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SNOW MEASUREMENT REMINDERS |
In observations sent via ROSA, do not send M's
for missing data....if data is missing, leave blank. If an M
is in the observation, the observation is not processed by the computer. On the
other hand, if an observation parameter that is reported is "0" (zero)
it should be reported as "0"
rather than left blank.
NOTE: If observations sent via ROSA are sent more
than 30 minutes before the time indicated in the observation, the observation
will not be processed by the computer. Coop Observers must change the
observation time to accurately reflect the time of the observation.
24 Hour Precipitation - (ROSA Code 10 - SHEF Code PP) 24 Hour Precipitation is just that... the routine 24 hour
precipitation report, usually taken at around 700am. It may be regular rainfall,
snow, sleet, freezing rain, or freezing drizzle. It is the water content of that
precipitation and is reported as ROSA Code 10. This measurement is easy in the summer...it
is simply the rainfall in your precipitation gage. In the winter, it is USUALLY
the melted snowfall from your rain gage. Melted precipitation is measured to the
nearest 0.01 inch, just like rainfall using the NWS provided measuring stick and
the smaller inner measuring tube. Do not measure the melted precipitation
directly in the larger 8 inch outer cylinder...it must be poured into the
smaller inner measuring tube to be measured.
Occasionally, especially during windy
conditions, you may have a significant snowfall, yet your gage remains nearly
empty. It will then be necessary to take a core sample of just the newly fallen
snow from the previous 24 hours. During windy conditions when it is determined
that the amount of snow caught in the gage is not representative the observer
will have to measure the snow at several points to try to come up with a
representative amount of newly fallen snow and this is the amount to be melted
for the water content and this is the figure that is reported in the observation
as the 24 Hour Precipitation (ROSA Code 10). It is reported to the nearest 0.01
inch.
Snow Depth - (ROSA Code 68 - SHEF Code SD).
This is the total depth of the snow on the ground. It is reported to the nearest
whole inch...2.4 inches is reported as 2 inches and 2.5 inches is reported as 3
inches.
24 Hour Snowfall - (ROSA Code 69 - SHEF Code
SF). This is the amount of newly fallen snow in the past 24 hours. It is
reported to the nearest 0.1 inch. It is not the total depth of snow on the
ground, but the additional accumulation in the past 24 hours. If the ground was
bare on the previous days observation, then of course, it would be the total
snow on the ground.
Snow Water Equivalent - (ROSA Code 71 - SHEF
Code SW). This is the water content of ALL snow on the ground...old and new. It
is reported at designated times during late Winter and early Spring (time of
year when the Snow Pack melts) usually about February 1 to the end
of the Snow Season. The Snow Water Equivalent is obtained by inverting the 8
inch rain gage can and pushing it through the entire depth of snow on the ground
that represents the average snow depth. Make sure that snow does not fall out of
the 8 inch can when you remove the snow core. It is very helpful to have a firm,
thin sheet of metal to slide between the surface of the ground and the rim of
the 8 inch can to cleanly gather the entire sample of snow. The snow is melted
and the liquid is measured by pouring it into the smaller inner measuring tube
and using the NWS provided measuring stick. This is reported to the nearest
tenth of an inch.
24 hour precipitation is reported to the nearest..........0.01 inch.
24 Hour Snowfall is reported to the nearest................0.1 inch.
Snow Water Equivalent is reported to the nearest.......0.1 inch.
Snow Depth is reported to the nearest........................1 inch.
