Application of Gravity Current Model to Analysis of Squall-Line Gust Front

Abstract

Abstract An analysis of a severe gust front is made to examine its three-dimensional structure. The data used are from the storm measurement network operated by the National Severe Storms Laboratory (NSSL). The important structural features shown in the analysis include: i) intense wind and thermal gradients at the leading edge of the air mass; ii) retardation of the cold-air front near the ground; and iii) vertical protrusion of the cold air to 1700 m at the front of the cold air mass, forming a bulge called a head. Upstream of the head, the depth of the cold air was almost constant at 3350 m; iv) a well defined circulation cell with a horizontal axis was found within the head; this wind field was associated with a core of maximum horizontal wind speed of 34 m sec−1 only 175 m above the ground, upward motion of 5–10 m sec−1 within the frontal zone, and weaker downward motion on the rear side of the head. In these structural characteristics, as well as in some substructural properties, this gust frontal a...