Icing and turbulence are two aviation safety weather issues that pose threats to passenger safety and aircraft operations. They are also among the most difficult situations to predict accurately.
To address these issues, the U.S. National Science Foundation National Center for Atmospheric Research (NSF NCAR) developed an integrated suite of aviation forecasts called the Domestic Aviation Forecast System (DAFS), designed to “generate more detailed forecasts of evolving icing and turbulence risks along a flight path.” The new system, which became operational on March 30, 2026, is run by the National Weather Service Aviation Center (NWS AWC) and covers the contiguous United States and Alaska.
DAFS utilizes the National Oceanic and Atmospheric Administration’s (NOAA) most advanced operational regional forecast model, the High-Resolution Rapid Refresh (HRRR), with a 1.8-mi (3-km) horizontal resolution grid and 50 vertical levels. The HRRR can access the latest three-dimensional radar data every 15 minutes. This allows aviation meteorologists to watch convective development as it happens. Convective clouds with strong vertical motions are most likely to produce extreme turbulence and, with temperatures aloft well below freezing, extreme icing conditions. Previous models were only updated every hour and had a larger grid space, which could miss smaller developing convective elements.
DAFS supports trajectory-based operations (TBO) by presenting a better picture of aviation hazards in real time allowing for rerouting. It also provides improved low-level hazard predictions important for the routing of drones, advanced air mobility, and electric vertical takeoff and landing aircraft. According to NOAA, “DAFS is a foundational building block for future in‑time aviation safety management.”
For the turbulence forecast, the DAFS includes an upgraded graphical turbulence guidance (GTG) algorithm, which covers a wide variety of turbulence situations, including low-level turbulence, clear air turbulence, mountain wave turbulence, and in-cloud turbulence for clouds of varying size.
In terms of actual turbulence forecasting, the GTG Nowcast (GTGN) went online on July 30, 2026. Previous turbulence forecast products were only useful for preflight route planning, but the GTGN provides real-time analysis and short-term forecasts that are updated every 15 minutes and can be used in flight to avoid turbulence. The GTGN, which is available on a mobile-friendly version of AWC’s website for pilots in flight, provides vertical resolution for 51 separate altitudes from100 ft above ground level to 50,000 ft. The horizontal resolution is the basic model’s 1.8 miles.
The GTGN utilizes real-time weather observations from ground-based lightning data, pilot reports (PIREPs), and ground-based weather stations. Besides using the HRRR forecasts, the GTGN incorporates data from the NCAR Turbulence Detection Algorithm. The GTGN has improved turbulence diagnostics, including updated clear-air turbulence algorithms, expanded mountain-wave turbulence detection, a new convectively induced turbulence parameter, and layer-specific calibrations for the planetary boundary level, troposphere, and stratosphere.
The icing forecast includes an upgrade of the NSF NCAR’s Forecast Icing Product, which provides “forecasts of in-flight icing probability, severity, freezing drizzle and freezing rain conditions, and super-cooled large droplet conditions.” The improvement in the ability to forecast in-cloud, large super-cooled water droplets is particularly significant for the general aviation sector. These smaller aircraft with less deicing capability are particularly susceptible to rapid ice accumulation and resultant loss of control. These situations continue to result in often fatal accidents.
DAFS was designed to aid aviation meteorologists at the Aviation Weather Center and at the U.S. Federal Aviation Administration’s 21 air route traffic control centers in creating tailored aviation products for airport areas and aircraft routes. Its input has been incorporated into the turbulence and icing forecasts available at the AWC.
Blake Cushnie, director, TBO Airspace and European Programs, NAVCANADA, says Canada is working on similar issues and is also developing technological solutions.
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Edward Brotak, Ph.D., is a former professor and program director in the Department of Atmospheric Sciences at the University of North Carolina, Asheville.
