RE: [pct-l] Snow, Sierras and 1977

["Reynolds, WT" <reynolds@ilan.com>]

Greg,
Using the snow surveys, the conditions on the Mt. Whitney Trail and the
"Forecast of Runoff Volumes for the Sierra" and some experience you can
predict the snow pretty accurately.

For example, for Forrester Pass the key measurement is the snow pillow in
Upper Tyndall Creek [UTC] @ 11,500. History [unfortunately very short]
indicates that this must be clear of snow for about 2 weeks for Forrester to
be passable without serious mountaineering skill and equipment and will be
reasonably passable to backpackers in about 4 weeks.....depending on snow
melt.

You find snow melt by looking at the Kern River data on the "Forecast of
Runoff Volumes for the Sierra". The first thing you look at is the peak
date. This year the peak was Memorial Day weekend. This is about average.
Later is slow melt, earlier is fast melt. Second, this page tracks snow melt
in 5 day intervals. Once UTC clears you track snow melt and adjust for
faster/slower melt.

I am convienced that this method is pretty accurate. I just lack the
experience to more accurately calculate the constants. If I had the
Forrester Pass conditions, the UTC readings, and the Runoff Volumes for the
last 12 years I could get pretty close. Unfortunately, I didn't start doing
this until 1998.

Other passes I calculate using comparative statistics. I predict Glen based
on Bishop [Glen clears before Bishop], Donahue based on Agnew etc, etc.

I will be back out on the trail June 18-20 at Sally Keys Lake and will
continue to ask hikers about snow and water crossings to increase my data.
My current prediction is that hikers that left Kennedy Meadows before June
15 faced plenty of snow on Forrester, a miserable Post-hole past Muir and a
diarreha moment crossing Evolution Creek. OTOH, hikers who leave KM  July 1
will walk through the same area. We'll see.

Tom

Note: There is more snow this year but it melted faster. Further the
snowpack reaches normal at a much lower latitude this year. While Southern
Sierra Snow is only 50-60% of normal [like last year], at Sally Keys Lake it
is 103% of normal. Last year you had to reach Tolumne Meadows to experience
a normal snow year.
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