### Author Topic: Snow ratio  (Read 601 times)

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#### Bashy

• Forecaster
• Posts: 804
##### Snow ratio
« on: December 08, 2017, 12:09:40 PM »
Hey guys, am I right in thinking the common used ratio for rain to snow is about 1/10, ie, 1mm rain = 1cm snow?
Yeah, I know it's not a given as it depends on a few factors but that's about in the middle isn't it?

I have some guys elsewhere saying it's 20mm of rain = 2cm
Kind regards
Bashy

#### alanb

• Senior Member
• Posts: 74
##### Re: Snow ratio
« Reply #1 on: December 08, 2017, 12:51:11 PM »
According to the NSSL (The National Severe Storms Laboratory) on the NOAA web site:

"How many inches of snow equals one inch of rain?

On average, thirteen inches of snow equals one inch of rain in the US, although this ratio can vary from two inches for sleet to nearly fifty inches for very dry, powdery snow under certain conditions."

I personally like the 10 to 1 ratio as it is easy to calculate.
« Last Edit: December 08, 2017, 12:53:31 PM by alanb »
Alan

#### Bashy

• Forecaster
• Posts: 804
##### Re: Snow ratio
« Reply #2 on: December 08, 2017, 12:53:02 PM »
So that's pretty much what Im saying, thanks for the confirmation
Kind regards
Bashy

#### PaulMy

• Forecaster
• Posts: 3790
##### Re: Snow ratio
« Reply #3 on: December 08, 2017, 03:27:41 PM »
From my posting on another forum recently:
Quote
In addition to my Davis rain gauge to which I have no heater, so rain is recorded when ever the snow in the gauge melts and that could be days later, I also have a CoCoRaHS gauge and use a snow board as well to manually measure and send the snow and the snow water equivalent (SWE) each day to CoCoRaHS https://www.cocorahs.org/ViewData/ViewD ... 9230552c2a While the rule of thumb is SWE = 1/10th of new snow, in reality it can fluctuate by double or half that 1-10 ratio depending on the type of snow.  Last winter season, 2016-2017, we had 32 days with significant new snow fall.  8 events had SWE within 10% of the 1-10 ratio, 15 events had SWE at lower than 1-10 ratio and 9 events had higher than the 1-10 ratio.

Enjoy,
Paul

#### Bashy

• Forecaster
• Posts: 804
##### Re: Snow ratio
« Reply #4 on: December 08, 2017, 11:46:23 PM »
Thanks Paul, much appreciated
Kind regards
Bashy

#### ValentineWeather

• Forecaster
• Posts: 4374
##### Re: Snow ratio
« Reply #5 on: December 09, 2017, 05:23:36 AM »
14:1 is most typical here but have already seen 20:1. Temperature during snowfall plays a role but isn't always absolute.
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Randy, the Aviator is my father in 1963 with his Indian bike

#### Bashy

• Forecaster
• Posts: 804
##### Re: Snow ratio
« Reply #6 on: December 09, 2017, 05:25:09 AM »
Thank you, that's some good ratio....
Kind regards
Bashy

#### ValentineWeather

• Forecaster
• Posts: 4374
##### Re: Snow ratio
« Reply #7 on: December 09, 2017, 05:39:02 AM »
These are the arctic snows typical on high plains for snowfalls occurring around 14F  (-10C) and lower, coldest I've seen was 4F (-15C) and was pure powder.
Randy, the Aviator is my father in 1963 with his Indian bike

#### Bashy

• Forecaster
• Posts: 804
##### Re: Snow ratio
« Reply #8 on: December 09, 2017, 05:51:18 AM »
Wow, I would love to live somewhere where it's decent snow in the winter and decent sun in the summer....
Kind regards
Bashy

#### PaulMy

• Forecaster
• Posts: 3790
##### Re: Snow ratio
« Reply #9 on: December 09, 2017, 09:13:16 AM »
Quote
Wow, I would love to live somewhere where it's decent snow in the winter and decent sun in the summer....
I could find you a place in our London suburbs with some good size backyards that will hold a lot of weather gear, or in the nearby country side.

Enjoy,
Paul

#### Bashy

• Forecaster
• Posts: 804
##### Re: Snow ratio
« Reply #10 on: December 09, 2017, 09:34:36 AM »
Oh if it was only that easy :/
Kind regards
Bashy

#### benay ra'am

• Senior Contributor
• Posts: 182
##### Re: Snow ratio
« Reply #11 on: January 04, 2018, 09:17:56 AM »
We had our 1st snow in Eastern North Carolina last night. I had 2.3" of Snow on my Snow Board. I took a sample with my CoCoRHS and the Liquid precip was 0.22". almost a 10:1 ratio..............

Edit to Add, Temp was 25 Degrees over night......
« Last Edit: January 04, 2018, 09:21:14 AM by benay ra'am »

CoCoRaHS: NC-JH-80