Guide to Measuring New Snow/Sleet / Guide to Measuring Ice

New snow/sleet is the amount of snow and/or sleet that has fallen since your last observation or since the snow and/or sleet began.  Sleet is small chunks of ice that are like small hailstones.  (This is different from freezing rain, see below.)

Recommended equipment:

-         Snowboard

-         Ruler or yard stick

It is recommended that the snowboard be a flat piece of plywood as close to a square as possible and at least 144 square inches (1 square foot).  It is probably best to have a 2 or 3-foot square (or nearly square) snowboard.  A larger snowboard is easier to find after several inches of snow.  A wooden deck away from buildings and trees is a suitable substitute.

The snowboard should be placed in a grassy area where snow accumulates uniformly.  Do not place the snowboard under tree branches or wires or near buildings, homes, automobiles, roads, driveways or sidewalks.  It you live in a heavily wooded area, try to locate your snowboard in an exposed clearing or in an area where there are less trees.  Do not place the snowboard where snow from a neighbor’s snow blower might land.  The snowboard does not have to be on the ground all winter, just when snow is expected.  (I don’t want you to kill your grass by leaving the snowboard out all winter.)

When you make an observation, use a ruler or yard stick and measure the depth of the snow and/or sleet on the snowboard to the nearest half-inch at several places.  The average depth is the new snow and/or sleet since the last observation reported to the nearest ½ inch.  When you are done making measurements, wipe all the snow and/or sleet off the snowboard.

It is fairly easy to measure new snow if the wind is light and there is no blowing and drifting snow.  When there is a lot of wind causing blowing and drifting, there may be no snow on your snowboard.  In this case, or if you feel the amount on the snowboard is not representative of how much snow fell, make a good guess on how much new snow fell.

Guide to Estimating Ice Accumulation

Ice Accretion on Tree Limb

Recommended equipment: - Ruler

Ice accumulation occurs when rain falls with surface temperatures below freezing.  This is commonly called freezing rain.

The best way to measure ice accumulation is to break off a very small branch/twig from a tree.  Use a ruler to measure the thickness of ice in tenths of an inch.  There may be one side of the branch or twig with a greater thickness of ice than the other side.  In this instance, please report the average thickness of ice buildup.

A half of an inch of ice buildup will usually start to bring down tree limbs and power lines.

Guide to Measuring Total Depth of Old and New Snow/Sleet

Snow/Sleet depth is simply the depth of snow/sleet on the ground, both old snow/sleet and new snow/sleet.  Since snow tends to compact and may melt from underneath, your last total snow/sleet depth plus your new snowfall usually will be more than your most recent total snow/sleet depth.  In addition, sleet or freezing rain falling on a fresh snow cover will cause a lot of compaction.

Recommended equipment: - Ruler or yardstick.

After making a new snowfall measurement, measure the total snow depth of both old and new snow.  To measure snow depth, simply go around an area where there is an average snowfall and make 5 to 10 measurements.  Make sure all measurements are at least 5 feet apart.  The average of these measurements is the snow depth.  Be sure to avoid making measurements in snowdrifts, in areas where most of the snow has been blown away, under trees, or near houses.  If there has been any wind at all, you will likely find significant differences in depth.


Reporting Procedure by Phone

Please phone the National Weather Service at 1-800-221-2856 as soon as possible after making an observation when an inch or more of new snow and/or sleet or any ice accumulation has occurred.  We would like to have all reports for the 7 AM observation by 8 AM, for the 1 PM observation by 2 PM, for the 7 PM observation by 8 PM, and the 1 AM observation by 2 AM.

Please take an observation and report it to the National Weather Service when either one of the following criteria are met:

1)     New snow and/or sleet accumulation (if equal to or greater than an inch) since the last observation or since the snow and/or sleet began.  Also include duration of time in which the new snow and/or sleet fell.

2)     Any ice accumulation.

There is no need to call us when the above criteria (1 or 2) are not met.  If you are calling us to report one of the above mentioned items, please include the following information as well:

-        Your location.

-        Depth of old and new snow and/or sleet.

-        Current weather (related to precipitation type and intensity, if any) including any blowing or drifting snow.  This would also include current temperature, if you have a thermometer.

During an active winter weather event we will make sure that additional people are here to take your reports.  In addition, you may phone in observations at other times, if you feel the information would be significant and the criteria 1 or 2 are met.

Reporting Procedure via SKYWARNTM AMATEUR RADIO NET

During significant and widespread winter weather events, SKYWARNTM net controllers will likely be running a mini winter weather net on 146.745 up to three times a day to take winter weather reports.  The times of these nets will be from 7 to 8 AM (for 7 AM observations), 1 to 2 PM (for 1 PM observations), and 7 to 8 PM (for 7 PM observations).  If the mini SKYWARNTM winter weather net is not active, please relay your observation to our office using the 800-phone number.  Observations relayed to the net controller will be passed to the National Weather Service.

Examples:

Snow starts to fall at the house of Jim Smith at 2 PM, some sleet begins mixing in around 5 PM.  At 7 PM, Jim takes an observation and comes up with 4 inches of new snow/sleet.  Jim measures a total depth of old and new snow/sleet at 5 inches.  Jim calls the National Weather Service and reports that 4 inches of new snow/sleet feel between 2 PM and 7 PM and the total snow/sleet depth at 7 PM was 5 inches.  In addition, Jim reports that snow and sleet were still falling and the temperature was 28 degrees.

Jack Cunningham measures a snow depth of 10 inches at his 7 AM observation.  At 1 PM Jack relays to the National Weather Service using the 800# that 5 inches of additional snow fell from 7 AM to 1 PM and the snow depth is now 13 inches.  (Note, melting or compaction occurred)

You take an observation at 1 PM and report 3 inches of new snow in the last 6 hours and a snow depth of 5 inches.  You take another observation at 3 PM and now have 4 more inches of snow and a snow depth of 8 inches.  You call this report into our office.  (Note, melting or compaction occurred)