Evaluation of WRF Forecasts of Tornadic and Nontornadic Outbreaks When Initialized with Synoptic-Scale Input
- 1 April 2009
- journal article
- Published by American Meteorological Society in Monthly Weather Review
- Vol. 137 (4), 1250-1271
- https://doi.org/10.1175/2008mwr2597.1
Abstract
Uncertainty exists concerning the links between synoptic-scale processes and tornado outbreaks. With continuously improving computer technology, a large number of high-resolution model simulations can be conducted to study these outbreaks to the storm scale, to determine the degree to which synoptic-scale processes appear to influence the occurrence of tornado outbreaks, and to determine how far in advance these processes are important. To this end, 50 tornado outbreak simulations are compared with 50 primarily nontornadic outbreak simulations initialized with synoptic-scale input using the Weather Research and Forecasting (WRF) mesoscale model to determine if the model is able to distinguish the outbreak type 1, 2, and 3 days in advance of the event. The model simulations cannot resolve tornadoes explicitly; thus, the use of meteorological covariates (in the form of numerous severe-weather parameters) is necessary to determine whether or not the model is predicting a tornado outbreak. Results indicate that, using the covariates, the WRF model can discriminate outbreak type consistently at least up to 3 days in advance. The severe-weather parameters that are most helpful in discriminating between outbreak types include low-level and deep-layer shear variables and the lifting condensation level. An analysis of the spatial structures and temporal evolution, as well as the magnitudes, of the severe-weather parameters is critical to diagnose the outbreak type correctly. Thermodynamic instability parameters are not helpful in distinguishing the outbreak type, primarily because of a strong seasonal dependence and convective modification in the simulations.Keywords
This publication has 57 references indexed in Scilit:
- A Five-Year Climatology of Elevated Severe Convective Storms in the United States East of the Rocky MountainsWeather and Forecasting, 2007
- A Simple and Flexible Method for Ranking Severe Weather EventsWeather and Forecasting, 2006
- On Improving 4-km Mesoscale Model SimulationsJournal of Applied Meteorology and Climatology, 2006
- Bow Echo Sensitivity to Ambient Moisture and Cold Pool StrengthMonthly Weather Review, 2006
- Properties of the Convection Scheme in NCEP's Eta Model that Affect Forecast Sounding InterpretationWeather and Forecasting, 2002
- A generalized approach to parameterizing convection combining ensemble and data assimilation techniquesGeophysical Research Letters, 2002
- The NCEP/NCAR 40-Year Reanalysis ProjectBulletin of the American Meteorological Society, 1996
- A Multiseason Climate Forecast System at the National Meteorological CenterBulletin of the American Meteorological Society, 1994
- The Role of Midtropospheric Winds in the Evolution and Maintenance of Low-Level MesocyclonesMonthly Weather Review, 1994
- Numerical Study of Convection Observed during the Winter Monsoon Experiment Using a Mesoscale Two-Dimensional ModelJournal of the Atmospheric Sciences, 1989