ZCZC SPCSWOMCD ALL ACUS11 KWNS 131008 SPC MCD 131008 CTZ000-NYZ000-NJZ000-131445- Mesoscale Discussion 0140 NWS Storm Prediction Center Norman OK 0408 AM CST Tue Feb 13 2024 Areas affected...northern New Jersey...southeastern New York...Long Island and southern Connecticut Concerning...Heavy snow Valid 131008Z - 131445Z SUMMARY...Sustained heavy snow rates of 1-2+ inches per hour may become focused across much of the Greater New York City Metropolitan area by 8-11 AM EST. DISCUSSION...Precipitation continues to develop east-northeastward into and through much of the northern Mid Atlantic into southern New England. This includes moderate to occasionally heavy snow developing on the northern periphery of the shield, but the changeover to snow and snow rates have been hampered at least some by boundary-layer temperatures initially above freezing, and a layer between 850-700 mb with above freezing temperatures, as far north as the northern Mid Atlantic vicinity. Significant surface cyclogenesis does now appear underway near/offshore of the Hampton Roads vicinity, with the rapid further deepening of the cyclone forecast as it progresses east-northeastward into the Atlantic through the day. This will be accompanied by southward advection of colder lower/mid-tropospheric air into the the northern Mid Atlantic, and the latest Rapid Refresh continues to indicate intensifying deep-layer frontogenesis in a zone across the northern New Jersey/Long Island vicinity through mid to late morning. Beneath strengthening divergence between coupled jet streaks aloft, models indicate that upward vertical motion will become maximized within mid/upper levels, including a layer near and just below 500 mb where temperatures are favorably cold to support large dendritic ice crystal growth. Forecast soundings suggest that saturating and sufficiently cold profiles with precipitable water around .70 inches may focus intensifying and heaviest snow across much of the Greater New York City area through 13-16Z. It appears that this probably will include rates on the order of 1-2 inches per hour and occasionally heavier. ..Kerr.. 02/13/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...OKX...PHI... LAT...LON 40707315 40407438 40667473 41207396 41397229 40827216 40707315 NNNN