ZCZC SPCSWOMCD ALL ACUS11 KWNS 170040 SPC MCD 170040 PAZ000-MDZ000-WVZ000-VAZ000-OHZ000-KYZ000-INZ000-170445- Mesoscale Discussion 0148 NWS Storm Prediction Center Norman OK 0640 PM CST Fri Feb 16 2024 Areas affected...The Upper Ohio River Valley into the central Appalachians Concerning...Heavy snow Valid 170040Z - 170445Z SUMMARY...A swath of moderate to heavy snow is expected to spread east across the upper Ohio River Valley into the central Appalachians through the evening hours. DISCUSSION...Over the past several hours, a semi-persistent band of moderate to heavy snow has shifted east across the Midwest and middle OH River Valley. Surface observations and web cams under this band have shown visibility reductions down to 1/4 mile at times, indicative of moderate to heavy snowfall rates. Snowfall reports over the past 1-3 hours support this idea with multiple reports of 3-5 inch snowfall totals since early afternoon. Recent upper-air analyses continue to show favorable overlap of broad synoptic ascent ahead of the approaching low-amplitude upper wave with a more focused zone of mesoscale ascent driven by a plume of warm advection and frontogenesis within the 925-850 mb layer. Favorable phasing of these mechanisms is expected to persist for the next several as the synoptic system shifts east towards the Mid-Atlantic. Consequently, organized snow bands capable of heavy snowfall rates upwards of 1-2 inch/hour will remain possible across the upper OH River Valley into the central Appalachian region for the next several hours. Locations downstream that are currently not below freezing may see a slightly delayed onset of snowfall as low-level saturation promotes temperature reductions below freezing. Furthermore, orographic ascent within the Appalachians may augment lift over eastern WV/western VA and increase the potential for 2+ inch/hour snowfall rates during the 04-06 UTC period. ..Moore.. 02/17/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...CTP...LWX...RNK...PBZ...RLX...CLE...JKL...ILN... LMK... LAT...LON 39078529 40128346 40368289 40838105 40987996 40967914 40867850 40627792 40337768 40067754 39707765 39477780 38457893 38267929 38127958 38077995 38098052 38438436 38468482 38538512 38638531 38848542 39078529 NNNN