FLOOD00005

• County: Statewide
• Title: Precipitation Records and Flood-Producing Storms in Cheyenne Wyoming
• Date: 10/23/2003
• Prepared For: Cheyenne
• Floodplain - Doc Type: Educational/Technical/Reference Information

T

WYOMING

104GS1'
41012'+

104044'
4"12'+

41~07'

o , 2 ~ 4 ~ MII.ES
b 1'.2 3 4 5, KILOMETERS

Figure 1.--Location of study area.

DATA AVAILABILITY

Precipitation data are often used for the purposes of design for flood
structures and land-use planning in areas where streamflow records of
adequate length are not available. When precipitation data are used for
this purpose, the value used will be the maximum amount of precipitation
that would occur during a given period, such as 1 or 2 hours, and be
exceeded on the average only once in a given number of years, such as 100
years. The maximum amount of precipitation that occurred in any i-hour
period, for example, can be measured and tabulated. Annual maximum 5-, 10-,
15-, and 3D-minute and 1- and 2-hour-duration precipitation data for
Cheyenne for the years 1902-84 (except 1968, 1969, 1971, and 1972) had been
compiled previously in computer-readable format by the National Weather
Service. Annual maximum 24-hour precipitation was compiled in computer-
readable' format by, the National Weather Service for the period 1891-1984.
The author' used additional, data from the files of the National Weather
Service. office in Cheyenne to extend the 24-hour record back to 1871-
During the sto,rm and: flood of 1896, 4.0 inches of precipitation occurred
during a 2-hou,. p,e'riod (U.S. Army Corps of Engineers, 1969). This data was
added to the 2-hour record. Annual maximum precipitation data for all
durations {,s,ed in 'this study are published in "Local Climatological Data"
monthly summaries (National Oceanic and Atmospheric Administration, 1985 and
1986)1 these data were, added to the record for the period 1985-86. Annual
maximum precipitation data ,used in this report are presented in table 1.

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