The 2004 NSSL/SPC Spring Program

This is the fifth year of the NSSL/SPC Spring Program, an annual event designed to investigate problems of mutual interest to NSSL research scientists and SPC forecasters. Participants from both organizations teamed with a diverse group of scientists and forecasters from across the country to assess the value of near-cloud-resolving versions of the WRF (Weather Research and Forecasting) model in the operational severe weather forecasting environment. Specifically, they wanted to find out if using the WRF model would give them a better idea of how the timing, location, and evolution of afternoon convection would unfold. Plus, they hoped to find that the high-resolution model would provide some guidance on convective morphology, or mode, since certain modes are associated with a disproportionate amount of severe weather.

The WRF is a new numerical weather prediction model designed for research, for operations, and for a broad range of other applications. "It was developed collaboratively by research and operational modelers--a community model with a direct path to operations," says Jack Kain (CIMMS), Spring Program PI for NSSL. "This is the first systematic testing of the hi-res WRF by operational severe weather forecasters." Each day, a map discussion is held to provide an update on the program.

The Spring Program began April 19, 2004, and concluded June 4, 2004. Weekly rotating forecast teams typically included one SPC forecaster, one NSSL scientist, and two visiting scientists or forecasters. In all, there were about 50 participants over the seven-week period, including contributors from numerous NOAA research and forecasting organizations, ten major universities, the Air Force Weather Agency, NCAR, and international visitors from Canada and Finland. The daily map discussion is held year round. It is open to anyone who is interested in operationally relevant science and research.

Probabilistic forecasts like these were issued on a daily basis. The control forecast (upperleft) was based on routine operational data and methods. The experimental forecast (lower-left) was prepared by the forecaster after the normal data stream was supplemented with high-resolution WRF output. The letters indicate actual reports of severe weather for the forecast period: t= tornado, a=hail >0.75 in., g=wind gusts >58 mph. The final outlook on the lower-left shows improvement in the forecast due to the use of the hi-res models.