Warn on Forecast: NEWS-e
The NOAA Warn-on-Forecast (WoF) research project is working toward the development of very short-range (0–1 h) probabilistic forecasts that accurately predict storm-scale hazards such as tornadoes, high winds, and flash flooding. In a future WoF system, storm-scale analyses and forecasts will likely be generated on very-high-resolution (grid spacing ~1 km or less), event-dependent grids, but preliminary work with a WRF-based ensemble data assimilation system has begun on coarser convection-allowing grids. This system—the NSSL Experimental Warn-on-Forecast System for ensembles (or NEWS-e)—will be run quasi-realtime during the NOAA Hazardous Weather Testbed 2016 Spring Experiment, and preliminary findings from these storm-scale radar data assimilation experiments are presented.
Storm-scale ensemble analyses and forecasts of severe weather events from spring 2016 will be produced on a 3-km event-dependent grid. This storm-scale ensemble is nested within a 15-km continental United States (CONUS) ensemble constructed from initial and boundary conditions provided by ESRL's experiment HRRRE system. NEWS-e will start at 1800 UTC each day based on a 15Z forecast from the 18 member HRRRE. Around the time of convective initiation, radar data and cloud water retrievals are assimilated every 15 min using the ensemble Kalman filter (EnKF) approach encoded in the Data Assimilation Research Testbed (DART). Each hour, two forecasts will be initialized from the resultant storm-scale analyses. At the top of the hour, a three-hour forecast is generated, while at the bottom of the hour a 90-minute forecast is generated.
This study is focused primarily on ensemble forecasts launched during or just before the 1 h preceding the onset of storm reports. Preliminary work will evaluate the ability of these forecasts to highlight severe weather hazards, including the low-level rotational characteristics of supercell thunderstorms and tornadic meso-convective system, thunderstorm winds, and flash flooding.
DOCUMENT: Jones, Thomas A., 2016: Impacts of interpolation and adaptive inflation when assimilating radar reflectivity using an ensemble adjustment Kalman filter (PDF, 23.9 MB), revised June 11, 2016, National Severe Storms Laboratory, 34pp.
NEWS-e Domain of the Day
Event Day : 18 June 2018. Centerpoint for the inner domain is . The large outer domain encompasses the continental United States and has 15-km horizontal gridpoint spacing, while the black box outlines a 675 x 675 km inner domain with 3-km horizontal gridpoint spacing. Radar data assimilation (DA) will take place on this storm-scale domain once convection initiates or the Storm Prediction Center (SPC) believes initiation is imminent. Gray dots indicate the locations of WSR-88D radar sites that can provide observations during the 15-minute radar DA cycles. Due to computational limitations, the number of radars that NEWS-e can assimilate is limited to four.