A Radar-Based Storm Climatology for the Contiguous United States for Improved Severe Weather Climatologies and Warnings

The National Severe Storms Laboratory and the National Climatic Data Center have been partnered for the past two years in an effort to reprocess all of the WSR-88D Level-II radar data archive through the Warning Decision Support System—Integrated Information (WDSS-II) software suite. This effort has been referred to as the Multi-Year Reanalysis Of Remotely Sensed Storms (MYRORSS). The goal of this effort is several-fold: 1) produce 3D merged reflectivity grids from quality-controlled single WSR-88D Level-II data; 2) produce 2 composite layer (low- and mid-level) merged azimuthal shear products derived from single WSR-88D Doppler velocity data; 3) produce several reflectivity-derived severe weather parameters, such as estimated hail size and Vertically Integrated Liquid; and 4) produce QPE grids. This presentation will focus on the base product production and severe weather products and projects. As of August 2014, all data from 2000 through 2011 has been processed. Efforts are underway to continue processing the most recent years (2012 through 2014).

Several projects related to severe weather climatologies and severe weather warnings are underway. The first of these are hail and rotation climatologies derived from daily accumulations of each parameter. These radar-derived climatologies are compared against those determined from storm reports within Storm Data. Another project uses a K-means segmentation method to identify individual storms or storm clusters from merged reflectivity. The storms, and different attributes associated with those storms, are then tracked through time. The attributes are used within a random forest storm typing algorithm. These data can be used in determining storm type climatologies, for instance preferred environments or storm lifetimes by type. The final project to be discussed uses several derived grids and storm tracking to evaluate NWS severe thunderstorm and tornado warnings and storm reports from Storm Data. The goal is to use the MYRORSS data to try to stratify verified and unverified warnings and then to use the results to develop better warning evaluation tools. All of the results and information will be used within ongoing research to operations projects including the implementation of an operational Multiple Radar, Multiple Sensor (MRMS) system within the NWS and the Forecasting a Continuum of Environmental Threats (FACETs) project.