FLOOD06061

• County: Statewide
• Community: State of Colorado
• Stream Name: Colorado River/Great Basin
• Basin: Colorado Mainstem
• Title: Probable Maximum Precipitation Estimates, Colorado River and Great Basin Drainages
• Date: 1/1/1984
• Prepared By: COE
• Floodplain - Doc Type: Educational/Technical/Reference Information

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"-
AVERAGE Of
I-o....y MAX.
20 PRECIPITATION L MAX '-DAY 20
PRECIPITATION
OF RECORD
IWINNEMUCCA, NEV.I

o

J FMAMJ JASONDJ
MONTH:

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---- Convergence PMP (HMR No. 43)
A-A~ Maxi111um precipitable water at subregion midpoint
----- "Eye" smoothed I-day station average (stations listed in table 2.2)
.-.- 0.02 probability level of 3-day maximum rains
1000-mb (100-kPa) convergence PMP at subregion midpoint taken
from analyses in figures 2.5 to 2.16

Figure 2.4. --Seasonal variation of convergence PMP and supporting
data for least-orographic sUbregions. AU values given in
percent of the maximum monthly value for that parameter.

Southwest Arizona and southern Nevada show spring minimums while northeast
Arizona has a late winter minimum and western Utah has a winter minimum. The
1-day maximum values from June to November very likely are influenced by
local-storm rainfalls.

Another rainfall statistic considered was maximum 3 consecutive observation
day precipitation. These data reduce some of the bias due to thunderstorm
rainfall, particularly in summer when short-duration thunderstorms predomi-
nate. In addition to the maximum for each month, the 0.02 probability level
of maximum 3 consecutive observation~ay precipitation was computed for
stations in each subregion. This is shown on figures 2.4a to 2.4e by dot-
dashed lines. The 0.02 probability level was computed using the Fisher-Tip-
pett type I distribution fitted by the method of Gumbel from the series of
maximum monthly values for each year from approximately 50 years of record
(1912-61) for one station within each subregion. Kingman, Ariz., while some-
what beyond the regional limits, was used for the southern Nevada subregion.