Graphically Depicting the Hazardous Weather Outlook for East Central Florida

The National Weather Service (NWS) office in Melbourne, Florida has piloted an experimental project that uniquely presents the daily "Hazardous Weather Outlook" (HWO) product in graphical format. The purpose is to graphically complement the official text version of the HWO, exploiting both the communication and display capabilities of the of the Internet. The HWO is issued daily at 7 AM as a planning tool for decision makers that describes expected hazardous weather during the next 12 to 24 hours. It can be updated anytime as needed. The spectrum of hazardous weather in east central Florida is wide-ranging and includes convective local storm hazards, flooding hazards, seasonal hazards, marine hazards, fire weather hazards, and tropical cyclone hazards. Due to the diversity of threats, as well as the chance for multiple coincident threats, the text version (alone) is often insufficient to properly express weather concerns. As a result, the text version may become overwhelmingly large in order to accommodate detail or overgeneralized to accommodate product length manageability. Both are undesirable. Adding a graphical component to the HWO greatly improves its usefulness and may revolutionize the way the NWS provides hazardous weather information to its users.

Uniquely, NWS Melbourne's graphical component of the HWO employs locally developed "Degree of Threat" (DoT) bar charts for each category of weather hazard. Within each category the DoT for any individual hazard is assessed through a series of locally defined threat assessment rules which are specific to east central Florida. Rules for longer-fused threats are based on pre-existing advisory criteria or are empirically derived while shorter-fused threat rules use weighting function calculations. DoTs range from Minimal (level 1) to Extreme (level 5) and are colored coded. In practice, for example, during a tornado watch the DoT would express a greater threat for tornadoes than for large hail and damaging winds but without minimizing the hail/wind threat. In tandem with the DoT, a Threat Area Map (TAM) is also provided. The TAM is used to depict those geographic areas at greater risk or to delineate the timing of a hazard. Switching between hazard categories is accomplished through the HWO control panel where current hazards are highlighted and easily accessed. Additional supporting infrastructure includes easy access to spotter activation status, safety rules, descriptions, definitions, and frequently asked questions. A "situation room" is also provided to obtain ready access to current weather conditions during breaking weather events. The graphical component greatly enhances the HWO by offering a complete package of both textual and graphical information for emergency managers, local media, businesses, schools, and the general public.