25th Anniversary of First Ever Tropical Cyclone Track Forecast from a Global Forecast Model, Occurred During Hurricane Andrew
On August 19th, 1992, a new implementation of NOAA’s global spectral model, then called the Aviation Model (AVN), produced a track forecast for Tropical Storm Andrew in the Atlantic Ocean. Over the next few weeks, the AVN model provided critical forecast information as Andrew grew to a category 5 storm, making landfall in South Florida early in the morning of August 24th, 1992.
[Track forecast from the first-ever tropical cyclone forecast from the Aviation Global Model. Blue lines represent the forecast, and the black line represents what Andrew actually did. Courtesy Gus Alaka – CIMAS/HRD]
Earlier that year, the model was upgraded so that it now had a resolution of about 210 km (130 miles), and it had 18 levels in the vertical. Here in 2017, the current resolution of the global model is about 13 km (8 miles) and 64 levels in the vertical. Along with the upgrade, a new system to initialize tropical cyclones, known as a synthetic vortex, was implemented. This ensured that the storms were started in each model forecast at the correct location (AVNO). The result was the first operational tropical cyclone forecast from a NOAA global model.
[Intensity forecast from the first-ever tropical cyclone forecast from the Aviation Global Model. Blue lines represent the forecast, and the black line represents what Andrew actually did. Courtesy Gus Alaka – CIMAS/HRD]
According to the National Hurricane Center, the Aviation Model performed especially well. However, this was the first storm for which AVN output was available to NHC forecasters. Hence, its operational reliability was not established. The output from the model was available to forecasters with about a six hour delay, around the time the next forecast cycle start.
[Hurricane Andrew average track forecast errors (nautical miles). AVN model (AVNO) performed well compared to other models, especially at the longer range. Image from NHC.]
For WeatherNation: Meteorologist Mace Michaels