Most people don’t think about the heavy snowfall in the mountains in late April and early May, but Such snow will become a reality this year.
Over the next 48 hours, 3-8 inches will fall across the Cascade passes and more is expected over the next week or so.
Stevens Pass on Sunday afternoon
The main cause of the upcoming cold and snowy weather is two upper-level lows moving in tonight and Monday night (see higher-level map at 2 a.m. Monday below). This type is very rare in this year’s El Nino winter.
So how much snow can we expect on Monday and early Tuesday?
Below is the high-resolution NOAA/NWS HRRR model’s cumulative snowfall forecast from 5 a.m. Sunday to 5 a.m. Tuesday.
Impression. More than a foot at higher elevations. 4-8 inches in passes. Great value in the mountains of southern British Columbia.
The UW High Resolution Modeling System has a similar solution, but we offer even more: we run a population of multiple forecasts to understand the uncertainty of the forecasts. Using this system, snow accumulation at Stevens Pass (approximately 4000 ft in the central WA Cascades) is shown below.
There is some uncertainty, but the average is about 6 inches for this event.
How unusual is a half-foot or more of snow on Cascade Mountain for this time of year?
To better understand this interesting question, below are the average daily snowfall and daily extreme snowfall amounts at Stampede Pass from 1944 to 2016.
On average, this location receives about 1 inch around May 1. But extreme days this time of year have received 10-15 inches. So having a little snow at this time of spring is not a big deal.
In any event, a significant increase in snowfall in the area is expected by midweek.
But what’s impressive is that the snow and cold didn’t end on Tuesday. The latest model forecast has some more lower cold snaps coming next week.
As a result, a LOT more snow is expected. For example, below are the cumulative snowfall forecasts over the next 5 days from the high dexterity Central European model. ANOTHER FOOT (or more) at several mountain locations.
And the forests that expanded then had even more snow.
Area ski resorts should consider reopening for their brilliant May skiing.
And no, global warming doesn’t cause a lot of May snow. 😉
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Notification: There will be no Northwest Weather Conference this year.
Why? Because we have lost two important partners. The National Weather Service Seattle Forecast Office has told me that they are no longer interested in hosting and participating in this regional weather meeting. And the remaining partner, the Puget Sound Chapter of the American Meteorological Society, has passed away. I’m looking for new partners for next year. Stay tuned.
