Lake-Effect Decision Tree from Niziol (1987)
1) Is Tlake - T 850 13 deg C or more? YES NO Lake-effect not likely.
2) Is the direction in the b.l. and 850 mb between: a) Lake Erie...230 to 340 deg? b) Lake Ontario....230 to 80 deg? YES NO Lake-effect not likely over W. and Central NY.
3) Is the directional shear between b.l. and 700 mb ណ deg? YES NO Is the shear between 30-60 deg? NO YES Instability exists, but shear detrimental to formation. Bands spread out, are less intense and may be cut off.
4) Lake-effect snow likely. PVA will enhance snowfall, esp. in SW flow. Inversion height/strength limits snowfall rate. Large fetches and instability will allow snowfall ɭ in/hr. Locator charts will pinpoint area.
5) Lake-effect snow possible. Directional shear makes location difficult to pinpoint and will limt intensity. Inversion height/strength limits snowfall. PVA will enhance activity. Locator chart only gives ballpark estimate of location.