WSP09246 - Laserfiche WebLink

Home Browse Search

OOJ82~ Rainfall produced by the thunderstorms was excessive and is listed in 5-minute intervals in Table 1, The storm cell over the north basin is estimated to have produced 8.70 inches of rain and heavy concentrations of pea-size and egg-sized hail between 1550 MDT and 1715 MDT. This cell was the most intense of the storm. Three separate storm cells moved across the basin in a train-effect to produce this heavy rain. The central basin rainfall was less intense but of longer duration than the north basin's. It is estimated that 7.30 inches of rain and lesser amounts of hail fell in this cell. Pictures of the hail swath, eyewitness accounts and a personal survey of the areal damage were used to estimate the amount of hail produced. Rainfall on the south basin was much less for the peak period than to the north with south basin rainfall estimated at 5.90 inches from 1700 MDT until 1755 MDT. However the south end of the basin was affected earlier by about 2.00 inches of rain between 1500 and 1540 MDT. Thus by laOO MDT most of the flash flood producing rainfall had ended. A brief burst of rainfall did fall on the central and south basins between 1820 MDT and 1845 MDT when an additional 1.30 inches and 2.45 inches Were reported respectively. The storm total rainfalls for the three basins were estimated to have been 8.70 inches OVer the north basin, 8.60 inches over the central basin and 10.35 inches over the south basin with total accumulations coming between 1500HDT and 1900HDT. During the most intense phase of the Wetzel Creek storm between 1550 - 1755 MDT the north basin received 8.70 inches, the central basin 7.30 inches and the south basin 5.90 inches. It is not difficult to perceive the reasons for the excessive flooding received in the drainage basin after these heavy and intense rainfalls. COMMENTS AND CONCLUSIONS The Wetzel Creek storm was an intense rainfall event for the basin but rather typical of the monsoonal season thunderstorms that roam Colorado's eastern plains. The storm complex was made up of several cells and the merger of two distinct thunderstorm systems. Rainfall totals from this complex ranged from 2 inches to almost 11 inches over the Wetzel and Badger Creek basins. Copious amounts of hail ranging in size from pea-size to egg-size were deposited on Windy Hill on the western edge of the Wetzel Creek basin. It is estimated that the individual rain cells in the storm complex may have produced rainbursts of 1.5 to 3.5 inches in 30 minute periods during the complex's life-cycle.