The Impacts of the Passage of Three Distinct Short-Wave Troughs on a Prolonged Lake-Effect Snow Event
Given that the first trough was the most pronounced, a detailed investigation of the 4-km NAM model forecasts of trough passage on 7 January was undertaken. This analysis revealed subtle differences in the positioning of the short-wave trough throughout the 36-h forecast period. However, the most pronounced error between the NAM forecasts and the actual pattern was actually in the amplitude of the downstream ridge. This lake-effect event began following the passage of a surface cold front. Diabatic heating associated with the front and surface low amplified this ridge in a manner that wasn't even captured by the 6-h forecast. This resulting amplification coupled with the sharp short-wave trough to the west resulted in a more curved flow and a distinctly different orientation to the lake-effect band than was captured in any model run. Thus, the lake-effect snow event began with a lake-effect snow band that had a different shape, orientation, and location than in the model forecasts.