MESOSCALE STUDY OF A LAKE EFFECT SNOW STORM

Abstract

During the 1964?65 snow season, the Atmospheric Sciences Research Center, State University of New York (ASRC, SUNY), and the SUNY College at Oswego maintained a mesoscale network of surface pressure, temperature, and wind-recording stations around the eastern end of Lake Ontario to observe the conditions attendant upon lake effect storms on a scale commensurate with storm size. The Cornell Aeronautical Laboratory combined the SUNY data with conventional weather and radar data for the February 3 and 4, 1965 storm period to produce a combination of streamline, isotach, isobaric, and isallobaric analyses from which a number of interesting features became evident. One important, storm characteristic is a narrow confluent-convergent wind shift zone (0.1 to 1.5 n.mi. wide) beneath the snow band. In the storm studied, the wind shift zone was evident beneath the full length of the overland portion of the storm, even when the west-to-east snow band migrated south of the lake. During a period in which two snow bands existed simultaneously, a wind shift line could be observed under each. Also observed were lee shore pressure patterns that changed in a consistent manner with changes in location of the snow bands. Although lee shore convergence and cyclonic vorticity increases were in evidence throughout the period, these patterns did not appear to be directly related to the snow bands. The analyses strongly suggest that while the formation of the lake effect bands is caused by heating of the air by a warm lake, the location and movement of the bands are controlled by winds aloft, rather than by surface conditions.