I received an email today from CoCoRaHS which clarifies some good information about reporting snow and winter conditions to them. For those who haven’t read the email yet, here’s an excerpt from it from Nolan and the CoCoRaHS team:
A good question about reporting snow.
I received this question this morning from a North Carolina weather watcher, and realized it may be relevant for many of us.
“I viewed the videos and PDF presentation on measuring snow, but I’m still a little confused about the recording requirements. Can you tell me if all of the blocks need to be filled out that are related to snow, or, if not, what is the required information that should always be entered?”
Here is how I answered:
The first priority, of course, is the precipitation amount — rain plus the melted water content from any snow and ice that fell. Beyond that it’s at your discretion. Personally, I try to fill out all values every day. For example, even on dry days with no precipitation and no snow remaining on the ground, I type in and submit 0.0 so that it confirms no snow. That is ideal but not required. The only required field is “rain and melted snow ” (i.e. the water content of the precip) All other fields (new snow, core sample water content of new snow, total depth of old/new snow, and water content of total snow on ground (the SWE)) are greatly appreciated. But they are not required. Measure and report what you can. Leave the others NA if you don’t take those measurements.
Snow Depth — the depth of snow (both old and new) remaining on the ground at your observation time.
I’ve noticed that quite a few of us skip this measurement, or report it only when new snow has fallen. But arguably it my be the single most important reading of any of our snow observations since it relates most closely to the impact snow is having on transportation, recreation and public safety in an area. You can infer a lot about the character of the snow, too, from day to day changes in snow depth. Many people tell me it’s a difficult measurement. I would argue it’s OK to start with an estimate — maybe just by looking out your window. With uneven snow it may be very difficult to determine if you have an average depth of 3.0, 4.0 or 5.5″ — but it’s easy to estimate if it’s closest to 1″, 4″, 8″ or 12″. Once it’s more than 12″ it gets challenging again, and you may do best to have a semi-permanent ‘snow stake” mounted in the ground in a convenient location. For more info on measuring snow depth (as opposed to new snowfall): https://youtu.be/2zbDygoJ2D4
“Condition Reports” —
Are you getting wetter or drier? Is your winter snowpack greater or less than average? How about the streams around you? Are they flowing more or less than “normal” for this time of year? Add value to your CoCoRaHS precipitation reports by adding weekly “Condition” updates. https://cocorahs.org/Content.aspx?page=condition
Winter precipitation measurement made easy (or at least easier) — use your kitchen scale
If you’ve got a kitchen scales that reads to the nearest gram, you may be in luck: https://cocorahs.org/media/docs/Training_SnowByWeight.pdf
Freezing rain
Based on historical experience, January and February are the core months of the freezing rain season. Do you know how to measure and report freezing rain? If not, don’t wait until its glazing . https://youtu.be/rLwlaP_CFl8
