Spotters and Winter Weather
As you know Northern Michigan receives a substantial amount of snow each year. Snowfall in Northern Michigan is also quite variable. For instance, in a lake effect snow situation, one location may receive 8 inches of snow while another location 15 miles away may only receive 2 inches of snow. With this tremendous amount of variability, it is very beneficial to the National Weather Service to receive snowfall amounts from our spotters.
Spotter snowfall amounts are sent to the media, which has a high demand for spotter snowfall reports, especially since the amount of snow is a driving force for Northern Michigan's tourism industry during the winter. In rare record snowfall events, spotter snowfall can be used to get disaster relief funds for your local area, so your reports are important!
We normally try to conduct winter spotter reporting classes in the fall, where the details of snow measurement are covered. For more information about these classes or other training questions, please email Warning Coordination Meteorologist Jim Keysor at the NWS in Gaylord.
Measuring Snowfall and snow depth
Two types of measurements are reported:
A snowboard is just a piece of plywood (ideally 16 X 16 inches), which you place on the ground and use as a base for your snow measurements. The snowboard is important, because it gives you a hard, flat surface on which to get accurate snow measurements from. If you don't use a board, then you run the risk of have erroneously high snowfall amounts because of the pocket of air and grass at the bottom of the snow.
How to site your snowboard. There are few tricks to measure snow. First, find a good place for your board. At the same time, find a place thatís convenient for you to walk to when it is snowing and ten below zero. Somewhere along an existing path to a shed or your rain gauge might do the trick. You may have to shovel out a path to your snowboard so along a path you have to clear anyway is a good idea. Remember when clearing the path you throw the snow on the opposite side your board is on! Place your board about an armís length off the path so you can reach it easily. The best place for your snowboard is in an area where you have a 45-degree angle view of the sky all around you. If this is not possible, try to get as clear as an opening above the board as possible. Another caution here.
You donít want to place your board in an open field that regularly gets scraped clean of snow during high winds. Having some trees or a house as a buffer somewhat in the vicinity of the board may be helpful. Place a blue flag where your board will be before the ground freezes. A covered snowboard may be slippery so be careful!
It snowed overnight - now what?
It snowed! The morning dawns on a fresh blanket of snow. Take your ruler and simply measure the snow on the board to the nearest tenth. Donít use English units like a ľ (quarter) inch. It is either .2 or .3 inches. Write down the amount of snow. Even small amounts of snow are important to us! Measure two or three times on the board and take the average of the measurements. Then clean the snow off or flip the board over. Donít scrape the board with the metal ruler. The ruler will damage the snowboard.
What about if the snow melts in between observations?
Remember, you want to report the greatest accumulation of snow since your last observation. If snowfall occurred several times over the past 24 hours and melted before the next snowfall...then report the total snowfall of the period.
Let's look at an example:
Two periods of heavy snow in a 24 hour period produce the following snow accumulations:
In between the periods of heavy snow, the sun comes out and the snow melts. So at the end of the day, there is only a trace of snow on the ground. When you call in your report of snow, what do you report for snowfall for the day?
the period: 5.2
Snow depth at time of observation: Trace
What if snow melts completely as it falls?
Frequently, early or late season snowfalls will melt completely as they fall. If this is the case, then just report a Trace of snowfall for the day.
What about measuring total snow depth?
Weíve measured snowfall, now letís measure the snow depth. This can be a little tricky sometimes. You can use a junk piece of wood to lay stationary on the ground all winter. A white board is best. If you do this, mark it with another blue flag so you can find the board under the several feet of snow on the ground. You can now measure the snow depth with the large ruler. Try to find a place that is representative of how much snow you get. Not where the snow drifts and not where it gets blown clear. If you do not have a board, you can just measure in three different places in your yard and take an average. Be careful that you are not measuring the air pocket that is under the snow caused by the grass.
Making a Report
Telephone or internet?
There are 2 basic ways to give your report to the weather service, either via the internet or on the telephone.
To learn more - eSpotter website.
When should I make my report?
We would like to receive at least 2 reports a day from our snow spotters, with 12 hour totals each time, as well as total depth on the ground. Ideally, a snow spotter would call with a morning report and then 12 hours later with an evening report.
Remember, one of the most critical pieces of information you provide is the time frame of your report (i.e. 12 hour total versus 24 hour total).
A few reporting rules of thumb
More information is always preferable, so never hesitate in providing us with a snowfall report. Here are a few tips to keep in mind with regard to snowfall reporting.