Quick thought on snow and planning for the PCT

imported
#1

Note, i’m not a meteorologist, and i take no responsibility for anybody’s actions regarding the following!

In the course of thru-hiking in 2008 and just being interested, i’ve looked at weather and snow depth data for the southern Sierra Nevada and northern WA. A lot. Looking at each year going back as far as 1986. I’ve never shared the info because i’m not a pro at this and i’m sure what i’m going to say will be proved wrong. But still, it’s time i just put it out there for hikers to at least consider.

Right now, the southern Sierra snowpack is low, roughly half of the average for this date in history. So what, you say? It’s too early for that to mean anything? Is it? Well, in the past 15 years there have only been 4 other times when the snowpack around this date has been similarly or more severely low: 07, 01, 00, and 99. In each one of those years, the snowpack remained low or average throughout the winter, and in all four cases the snowpack level was VERY low by May. So i’m suggesting, maybe in no better than a Farmer’s Almanac kind of way, that it is a good year to plan an early start on the PCT.

But there’s more: maybe not just a good year, but a necessary year to start early. Considering the past 26 years, the average date that the northern WA snows were considerable and seasonal-permanent (they didn’t melt out within a few days) has been ~October 19th. But on these “early low Sierra snowpack” years the average WA snow-in date has been ~October 12th. What’s more, the more extreme the low snow in the Sierra is, the earlier the snow in WA tends to come in autumn. For example, our last really early snow-in was 2007, that saw hikers forced off trail for the year ~September 28th. Well that just happens to be one of the lowest southern Sierra December snowpacks on record.

I don’t think it’s a coincidence, though i don’t know the science or weather pattern that would cause this correlation.

Anyway, i’m suggesting that you may want to consider starting and ending the PCT this year a week or two earlier than the standard dates. Instead of an April 25 to October 5 hike, you might consider an April 15 to September 25.

Don’t blame me if i’m wrong, but please give me tons of credit if i’m right. Happy hiking!

markv

#2

These are rough numbers based on sno-tel and NWS info.

2011: 12/21 southern Sierra snowpack: ~250% of normal. 5/21 S.Sierra snowpack: ~400% of normal. northern WA “snow-in” date: 10/28.

2010: 12/21 S.Sierra snow: 300% of normal. 5/21: 250%. WA snow-in date: 10/23.

2009: 12/21: 140% of normal. 5/21: 10%. WA snow-in date: 10/27.

2008: 12/21: 90%. 5/21: 10%. WA snow-in: 10/21.

2007: 12/21 80%. 5/21: 0%. WA snow-in: 9/28.

markv

#3

Thanks for the info and analysis. What a change from last year, eh!:cheers

jalan

#4

Mark, I think this winter, so far, has been a freak anomaly and wouldn’t be surprised if we phase back into a typical La Nina pattern just like last winter. The Pacific Ocean water temperature regime certainly supports La Nina weather patterns. What’s unusual lately is that the southern branch of the jet stream has been over Baja, which is a very southern trajectory, even under El Nino, which we’re definitely not in. Normally El Nino brings heavy snow totals from the Sierras eastward and south. This recent pattern hasn’t fit that mold. But neither would a switch to more standard La Nina fare necessarily say much about eventual snowpack totals in the Sierras, since that range can just as easily be in a transition zone between wetter weather to the north and drier conditions to the south, like we had last year under La Nina.

Nobody could’ve predicted just how wet November and December in SoCal and the Southwest have been this year. Or that the line between the haves and have-nots would be drawn so sharply and at such a low latitude. These conditions just haven’t been reflected in the broader metrics that the weather guys use to predict long-term weather patterns. I think it’s too soon to call this one. Big changes could be in store yet this winter.

blisterfree

#5

I’m definitely cautious in my forecast, and i know my limitations, and what you’re saying (and i’ve read elsewhere) makes sense. But to be clear, my main point isn’t as much that early CA snows predict late CA snows. There have been many years that have started high snow in December and ended low snow by May. There have been a few that started low snow and ended high (though not in the past 15 years).

My main point is that there seems to be a consistent correlation between heavy early southern Sierra snows and a later onset of the next winter in WA. Or in this year’s case, the opposite.

markv

#6

It’s an interesting correlation. Heavy southern Sierra snows often result from a strong El Nino pattern. Conversely, El Nino usually starves the Pacific Northwest of snow. Some years an El Nino phase can linger from one winter into the following fall, or beyond. Same as the current La Nina, which is now in its second consecutive season, although not nearly as strong as it was this time last year.

The weaker the El Nino or La Nina phase, the less of a correlation with actual weather events. That could be what we’re looking at right now. But in a strong El Nino, which would predict heavy snows in the southern Sierra and less snow in the Pac NW, we might expect the type of statistical correlation you’re pointing out, especially if the El Nino lingered into the following fall.

It’d be interested to know how those late starting snow years in the PNW ultimately turned out. Is there also a correlation between late first fall snows and low total season snowpack in that region? Early fall snows and high season totals? Unusually high or low PNW snowpack totals are the hallmark of strong La Nina or El Nino respectively. Would be interested to know if there’s a correlation between these weather events and everything you’ve pointed out.

blisterfree

#7

If i have some extra time over the holidays i’ll check into that. It makes sense, but what i’ve written down and compared info for in the past has only been southern Sierra winter and spring, and WA fall, since obviously that’s (at face value) what affects thru-hikes.

markv

#8

to much thinking…JUST DO IT

long walk

#9

Einstein vs Nike, the no-holds barred tag-team grudge match.

__

#10

It’s December 22nd. One can’t Just Do It today. Might as well think about it, in hopes of doing it well later?

markv

#11

The measurement for the level of snowpack that has been most informative over the past century (give or take) has been the April 1st snow water equivalent (SWE). James Church produced his first water forecast based on these data in 1910 and published his principal papers on snowpack in 1933 and 1935. La Nina and El Nino move the snowpack around a lot, but if you are looking for planning data, go with the April 1st SWE.

Jim

#12

That’s kinda like saying the best forecast for Friday afternoon is to look out your window on Friday at 11:45am.

Many people like to plan a bit prior to April 1st. :cheers

markv

#13

For most people their start date is tied to kickoff. Additionally, even an April 1st SWE reading will not tell you how much snow was hanging around the Sierra in early/mid June, cool spring weather will cause the snow to hang around longer.

Take last year. There was pretty good indications early that it was going to be a big snow year. Yet few started later. I did wait for the April 1st data to set my start date but I probably should have started June 1st instead of May 21st.

But, in reality a week or even two wouldn’t have made much difference in the overall difficulty. Some believe that the earliest through the Sierra may have had an easier time than some of the later entries. Why, we had more snow bridges across some of the streams and there was few suncups to deal with. Yes, we still had raging streams, hundreds of miles of snow and a couple of narely passes but two weeks would have changed little.

Now where it would have helped was in NoCal and north. I still had snow in many areas that would have been significantly reduced had I gone through two weeks earlier.

So bottom line, it is fun to watch the snow levelsbut it will not be actionable for the vast majority of hikers.

gg-man

#14

I realize that very few hikers, even those that could, make any effort to take that year’s conditions into account when planning their start date. I’m obviously suggesting that perhaps they should. After seeing people drop out last year because of snow struggles when this sort of forecast would have suggested that they could have started June 1st and still had plenty of time to finish, and on the other hand after seeing people in 2007 get snowed out short of Canada when they certainly could have planned to start April 1st instead of all starting at Kickoff…well it’s too bad.

I understand it, believe me. My own thru was tied to work obligations, and i had no flexibility with dates. If i did have flexibility though, i’d take these early conditions indications seriously and try to plan my optimal “natural” starting date.

markv

#15

I’m a pretty big believer in the difference that a week or two can make. I left Kennedy Meadows on June 5th of 2008. There was quite a bit of snow, very few tracks, etc. It was surely manageable, but well there was a lot of snow. When i got to Mammoth Lakes i had to leave the trail for 8 days. When i came back, it was like 99% of the snow had just disappeared.

On the tail end of the hike, i finished in mid-September in literally sunny skies and 75 degree weather. My friends who finished 10 days later had snow.

There are no guarantees, and it’s guesswork to an extent, but it’s not an entirely idle hobby to be interested in conditions and forecasting.

markv

#16

“Take last year. There was pretty good indications early that it was going to be a big snow year. Yet few started later.”

Of course that’s a whole different discussion. The reason few started later is because, well yes, almost everyone times their start dates to match the Kickoff. That can certainly be a problem in a heavy snow year, but it’s nobody’s fault for pointing out a possible solution that hikers could act on if - A) They only knew about, and B) Weren’t dissuaded from acting on it by the fixed timeframe of the Kickoff. Both the hikers and the event organizers share some of the blame here. But it’s the hikers that might actually be open to delaying their hikes given “actionable intelligence” that should give the KO organizers pause, in terms of reassessing the wisdom of the fixed KO itinerary.

Of course, this discussion has been beaten silly on other forums. I’m not hoping to continue it here. That would indeed be an idle hobby. But just in conclusion: No one with a possible solution to a problem should be resigned to accept that no one will ever heed it. The most important thing is just to get the idea out there in front of the people.

blisterfree

#17

A good measure of when the Sierra opens could be the Tioga Road opening. While not completely relevent to hikers I suspect that an offset from that opening date could be used for “acceptable snow level for hiking.” There is a list floating around of the opening date for Tioga. I also have the last 30 years of Tyndall daily data already in a spreadsheet if that is of any use to you.

gg-man

#18

I think what most discussions of this never cover is what is acceptable snow? I thought like most do these days on my first hike, that postholer data was a solid recommendation and big snow could make the Sierras impassable. Two thru-hikes and one long section hike later and I can definitely say I’ve adjusted my understanding of snowpack in the sierra and how it effects hiking.

Basically, the snowpack in the southern sierra really doesn’t matter as much as people think it does, at least as regards finishing a thru-hike. I entered early every time, by conventional wisdom. June 5th 2008, June 3rd 2009, June 2nd 2010. Every time I hiked on tons of snow, although there was more each year respectively. 2008 was fairly suncupped and snow free as compared to 09 and 10, what I would imagine a June 15th hiker encountered in 2009 and a June 25th hiker in 2010. And to be honest, it was about equally hard as the other years with my dates. Traveling most of the day on snow that’s packed is about equally tiring as traveling only some of the day on snow that’s suncupped and mushy.

The only thing that really changes is probably river crossings. 2008 and 2009 had laughable river crossings, even as early as I was there. 2010 had some challenging ones but ultimately I believe you can pretty much get across in nearly any conditions, especially if you’re with a group, being smart and willing to travel up and down river. So that’s no impassable hurdle either.

I’d honestly say the barrier to entry for your average flexible thru-hiker willing to travel on snow is probably avalanches, not some blanket snowpack measurement. Once the avalanche danger has passed, I say go on in if you want to.

The real challenging thing about a high snow year isn’t snow in the sierra, is what this all comes down to (in my opinion). It’s snow in norcal and possibly even oregon. That snow, in the trees and in an area you don’t expect to be slowed down in, is what will slow you and demoralize you just enough to either cause you to be too late or quit. You EXPECT snow in the Sierras, and any first time hiker doesn’t really have any conception of what they’re getting themselves into anyway so I feel like they’d be more likely to put up with some snow than someone who’s hiked in snow free conditions and has an expectation of ease. But when you’ve been doing 15-20s since kennedy meadows and now you’re in Belden, things start to get sketchy.

Of course, this is all my way of looking at it. And doesn’t have much to do with the original topic of snowpack and early snow years, but so be it!

Joker

#19

Joker, i left K Meadows just one day behind you in 2008? You weren’t hiking with the pipe sleeper people were you? I did some crazy mile days out of K Meadows, so i’m surprised i don’t remember meeting you until way further on, like in Oregon.

Anyway, i’m 100% with you on your post. I’ve concluded that more important than Sierra snowpack is San Jacinto snowpack, and just sheer quantity of miles done in snow. For San Jac, it’s more a question of getting lost on the east and north slopes, and by norcal it’s the demoralization you mention. But i never did find good historical snow data for San Jacinto, so i started with the snowpack measurements for Casa Viejo and Crabtree, and on up from there.

More than anything i was trying to, like i said before, pick up any correlations or indicators of when the snow perma-flies in WA in fall. When that happens, it’s really hard going to fight through it. I’ve yet to hear of a thruhiker making their way through more than a day or two of it. The weather is much colder, things never dry, fewer hours of daylight, there’s more confusing navigation in the trees and along ridgelines, etc. And it happens at such a wide variety of dates.

For 2007, i concluded 9/28 as the beginning of the storm that shut it down for thru-hikers. If you know of someone who came through, on-trail, to finish later than 9/30, let me know. Yet for this year, no shut-down storm until October 28th! For 1987, i concluded November 8th!! That’s over 40 days difference. Of course if you’re a fast thru-hiker, this doesn’t matter. You just start when you want and finish by 9/28. But for many hikers who need or just want the full 5-1/2 months, it would be incredibly useful, especially mentally when you’re feeling pushed to keep grinding out big mile days, to know whether you might have any extra 20 days or not.

I wish i had reason to be incredibly confident that this correlation i found is a good forecast indicator. How about i quit my job, thru-hike again this year, and i’ll plan my end date to coincide with my forecast? I’ll be the one to take the chance, and let you know how it turns out. :cheers

markv

#20

Latest reports give snow pack at 38% of normal. That’s based on water content which is important for farmers that irrigate. Don’t know how that relates to PCT hikers, but it’s still a dry winter so far.

bowlegs