90 Dynamic Ensemble Model Evaluation of Elevated Thunderstorms sampled by PRECIP via MET and MODE

Monday, 23 January 2017
4E (Washington State Convention Center )
Joshua S. Kastman, University of Missouri, Columbia, MO; and P. S. Market

The University of Missouri’s Program for Research on Elevated Convection with Intense Precipitation (PRECIP) sampled eight cases of heavy rainfall associated with elevated convection during the summers of 2014 and 2015. Determination of deployment timing and location were forecasted using both operational deterministic and probabilistic model forecasts. It was found that these model forecasts struggled with handling the mesoscale details of frontal and elevated thunderstorm interaction which often led to an incorrect forecast of location and intensity of heavy rainfall. These cases have been run through a high resolution dynamic model ensemble designed to outperform operational model forecast and provide a much more detailed precipitation forecast. This ensemble model, called the High Resolution Heavy Precipitation Ensemble Forecasting System (HRHPEFS), is generated using the Weather Research and Forecasting (WRF) model with the Advanced Research WRF (ARW) core and is made up of 48 members which vary microphysics, cumulus parametrization, boundary layer physics and moisture advection schemes. Each member uses RAP initial fields for lateral boundary and initial conditions, and is run with a 9 km grid spacing with a 3 km inner nest focused on the area of heaviest observed precipitation. The dynamic ensemble more rapidly introduces spread in solutions than a traditional initial condition/lateral boundary condition perturbation ensemble, while handling mesoscale details of the frontal-thunderstorm interaction better than operational deterministic model output. This presentation will feature comparisons of quantified precipitation estimate (QPE) (using the NCEP Stave IV data) between observed and HRHPEFS output using the Model Evaluation Tool (MET) and Method for Object-Based Diagnostic Evaluation tool. Both classic point-to-point verification and neighborhood verification statistics will be presented.
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