ESRL Global Systems Division

Glider Soaring Distance Record with the Aid of GSD's HRRR Forecast System

One of NOAA's most recent contributions to the country's aviation community is definitely one of its most unique and interesting. Forecast output from the High-Resolution Rapid Refresh (HRRR), a real-time experimental weather forecast system from ESRL's Global Systems Division (GSD)/Assimilation and Modeling Branch (AMB), provided critical weather guidance to members of the soaring community, helping to enable a probable new glider soaring distance record. The mid-April glider flight and the critical role that the real-time HRRR forecasts played in providing crucial information about expected mountain wave activity across the western U.S. were detailed in a recent article in a soaring community electronic journal.

Based on large-scale forecasts of favorable conditions, the flight was planned for Sunday, April 14, 2013. With extensive use of HRRR forecast guidance to pinpoint mountain range specific lee waves and quantify their expected amplitude, team meteorologist Walter Rogers was able to successfully route Gordon Boettger on his flight from Minden, Nevada to Gunnison, Colorado (a probable new United States multiplace distance record of some 700 miles). The flight utilized lee wave and jet stream induced tail winds and required careful routing to successfully navigate into favorable lee wave 'sweet spots' to obtain maximum lift. Specific HRRR forecast fields, including mean layer vertical velocities and maximum updraft were used to anticipate the location and timing of these sweet spots and determine the best route for Captain Boettger to utilize them in his flight.

The following commentary, provided by Walter Rogers, also a retired NOAA NWS Forecaster, glider pilot, and forecaster for the 2012 World Gliding Championships, summarizes the critical role that the HRRR played in the success of the flight. "As the operational forecaster in communication with Gordon via Iridium text and voice messages, I was able to point him to the 'sweet spots' of the strongest lee wave updrafts. Most of the flight was in the clear with long downwind runs of up to 120 nmi between 15,000 ft and 27,000 ft. Success of this flight was critically dependent on the HRRR Forecast System 'mean vvel' and 'max updraft' graphics which I sampled every hour."

The HRRR is a 3-km, hourly updating, convection resolving, weather prediction system developed at ESRL/GSD by AMB staff. The HRRR is initialized from the 13-km GSD Rapid Refresh version 2 (RAPv2), which includes an ensemble variational assimilation, radar reflectivity assimilation, a detailed cloud analysis, and numerous other recent model and assimilation enhancements. The RAPv2 initial fields supplied to the HRRR are supplemented by a 3-km HRRR pre-forecast cycle with high resolution radar reflectivity assimilation and assimilation of conventional observations. The CONUS HRRR runs in a real-time experimental setup at GSD and provides detailed forecasts of thunderstorms and other localized weather events. It is used heavily by aviation, severe weather, energy, and general forecast communities.

NOAA's mission is to understand and predict changes in the Earth's environment, from the depths of the ocean to the surface of the sun, and to conserve and manage our coastal and marine resources. NOAA works to keep citizens informed of the changing environment around them and its mission touches the lives of every American. This support to the soaring community is yet another example of the diversity of uses for ESRL/GSD's multiscale numerical weather modeling work and the value of this work to the nation.

Contact information
Name: Stan Benjamin
Tel: 303-497-6387
stan.benjamin@noaa.gov