WMOD00459

• Title: Snow Accumulation Algorithm for the WSR-88D Radar, Version 1
• Date: 6/1/1996
• Weather Modification - Doc Type: Report

Table 7. - Summary of snow water equivalents for 5 Cleveland gages for the first 2 months of the
winter, and for 5 Denver gages for the first 3 months of the winter. Units are inches or inch h-1 snow
I, water equivalent.
Cleveland gage number 1 2 3 4 5
Total Snow Water Equivalent 2.86 4.88 4.78 4.72 4.35
Hours with Detectable 146 241' 190 205 225
(0.005 inch) Snowfall
Half Total S Produced at 0.030 0.035 0.050- 0.040+ 0.030+
Hourly Accumulations :::;
Median Hourly Accumulation 0.010 0.010 0.010 0.010 0.010
Average Hourly Accumulation 0.020 0.020 0.025 0.023 0.019
Maximum Hourly Accumulation 0.100 0.140 0.195 0.120 0.155
Denver Gage Number 1 2 3 4 5
Total Snow Water Equivalent 1.23 1.25 1.84 0.52 3.01
Hours with Detectable 71 55 92 35 136
(0.005 inch) Snowfall
Half Total S Produced at 0.030 0.035 0.030- 0.025 0.035
Hourly Accumulations :::;
Median Hourly Accumulation 0.010- 0.010 0.010 0.010- 0.010
Average Hourly Accumulation 0.017 0.023 0.020 0.015 0.022
Maximum Hourly Accumulation 0.095 0.115 0.080 0.065 0.175

experienced a very dry winter. Numerous storms occurred near Denver (table 5), but they
typically produced light' snowfall accumulations over limited periods. Even the mountain
gage west of Denver received fewer hours of detectable snowfall than any of the Cleveland
gages. The gages near Denver had only 55 to 92 hours with measurable snowfall as
compared to 146 to 241 hours for the Cleveland gages. The frequency of snowfall is the main
difference between the Cleveland and Denver area data of table 7; average and' median
snowfall accumulations are similar. Because of the lack of any major storms near Denver,
maximum snowfall accumulations tended to be higher in the Cleveland area, with the
expected exception of the Denver mountain gage (No.5).

Calculation of the median hourly rates provided almost identical values at all 10 gages-near
0.01 inch. No doubt the medians would be even lower if gage resolution was less than 0.005
inch. Average accumulations were also similar at most gages, near 0.02 inch h-l. Moreover,
half of the total snow water equivalent at each gage occurred at similar low hourly
accumulations-from 0.025 inch h-l or less at the dry mountain valley site to 0.050 inch h-l
or less at Cleveland's gage No. 3. The other 8 gages all produced half of their total snowfall
at accumulations less than or equal to 0.030 to 0.040 inch h-l.

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