Can you predict when the Sun Road will open?

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Can you predict when the Sun Road will open?

Postby paul46038 » Wed Jan 18, 2017 9:16 am

(Warning: Long post of limited general interest. You should probably turn back now.)

I have mentioned elsewhere that my family and I are coming to explore Glacier in the second half of June, despite a known risk that the Sun Road may not be open when we’d like it to be, or even by the end of our trip. It has been volunteered that this has been a relatively heavy snow year so far which may not mean much but certainly doesn’t seem like it can be a sign of an early opening.

It got me wondering if the opening date could be predicted based on something like recorded snowfall, without any announcement or guidance from the park service. If so, how early and how accurately can such a prediction be made?

(This is a good time to point out that we will no doubt have an excellent trip whether or not we get to stand on Logan Pass. This post is driven by intellectual curiosity and my penchant for numbers geekery.)

I found an April 2015 article in the Flathead Beacon which at least implied that a correlation indeed exists between snowfall and the road opening. Further, it pointed me at a wonderful, publicly-available statistic: the Snow Water Equivalent (SWE) measurements from the Flattop Mountain SNOTEL site. SWE, as I understand it, is a calculation based on both the depth and the density of the current snowpack. A little further digging assured me that there is no more appropriate SNOTEL site than Flattop Mountain from which to gather data.

So I gathered data: SWE numbers for the first day of each month from January to June for the last 15 years. I already had the Sun Road opening dates for those years. I looked at the data from several angles and certainly saw a general correlation between SWEs and opening dates but nothing real definitive.

To make a long story medium, I got better results once I decided to make my question much more specific (and much more Paul-centric). My new question was this: Based on SWE measurements, can I predict whether this will be a “good” year (Logan Pass opens by June 21), a “bad” year (Logan Pass opens after June 26), or a “so-so” year (Logan Pass opens some time in between)?

Looking at both discrete SWE numbers and the change in SWE over certain periods, I found some pretty decent correlations and created some matrices that support making predictions on March 1, April 1 and May 1.

(Tagging back to the first paragraph, is there no correlation between January snowfall and the subsequent road opening? Yeah, there is a little, but just a little. In fact, neither of the two highest January SWEs in my data occurred in “bad” years and neither of the two lowest January SWEs occurred in “good” years. The 2017 measurement of 19.9 inches is the third highest of the last 16 years.)

Anyway, below are my matrices, in which I tallied the timing of the opening against various SWE measurements for 15 years. I was trying to find SWE values for which my tallies would end up in the upper-left or lower-right corners of each matrix.

Image

What does this mean? Let’s look at how this would have worked in 2016 as an example. (The 2016 data would not have been in the matrices then, but that doesn’t change the story much.)

Here’s how 2016 would have played out:
• January 1: SWE of 17.7, slightly below average but we know that doesn’t mean much.
• March 1: SWE of 31.7. This is less than 35 so we’re already feeling pretty good that it won’t be a bad year and we have about a two-thirds chance of seeing a good year.
• April 1: SWE of 41.8, an increase of 24.1 from January 1. This increase is less than 30 so we have roughly the same conclusions as we did a month ago. There is a slightly stronger indication of a good (as opposed to a so-so) year.
• May 1: SWE of 38.3, a decrease of 3.5 from April 1. The discrete measurement is less than 50, so again we think it’s most likely going to be a good year and almost certainly not a bad one. The change from April is less than a 2 inch increase, so that table tells us to expect roughly the same thing.

The Sun Road opened on June 19, 2016 – a good year on the Paul-centric scale, as the matrices predicted.

As would any self-respecting numbers geek, I will certainly update this thread as 2017 unfolds.
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Re: Can you predict when the Sun Road will open?

Postby paul » Wed Jan 18, 2017 2:13 pm

Well, if you can successfully predict the Sun Road opening date then you'll want to compete in this year's Sun Road contest. The winner gets a virtual keg of beer! :wink:
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Re: Can you predict when the Sun Road will open?

Postby PeteE » Sat Jan 21, 2017 9:16 am

Paul, I engage in those mental acrobatics as well trying to figure out when the road may open.
You need to factor in non weather related events as well.
In the past it's been the seemingly never ending Sun Road construction project.
That's pretty much finished.
However, you never know about things like avalanches which might delay opening at the last minute. 8)

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Re: Can you predict when the Sun Road will open?

Postby Jay w » Tue Feb 28, 2017 8:26 pm

I love it. I'm a bit backlogged, but I'd love to gather the data and do a multiple non-linear regression analysis including the price of Glenlivit...or at least the sampling of.

Seriously, couldn't the data be graphed based on March, April, May data, maybe against opening date by days from June 1? Don't get me wrong, I love what you've done so far.

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Re: Can you predict when the Sun Road will open?

Postby Pizza Bob » Tue Feb 28, 2017 11:34 pm

“It's tough to make predictions, especially about the future.”
--- Yogi Berra

I virtually guarantee it will open on Thursday, June 22, around 11am. Good progress
plowing in May, but the current heavy snow fall combined with the accurately forecast 3 day
snowstorm the first week of June will delay the opening.
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Re: Can you predict when the Sun Road will open?

Postby llholmes1948 » Thu Mar 02, 2017 8:18 am

paul wrote:Well, if you can successfully predict the Sun Road opening date then you'll want to compete in this year's Sun Road contest. The winner gets a virtual keg of beer! :wink:


Not of course that I have ever been officially appointed as chairman of the Sun Road Opening Contest, but we usually begin the contest on or about April 15 of each year as a respite from taxes and I plan to do so this year as well.

I will also have to be in touch with the sponsor of the virtual keg of beer to be sure that it is still available for another year.

Stay tuned,
Lyman
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Re: Can you predict when the Sun Road will open?

Postby Jen » Thu Mar 02, 2017 9:01 am

llholmes1948 wrote:
paul wrote:Well, if you can successfully predict the Sun Road opening date then you'll want to compete in this year's Sun Road contest. The winner gets a virtual keg of beer! :wink:


Not of course that I have ever been officially appointed as chairman of the Sun Road Opening Contest, but we usually begin the contest on or about April 15 of each year as a respite from taxes and I plan to do so this year as well.

I will also have to be in touch with the sponsor of the virtual keg of beer to be sure that it is still available for another year.

Stay tuned,
Lyman


I officially appoint llholmes1948 as chairman of the Sun Road Opening Contest. (strikes virtual gavel)
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Re: Can you predict when the Sun Road will open?

Postby Pizza Bob » Thu Mar 02, 2017 7:07 pm

I can give you last year's virtual keg, now empty, in case you can get a deposit back on it :D
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Re: Can you predict when the Sun Road will open?

Postby Jen » Thu Mar 02, 2017 9:30 pm

Pizza Bob wrote:I can give you last year's virtual keg, now empty, in case you can get a deposit back on it :D


LMAO!
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Re: Can you predict when the Sun Road will open?

Postby akamina3 » Sat Mar 18, 2017 6:19 pm

Will the entire road be open by June 21? I am not planning on it.

If the road does not open by June 21, keep in mind that it will be more open than it is now.

From the west, you will most likely be able to hike/bike well past the Loop.

From the east, you will most likely be able to hike/bike most of the way to Logan Pass.
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Re: Can you predict when the Sun Road will open?

Postby sperryKev » Mon Mar 20, 2017 4:06 pm

As a person who also watches the Flattop Snotel data religiously every spring, complete with keeping my own spreadsheets and predictive calculations, I have developed a few general rules of thumb. (Not for Sun Road, but to be mindful and ready for other high country accessibility.)

* It is impossible to predict the dates of high country openings before May 1. (unless you count wishful thinking as a prediction.)
* It is impossible to accurately predict any opening dates before June 1.
* The month of June itself, how warm/cool it is and how wet/dry it is, can have just as much impact on opening dates as the overall snowpack. ie: a heavy snow year with a warm June will have a comparable opening date to a year with average snow pack and a cool/wet June.

And all predictions are subject to audit by the whims of Mother Nature. She does not issue press releases.
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Re: Can you predict when the Sun Road will open?

Postby paul46038 » Tue Jun 06, 2017 9:30 am

I originally intended to post here as each month ticked by, but it turned out that the March 1 and April 1 SWE measurements were about as right-down-the-middle as you could get. So there wasn't much predictive fun to be had. Then April happened and the May 1 numbers were terrible and I had to take time out to be sad (not really, it's all good). But I'm over it now and feel the need to put a bow on it. So here are the matrices with the 2017 numbers noted under the appropriate column:

Image

And since a line graph is worth four matrices, here's one of those. Each line represents a year. The green ones are "good" (road opens by June 21, the red ones are "bad" (road opens after June 26 and the yellow ones are the years where the opening was between June 21 and June 26. The blue line is 2017 which, even now in June, doesn't look good for an opening before the end of our trip.

Image
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