Exploration of Targeted Profiler and Radiosonde Observations for Improving Severe Storm Forecasting

Reports from the National Research Council and instrumentation workshops have generally recommended that networks of ground-based profiling systems (e.g., microwave and infrared radiometers, Doppler wind profilers and lidars, and water vapor lidars) be developed for monitoring rapid changes in the local severe convective environment. To explore the potential of these systems for severe weather forecasting applications, the University of Oklahoma and NSSL have developed the Collaborative Lower Atmosphere Mobile Profiling System (CLAMPS-2), which contains a Microwave radiometer and an Atmospheric Emitted Radiance Interferometer (AERI) to retrieve temperature and water vapor, a Doppler Wind Lidar (DWL) to profile the wind in the lower atmosphere, and a radiosonde system.

In 2016 and 2017, CLAMPS-2 and two separate mobile radiosonde vehicles were deployed in the pre-convective and near-storm environment for 14 severe weather events and observed large changes to environmental variables that are known to control the intensity, mode, and longevity of severe convection. Retrievals made from the DWL in particular show great promise in observing high-temporal changes to the wind profile in the lowest 1-2 km, a layer that is vitally important for diagnosing the potential for tornadoes. Examples of these rapid changes in vertical wind shear in the environment of supercell thunderstorms sampled by CLAMPS-2 will be presented.

Furthermore, the impacts that both nearby radiosonde observations and the profiler observations can have on short-term convection-allowing model forecasts of convection will be presented. The CLAMPS-2 observations were guided by real-time ensemble sensitivity analysis (ESA) to increase the likelihood that observations were obtained in regions of the environment that impact later forecasts of convection. The AERI, DWL, and radiosonde observations (along with routine observations, including reflectivity and radial velocity from nearby WSR-88Ds) will be assimilated simultaneously on a 15-km grid and a nested 3-km grid using the WRF-DART assimilation system. These ensemble analyses will then be used to initialize an ensemble of 9-h forecasts of convection on the 3-km grid. Changes to these forecasts with and without the targeted profiler observations and radiosonde observations over all 14 days will be presented.