It was quite cold this weekend, and this week offers warming temperatures, but not without an interesting transition during the warm-up.

The surge of modified arctic air from the interior of Western Canada Thursday and Friday, along with a little lowland snow, resulted in cold but not necessarily record-low temperatures.

Reviewing low temperatures for many Western Washington locations, some plunged into the single digits over the weekend. The north end was the coldest. Bellingham and Sumas dropped to just 3 degrees above zero, while Lynden reached 4 degrees, Arlington to 7 degrees, and Mt Vernon to 8 degrees.

Temperatures in the south sound region ranged from lows of 10 degrees at Shelton and Yelm to Bremerton at 12 degrees and McChord Field in Tacoma at just 14 degrees.

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This cold wave was competing against what was likely the coldest period of weather in the 20th century, January 1950. Those temperature records for both the low and cold high temperatures still stand for the most part after more than 70 years. Yet, Seattle-Tacoma International Airport did set a new record cold high temperature on Jan. 12 with a high of only 25 degrees. Olympia Airport did the same on Jan. 12 with a high of just 30 degrees, setting a new record.

For those who have had their share of cold weather, warmer, more average mid-January weather is on the way. Today will offer more sunshine, with highs nudging above freezing for the first time in several days with temperatures in the 30s. Lows tonight in the region will again be cold, ranging from the mid-teens into the 20s.

Then, a Pacific weather system is expected to reach the region starting tomorrow, spreading moisture up and over the resident colder but also slowly modifying the surface cold air mass.

When precipitation begins later Tuesday, it could be in the form of a wintry mix involving snow, rare sleet, and freezing rain – all that is likely to be short-lived – a matter of a few hours before turning to cold rain. Yet, that wintry mix may come during the Tuesday evening commute. The greatest threat of freezing precipitation in the form of sleet or freezing rain is expected in the south sound, southward through Lewis County.

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Highs on Tuesday will generally only be in the 30s and should remain there through the night as milder air sweeps inland from the Pacific with this weather system. Wednesday and Thursday will offer periods of rain, with highs back to near normal, in the 40s, with lows in the mid and upper 30s.

With warmer rain returning to the Western Washington lowlands, snow resumes in the mountains. Snow is expected to begin again late tomorrow and continue at times through at least Thursday.

Snow levels will remain below the Cascade Range passes, climbing to around 1500 feet on Wednesday and 2500 feet on Thursday. Another 1 to 3 feet of new snow is expected by Thursday morning. Freezing rain may also accompany the snowfall tomorrow night and Wednesday.

Motorists should be prepared for rugged winter weather driving conditions again. Road crews will be busy trying to keep the mountain pass highways open, but they may need to close at times, including the possibility of avalanche control. Skiers, snowboarders, and water managers should be delighted with the news of more snow in the mountains.

By the coming weekend, even warmer conditions will be in play, with lowland high temperatures perhaps rising above 50 degrees and mountain snow levels climbing to around 5000 feet.

After this cold snap, more typical and comfortable mid-January weather will resume later this week.

Follow Ted Buehner, the KIRO FM news meteorologist, on Twitter