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Sierra Entry Indicator

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Sierra Entry Indicator

Postby postholer » Sat Jan 31, 2009 3:31 pm

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.

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Updated Link

Postby rybozz » Sat Dec 19, 2009 3:59 pm

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
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Re: Updated Link

Postby postholer » Sat Dec 19, 2009 6:32 pm

Done! Thanks a bunch for pointing that out!

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Re: Updated Link

Postby gbronner » Mon Feb 13, 2012 12:15 pm

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

Postby postholer » Mon Feb 13, 2012 12:46 pm

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

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