About the MMM Spring/Summer High-Resolution Forecast Experiment



For the past 2 years, 4 km convectively explicit realtime forecasts with the WRF-ARW model have been run over the central US from May through July to test the capabilities of such high-resolution simulations to forecast significant convective outbreaks.

This year, WRF-ARW realtime convective forecasting at 4 km horizontal resolution will again run from April 18 through July 31, with the domain now extending from Nevada to the east coast (see map). Simulations are initialized each night with 00 UTC data from the ETA (NAM) model (40 km data), and are run for 36 h using ETA boundary conditions. This year, we are running WRF-WRF version 2.0.3.1, using the WRF single-moment 6 class microphysics scheme (WSM6) in place of the LIN scheme used in past years. Also new for this year, the soil moisture/temperature initial conditions are specified based on a high-resolution land data assimilation system. Forecast output is usually available by 8:00 am each morning.

Some of the primary physics options used include:

...WRF single-moment microphysics, 6 classes (WSM6)
...Yonsei University PBL
...Noah LSM
...RRTM longwave radiation
...Dudhia shortwave radiation
...2nd order Smagorinski diffusion
...No cumulus parameterization scheme

Output from these runs along with radar and precipitation verification is also catalogued at: http://www.joss.ucar.edu/wrf-2005/catalog/

Results from the past two years are catalogued at:
2005:http://www.joss.ucar.edu/wrf-2005/catalog/
2004:http://www.joss.ucar.edu/wrf-2004/catalog/

WRF Realtime Spring/Summer Forecast Staff

Research: Wei Wang, Morris Weisman, Joe Klemp, George Bryan, Chris Davis, Jimy Dudhia, Jim Bresch, Jordan Powers
Forecast Image Production: Jim Bresch
Website & Online Forecasts: Kristin Conrad

Storm Prediction Center (SPC)/ National Severe Storms Lab (NSSL) Spring Program:

This year, the MMM 4 km WRF-ARW realtime forecasts, along with similar forecasts from WRF-NMM, and 2 km WRF-ARW simulations run over a smaller domain by CAPS, will again be a centerpiece of the SPC/NSSL spring forecasting exercise, where forecasters and researchers will be evaluating the potential for such high resolution numerical forecasts to improve severe weather forecast guidance. More information concerning the SPC/NSSL program can be obtained at the SPC web site.

Weather Research & Forecasting Model in MMM

For more information on the WRF mesoscale model, please visit wrf-model.org.

For more information on the Mesoscale & Microscale Meteorology Division at NCAR, please visit www.mmm.ucar.edu