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Sierra Entry Indicator

PostPosted: Sat Jan 31, 2009 3:31 pm
by postholer
The Sierra Entry Indicator is back!

http://postholer.com/postholer/index.php#sei

Want to encounter a manageable amount of Sierra snow? Using June 15th in a normal snow year as the 'optimal' time for a northbound hiker to set off into the Sierra from Kennedy Meadows, this graphic will give you a ballpark idea.

If you click on the 'blue bar' you'll get the handy CDEC Snow Graph for
northern, central and southern California.

It uses current conditions to determine the best time. It is not a forecast tool. It is most relevant the beginning of April when the snow is typically at it's peak. It is not a substitute for planning, use for entertainment purposes only, YMMV, etc.

-postholer

Updated Link

PostPosted: Sat Dec 19, 2009 3:59 pm
by rybozz
Hey thought I'd let you know the link is not current here is the current link.
http://cdec.water.ca.gov/cgi-progs/repo ... T_SWC.2010

Thanks

Re: Updated Link

PostPosted: Sat Dec 19, 2009 6:32 pm
by postholer
Done! Thanks a bunch for pointing that out!

-postholer

Re: Updated Link

PostPosted: Mon Feb 13, 2012 12:15 pm
by gbronner
rybozz wrote:Hey thought I'd let you know the link is not current here is the current link.
http://cdec.water.ca.gov/cgi-progs/repo ... T_SWC.2010

Thanks


I did a series of regressions based on the weather stations in the Southern Sierras and came up with the following formula:

April 28th + 1.85 days per inch of SWE on Feb 1 at your target location + 10 days per 1000' above or below 10,000 ft altitude.

(this applies to 'normal' years where the SWE on Feb 1 < 30 -- the other years are more affected by spring weather).

I'm also not sure how well a SWE of 0 correlates with actually being able to walk on the trail.
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Re: Updated Link

PostPosted: Mon Feb 13, 2012 12:46 pm
by postholer
boner wrote:I did a series of regressions based on the weather stations in the Southern Sierras and came up with the following formula


The best any algorithm would give is a probability or 'percent chance' based on previous years data.

For it to be predictive and accurate you would need to know how much snow will fall in the future and what the melt rate will be. Those 2 things cannot be known, thus a truly predictive formula cannot be realized.

That's why the 'Sierra Entry Indicator' reflects *current* conditions. No one can predict the weather that far out (yet). You can only make probability based 'guesses'.

:D

-postholer