NOAA Hazardous Weather Testbed
2005 SPC/NSSL SPRING EXPERIMENT

WORKING HYPOTHESES

comparison of WRF forecast to Observed BREF

  1. Numerical modelers can learn to incorporate more operational relevance in their research efforts if they work closely with forecasters in an experimental forecasting exercise.
  2. Operational forecasters can make more skillful interpretations of numerical model output if they work with numerical modelers in an experimental forecasting exercise.

SPECIFIC OBJECTIVES

Research perspective:

  1. To identify characteristic behaviors and specific strengths/weaknesses of the different WRF configurations and provide focused feedback to model developers on the performance of the experimental WRF models during severe thunderstorm episodes.
  2. To evaluate the sensitivity of explicit convective forecasts to grid resolution by comparing forecast with 2 km and 4 km grid spacing.

Operational perspective:

  1. To evaluate the operational utility of several experimental high resolution versions of the WRF model during severe weather episodes
  2. To evaluate the ability of new methods to identify WRF model predicted supercell thunderstorms and determine the correspondence between model supercells and observed supercells

RESULTS

  1. Numerous systematic biases were identified in different configurations of the WRF and linked to various physical parameterizations. Biases were reported to model developers.
  2. The different WRF configurations performed with comparable skill in predicting mesoscale aspects of convective initiation and evolution; there was no clear advantage for 2 km grid spacing.
  3. Newly developed algorithms appeared to be quite effective at identifying rotating updrafts in model output.
  4. Simulated reflectivity fields derived from model output revealed detailed mesoscale structures that were not evident in traditional output fields.

PAYOFF

  1. Numerical modelers at NCAR and NCEP/EMC are mitigating systematic biases revealed during the program, especially those associated with turbulence/boundary layer parameterizations.
  2. SPC forecasters are becoming skillful users of convection-allowing models. Experimental high-resolution model runs continue on a daily basis at EMC and output from these runs has had a positive impact during several severe weather outbreaks.

RELATED PUBLICATIONS

Koch, S. E., B. Ferrier, M. Stolinga, E. Szoke , S. J. Weiss, and J. S. Kain, 2005: The use of simulated radar reflectivity fields in the diagnosis of mesoscale phenomena from high-resolution WRF model forecasts. Preprints, 11th Conference on Mesoscale Processes, Albuquerque, NM, Amer. Meteor. Soc., CD-ROM, J4J.7

Kain, J. S., S. J. Weiss, M. E. Baldwin, G. W. Carbin, D. R. Bright, J. J. Levit, and J. A. Hart, 2005: Evaluating high-resolution configurations of the WRF model that are used to forecast severe convective weather: The 2005 SPC/NSSL Spring Program. Preprints, 21th Conference on Weather Analysis and Forecasting/17th Conference on Numerical Weather Prediction, Washington, D. C., Amer. Meteor. Soc., CD-ROM, 2A.5.

 

2005 SPC/NSSL Spring Experiment OPERATIONS

2005 SPC/NSSL Summer Program OPERATIONS

Photo Gallery

SUMMARIES of previous SPC/NSSL Spring Experiments:
2007200520042003200220012000

11/15/06