Abrupt Changes in Wind Conditions at the Memphis International Airport

Memphis International Airport serves as the global hub for FedEx Express and is the second largest cargo airport in the world. Three of the four runways at Memphis are oriented north/south and the FedEx hub is located at the north end of the airport. Pilots desire to land to the north to reduce taxi time and conserve fuel. Normally, aircraft will land into a headwind; however, FedEx meteorologists have determined that their aircraft can land in a tailwind up to 8 knots. Abrupt and unexplained increases in wind speed above this threshold have been observed during the late evening hours when airport traffic is heaviest. These increases in wind speed require the airport to reverse the direction that aircraft land, causing delays. The purpose of this project was to study why this change in wind speed occurs to create more accurate forecasts. Observed conditions made by airport weather stations from 2006-2017 were compared with predicted conditions from a forecast model to find days when these wind events occurred. For those cases, maps of temperature and pressure gradients were plotted to visualize local scale conditions. Results showed that a cold front moved through the area the day before the event followed by a greater than normal diurnal pressure decrease (7-12 millibars) on the day of the event. In addition, it was observed that Memphis is usually warmer than surrounding locations indicating a potential heat island effect. These results can be used as a guide when creating wind speed forecasts for the airport.