Forecast Improvements

SPC Project 12 – Advancing Science to Improve Knowledge of Mesoscale Hazardous Weather

Dean (CIMMS at SPC)

Funding Type: CIMMS Task II

Objectives
Study research methodologies that can be used to verify predicted outcomes of meteorological phenomena; present research results to the meteorological community; assist SPC scientists and managers in science and technology transition efforts.

Accomplishments
Work was focused on the investigation of the frequency and distribution of convective storm environments that occur across the United States. The goal is to provide forecasters more specific information regarding forecast performance in different environments. Methods to determine the frequency of particular environments and how often they produce severe convection are also being investigated.

Initial storm environment estimates were provided by SPC’s hourly surface objective analysis grids, which uses the RUC as a background field and incorporates surface observations into the analysis to provide estimates of convective storm parameters such as CAPE, CIN, wind shear, helicity, etc. The environment for each official storm report from 2003-2006 was estimated using the analysis values from the nearest grid point at the most recent analysis time before the report. These analysis values were placed into a PostgreSQL database, allowing the data to be retrieved and displayed in many different combinations and formats. In order to assess the soundness of the objective analysis, sounding data from 2003-2006 was entered into the database so that comparisons could be performed. This analysis is underway; preliminary results suggest that the objective analysis provides good estimates of the environment in most but not all cases. It is also planned in the near future to add North American Regional Reanalysis (NARR) data to the database. The NARR data would potentially provide estimates of storm environments back to 1979, assuming that it proves to accurately estimate convective parameters.

This project is ongoing.

Publications
Dean, A.R., and D. Imy, 2006: A look at the tornado and tornado watch climatology for the continental United States from 1986- 2005. 23rd Conf. on Severe Local Storms, St. Louis, MO, Amer. Meteor. Soc., CD-ROM.

Dean, A.R., and J.T. Schaefer, 2006: PDS watches: How dangerous are these “particularly dangerous situations?” 23rd Conf. on Severe Local Storms, St. Louis, MO, Amer. Meteor. Soc., CD-ROM.

Dean, A.R., and J.T. Schaefer, 2006: The skill of forecasting relatively isolated severe thunderstorm events. 18th Conf. on Probability and Statistics in the Atmospheric Sciences, Atlanta, GA, Amer. Meteor. Soc., CD-ROM.

Dean, A.R., R.S. Schneider, and J.T. Schaefer, 2006: Development of a comprehensive severe weather forecast verification system at the Storm Prediction Center. 23rd Conf. on Severe Local Storms, St. Louis, MO, Amer. Meteor. Soc., CD-ROM.

Locations of reports from 2003-2006 that occurred in relatively low CAPE, high shear, low LCL environments, based on environmental estimates from SPC's surface objective analysis.