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<br />',~- ,~:~~~;:-~~~-_......; <br /> <br />I <br /> <br />SUMMARY OF 24 OCTOBE~ 1996 EXTREME PRECIPITATION STUDY <br />STORM LIST REVIEW WORKSHOP AT OFFICE OF THE STATE ENGINEER, <br />DENVER <br /> <br />I <br /> <br />Opening coments by Alan Pearson <br /> <br />Current directions in extreme precipitation an<lJysis. US Bureau of Reclam;:Jtion~ Lou Schreiner <br /> <br />I <br />I <br />" <br />I <br /> <br />* Bireau of RecIamation Dan Safety Department is getting into risk analysis for hydrological structures. <br />· Bureau will be looking at loading consequences on slmctures from an assortment of evenls (e.g., floods, <br />earthquakes, etc.). Probability of failure and loss of life wiH lead to structure designs. Bureau "ill need <br />probabilities for a whole range of floods (from 10,000 year event to 1,000,000 year event to PMF). By <br />examining historical precipitation records and then computing the 1,000,000 year event, the PMF "ill be <br />determined. At the present time for the state of \Vashington, they hal"e assigned the 1,000,COO year eyent <br />as equivalent to the PMP for creas west of tIle Cascades and the 10,000,000 year event for areas east of the <br />Cascades. Associated PMF probabilities are e,'en more extreme. B.C. Hydro is working 011 sImilar risk <br />analysis for life and property. <br />* Cost of sophisticated wami ng systems on the order of SIOO,CiOO to SI50,000. <br />. Lou has half of the funding he requested for modelling of extreme precipitation e, ents. (It <br />appears this funding is earmarked for the Cotton group at CSU and for :\'CAR modellers). <br />.,.. Bureau is trying to get se\.eral models up and running on their workstation. <br /> <br />Colorado Extreme Precipitat.ion Data Study, {hcryicw of Accomplishments. Tom r\-1cKce, Colorado <br />Climate Center, Colorado State UniYersit~. <br /> <br />. Tllis Workshop represents the end of PhMe I. <br />* As a result of Phase I, a much better data set is now availablE: from CCC (more compreheflSiyc than that <br />used for NOAA Atlas II). A better definitiOIl oflhe 100'jT event is now ayailable. <br />* Analyses of very short duration events is a problem for NOAc\ Atlas II. <br />* CDal of to day's Workshop is to identif~' 15 to 20 design storms for 6 defined regions in Colorado. <br />These design storms will hayc potential application for regional and site-specific PMP studies. <br />* Phase I has resulted in the generation of climatological distrii)utions ofyariabJes from upp;:.r-air <br />soundings. <br />'Summary of Results of Mode; ling Workshop hejd at CSU last May: <br /> <br />II <br />I <br /> <br />1. Models do appear capable of simulating ]ar~e storms. <br />2. A wide yariety of models exist. <br />3. Application of 3-D models is biggest challergc. La:~ge data sets are necded to initializc them. <br />4. One recommendation for 3-D mOdel u~:e is to use th:::m with a perturbed, fully initialized <br />storm. And rather than find a fully initialized historical storm, ,:onccnsus of \Vorkshop was to <br />recorrunend to NWS, NOAA, and others thm obsen'ations s,'stems (e.g.. NEXRAI), satellile) be geared up <br />to fully capture the initial conditions of future storms as .:hey occur. <br />* Rapid City storm has been well -simulated. <br />. A Summary of Modelling Workshop will be included in the C'CCtCSU Final Report on Phase L <br /> <br />Comments by Bob Jcrrett: <br /> <br />* Many people are inyolyed in rainfall rcconstmction fo:; BU..l.!falo Creek. <br />* Cited USGSlHighways Departll1cnt coop program for instrum=nting small watersheds for r;liIlfalI with <br />5-minute rainfall and streamflow resolution. HC.$ seen data for 30 watersheds in tbe Denver area. <br />Several attendees asked for mpre info on this program and he promised to provide CCC with more det2ils <br />later. He did say the program uses a non-st2ndard raingallge with a~" orifice. Data in a punched [annat. <br />