Snow math

I wonder how they determine how much snow has fallen and how much during a certain time frame? An inch at a time? I know some snow storms the weatherperson says we received "X" amount of snow today and when I look outside, it only looks like a few inches to me, not the 6-8" that was mentioned being received. Depend on the location they use for measuring, like the airport? A cold surface so snowfall does not melt before it can be measured? In High School, in the middle of Nevada, we had a Government weather station of sorts on our farm and everyday before school I took the readings for my mom and she melted any snow to detemine precipitation.

I have been thinking about this for a long time, then was moved by a long distance phone call from a neighbor. I work out of town and was off snow camping this last weekend, so did not make it home, so I missed the 3' more of snow we received on top of the 22" from the weekend before where I live.

Hi Duane,

There are guidelines for pretty much everything, including snow measurement. Here is one set from NOAA.

How to measure snow, the NOAA way

The west is scattered with remote snow sensors (usually "pillows") that measure snow depth in real time and transmit the data. Monthly, we have a manual snow survey to gather more definitive data and correct automatic station errors (the snow can hang up, giving false readings).

It so happens the California monthly survey is today, and we should have good news about our water supply afterwards.

Cheers,

The purpose of CDEC snow surveys is NOT to inform us backpackers and skiiers! It is to estimate the runoff for water supply deliveries and flood control. Thus, it is mostly geared to water content of the snow, not snow depth per se. The sites chosen for sensors are based on getting a good statistical sample. More sensors are also placed in watersheds that cause flooding and are significant water sources for the State Water Project. Thus, fewer sensors on the east side of the Sierra. Nevertheless, it is a wonderful service to backpackers. Here is an example of something our taxes are paying for and we get an extra bonus. I suggest everyone who is backpacking in California get familiar with CDEC's website. It is great!

http://cdec.water.ca.gov/snow_rain.html

Good summary. It's a lot of fun to dig around the data and look at individual sensor locations--a few have extended data sets including wind speed.

Today's snow survey brings good news for everybody who's not in the northbound PCT class of 2011.

3.1.11 Snow Survey

Cheers,

Thank you Rick, that didn't help much, mostly talks about measuring the amount of precipitation, which is how we did it on the farm. I thought they had a more scientific method. Snow gets compacted by more snow, so I was wondering how they arrive at a foot, when it looks like 8" to me and they only measure at specified intervals. It can snow 2"-3" an hour and if you only measure the snow every 4-8 hours, the snow has settled already. Not meant to be scientific or just standardized procedure?

I remember an article about a couple of guys who traveled the Sierra on skis measuring the snowpack. I think they worked for the L.A. city DWP? They jammed hollow tubes into the snow all the way to the ground, then pulled them out to measure and weigh the core of snow in the tube. The readings gave them both snow depth and density.

That's my dream job!!!!!!

Amazing, huh! But if they were in the Owens valley water shed, LA DWP are the guys. Early in the last century, someone in LA finagled the water rights to that area (remember Chinatown with Jack Nicholson). That is your drinking water they are measuring. I have long forgotten the details but prior to pumping, Mono Lake didn't have the exposed spires and they ran gold barges up and down the river.

Duane, they have "specially" selected locals for statistical purposes and consistency. Landforms and storm directions have many effects on the amount of rain or snowfall in any particular area; so much so that a 50% variation is not uncommon.

Three of us did this job on a ski trip in Arizona's White Mountains. They provided the tube and scales with a modicum of training and paid us enough to take care of gas and food. We used the tube as a center pole in our REI McKinley tent.

It's always good to engage in something that has some depth to it.

I have always loved doing field work. Great stuff oldranger.

BTW. There was 24" of snow in the Lagunas (San Diego) from this storm. You can bet there was over 4' in the Sierra San Pedro Martir from the same storm. It would be great to be up there now. I have done it in the past but the way thing are now...

:):) Too funny. Multiple use out of the "pole"? I'm aware of the tools/procedure for snow surveys. See photos all the time and on the news as I work out of town, close to Lake Tahoe.