Forecast Flight Conditions

Product Description

Abstract: These polygon shape files depict the lowest flight rules (the combination of cloud ceilings and surface visibility) forecast during each of the next 1, 2, …, 23 hours. The forecasts are created by DTN meteorologists, and are updated every hour.

Purpose: These shapefiles can be used for flight planning, airport and helicopter operations, and other applications impacted by low clouds and visibilities.

Description: These polygon shape files combine the cloud ceilings (areas where the cloud cover is forecast to be broken or overcast) and surface visibility into a single flight category forecast during each of the next 1, 2, …, 23 hours. The forecasts are created by DTN meteorologists, and are updated every hour. The forecasts cover North America from Southern Canada south to the Gulf of Mexico. The polygons are contoured by flight rule into four aviation categories: (i) Low Instrument Flight Rules (LIFR): Ceiling below 500 feet AGL AND/OR Visibility less than 1 mile, (ii) Instrument Flight Rules (IFR): Ceiling 500 to below 1000 feet AGL AND/OR Visibility 1 mile to less than 3 miles, (iii) Marginal Visual Flight Rules (MVFR) Ceiling 1000 to below 3000 feet AGL AND/OR Visibility 3 mile to less than 5 miles, (iv) Visual Flight Rules (VFR) Ceiling greater than 3000 feet AGL AND Visibility greater than 5 miles. By definition, IFR is ceiling less than 1,000 feet AGL and/or visibility less than 3 miles while LIFR is a sub-category of IFR, and VFR is ceiling greater than or equal to 3,000 feet AGL and visibility greater than or equal to 5 miles while MVFR is a sub-category of VFR.