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Measuring
& Recording Snowfall
The following is a
summary of guidelines that pertain to measuring snowfall; specifically
for north Texas. These procedures include those observers who use a
snowboard to measure snowfall. For a more complete description or the
full guidelines, you may view this link: NWS
Snow Measurement Guidelines. You may also request a DVD
on measuring snowfall from the National Weather Service Office in Fort
Worth.
NOTE:
Snowfall depth is recorded to the
nearest tenth of an inch, meaning one decimal place (i.e. 0.5",
8.4", 15.9"). Round to the nearest tenth of an inch in all
cases.
Use the below
images as a reference for recording snowfall measurements based on
your type of form.
B-92 Form
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Before
an anticipated winter weather event or snow event, remove the
plastic funnel and inner tube from the rain gauge. This will allow
the outer can to catch precipitation of all types and sizes
without clogging the funnel.
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Place your
snowboard in an unrestricted area. Hopefully the placement
location will already have been determined when your station was
established, but the location should be away from buildings,
trees, and not in an area where drifting snow would result in
higher snow depth amounts.
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There are three
measurements you will need to take at your observation time:
1.
Measure and record
the water equivalent of snow since your last reading
2.
Measure and record
the total snowfall depth
3.
Measure and record
the new snowfall amount since your last reading
To measure and record the water equivalent of snow: (There are two
ways)
| 1. Bring the
outer can inside. |
| 2a. Wait for
the freezing precipitation to melt (if it’s not snowing,
sleeting, etc... outside) |
| 3a. Put
the plastic funnel back over the inner tube and pour the
contents of the outer can into the plastic tube. Measure
this total as you would a rainfall event with the rain gauge
stick. This measurement
is your total
water equivalent of freezing precipitation. |
| 4a. Record the
total on your B-91 or B-92 form, under the column titled
"Rain, Melted Snow, etc"; just as you would record
regular rainfall. |
| 5a. Dump out
all the water and return the outer can back to its location
outdoors. |
| OR... |
| 2b. Fill
part of the inner tube with hot water and measure that
amount using the rain gauge stick. |
|
3b.
Pour the hot water into the outer can causing the
freezing precipitation to melt.
Slosh the water around, if needed, to melt all the
freezing precipitation but be careful not to slosh any of
the water out.
|
|
4b.
Put the plastic funnel back over the inner tube and pour the
contents of the outer can into the plastic tube. Measure
this total as you would a rainfall event with the rain gauge
stick.
|
| 5b. Subtract
the amount of hot water that you poured in (Step 2b) from
the total amount of water you just measured (Step 4b) to get
the total water
equivalent of freezing precipitation. |
| 6b. Record the
total on your B-91 or B-92 form, under the column titled
"Rain, Melted Snow, etc" under the "24-hour
Amounts" heading under the "Precipitation"
section (Box #1 above); just as you would record regular
rainfall. |
| 7b. Dump out
all the water and return the outer can back to its location
outdoors. |
To measure and record the total snowfall
depth:
| 1. Using the
snow stick, measure the depth of the snow on your snowboard. |
| 2. Write the
total in the column titled "Snow, ice pellets, hail,
ice on ground" under the "At Ob" heading
under the "Precipitation" section (Box #3). |
To measure and record the new snowfall
amount since your last reading:
| 1. Using the
snow stick, measure the depth of the snow on your snowboard. |
| 2a. If there
was no snow on the ground the day before, then your measured
snow depth will be the same value as your total snow depth.
Skip to step number 3. |
| 2b. If there
was snow on the ground the day before, subtract the total
depth that you just measured from the depth of snow that was
on the ground the day before (this would be the total snow
depth that you recorded the day before). This value will be
your new snowfall amount since your last reading. For
example, if on the 16th you measure 2" of snow on your
snowboard and on the previous day (the 15th), you had
measured 0.5", then 2" - 0.5" = 1.5" and
this would be your new daily snowfall. You would record
1.5" as described in Step #3. |
| 3. Write the
total in the column titled "Snow, ice pellets,
hail" under the "24-hour Amounts" heading
under the "Precipitation" section (Box #2) |
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www.srh.noaa.gov 
