Cloud-to-Ground Lightning Probabilities and Warnings within an Integrated Warning Team

As part of the Probabilistic Hazard Information (PHI) Experiment in the Hazardous Weather Testbed (HWT), an integrated warning team of National Weather Service (NWS) forecasters, emergency managers, and broadcast meteorologists were asked to issue, utilize and evaluate probabilistic cloud-to-ground (CG) lightning hazards and warnings in context of their typical activities. While lightning poses a significant hazard to lives and property, a lightning-specific product does not exist. The PHI tool was utilized in our experiment by NWS forecasters to communicate lightning hazards to end-users.

In order to acquire feedback across a wide variety of participants, all forecasters and end-users completed a two-hour long weather warning simulation. This event encompassed 1755-1955 UTC on 1 Sept 2016 as Hurricane Hermine made landfall in western Florida. NWS forecasters were responsible for the entire Melbourne, FL county warning area. Emergency Managers were given the option of handling responsibility for the Walt Disney World Complex, the Cape Canaveral area, or both. Broadcast meteorologists were responsible for the Orlando designated market area. During this case study, multiple small storm cells capable of producing CG lightning developed over the region eventually growing upscale as the hurricane moved onshore.

NWS forecasters were provided with automated storm-based CG probability guidance, but had the opportunity to modify the guidance, shorten or extend the warning, and add discussion. End-users were able to view the product through the NWS Enhanced Data Display (Fig. 1), but could also ask questions and make comments within NWS chat. Multiple aspects of the probabilistic CG lightning information were tested during this evaluation, including: use and understanding by forecasters and end-users of probabilistic information, kinds of action taken for both automated and forecast probabilities, and perceived workload associated with use of the tool and guidance.

Whether NWS ultimately creates formal CG hazard products or incorporates more detailed lightning information in decision support services, this experimental process in the HWT offers the opportunity to develop clear communication approaches. This work will assure that CG lightning information is offered in a way forecasters can work with and end-users can successfully access, understand, and use to aid decision-making.