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<br />[:::::::::~~:~~i!::::~::::i.~i!.~!~;::::!!Y.~i.;'~~:::;;'::~:;1:~:::~M.::::~i.i.ii.i.i.:::;:Q~Q:Q;:~~~:~~:i.;::::~~X;i.~~:;':::~~j~i~:i:i::::::::::i::::] <br /> <br />Date: Thu, 25 Sep 1997 17:46:51 -0600 <br />To: Eric Holloway <Eric.Holloway@noaa.gov> <br />From: "Robert D Jarrett, Hydrologist, Denver, CO" <rjarrett> (Bob Jarrett) <br />Subject: Western Colorado Rainfall and flooding <br />Cc: "Robert D Jarrett, Hydrologist, Denver, CO" <rjarrett>, tom.browning@state.co.us, <br />nolan@ulysses.atmos.colostate.edu, "Jerry E Vaill Jr., Hydrologist, Grand Junction, CO" <br /><jevaill>, "Mark E Smith, Hydrologist, Denver, CO" <mesmith>, "John B Weeks, Chief, Branch of <br />Reg. Res., Denver, CO" <jbweeks> <br />X.UIDL: 875231325.000 <br /> <br />. Eric writes: <br />> Sir, do you kow of any plots for the maximum instantaneous, <br />> or peak, flow for a particular sized basin in western <br />> Colorado? This would give me a rough estimate of the <br />> maximum probable flow for ungaged basins. <br />> <br />> et <br /> <br />****************** <br /> <br />Eric <br /> <br />As requested, enclosed are copies of envelope curves of maximum 24.hour <br />rainfall and rainfall.runoff peak discharges for Western Colorado that can <br />be used to help assess flash-flood potential. These interpretations are <br />summarized from several of my reports and journal articles on flooding in <br />Colorado. [The data are published in McKee, T.B., and Doesken, N.J., 1997, <br />Colorado extreme storm precipitation data study: Department of Atmospheric <br />Science, Colorado State University, Fort Collins, Climatology Report #97-1, <br />109 p.] Western Colorado is defined as areas west of the Continental <br />Divide (figure 1). For simplicity, western Colorado is subdivided into <br />northwest, west, and southwest Colorado to reflect general variations in <br />hydrologic homogeneity. These graphs are general interpretations about <br />maximum rainfall (figure 2) and flooding (figure 3) within each region; not <br />all streams would have such floods due to local hydroclimatic variability. <br />Only larger rainfall amounts and floods that define maximum (enveloping) <br />are shown on the graphs because of time constraints and ongoing flood <br />threat in western Colorado. <br /> <br />1. NORTHWEST COLORADO (NW) This area covers the Yampa and While River <br />basins. East Tavaputs-Roan Plateau (figure 1), which forms the divide <br />between the White and Colorado River basins. is a major topographic barrier <br />to the southwesterly flow of moist air during summer months (flash. flood <br />season). Rainfall runoff is very limited in areal extent from localized <br />convective storms ranging in size from about 20 to 40 mi2. <br /> <br />2. WEST COLORADO (W) This area primarily covers the Colorado and Gunnison <br />River basins bounded by the East Tavaputs'Roan Plateau to the north and <br />Uncompahgre Plateau (figure 1) on the south. Summer convective storms are <br />limited to about 50 mi2 (and usually much less) below about 7,500 feet. <br /> <br />Printed for r'arrett@servrcolkr (Bob Jarrett) <br /> <br />1 <br />