P55  Evaluation of Two Regional Ensembles During the 2011-2012 Hydrometeorology Tested-West Winter QPF Experiment

Jensen, Tara, National Center for Atmospheric Research/RAL, Edward Tollerud, NOAA/ESRL, Evan Kuchera, AFWA, Brian Etherton, NOAA/ESRL, Linda Wharton, NOAA/ESRL, Scott Rentschler, AFWA, Paul Oldenburg, NCAR/RAL, John Halley-Gotway, NCAR/RAL, Barbara Brown, NCAR/RAL

The Developmental Testbed Center (DTC) collaborated with two organizations this past winter to evaluate their WRF-based regional storm-scale ensemble forecast systems.  The National Oceanic and Atmospheric Administration/Earth Systems Research Laboratory/Global Systems Division (NOAA/ESRL/GSD) ensemble was initialized using a 9 km resolution covering southern Oregon and California; a 3 km nest was embedded to provide fine scale details over the American River Basin.  The Air Force Weather Agency (AFWA) provided a 4km run that matched GSDs outer domain.  In addition, DTC evaluated the 32-35 km Short Range Ensemble Forecast (SREF) system from NOAA/Environmental Modeling Center (EMC) as an operational baseline.   Evaluation of the two storm-scale and the meso-scale ensemble system were performed from 25 December 2011 – 15 April 2012.  Evaluation variables included QPF as well as several state variables: temperature, specific humidity, winds, and height. Precipitable water and freezing level were also evaluated to provide insight into ensemble response to critical forecast variables for cool-season precipitation events on the west coast.  Preliminary results will be provided, along with a discussion of how the AFWA and GSD ensembles performed as compared with the SREF operational baseline.