ZCZC SPCSWOMCD ALL ACUS11 KWNS 100427 SPC MCD 100427 MEZ000-NHZ000-100930- Mesoscale Discussion 0214 NWS Storm Prediction Center Norman OK 1027 PM CST Sat Mar 09 2024 Areas affected...parts of northern New Hampshire into western Maine Concerning...Heavy snow Valid 100427Z - 100930Z SUMMARY...Sustained heavy snow appears most likely to become focused across the mountains of northern New Hampshire into northwestern Maine overnight into daybreak Sunday, including hourly rates increasing to 1-2+ inches per hour. DISCUSSION...A developing surface cyclone appears to be undergoing a period of more rapid deepening as it migrates across the northern Mid Atlantic region toward southern New England. Strengthening deep-layer ascent to the north-northeast of this feature, supported by lower/mid-tropospheric warm advection beneath an increasingly difluent and divergent upper flow field, is in the process of overspreading much of eastern New York and western New England, accompanied by moderate to heavy precipitation. Thermodynamic profiles near or below freezing are generally focused across the higher terrain, and with further low-level warming, may become increasingly confined to the mountains of northern New Hampshire into northwestern Maine overnight. This is where ensemble output (including the latest NCEP SREF and HREF) suggest highest probabilities for heavy snow rates developing and being maintained, perhaps at rates in excess of 2 inches per hour by 09-12Z. It appears that precipitable water within the saturating, sub-freezing profiles across this region may increase up to around .70 inches. Rapid Refresh forecast soundings indicate that this will coincide with a period of intensifying lift within a layer between roughly 600-500 mb, where the environment will become most conducive to large dendritic ice crystal growth with temperatures around -15 C. It appears that a fairly deep layer layer through the lowest few kilometers above ground level may become characterized by isothermal profiles near freezing, contributing to potential for considerable continuing snow flake growth via aggregation before reaching the surface as a "heavy, wet" snow. ..Kerr.. 03/10/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...GYX... LAT...LON 45247007 44937001 44097102 43867142 44037185 44787129 45567048 45247007 NNNN