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<br />OO[)399 <br /> <br />The meso-meteorologists produce a routine series of analyses of <br />this data in the pre-storm environment to determine the rainfall potential <br />for the day, detailed cloud structure, likely storm formation zones, <br />predicted storm tracks and anticipated flash flooding areas. Much of <br />this output comes from the HKA Excessive Rainfall (ECR) Model. During <br />the actual storm period analyses focus on individual storm rainfall <br />prediction, prediction of flooding zones, storm paths and duration. <br />A series of messages conveying this information are sent to designated <br />communication centers for fan-out distribution to appropriate agencies <br />for immediate action. Figure 3 shows a schematic of the data and sources <br />relative to a storm system. <br /> <br />A typical flash flood day scenario begins with a thorough surface <br />and upper analysis, mesoscale regional surface analyses and an assessment <br />of the rainfall and thunderstorm severity potential, Key inputs to these <br />analyses come from the surface, upper air, mesonet, radio-sonde, <br />satellite and radar observations. If the assessment determines that an <br />excessive convective rainfall event could occur within the District the <br />rainfall predictions are run through a qualitative scenario for the <br />basins likely to be affected. Appropriate messages and advisories are <br />then issued to the areas that may be affected. The mesonet, satellite <br />and radar observations are used to metwatch the area for the beginning of <br />thunderstorm development or movement of the thunderstorm/rain systems <br />into the basin areas. Radar is then used in concert with rain gage <br />measurements, the ECR model and "scenario models" to keep the potential <br />for an ECR event assessed on an individual storm basis. Heavy rainfall <br />predictions are made for each basin to be affected before the flash flood <br />occurs. Specific updates, advisories and warnings for the flooding are <br />then issued as needed until the event ends. <br /> <br />A crucial aspect of the F2-P2's success is the communication of the <br />forecasts to affected local government agencies. For the past seven <br />years a telephone hub-fanout system has been used effectively. In this <br />system a communications center focal point in each county acts to <br />receive the F2-P2 messages, Upon receipt of the message or storm update <br />the center distributes the information to the appropriate affected <br />agencies. At best this system delivers the information in minutes during <br />emergency situations while in more relaxed situations fan-outs can take <br />up to one hour, While this system works new ways to more quickly speed <br />information to decision-makers within the F2-P2 are being investigated. <br />An example of this effort is the local electronic mail delivery of <br />messages via computer-to-computer technology. 1985 tests suggest that <br />this method of text delivery will become a backbone of the system for <br />routine messages. Innovative delivery techniques for emergency weather <br />situations are being explored. <br /> <br />The forecasts are communicated in a message text or verbal format <br />that conveys increasing levels of urgency to the users. The general <br />message types are: <br /> <br />a. Message 1: Internal use only alert that indicates the likeli- <br />hood of an ECR event in the county. Thunderstorm <br />rainfall intensity, storm total rainfall, durations, <br />paths and affected basins and urban areas are <br /> <br />-6- <br />