The 2017 Hazard Services – Probabilistic Hazard Information (HS-PHI) Experiment at the NOAA Hazardous Weather Testbed
Greg Stumpf, CIMMS/Univ Oklahoma and NWS/MDL, Norman, OK
Tracy Hansen, ESRL/GSD
Alyssa Bates, CIMMS/Univ. Oklahoma and NWS/WDTD
Chris Golden, CIRES/Univ. Colorado and ESRL/GSD
Joseph James, Univ. Akron

Abstract
Forecasting a Continuum of Environmental Threats (FACETs) is a proposed next-generation severe weather watch andwarning framework that is modern, flexible, and designed to communicate clear and simple hazardous weather information to serve the public.  One of the underlying aspects of FACETs is rapidly-updating probabilistic hazard grids, known as Probabilistic Hazard Information (PHI).  PHI can be used to provide custom user-specific products that can be tailored to adapt to a variety of needs – for example, providing longer lead times, at lower confidence, for more vulnerable populations with a lower tolerance for risk.

The National Severe Storms Laboratory has developed a prototype PHI tool which allows forecasters to integrate probabilistic guidance and their own interpretations of the atmosphere to issue PHI for severe convective hazards - hail, wind, and tornadoes.  This prototype tool was tested in the NOAA Hazardous Weather Testbed (HWT) in the springs of 2014-2017 in order to facilitate its transfer to National Weather Service (NWS) operations. 

We are adapting an experimental version of the NWS Advanced Weather Information Processing System (AWIPS) Hazard Services (HS) software to include the capabilities for forecasters to provide PHI at the 0-2 hour “warning” scale.  For the second year, forecasters participated in the HWT testing the software on six archive case scenarios.  These cases were specifically chosen to first familiarize the forecasters to the software and concepts, and eventually introducing them to more complexity in the scenario –single isolated supercells, splitting and decaying storms, quasi-linear convective system tornadoes, low-shear summertime microbursts, and more.  Meteorologists, software developers, and human factors experts collected data on the effectiveness of the software and the concepts of PHI for NWS warning operations.  For this second year, more features from the original PHI prototype were incorporated, including automated and semi-automated interaction with convective guidance based on the ProbSevere model.