Tuesday, December 19, 2017

Snow Returns to the Northwest Mountains (and Even Some Lowlands)

With high pressure dominating our weather during the past week or so, our mountains have had a snow drought of sorts.  But all of that changes today.

A vigorous frontal system and associated low center will cross the Northwest today, bringing substantial precipitation everywhere and several feet of snow to most of the Cascades.

Let me show you some of the UW WRF model runs for the next few days.  You will be greasing your skis before I am done!

The snowfall for the 24h ending 4 AM Wednesday, shows bountiful snow (1-2 ft) over the Cascades above 4000 ft from southern BC to the CA border.  With cool air pushing through the Fraser River Valley, Bellingham and the San Juans get some white stuff as well.

 The following 24-h (4 AM Wednesday to 4 AM Thursday), shows the end of snow over WA, with light snow over the portions of Oregon.


 Here is a closer view of the 72h snowfall ending Thursday at 4 AM.  Nearly 3 ft will fall over higher terrain (remember snow depth will be less!) and the mountains surrounding the Columbia Basin will get snow as well.


After the Tuesday snowfall/precipitation event the spigot will turn off as ANOTHER ridge of high pressure develops over the eastern Pacific. Here is the upper level (500 hPa) map for 1 AM Thursday.  A ridge offshore will keep us dry.


And by Sunday morning at 8 AM, the ridge strengthens, with high pressure up and down the West Coast.   So there should be some amazing skiing for few days Thursday through Saturday at least).


One final caution.  The system today will bring windy conditions (gust above 40 mph in some locations) and the snow level should drop \ to around 500 ft Tuesday night--so snow showers are possible on hills and higher elevations.

16 comments:

Terry McDonald said...

Much needed! Big improvement here but it looks like another 2 weeks of incoming Rex block. Meaning only 2-3 days of snow for PNW for Dec, and about 25 percent of average precip. What happened La NiƱa?

P Aronson said...

How about some Christmas snow?

Plasmanoir said...

Over 6 inches of rain has fallen West of Maple Falls since Sunday morning. So glad we are still above freezing!

Joseph Ratliff said...

La Nina probabilistic "effects" don't really start to take hold until Jan-Feb, when official Winter really ramps up.

I'll bet we get some decent snow then. :)

Here is a good resource for those who might want to keep up with the Seasonal Outlooks:

http://www.cpc.ncep.noaa.gov/products/predictions/long_range/two_class.php

sunsnow12 said...

"Meaning only 2-3 days of snow for PNW for Dec, and about 25 percent of average precip."

The majority of the state is well over 100% precip for the water year, including our Cascade watersheds. Seattle is currently over 120% for the ‘17/’18 water year, 125%+ ytd. Even if we end the year here we will still be ahead of average precip for the water year, and the state snowpack after this dump will be near normal (some areas will exceed it – the Olympics are almost 150%). Our reservoirs are above normal, and this snowfall will take watershed snowpack to average.

I just do not get the hand wringing over a dry week or two in the winter here when every general metric points to a very normal water year – or in this case above average.

PS: Hat’s off to Weather Underground for coming the closest to nailing this forecast a week ago.

BAMCIS said...

Hey Sunsow12, are you aware that the RRR is a major factor in California's fires? Or it was/still is a major factor to the drought down there?

Your logic is there but its confined to the present and just our area. When the RRR persists, other than the nice sunny days there is not enough checks on the plus column to offset the negatives. This is something no one should want loitering around. When billions of dollars in damage results as well as lives loss, your statement about hand wringing is justifiably labeled as being petty and self centered.

Also just in our area, Seattle is averaging a net population gain of supposedly 57 people per day. Unless the water supply is matching that growth rate, then having a water surplus today might just be breaking even tomorrow or even a deficit. The boom won't last forever but once a city reaching a certain tipping point, it will attract people even without a boom. The growth will slow but not stop.

If the RRR becomes a "new normal" with climate change, than our area is going to be in distress. Few will bother to acknowledge that there could have been something done about it, since like all boom areas everyone lives in the now and the future never comes.

John Forsythe said...

@sunsnow12
The hand wringing is because people can't look past the end of their nose when it comes to weather/climate. It's dry for the last two weeks so we must be in a drought. It is very short sighted. Thanks for putting up the percentages on our current water reserve levels.

John Marshall said...

Sunsnow12: I share your frustration with people freaking out over variations in weather without considering the seasonal patterns and sources of variability.

But I suppose if your life is dedicated to fitting data to a theory, then monthly, weekly and even daily variations from the norm could be considered "events worth reporting".

Strangely, the same people don't seem to get excited at all when the weather gets wetter or colder than average, which was the case in early November.

If one direction of variation supports the theory, then doesn't short-term variation the other way refute it?

Of course not. In reality, weather doesn't prove or disprove anything. Climate trends over decades and centuries, however, are VERY interesting.



DJ said...

CLiff-
I love the UW model output graphics that you include in your blog but I can never find. Truthfully, I find navigating through the UW weather pages very challenging.

Can you include URLs with the model output graphics you post?

Thanks

Lucas Flanders said...

Looks like another setup for Santa Ana winds in southern Calif.

AnneScott said...

Good points. We also had a very wet November and despite the dry summer, overall 2017 was wetter than average. People seem to forget that it is perfectly normal to see occasional periods of extended high pressure patterns in the winter months. I remember some dry Fall/Winter periods of the past such as Nov 1985, Jan and Feb 1993, the entire Fall and Winter of 2000-2001,much of Fall and Winter 2002-2003 and even a few years ago,the year of the "blob". I think it was 2013-2014 especially October through December 2013 was extremely dry overall.

alexis julian. said...

Is the wind the reason why Port Townsend, WA is smokey today? California wildfires again?

Eric Blair said...

"Also just in our area, Seattle is averaging a net population gain of supposedly 57 people per day. Unless the water supply is matching that growth rate, then having a water surplus today might just be breaking even tomorrow or even a deficit."

Which is why there were calls for more damns to be built all along the West Coast back in the 70's and 80's, when population demographers foresaw the swelling population growth. But when the wealthy NIMBY's joined forces with the environmental groups and started launching lawsuits in order to prevent more damns from being built, here we are. Not only that, but after politicos kept diverting tax monies to favored crony businesses instead of critical infrastructure needs, we saw the predictable almost - catastrophic failure of the Orville Damn last year. This damn had been on the critical list from the Army Corp. of Engineers for many years, but despite record tax revenues in CA, it was never addressed.

Asher said...

Yeah, homebody tends to forget about anyone but skiers. I just need some snow for cmas.

Stu Smith said...

Eric Blair: You are certainly correct; they are damns...

J said...

Check out the Ice Age Farmer, Oppenheimer Ranch Project and Adapt 2030 YouTube Channels. They'll link you up to a little more sanity than this everything is fine, but we're warming nonsense. Seriously, snow on the ground on Christmas is rare, and it's not just here in the Pac NW! Plenty of places across this country are having this. Give it a few more years, and let's see how this AGW meme holds up even with the most ignoramus of the population, i.e. the appeal to authority folks.