Mesoscale Discussion 0042 NWS Storm Prediction Center Norman OK 0713 PM CST Mon Jan 20 2025 Areas affected...portions of far western New York Concerning...Heavy snow Valid 210113Z - 210415Z SUMMARY...Heavy snow should develop through tonight with an approaching lake-effect snow band. 2-3 inch/hour snowfall rates are likely, at least on an intermittent basis. DISCUSSION...While heavy snow has recently been reported by the KART ASOS, the ongoing snow-band should shift several miles southward over the next couple of hours, as indicated by KTYX regional radar data. The CWQP surface observation along the Ontario shoreline showed an abrupt wind-shift and brief increase in speed as the snow-band shifted to the south of this location, indicating potential appreciable low-level convergence. The strong convergence associated with the approaching snow-band, amid 8+ C/km 0-3 km lapse rates, suggest that the snowfall is likely associated with low-topped convection. The low-topped convection will benefit from a long fetch of Lake Ontario moisture as low-level flow parallels the lake axis this evening. Heavy lake-effect snow should begin soon, and given convective banding with 90 percent RH in the dendritic growth zone, production efficiency may be high enough to support at least 2 inch/hr snowfall rates, perhaps reaching 3 inches/hr at times. ..Squitieri.. 01/21/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BUF... LAT...LON 43867632 43927582 43917548 43787548 43697575 43687615 43757627 43867632
Storm Prediction Center Mesoscale Discussion 42

20
Jan