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<br /> <br />FINDINGS AND RECOMMENDATIONS <br /> <br />Finding 1: The initial severe thunderstorm warning issued by WSFO Denver <br />at 7:35 p.m. was largely attributable to the performance of the radar <br />operator at WSMO Limon and the information he supplied to the forecaster. <br /> <br />Recommendation: The radar operator should be commended for his actions <br />the evening of July 31, 1976. <br /> <br />Finding 2: The outage of the WBRR hampered the lead forecaster in per- <br />forming his duties. This equipment had been out of service for more than <br />24 hours prior to the flood. <br /> <br />Recommendation: NWS should examine the existing maintenance schedule and <br />procedures for this equipment to insure that outages are kept to a minimum. <br /> <br />Finding 3: One of the uncertainties facing the lead forecaster early in <br />the evening of July 31 was an apparent discrepancy between the very high <br />radar echo tops and relatively low reflectivity values reported by WSMO <br />Limon. The NWS standard procedure available to him indicated a rainfall <br />rate between one-half inch and one inch per hour for the reported radar <br />reflectivity values. This indicated rate of rainfall was much lower than <br />that which was actually occurring in the canyon. Furthermore, cumulative <br />totals of radar-estimated rainfall did not meet the alerting limits con- <br />sidered necessary for flash flooding. <br /> <br />Recommendation: NOAA should, as a matter of high priority, initiate a <br />project to review the scientific basis for estimating rainfall rates from <br />radar returns and revalidate or revise the present standard relationships. <br /> <br />Finding 4: The Denver forecaster received no feedback information or <br />surface reports from the affected area in time to allow him to refine his <br />original warning by adding the precise location and a better estimate of <br />the magnitude of the threat. <br /> <br />Recommendation: Actions should be taken by NWS to establish and maintain, <br />consistent with available resources, cooperative river and rainfall report- <br />ing points in flash-flood prone areas. Special emphasis should be given <br />to populated areas and favorite recreation spots. The cooperative networks <br />should be exercised periodically to assure that both NWS personnel and the <br />cooperating individuals or offices are aware of the system. <br /> <br />Finding 5: The test network of AHOS/S sites had not been commissioned. <br />It had maintenance problems, primarily with the radio sets. The one <br />AHOS/S rain gage of this test network in the Big Thompson Canyon was <br />inoperative and was washed out by the flood. <br /> <br />25 <br />