Rittenhouse

NAM is a bust for DC: a few hours of snow, followed by a brief period of heavy sleet, then several hours of light sleet and freezing drizzle. North of I-70 around Frederick, where the deformation axis sets up, does okay. I think the heavy precip will partly compensate for the warm nose there. I'd caution against looking too closely at the colors on the simulated radar. For some, the changeover will be slower than the models are showing. It will come down to band placement. However, since the NAM is better at detecting these features, there is a high bust potential for DC right now. I think the GFS snow totals are likely on the high end for the coastal plain.

From the NWS discussion: I performed a cursory analysis of current conditions this morning and I found that temps are running a few degrees cooler than forecast with dewpoints in the single digits. Up stream observations in NC and southern VA suggests that snow is over performing. I have adjusted my snow ratios this morning to account for the well below freezing layer ahead of the precipitation which should allow for higher snow rates. Initial onset of precipitation is on track this morning and snow should fluffy to start before switching over to wet snow as the layer starts to warm and transitions over to a wintry mix for most areas along and east of I-81. I will continue to monitor current conditions to see if I need to up snow totals. It wouldn`t surprise me if we get higher snow totals further eastward than expected due to extremely cool air mass ahead of this system.

This one was a NYC metro jackpot.

Had no idea that 12"+ snowfalls were that unusual. Seems like we have one every couple of years or so these days.

NYC closing in on a foot... PRELIMINARY LOCAL STORM REPORT NATIONAL WEATHER SERVICE NEW YORK NY 1044 AM EST MON FEB 1 2021 ..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON... ..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE.... ..REMARKS.. 1030 AM HEAVY SNOW CARROLL GARDENS 40.68N 74.00W 02/01/2021 M9.5 INCH KINGS NY TRAINED SPOTTER

The models seem to underestimate overrunning/front-end snows but overestimate back-end snows for NYC. Not sure the science behind it.

Upton explaining why they didn't issue blizzard warnings: For coastal areas, winds 20-40 mph with gusts 40-60 mph will help create near-blizzard to blizzard conditions from roughly mid-morning into the afternoon, possibly even into the evening. Working against this however is that an elevated warm nose then likely pushes into much of Long Island and SE CT, possibly even into the city as well. This then introduces mixed precipitation for these locations, with even a complete changeover to rain across the Twin Forks and potentially even coastal SE CT with the help of boundary layer temperatures and the warming aloft. Do not have enough confidence of 3 hours of blizzard conditions to go with a blizzard warning - whether it be due to uncertainty of PCPN type or winds being consistently strong enough while it`s snowing. There is still a potential that some areas get converted to a blizzard warning if confidence increases. The strongest frontogenesis is likely to the north of these areas in the evening, so dynamic cooling won`t be much of a factor for much of the forecast area at this point. The city, especially LGA, probably has the best chance for blizzard conditions, being less likely to mix while still being close enough to the coast for the winds.