Thursday, May 19, 2011

What Is the Alta Snowfall Record?

Source: NWS
Note from Jim: Post updated 2:25 PM 19 May with correct information from Utah Weather and Climate. 

It's a pretty simple question really, "What is the Alta Snowfall Record?"  Good luck, however, finding a consistent answer.

According to the Western Region Climate Center, Utah's maximum winter snowfall is 846.8", set at Alta in 1982-83.

According to Utah Weather and Climate by Pope and Brough, the Alta "year" (Sep 1983–Jun 1984) snowfall record is 808.5" set in 1983–84 and the seasonal snowfall record is 743.5" set Nov 1983–Apr 1984

What gives?

There are several issues here.  First, what is the time period of the observations and what is meant by winter, year, or season.

There does not appear to be a definition of winter on the Western Region Climate Center, but I suspect they are actually referring to the water year, which is from Oct-Sep.

I don't know what the definition of season is.  Based on the Alta snowfall history page, the ski area presently uses Oct-Apr.  What they used in 1983-84 I don't know. Pope and Brough used Nov–Apr for Utah Weather and Climate.

Now, let me add some additional flies to the ointment.

The ski area presently collects observations on the upper mountain, but in the past has done it at the base.  It does snow more on the upper mountain.  Are we comparing apples and oranges?

The official record cited by the Western Region Climate Center is based on data from the Alta cooperative observer.  I suspect that data is probably not from the ski area, but instead UDOT or a volunteer at Alta (in fact, over the years different groups may have provided data).

The Western Region Climate Center lists four locations at Alta which data has been collected since 1948.  All have the same lat-lon: 40.36N, -111.38W.  Pump that into googlemaps and you get a location south of Heber!  Not exactly helpful...

Finally, we have the issue of whether or not the methods and location of the snowfall collection have been done consistently over the years, even if the official location has stayed the same.

Someone should pull the climate data for the Alta coop site from NCDC just so we can verify the seasonal and water-year records (volunteers?).  Once that's done, we can worry about all these other issues.

Then again, we could just go skiing...

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