Most folks are not thinking about substantial snow in the mountains during late April and early May, but such snow will be a reality this year.
During the next 48-h, 3-8 inches will fall on the Cascade passes and more is predicted during the next week or so.
The key source of the upcoming cold, snowy weather are two upper-level lows that will move in tonight and Monday night (see upper-level maps at 2 AM Monday morning below). This kind of pattern has been rare this El Nino winter.
So how much snow could we expect on Monday and early Tuesday?
Below is the 5 AM Sunday accumulated snowfall forecast through 5 AM Tuesday of the high-resolution NOAA/NWS HRRR model.
Impressive. Over a foot at higher elevations. 4-8 inches in the passes. Large values in the mountains of southern British Columbia as well.
The UW high-resolution modeling system has a similar solution, but we have even more to offer: we run an ensemble of many forecasts to understand the uncertainty of the forecasts. Using this system, the snow accumulation at Stevens Pass (around 4000 ft in the central WA Cascades) is shown below.
Some uncertainty, but the average is about 6 inches for this event.
How unusual is a half foot or more of Cascade Mountain snow this time of the year?
To gain some insights into this interesting question, below is the daily average and daily extreme snowfall at Stampede Pass from 1944 to 2016.
On average, this site receives about an inch around May 1. But extreme days this time of year have received 10-15 inches. So getting some snow at this point in spring is no big deal.
And the extended forests after that have even MORE snow.
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Announcement: There will be no Northwest Weather Workshop this year.
Why? Because we lost two important partners. The Seattle National Weather Service Forecast Office has told me they are no longer interested in hosting and participating in this regional weather gathering. And the other partner, the Puget Sound Chapter of the American Meteorological Society, has died. I am looking for new partners for next year. Keep tuned.
Is climate change (the "go to" blame for almost all ills, real or imaginary) just another way to say weather? Asking for a friend.
ReplyDeleteSo far, this is spot-on. I'm seeing significant snowfall here in the mountains right above Glacier, at an elevation as low as 1400-1600 ft (I've taken some snapshots). And it's been cold and rainy here in the valley: overnight low was 32.5 F and the 24-hr rainfall was .70" at 7 am (I report to CoCoRaHS). Some of the locals will be delighted to do more cross-country skiing.
ReplyDeleteToo bad about the Weather Workshop. Best of luck getting it going next year.
ReplyDeleteI agree, I often attend.
DeleteHi Cliff, I am curious about something I saw on the UW radar loop this morning. At 6 AM it showed scattered rain falling well south of the San Juan Islands. Then at 6:45 a large cell appeared over Lopez Island, from the direction of Vancouver Island, with intense rain and hail mixed. Where did that come from and why did it not appear on the radar earlier? Did it just form above the island or is there a blind spot in the radar? Thanks,
ReplyDeleteHonestly this is really hilarious after that equally hilarious drought emergency declared by the state. Rain and snow and more snow lmao.
ReplyDeleteI should have not removed the chains from the trunk of the car.
ReplyDeleteSomeone in the Seattle Times comments a while back said that late season snow doesn't help with the summer water supply as much as snow earlier in the season. Is there any validity to this? The premise didn't make much sense to me.
ReplyDeleteNo....that does not make any sense. In fact, it is just the opposite.....late season snow is FAR more valuable.
DeleteThe phrase "the premise didn't make much sense to me," should apply to anything the Times puts out.
DeleteCliff, in your April 24 "Drought Buster" post, you said, "I suspect the snowpack will increase to around 80% of normal over Washington State and more than 100% of normal over much of Oregon within roughly 10 days." Six days later, we're still below 65% of normal statewide. Do you expect a much more dramatic change in the next few days?
ReplyDeleteBe patient Jerry.
DeletePS: Just checked on the SNOTEL site. The region is now up to 76%!
Delete"Be patient" is great advice, thanks.
DeleteWhat do you mean by "the region" in this case?
The Pacific Northwest:
Deletehttps://nwcc-apps.sc.egov.usda.gov/imap/#version=169&elements=&networks=!&states=!&basins=!&hucs=&minElevation=&maxElevation=&elementSelectType=any&activeOnly=true&activeForecastPointsOnly=false&hucLabels=false&hucIdLabels=false&hucParameterLabels=true&stationLabels=&overlays=&hucOverlays=2&basinOpacity=75&basinNoDataOpacity=25&basemapOpacity=100&maskOpacity=0&mode=data&openSections=dataElement,parameter,date,basin,options,elements,location,networks&controlsOpen=true&popup=&popupMulti=&popupBasin=&base=esriNgwm&displayType=basin&basinType=2&dataElement=WTEQ&depth=-2¶meter=PCTMED&frequency=DAILY&duration=I&customDuration=&dayPart=E&monthPart=E&forecastPubDay=1&forecastExceedance=50&useMixedPast=true&seqColor=1&divColor=7&scaleType=D&scaleMin=&scaleMax=&referencePeriodType=POR&referenceBegin=1991&referenceEnd=2020&minimumYears=20&hucAssociations=true&relativeDate=-1&lat=44.009&lon=-118.312&zoom=6.0
Thank you. Still a ways to go but I'll follow your advice and be patient 🤞
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