GSD demonstrates modeling systems in flash flood prediction experiment

Image of rescue teams in floodwaters on the overpass in Texas

Image courtesy of the Texas Army National Guard

June 18 - July 20, 2018

GSD is demonstrating modeling systems at the 2018 Flash Flood and Intense Rainfall Experiment (FFaIR) in College Park, MD from June 18 through July 20. Participants from across the weather enterprise will work in a real-time pseudo-operational environment to explore the utility of emerging model guidance for improving flash flood forecasts.

GSD’s experimental High-Resolution Rapid Refresh version 3 (HRRRv3) is being demonstrated in FFaIR. HRRRv3 ingests conventional weather observations (including commercial aircraft observations) and lightning flash rates to complement radar reflectivity observations. HRRRv3 will replace HRRR version 2 in National Weather Service (NWS) operations on July 11.

GSD’s High-Resolution Rapid Refresh Ensemble brings in the same observations as the HRRR, but each ensemble member has small variations in the weather conditions (perturbations) and produces unique forecast snapshots of possible hazardous weather every hour. The ensemble of forecast outcomes provides the degree of certainty or uncertainty of the hazard occurring. For example, several HRRRE snapshot forecasts agreeing that a significant amount of rain could fall at a specific place and over a short period will provide users with more confidence in that forecast. HRRRE is feeding the NEWSe (NSSL WoF prototype ensemble) for FFaIR this year to help produce 0-6 hour forecasts of probabilistic forecasts of precipitation amounts.

The ensemble forecast information can also be processed to create flash flood-specific guidance. For example, NWS flash flood rainfall thresholds or statistics on historical rainfall and streamflow data can be merged with the real-time HRRRE forecasts to allow the forecasters to assess the risk for flash flood-producing rains. These innovative products have the potential to improve flash flood watches and warnings.

For more information contact: Susan Cobb 303-497-5093