Snow-Band Formation and Evolution during the 15 November 1987 Aircraft Accident at Denver Airport

Abstract

The formation and evolution of convective rain and snow bands prior to and during the crash of Continental Airlines flight 1713 on 15 November 1987 at Denver Stapleton Airport are discussed. Convective rain occurred during the early stages of the storm in association with the approach of an upper-level trough from the west. Snow bands were observed following the passage of a shallow Canadian cold front from the north. These bands formed above the cold front and moved from southeast to northwest at 7 m s?1 with a horizontal spacing of 10?30 km. The winds within the cloud layer were southeasterly from 5 to 10 m s?1, suggesting that the bands were advected by the mean, cloud-layer flow. The most likely mechanism producing these bands was a convective instability in the shear layer above the cold front. As the upper-level trough moved to the east, the winds in the cloud layer shifted to northerly, causing the bands to move southward with the major axis of the band oriented north?south. The high snowfall rate just prior to the takeoff of flight 1713 occurred as a result of one of these north?south?oriented bands moving over Denver Stapleton Airport from the north during the latter stages of the storm.