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<br />OOJ4Ul <br /> <br />identified. These messages are received with <br />general lead-times of 1-3 hours prior to event <br />occurrence. <br /> <br />b. Storm <br />Updates; <br /> <br />Issued 30-60 minutes before to during individual <br />storm impact periods with more definitive <br />information on categories in Message 1. <br /> <br />c. Message 2: Relays and interprets National Weather Service <br />Flash Flood Watch information relative to each <br />county. <br /> <br />d. Message 3: Similar to Message 2 but for NWS flash flood <br />warnings. <br /> <br />e. Message 4: All clear <br /> <br />In general the ascending scale of urgency of message release has <br />been effective but individual counties have developed complementary modes <br />of urgency for their own internal use. Other modes of information <br />transmission to be tested include graphics and cable-TV transmissions. <br /> <br />The Present F2-P2: It "Works" But Can Be Improved <br /> <br />Successful flash flood precition requires accurate rainfall timing, <br />pattern and intensity forecasts, It demands that the severity of the <br />event be anticipated and communicated with sufficient lead time to <br />responsible public and law enforcement officials for protection of the <br />public's safety. The Denver F2-P2 has been meeting that requirement for <br />the past six years but in a quasi-quantitative manner. <br /> <br />While heavy or severe rainfall events can be predicted over discrete <br />basins with accuracy, the ability to assess the true impact of the rainfall <br />in terms of flooding is still very qualitative. Words now replace the <br />ability to assess a rainfall event potential on an individual basin basis <br />to cause 10, 20, 30, 50 or 100 year event. While the words or qualitative <br />forecasts have been sufficient the customer would prefer to be given more <br />specific advice on the degree of flooding expected. For this quantitative <br />step to be taken meteorological and hydrological models must be meshed. <br />It is a formidable but achievable challenge. Additionally these <br />quantitative predictions must be translated into decision-matrixes for <br />local government officials. <br /> <br />Exces3ive Convective Rainfall Model <br /> <br />Development of an objective excessive convective rainfall model <br />(ECR) to predict thunderstorm peak intensity, total rainfall, storm <br />duration and storm track was begun during 1983. The purpose of the model <br />is to provide a dynamic meteorological model to interface with hydrologic <br />models being developed for the program. The model is based on cloud <br />physics and mesoscale dynamics. Results of the 1984 season verification <br />will be presented. <br /> <br />-8- <br />