Is the PDO correlated to road openings?

Anthony Watt’s post at WUWT yesterday (Snowbound USHCN weather station at Crater Lake set me thinking. Or perhaps I should say more specifically that it was Ric Werme’s comment about road openings:

“Washington State DOT reopened Rt 20, the North Cascades Highway for the summer. Apparently it’s one of the latest openings (May 25th)…”

And Chinook Pass Update from Washington State Dept. of Transport:

Looks like winter in June. (Photo and comment from Washington State DoT Website

Updated June 2, 2011

– WSDOT crews hopes to reopen Chinook Pass by the end of June.”

“What are the usual opening and closing dates?
In an average year, Chinook Pass closes in November and reopens in May.”

Washington State DoT has tabulated Mountain Pass Closure and Opening Dates:

Road opening dates for Chinook Pass and Cascades Highway.

In plotting the graph of openings, I left off the first opening date for the Cascades Highway – 02 September 1935 1972 – as I imagine that to be exceptional, perhaps surmounting unexpected challenges for the first time on the road in a reasonably heavy snowpack that year (Chinook Pass did not open until 22 June).   [Update – reader ‘Gary’ emailed to point out my date error, saying: “You are correct to leave it out as I believe that it also had to do with the finishing the construction of the highway that year.  1972 was also a cool spring year with 2+ inches total of snow for the month at the Olympia Airport (elev. <200 feet).”]

Well it certainly looks as if there was an abrupt change from 1978. This coincides rather neatly with the shift in the Pacific Decadal Oscillation (PDO) to its warm phase in 1977.

If the snowpack and opening dates are correlated with the PDO shift, why does the earlier flip from warm to cold in 1946 fail to show up?  I can only speculate that there is not enough data (1935-1945) for the eye to pick up a trend, or that road clearing was lower priority and probably still in its infancy as a regular state-wide service.  Anyone know anything about how the efficiency of ploughing/plowing technology has changed since the 1930s? The equipment had been around for quite some time:

Well, it will be a few years before we see if there is any ‘flip’ back to greater snowpack and later openings, but then, if the cold PDO does bring more snow ‘on average’, economics will likely play a part these days – the pressure to get the roads open for commerce and the pressure on state budgets of doing so.

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10 Responses to Is the PDO correlated to road openings?

  1. E.M.Smith says:

    Great observation…

    FWIW, I think that in the ’30s and ’40s there were not that many people out here and cars were fairly “new” (only about 20 years… for most folks) so the “typical” was just to expect roads to be closed in winter and open when the snow melted. If you needed to ship goods then, you sent them by train (commercial long haul trucking was not common – it came out of the Red Ball Express of W.W. II ) and folks would travel by rail in bad weather. (as even in good weather you were changing a tire every so often on an old Model T … and there were basically no AAA or Towing Services to speak of in the early years. And no way to call them if you were stuck out in the snow 40 miles from nowhere).

    So why “open” a road that nobody was going to use until spring anyway?

    What I’d expect to see is that the “early years” are recording the natural melt based opening dates, then after about 1950 you will get “plough dominated” dates and the open will depend on the importance of the road and the current plough tech. (So I-80 is now “always open” other than during blizzards, but hwy 108 near it is often closed.)

    At least, that’s how I’d interpret it…

    So pick a fairly constant use “medium value” road (i.e. NOT the major east / west intertie of 500 miles of West Coast at I-80) and it ought to have opening dates based on when the snow has stopped and is of such a depth that the plough can clear it. As they tend to use the same ploughs for decades, the data out to have decadal consistency.

    I suspect that 108, 104 and the opening date of Yosemite Park would all work too.

    gives some idea how the history of a highway can change over decadal time scales.

  2. Verity Jones says:

    I think that sums it up nicely. I wonder if it is possible to find anything on road plough policy.
    I’ve been following the ploughing of Going-to-the-Sun Road in Glacier National Park for years, but have not found a record of opening dates.

    There are plenty of snowpack records – too many – back to the 1920s in places, but I’ve only started looking at them.

  3. pascvaks says:

    Think Chiefio nailed it! (1st time with your new Reply block, seems BIGGER than it should be. Got a feeling somethings not quite right. Type now just started going out of box, word wrap not working. Hitting enter now, don’t see an Enter Button to use with mouse. Nope, that didn’t work;-( Tried changing Text Size and Encoding, no help.

  4. pascvaks says:

    Finally! OK, feedback time. Something’s not right with NEW comment gizmo. Tried for sometime earlier and then –after testing over at Chiefio’s– finally got something up here. Check with Chiefio, I guess is the best advice. His block actually has an ENTER button. I couldn’t find one here earlier and don’t see one now. I went clicking all over and finally got lucky, the word ENTER here is invisable. There’s a grey bar down on the side of the page that seems to be your ENTER button. Anyway, for what it’s worth, hope I’ve been of some help. (For what you folks pay, you’d think WORDPRESS would have all the kinks worked out before adding a new feature;-). Oh yes it takes longer now to open the page and reopen after a comment is entered. Here goes attempt 1,200,345, hitting the grey bar now… hummm no luck..

  5. pascvaks says:

    Last note – promise-
    On my old computer the last comment entry doesn’t clear once I successfully find and hit ENTER at your site and the page reopens. The ENTER button is not on the side as I said earlier but the grey box below the comment box, which is nearly as large as the comment box itself, but has nothing typed in it to say what it is. Going to delete all entries in memory for diggingintheclay and reopen to see if that does the trick, doubt it.

    • Verity Jones says:

      Well that all came through – sorry you had problems. I can see a ‘Post Comment’ button below the box – to the right.

      • pascvaks says:

        Still can’t see it. Between here and Chiefio wordpress comment box something amiss. If you can see “‘Post Comment” it’s likely on my end but his OK and your’s not. Hummmmm..??

  6. Pingback: Massive drifts and late-melting snowpack | Watts Up With That?

  7. Anthony Watts says:

    Lassen Park loop (89) would also be a good proxy

Comments are closed.