As mentioned above, according to the NWS, about 10 inches of snow fell in Ames during
the main snow event. LEDWI data from the METAR site indicates a total snowfall of
just over 9 inches (Fig. 10.59). The liquid equivalent precipitation as measured by the
tipping bucket gauge appeared to be reasonable early in the case, when wind speeds were
quite low, providing a snow to liquid ratio near 10:1. During the more windy periods
later in the event, the tipping bucket gauge indicated a far higher ratio. However, given
the steady temperatures during this event it is likely that the 10:1 ratio was appropriate,
and could be applied to the entire event for a fairly accurate prediction of the actual
snowfall accumulation. Thus, roughly 0.9" of liquid is estimated to have fallen at Ames
during this event.
Fig. 10.59. Estimated snow accumulation (inches) from the LEDWI
sensor on the left axis (black) and liquid precipitation (inches) from the
tipping bucket gauge (blue), both located at the METAR site.
The RWFS forecast of snowfall depth (Fig. 10.60), had about 8 to 8.5 inches of snow at
the METAR and RWIS sites, based on forecasts of 0.8-0.85" of liquid equivalent (QPF)
and a 10:1 ratio. This ratio worked quite well in this case. The observations as used in
the RWFS, acquired from the METAR and LAPS QPE data, indicated only about 6
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