Global Warming and Snowfall in the PNW

[cmor]

I did some math:

http://www.winterscience.com/lab/climate.htm

It was much bleaker than I expected. Any thoughts on the methodology or outcome?

[::: :::]

Not in a position to offer thoughtful critique, but interested in the discussion...thx for the work

[PNW_Skier206]

Well that was horribly depressing


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[WTF is dat]

It has been a while since I have skied the northwest, however aren’t the base areas of many of the mountains already regularly at or below the rain level ?

[wendigo]

Nice work. Seems a regionally downscaled temperature projection may prove more informative than a global projection. Maybe a shiny app for result presentation?

[mall walker]

in before the first "it was cold today lol there's no global warming" post

[PNW_Skier206]

It has been a while since I have skied the northwest, however aren’t the base areas of many of the mountains already regularly at or below the rain level ?

Yeah. Especially early in the season or in the spring.


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[Greenstateofmind]

Pretty cool report. I don't think there's any denying that your numbers catch a highly probable outcome. Here in VT, I've heard predictions (from University, take it fwiw), that we'll lose half of our resorts by 2050. Without overthinking this, and I'm hardly a trained statistician or climatologist, I've always wondered how effective it is to use the century average temp? Statistically, it's probably pretty sound, but...

[subtle plague]

I guess you did the right math but you posted 25mm of rain equal 25mm of snow (you really do inches in science? ). The normal factor is 1:10 I thought. I guess you just had a typo.
So 25mm precipitation is 25cm of snow.

[MagnificentUnicorn]

Not a climate change denier and I agree the future of skiing is looking bleak but you made the chart with the 2.6F change across the board. I may be wrong but if the average increase in global temps is 2.6f it seems like the summers are a lot hotter(more than a 2.6 degree change) and the winters are warmer(maybe not 2.6 degrees warmer). I'm not a statistician so maybe I'm totally off base here.

[californiagrown]

Not a climate change denier and I agree the future of skiing is looking bleak but you made the chart with the 2.6F change across the board. I may be wrong but if the average increase in global temps is 2.6f it seems like the summers are a lot hotter(more than a 2.6 degree change) and the winters are warmer(maybe not 2.6 degrees warmer). I'm not a statistician so maybe I'm totally off base here.

I think that is a good question to ask and understand. I have a feeling that it is very regionally dependent and also depends on how the local jet stream and weather patterns are affected. some areas could recieve wetter summers (cool) and warmer winters. Others might recieve cooler, wetter winters and dry hot summers.

The average yearly temp will go up, but how that affects the general weather patterns might affect the seasonal temps and precips is a really good mechanism to try and understand. Unfortunately, i have absolutely no idea.

[Ale_capone]

It's not so much the 2 degree average rise. It's more the high end days that increase the average. Been some good days, but a lot more days where the freezing levels get crazy high. Even if the resorts where higher.. rain has been going up to the alpine a bunch this year...

I'm about to hit the half century mark, so I'm not sure how much of this demise I'll live through. I don't have kids, so not much vested in the future.. but I'm not part of the problem either.

[ridinshockgun]

Even if the resorts where higher.. rain has been going up to the alpine a bunch this year...

When you're talking pineapple events like this, it's not a 1-2 deg temp change that matters. These just are what they are. Warm air from the tropics, not really because of climate change and I think have always been a part of PNW winters?

Seems to me most of storms, snow levels depend more on whether it's SW, W, or NW flow as the existing temperature is usually quickly overrun by the incoming fronts.

I've only been here 3 winters, but is it also possible that we remember the good days and the good storms and over time forget about the rain in past years?

[cmor]

It's hard to abstract weather from climate. It's not uncommon to have 20 degree changes day to day, but overall I just took every hourly temperature and added the anomaly. Assumption is that although weather patterns will be different, when we sum up a longer time period it should reflect the overall pattern. We've had seasons in the past 15 years with better snowfall totals than what I would expect the 20th century average to be, but it looks like on average it's an uphill battle.

I looked at temperature ananmoloy by month (does summer bear the brunt of warming) and did not find this to be the case. It looks like all months lift similarly.



It's also not a flat lift regionally, but when you look at historical maps it's been pretty uniform thus far. I tried to pull maps off of NOAA but got this in response: "https://government-shutdown.noaa.gov"

[cmor]

I guess you did the right math but you posted 25mm of rain equal 25mm of snow (you really do inches in science? ). The normal factor is 1:10 I thought. I guess you just had a typo.
So 25mm precipitation is 25cm of snow.

I don't see this error, but agree it's a little odd to not use mm and C. I thought it would be easier to understand with F and inches.

[The AD]

I see a problem with this statement:

If it's 25°F out, and there is .1 inch of precipitation (water) measured, there will be about 1 inch of snow. If it's 35°F out, it's raining.

Not necessarily true. It can still snow when the temp is above freezing. From all your data is there a way to find out how much snow accumulation occurred when the temp was above freezing? I have a feeling this could change the data substantially.

[subtle plague]

I don't see this error, but agree it's a little odd to not use mm and C. I thought it would be easier to understand with F and inches.

Sorry my mistake i didn't see the dot in the original layout

Im getting old. just put a 0 before the .1 for old folks like me.
"We can estimate the snowfall at each station by doing some simple math on the temperature and precipitation. If it's 25°F out, and there is .1 inch of precipitation (water) measured, there will be about 1 inch of snow. "

edit: AD: Yes and no. It depends hugely on air humidity. I've heard of snowfall at +3°C and more, but usually in very dry inner alpine conditions and it doesn't really accumulate in these conditions.

[ridinshockgun]

Not to mention at Snoqualmie Pass you can have pouring rain at 22 degrees

[The AD]

edit: AD: Yes and no. It depends hugely on air humidity. I've heard of snowfall at +3°C and more, but usually in very dry inner alpine conditions and it doesn't really accumulate in these conditions.

cmor has the data for the temps and the snow depths, so he should be able to determine whether or not this is true. I would think in this area where we're talking about snow levels often flirting with rain or snow at pass levels it could be statistically relevant.

[cmor]

I see a problem with this statement:


Not necessarily true. It can still snow when the temp is above freezing. From all your data is there a way to find out how much snow accumulation occurred when the temp was above freezing? I have a feeling this could change the data substantially.

Your're right that it doesn't all turn to shit exactly at 32F. The two other main variables at play are RH and the vertical column of air the snow is falling through. The general rule of thumb is that the freezing level is 1000 feet above the snow level. NWAC's forecast will account for this, when there is no precip they forecast freezing level. When there is snow they forecast snow level, as they are two different things. I find that it's usually around 33F when the transition occurs,

I intentionally was vague in the description you noted, and used 35 in the example because it's almost always rain by then. I used a linear scheme that changes the density of the snowfall based on the temperature. Temperature is the biggest influence here. It's an estimate because although I do have model data that I could merge to, I don't think in the end it would help all that much and it would be a lot of work. The RH is so often near 100% that it's virtually a constant. I tuned the parameters using the empirical evidence at hand, I have manual measurements I can match to snowfall at Crystal, and can see if my season totals are close for most areas. They are in the ballpark, and further mitigating the error is I'm providing a relative change. So as all models are, it is wrong, but I think it's a good estimate. I did note at the bottom I would be interested in working with anyone who has some work on this, because there is some room for improvement.

[dufferdan]

Interesting read, definitely concerning. That being said, as someone else suggested, a lot will depend on regional flows and zonal patterns , so hard to extrapolate.

Also, keep in mind, back in the early 80’s we had several years in a row where Whistler didn’t get a lot of snow, temperatures were warm and you had to download from mid-station for almost the entire season. Banff also had a major drought in the early 80’s. Much much warmer than what we have experienced here and there in the last 15 years. And theoretically we are on average warmer today than back then.

[LightRanger]

Hey cmor,

You see Dr. Ben Hatchett's (213 on TGR) recent paper on snow droughts in the Sierra? Got a bunch of regional press here locally. Check it out...
http://journals.ametsoc.org/doi/abs/...EI-D-17-0027.1

https://www.reviewjournal.com/news/s...-in-wet-years/
http://www.sfgate.com/news/article/r...A-12392508.php
https://ww2.kqed.org/science/2017/11...phill-rapidly/

Note: This tracks anecdotal evidence from friends I've chatted with who were born and raised in the Sierra Foothills dating back to the 50s. And, hell, even myself and I'm only 34.

[k2skier112]

When you're talking pineapple events like this, it's not a 1-2 deg temp change that matters. These just are what they are. Warm air from the tropics, not really because of climate change and I think have always been a part of PNW winters?

Seems to me most of storms, snow levels depend more on whether it's SW, W, or NW flow as the existing temperature is usually quickly overrun by the incoming fronts.

I've only been here 3 winters, but is it also possible that we remember the good days and the good storms and over time forget about the rain in past years?

I've been up to Mt Hood for 39 consecutive winters, snow level has gone up about 1700' in that time.

[dan_pdx]

I've been up to My hood for 39 consecutive winters, snow level has gone up about 1700' in that time.

Yeah, anecdotes are not data but I have a very clear memory of a couple of inches of rutted ice on Highway 26 all the way down to Zig Zag that was there for weeks (months?) during one winter in about 1994 or so. I haven't seen consistent cold temps like that in the last 10 years.

[b0ardski]

receding /disappearing glaciers don't lie...
and they're not gonna grow in my lifetime