# Precip-->Snow calculation for those with heated rain collectors

As suggested by member Aifan27 in another post… it would be cool if WD could turn precip measurements and outside temp into a snow fall estimate for those with heated rain collectors

Using the article and table he found at

http://www.stormcenter.com/envirocast/2003-01-01/envirocast-article2.php

text below, see url for conversion table.

Snow to Liquid Equivalent Conversion

People often think of snowfall in terms of how many inches of snow accumulated after a snowfall event. Anyone who lives in an area that often receives snow knows that different snowfall events can produce snow of different densities. We can get “wet,” heavy snow or the very “dry,” powdery variety. Meteorologists and hydrologists tend to express snowfall amounts in terms of “liquid water equivalent,” which is simply the amount of liquid water that you would get if you were to melt the snow. Another way of thinking about it is that the liquid water equivalent is how much rain would fall if it were warm enough for the snow to fall as liquid, instead of frozen, precipitation. A commonly used rule of thumb is that every 10 inches of snow that falls is equivalent to 1 inch of liquid water. This “10-to-1 rule” doesn’t always apply, however, as the actual liquid water equivalent of snowfall varies quite a bit, depending on meteorological conditions and geographic location. See Table 1 for a table showing how much liquid equivalent to expect for various snowfall amounts, depending on what the outside temperature is.

aifan27
Tim
Rain Maker

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Location: Pennsylvania
Station Type: VP2 w/ FARS, rain collector heater
Posts: 1275

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That would be tough - at least here in Pennsylvania.
Every snow we get is different - from dry powder to heavy sleet type.
The liquid equivalent would vary greatly in my opinion - too much to estimate actual snowfall.

if you check the url… at the bottom of the article they have a table that shows snow density based on temp… seems pretty comprehensive… im assuming this would make it a pretty close est. of actual snowfall if implemented as shown

The liquid equivalent is independent of snow density.
I like dave7101

The only anecdotal evidence we have about the accuracy of the data in the table came from aifan27 who has reported that, for the one significant fall that he’s had since getting the heater (and finding the table), the liquid volume derived from the table was significantly different to the amount actually measured.

As I said in that post, I’m working on my own SLR table with someone else on another weather forum. I will let you guys know how it worked out and post in on the forums.

Yes, that is correct, Chris.

–Tim

Hello Chris,
you mentionned above “the liquid volume derived from the table was significantly different to the amount actually measured.”
What is the amount actually measured? Is it the measured snow height? Is it the amount of water you get when you melt the snow?

I don’t know. We get so little snow here that I don’t normally pay much attention to snow melt. Perhaps Tim can point you at his previous discussion on this topic?

Clarence,

I can’t really remember the exact ratio, but using the table was very inaccurate. I think it was something like I measured 0.57" of melted precipitation and I measured approximately 6" of snow, but according to the table I “should” have measured about 8.7" of snow. Of course you have to take into effect the wind speed and other variables, but that table is not even close.

I think I will be making my own temperature categories with the new table.

If you’re interested in participating, please let me know.

Thanks.

–Tim

Hi Tim,

You wrote:

I can't really remember the exact ratio, but using the table was very inaccurate. I think it was something like I measured 0.57" of melted precipitation and I measured approximately 6" of snow

So, we are quite close to the 1 to 10 rule.

Here in Belgium, in the south part we have a little bit of snow. I remember having measured the deph of snow and measured the liquid-equivalent water and it was also close to the 1 to 10 rule.

Now snow is melted. I 'll measure again next snow fall. It’s not forecasted for the next week anyway.

I’ll let you know my measurements.

Thanks.

Clarence,

(I think) The only reason why it is close to the 1:10 ratio is because the temperatures were close to that 32 degree mark (within a few degrees F), therefore the ratio being closer together. Now if the temps were more like 25 degrees F and lower, this would be a whole different story. As Chris said in one of his other posts, there is no “true” way to measure snow using a rain collector heater.

Take care and a Happy New Year to you.

–Tim