Why Has It Been So COLD On The West Coast? – Weather “Whys” For Kids

Why Has It Been So COLD On The West Coast? – Weather “Whys” For Kids

Cactus covered in a blanket of snow. Multiple sub-freezing mornings in the suburbs of San Francisco. The snowiest month in a half-century in Seattle. Frost in Death Valley. Flurries at The Rose Bowl in Pasadena. And the first snow day in the Las Vegas area since 2008.

All of these weather events have actually happened in February. One or two of them would be noteworthy. But winter has been especially cold… and wet… for the entire West Coast since the middle of January. It’s almost as if the entire winter pattern has shifted south by several hundred miles. Arizona has been getting “Utah weather”. Los Angeles has been getting “Bay Area weather”. San Francisco has been getting “Seattle weather”. Lastly, Seattle has been the recipient of a weather pattern that’s more like Canada than anything else. Western Washington has received a snowstorm — or more — nearly every week. This pattern has been anything but normal.

Weather Records Continue To Fall…

Here’s a short list of the record weather events that have happened over the past several weeks:

*Flagstaff, AZ — 35.9″ snow fell in this northern Arizona city on February 21, 2019. This broke the all-time record of the snowiest day in the city’s history. The previous record was 31″ snow on December 30, 1915.

*Seattle, WA — February 2019 is the snowiest February on record since weather data started being recorded at SeaTac Airport. The 20.5″ snow that has fallen makes this month the 5th snowiest month ever in modern Seattle history.

*San Francisco, CA — Rarely is the Bay Area both cold and wet during the winter. It’s typically one or the other (cold & dry, wet & warm). But this has been the 2nd coldest February in the city in the past 70 years, and areas north of San Francisco have received more than 17″ rain from just one storm.

*Squaw Alpine Ski Resort, CA — More snow has fallen at this spot in the Sierra than in any month in the resort’s history. More than 23 FEET of snow (286″) has been recorded as of February 26. That’s almost a foot of snow per day!

So… WHY Is This Happening?

It’s quite an interesting… and rare… setup in the atmosphere this year. The typical winter pattern on the West Coast is a westerly flow from the Pacific Ocean, which brings in storms on a regular basis, but also keeps the region mild because of the mild ocean temperatures (50s) in the Eastern Pacific. Further, when it does get cold, it’s because the source of air shifts from the Pacific to Canada, where cold but dry air filters down from British Columbia and Alberta.

But this year we’ve had the rare combination of the cold Canadian air mixing with the storms that move across the Pacific Ocean. The picture above shows this pattern. That purple-shaded oval over western Canada and Western Washington is the cold air that came from the Arctic. But notice exactly where it is. It’s over land, but it’s also sitting over the ocean. So it’s not cold and dry… it’s cold & wet. There’s an area of high pressure sitting in the perfect position that is allowing this cold air to take this exact trip down the West Coast. Just a little more inland and it would be cold with no rain or snow. Just a little more out in the ocean and it would be wet but mild. It’s this narrow path that is allowing storms to “hug the coast” and bring snow to places that haven’t seen this much in more than a generation.

Spring Outlook

The Climate Prediction Center issues a 90-day outlook every month. The most recent one issued does offer hope that this cold and wet pattern for the West Coast will end. The CPC outlook for March through May calls for a good chance of above-average temperatures for Washington, Oregon, and California. It may not feel like it now, but all of that snow will melt, and perhaps sooner rather than later.

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