New Jersey's Weather Divide: North Gears Up for Snowfall, South Braces for Mainly Rain

As we approach the anticipated snowstorm, it's important to note the absence of our typical arctic air mass. Currently, New Jersey is experiencing significantly warmer than average temperatures, complicating predictions regarding snowfall totals. If you've been monitoring various model runs indicating snowfall outputs, you'll find that they generally assume a 10:1 snow-to-liquid ratio. However, this system will deviate from the norm, presenting ratios between 4-8:1, substantially altering the expected snowfall depicted in online forecasts.

The Details

The approaching system finds us in a deficit of significant cold air, awaiting a cooler air influx as the surface low departs off the coast. This incoming cooler air will gradually replace the current warm temperatures. Additionally, the region's warm soil temperatures present another challenge, as snowfall must be particularly heavy to overcome the initial melting upon contact.

Geographical Impact Analysis:

• Green Section (No Accumulation): Residents in this area will experience predominantly rain throughout the storm's duration, with a transition to snow towards its conclusion. However, given the marginal surface temperatures, no accumulation is expected, a phenomenon often described as 'White Rain,' where snow falls but does not settle.

• Light Blue Section (Coating - 2 inches): This area will initially see rain, followed by a swift transition to snow. This shift increases the likelihood of minor accumulations on cooler surfaces, including grassy areas and vehicle tops.

• Dark Blue Section (2 inches - 4 inches): Expect a mix of rain and snow at the onset, with a quicker transition to snow. The presence of heavier snow bands may counteract the warm surface temperatures, allowing for some accumulation, primarily on cooler surfaces.

• Purple Section (4 inches - 8 inches+): Areas within this section will experience a brief period of rain or mixed precipitation before transitioning to snow, positioned favorably for frontogenesis and the formation of heavy snow bands. The inclusion of potential accumulations exceeding 8 inches in elevated areas accounts for less marginal temperatures and more rapid accumulation.

Timing

The storm will advance across the state from south to north, starting late Monday night into early Tuesday morning. Those within the 4-8" forecast range should anticipate an early transition to snow, with conditions evolving by sunrise. The heaviest snowfall is predicted between 5 AM and 10 AM on Tuesday, diminishing by the afternoon. The expectation is for precipitation to cease statewide by 5 PM Tuesday evening.

Summary

• Temperature Context: The lack of arctic air and warmer than average temperatures will significantly impact snowfall predictions, with expected snow-to-liquid ratios ranging from 4-8:1, rather than the typical 10:1. This means less snow accumulation than what might be suggested by standard snow maps.

• Precipitation Breakdown:

• Green Section: Predominantly rain with a late transition to non-accumulating snow ('White Rain').

• Light Blue Section: Initial rain turning to snow, with possible light accumulations on cold surfaces like grass and car tops.

• Dark Blue Section: Rain and snow mix leading to 2-4 inches of accumulation, mostly on cooler surfaces.

• Purple Section: Brief rain/mix, then heavy snow leading to 4-8 inches+ of accumulation, especially at higher elevations where it sticks more readily.

• Timing: Rain spreads from south to north late Monday night, transitioning to snow by early Tuesday morning. The heaviest snowfall is expected Tuesday between 5 AM and 10 AM, tapering off by the afternoon with precipitation ending by 5 PM.