Flood Categories Minor - Some public inconvenience, but minimal or no property damage likely. Moderate - Closure of secondary roads. Transfer to higher elevation may be necessary to save property. Some evacuations may be required. Major - Extensive inundation and property damage. Usually characterized by the evacuation of people and livestock and the closure of primary and secondary roads Record - The highest observed River stage or discharge at a given site during the period of record keeping.

Categorical Flood Forecast Verification System - Cumulative River Forecast Center Verification Statistics 1st Quarter (Oct 2008 - Dec 2008) FY2009 Average Lead Time A categorical lead time is the number of hours from the time of forecast issuance to the time of the forecast hit. A lead time is only computed when, (1) the ordinate�s forecast and observation are in the same category, and (2) the previous ordinate�s observation was lower than the current category. This restricts lead time calculations to instances where the stage is rising, and crossing categories. Average Lead Time Trends Minor Flooding Moderate Flooding Average Categorical Errors This is the amount the forecast would have to be changed to reach the observed category. Categorical error is only computed when you have a miss. Long Term Averages Average Categorical Error - Long Term Number of Events Number Of Events The number of events during the quarter for each flood category. False Alarm Ratio (FAR) The number of missed categorical flood forecasts divided by the total number of categorical flood forecasts issued. FAR = (False Alarms / (False Alarms + Hits) ) {0.00 is best} Day 1 Day 2 Day 3 FAR Trends Minor Flooding Moderate Flooding Probability of Detection (POD) The number of categorical flood forecast hits divided by the total number of categorical flood forecasts observed. POD = (Hits / (Hits + Misses + No Forecast Misses) ) {1.00 is best} Day 1 Day 2 Day 3 POD Trends Minor Flooding Moderate Flooding