Laserfiche WebLink
<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />6.0 ConclusiDns <br /> <br />A survey of rainfall characteristics of foothills thunderstorms <br />which occur at or above elevations Df 7,500 feet in the central <br />Colorado Front Range was completed. The primary data source for the <br />survey was the publication Storm Data for the years 1979 to 1988. <br />The conclusions supported by the survey are as follows: <br /> <br />a. The potential fDr short duration, high intensity rainfall from <br />thunderstDrms appears to exist in the central ColoradD Front <br />Range foothills at or above elevations Df 7,500 feet. <br />Observations support the occurrence of rainfall of 2.00 inches <br />or more over durations of 3 hours or less in this region during <br />the period of 1979 to 1988 due to thunderstorms. <br /> <br />b. Thunderstorm storm total rainfall of 3.00 inches Dr more appears <br />both possible and likely at elevatiDns of 7,500 feet Dr mDre. <br /> <br />c. The fDllowing heavy thunderstorm rainfall characteristics <br />for the survey storm sample are: <br /> <br />1. Storm average rainfall is 2.06 inches with a range from <br />0.50 to 5.00 inches. The sample included 2 storms of 3 <br />inches, 1 storm of 4 inches and 1 storm of 5 inches of <br />total rainfall. <br /> <br />2. Average storm duration is 38 minutes with a range from 5 <br />minutes to about 3 hDurs. <br /> <br />3. Average storm hourly rainfall intensity is 3.25 inches per <br />hour with a range from 2 to about 11.50 inches per hour. <br /> <br />d. The observations of thunderstorm rainfall occurring at or abDve <br />an elevation Df 7,500 feet found in this survey appear to be at <br />odds with the results reported in Jarrett, 1989. Thus a <br />definitive conclusion on the occurrence, importance and effects <br />of heavy rainfall occcurrence at or above an elevatiDn of 7,500 <br />feet in the central ColoradD Front Range does not exist at this <br />time. <br /> <br />e. The axis of the storm would likely stretch from sDutheast tD <br />northwest with storm movement tD the north at 10mph. The <br />horizontal extent of the storm rainfall area could COlver <br />an area Df 75-100 square miles in roughly an DblDng of 15 <br />by 10 miles. <br /> <br />These conclusions should be cDnsidered tentative and are limited <br />by the scope of the survey. Despite these limitatiDns the <br />observations found in Storm Data support the need for additional <br />definitive meteorological and hydrDlogical investigation Df <br />rainfall events occurring at elevations above 7,500 feet in the <br />ColoradD Front Range. <br />