Winter Storm Warning issued for NYC as major storm approaches

A Winter Storm Warning has been issued for New York City from 4am to 6pm Tuesday. Heavy snow and gusty winds are expected, with snowfall totals of 4 to 8 inches likely and locally higher amounts possible.

A dramatic southward shift in the track of Tuesday’s storm has led to a sudden increase in expected snowfall in NYC. Latest guidance suggests that 4 to 8 inches of snow is likely, with locally higher amounts possible. Gusty winds are also expected, with significant impacts to both the morning and evening commute on Tuesday.

A strong low pressure system is in the process of developing south of our area, and will continue tracking northward on Monday evening. This low pressure system will press northward towards the Mid-Atlantic before eventually slipping eastward off the coast on Tuesday morning. Warm air will surge northward with the storm, while cold air to our north presses down from Canada and New England.

The combination of the two will set up a battle ground over our area, more technically known as a convergence zone or thermal/temperature gradient. This enhances precipitation rate and can result in intense banding of precipitation. Model data had previously indicated that warm air would win out, sending the storm system northward into New England. Recent model trends reversed southward, with a weaker storm system more easily shunted southward by the cold to our north.

The result has been a 24 hour-long southward trend of this storm system. Locations in New England that were once expected to see up to a foot of snow are now in line for…nothing. Meanwhile, a once rainy forecast for the NYC Metro has taken a snowy turn. In fact, it is increasingly likely that Tuesday’s storm will be the biggest snowfall in the city in over two years.

Timing and travel impacts

Forecast models suggest that precipitation will begin as rain late on Monday evening. Light rain and drizzle could continue for an hour or two as temperatures begin to fall. Gradually, heavier precipitation will move into the area. This will cool down the atmospheric column in a process known as dynamic cooling. As a result, a transition from rain to a heavy, wet snow is expected.

This transition will occur in the interior first, and then work southward towards NYC around 4-5am. By the morning commute, heavy snow could be ongoing in Northern NJ and the NYC Metro area. The snowfall intensity (1-2″ per hour) means that despite warm ground temperatures, snow could accumulate rapidly. This creates concern for a dangerous and slippery morning commute.

The transition to snow will then work all the way southward through Long Island and towards the NJ Shore by 7-8am. Periods of heavy snow are then forecast to continue into the late morning and early afternoon, with winds picking up and snow rapidly accumulating throughout the area. Conditions will continue to remain very difficult for travel – which is not recommended.

Finally, the system will begin to wrap up from west to east between 12-2pm, with wind whipped snow finally ending and temperatures falling. Road conditions could remain very slick through the evening commute, with delays likely to continue into the early evening hours.

Snowfall expectations

The current forecast calls for 4 to 8 inches of snow throughout the NYC Metro area. However, it is worth noting that the forecast is still prone to major adjustments. We saw how quickly the system trended southward in the last 12 hours, and so we’re approaching this system with extreme caution.

The average spread among forecast models still leans higher within that 4 to 8 inch range, as advertised by the box and whisker plots that are pictured here. In other words, there is still a chance that snowfall totals end up higher than the range we are forecasting. The 4 to 8 inch forecast is the highest confidence and highest probability forecast at this time.

We’ll be tracking this storm all evening long and into Tuesday morning. Stick with us and stay tuned for the latest information!