We’re in for a wild ride over the course of the next 24 hours as our weather goes from possibly record-breaking warmth to what is expected to be the most significant winter storm so far this season. Significant snow accumulations over 6″ and possibly as much as a foot are expected across the region, resulting in a winter storm warning for all of the NYC metro region.

Timing

Judging by the amount of sun we’re getting, temperatures will likely hit record-breaking levels in the low-60s in the city today. They will drop steadily to around 50ºF by the evening commute as a cold front pushes through and Arctic air flows in from the north. Overnight, temperatures will continue falling rapidly to around freezing. Precipitation is expected to begin around 3-4AM Thursday here in the city and continue through the early afternoon. Unfortunately, the timing of the heaviest precipitation does look to bring significant impacts to the morning commute.

Impacts

Rain/snow mix to start, but by the morning rush, expecting all snow through the region. Heavy snow at times possibly reaching 1-2″/hr. Some thundersnow could occur. Hazardous travel conditions during the morning rush as plows will have trouble keeping roads clear with traffic and the moderate to heavy snow. Gusty winds could produce near-blizzard conditions with low visibility.

Snowfall Totals

Here are some graphics for snowfall totals from our local National Weather Service Forecast office. The general forecast calls for 6″-12″ in the city. The exact extent of totals will depend, as is generally the case with this type of storm, on where the heaviest snow bands set up and for how long they sit over an any given area.

Probabilities for 4″+ and 6″+ of snow respectively

Discussion

An shortwave that’s made its way rapidly across the country from the Pacific will move along the cold front that is pushing through today. As it does so, it will spawn a secondary low off the Mid-Atlantic that will strengthen rapidly as it moves over open water. At the same time, plenty of cold air will wrap around the deepening coastal low with high pressure to the west. This will put in place all the ingredients for a classic coastal winter storm for this area. The only thing keeping this storm from being a major blizzard with snowfall totals exceeding 2 feet is the fairly quick pace that it’s expected to move at.

This coastal storm will drive the expected heavy snows tomorrow. Its track is expected to take it just outside the 40ºN 70ºW benchmark, a spot that from a climatological perspective has translated to heavy snow storms for this region.