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<br />information for each ofthe 10 extreme storms that you maximized and transpositioned. <br />Specify both the sources that others can go to to find the isohyetal patterns that you show <br />(or explain why yours differ from those originally done) and also give the exact source of <br />the hourly rainfall data that you show for each "center". On a related topic, sort of, <br />please explain again why the Big Thompson storm was not used on your final list of 10 <br />maximized storms <br /> <br />7) Can you offer some sort of confidence in the accuracy ofthe time distribution and <br />hourly rainfall rates you show in section 4,1. I don't recall being as confident as you <br />about hourly rates, particularly from the 1935 storms. We find that eye witnesses, <br />without the benefit of recording gauges, often unintentionally exaggerate hourly rates, <br />Even an error of just 10 minutes in how long very heavy rains lasted could be a 17% <br />overestimate of hourly rainfall. Since we did have pretty good estimates ofthe observed <br />rainfall rates with the Fort Collins and the Pawnee Creek Floods, we learned that those <br />events did not have extraordinarily high rainfall rates and yet produced major flooding. <br />While I agree it is possible, we've never actually seen hourly rainfall rates exceed 6" per <br />hour for an entire hour. I guess this may help argue that rate and timing information that <br />you show may already be hedged on the conservative side. <br /> <br />8) Wording, etc. I found a number of small problems in the narrative that had passed the <br />author's editorial eyes, Hopefully they have been caught and fixed now as I would rather <br />review other aspects of the report. For example "were not scare"in the last sentence of <br />the first paragraph of section 4.1 on page 46 was undoubted a mistake. What should it <br />have said? -- "scarce"?? <br /> <br />Related remark. <br /> <br />This in-depth look at "Eastern Colorado's Greatest Rains" has been very interesting for <br />many of us. A couple of things that I come away with are : <br />1) Really big storms do occur and often pretty dam close to Cherry Creek. <br />2) The weather conditions required to produce very heavy rains tend to linger over <br />eastern Colorado for longer than just one day, <br />Therefore, the most likely scenario for extreme precipitation in eastern Colorado would <br />be multiple precipitation events over a 2-4 day "episode" in which conditions (high <br />dewpoints, etc) could support two or more periods of intense precipitation. While no <br />individual event would achieve PMP magnitudes most likely, very large multi-day totals <br />could occur should storm centers coincidently occur in the same basin more than once <br />during the episode. Two days in a row with storm centers yielding 10" or more of rain in <br />Cherry Creek basin is much more likely than one day with a 18" center. Furthermore, a <br />third day could yield 6" somewhere in the basin. As long as facilities can handle those <br />sorts of "more likely extremes" as well as large one-day PMP storm, we should all be <br />able to live and breath comfortably in the Cherry Creek basin, <br />