Aviation Weather Improvement Act This bill requires the National Weather Service (NWS) to establish certain programs to improve weather forecasts for aircrafts. Specifically, the NWS must establish an aircraft-based observation program. Under the program, the NWS must partner with the weather industry to deploy critical atmospheric sensors on aircrafts to support certain weather data collection. Additionally, the NWS' Aviation Weather Center must incorporate turbulence events into its forecasting capabilities and timely deliver this information to the world airspace system. The NWS must also work with the Federal Aviation Administration to improve weather and turbulence forecasting, such as through identifying data gaps that can inform flight plans.