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I I I I I I I I I I I I I 1:1 I I I I I 3. FLOOD THl{l!;AT RECOGNITION Flood Threat Recognition consists of actions that enable early identification and subsequent monitoring of potential flood situations. The purpose of the flood threat recognition component is to determine if a flood is impending and predict the time of its occurrence and its magnitude. The flood recognition step is vital to a preparedness program because it provides the trigger for putting the warning arrangements into action. TWo approaches are available for flood recognition. The one most commonly used is prediction of floods based on precipitation received in upstream areas. The other is prediction of flooding based on observation of upstream water levels. For the Florence area, we will use a combination of both approaches - prediction by the Rational Weather Service (HWS) of high precipitation and/or the observation of rising water levels around the area, particularly at the State Highway 67 Bridge located in Florence. It is necessary to note that the Rational Weather Service forecast is based only on the Arkansas River gage at Canon City (approximately 8 miles upstream of Florence), other flows from downstream tributaries can occur. A lOO-year flow of 7,500 cfs in addition to the 100-year flow of 20,500 cfs at Canon City is possible from tributaries located further downstream. In addition, the bridge site at Colorado State Highway 67 is used for observation in order to give the maximum protection to the City of Florence since it's easily accessible and will include any of the additional flows from the drainage areas below the Canon City gage. Figure 3 shows the stage information for the State Highway 67 Bridge. In this section, the roles of the various governmental agencies and the identification of the level of threat are discussed. The recognition may begin with the National Weather Service forecast, or with persons/spotters calling to the Florence Police/Fire Departments or Fremont County Sheriff's Department to report observed conditions. 3.1 Role of the National Weather Service The Rational Weather Service (HWS) Office in Denver is responsible for flood forecasting. Their Denver Office is a 24 hour a day operation. The Rational Weather Service Office in Pueblo is open from 6 AM to 10 PM seven days a week. When they are closed, the Denver office takes over their flood forecasting responsibilities. In the event of a flood or flaah 4 li1 The National Weather Service in Denver provides weather information to the Fremont County area.