Saturday, 13 January 2007
New York State Finger Lakes Winter lake-effect events: Surface, sounding, and synoptic environment
Much of the current knowledge regarding lake-effect snow storms is associated with large water bodies, such as the Great Lakes and the Great Salt Lake. Snowfall events attributed to small lakes (fetch < 100 km) have received less attention, although significant snowfall totals have been documented with these systems. This study uses data from the eleven winters (October – March) of 1995 through 2005 to examine the characteristics of lake-effect systems in the Finger Lake region of New York State (NYS). WSR-88D radar data from Binghamton, NY was used to identify 108 lake-effect events which contained quasi-stationary precipitation bands aligned with a major-axis of one or more of the Finger Lakes. The lake-effect events were classified into three main categories: Finger Lakes (36), Lake Ontario-enhanced (57), and synoptic-enhanced (15). In addition, 17 cases occurred which transitioned from one main category to another during the lake-effect systems evolution.
Hourly surface data and soundings were used to investigate atmospheric conditions during lake-effect events. Surface temperatures and wind speeds were found to be lower during Finger Lakes lake-effect events than either Lake-Ontario enhanced or synoptic enhanced events. Wind directions were most commonly from the northwest; however mesoscale variability in wind direction was observed at surface station throughout the western NYS region. Analyses of soundings which occurred during events found that the mean base of a lower-tropospheric stable layer was significantly lower during Finger Lake events (880 hPa). Examination of the synoptic environment favorable for lake-effect events within the NYS Finger Lakes region showed a systematic shift in the surface temperature and sea-level pressure patterns between synoptic-enhanced, Lake Ontario-enhanced, and Finger Lakes events.