eMap HDF is a weather app that provides high-resolution predictive NOAA Doppler storm radar with a weather map. The app offers various layers provided by the National Weather Service (NWS) & NOAA, including snow and rain radar, severe weather alerts, tornado tracker, heavy rain and wind alerts, lightning strike map, and cloud satellite layer. It also provides worldwide layers such as typhoon and hurricane tracker, accurate weather forecast for 10 days, hourly weather forecast for 24 hours, air quality and air pollution, earthquake map, temperature map, sea temperature, tide charts, local time in each city, number of residents in cities, road traffic, buoys, dew point, humidity, and wind map.

The storm radar app calculates a one-hour prediction of rain and snow in five-minute frames, and NOAA radar has a six-hour weather radar history. Tide times are available for over 10,000 tidal stations in the US, UK, Canada, etc., with forecasts for several months. The earthquake app includes earthquakes filtered by magnitude and depth, and the earthquake tracker data is provided by the USGS. The air quality app includes concentrations of various pollutants from various sources.

The app also offers a distance measurement tool, travel weather, and an archive that includes sea and air temperature, precipitation, and cloud cover for the last few years. However, the data published in eMap HDF is not subject to use on the voyage, so it should not be used for navigation purposes.

Overall, eMap HDF is a comprehensive weather app that provides a wide range of weather-related information and tools for users to stay informed and prepared for any weather conditions.