AM All Zones Update: Snow and ice threat for the interior Sunday

Clouds will be around much of the day, as a warm front lifts through region. But some breaks of sunshine are likely as drier air moves in to the mid-levels of the atmosphere. A southwest flow developing near the surface today will also help temperatures warm into lower to middle 40s. However, weather conditions will take a turn for the worst again late tonight and tomorrow morning, as a storm system approaches the region. Clouds will increase again overnight, thanks to some warm-air advection aloft, and some light precipitation could break out sometime closer to daybreak.

Latest guidance suggests that cold-air damming will be stronger over northern parts of the region. This is largely due to a strong high over Canadian Maritimes forcing low pressure over the Great Lakes to transfer faster to a secondary low, developing over the Southern New Jersey and Delaware. This will keep low-level winds more east-northeast and enhance a thermal gradient with stronger lift over the region. Thermal profiles in the atmosphere at the time will still likely support this precipitation to come in as snow or wintry mix in many areas, especially north of Central New Jersey.

Currently we anticipate many of the higher elevations over Northwest NJ, Lower Hudson Valley and Connecticut to see snow, sleet and freezing rain for much of day tomorrow. Colder air will likely be tougher to scour of these locations, especially with the remaining snowpack enhancing more cooling. Several inches of snow and some icing is possible. Highest snowfall totals are likely just north of I-84 and over northern CT, where precipitation may be mostly if not all snow.

Over the lower elevations, including Northeast New Jersey, New York City and Long Island, there may snow, sleet or freezing rain early tomorrow morning, before enough warm air comes in off the ocean to change precipitation to rain by the midday hours. Snowfall accumulations -if any- will be much lighter and minor. But roadways and walkways already treated from the last snowstorm, could become slick again with just a light coating of snow and/or ice. Further south over Central and Southern New Jersey, and Southeast Pennsylvania, mostly if not all rain is expected with lighter precipitation and warmer temperatures.

This storm system will be begin moving away from the region early tomorrow night with any lingering precipitation winding down in all zones. Skies will begin clearing late Sunday night and Monday, but low pressure will intensity rapidly east off Southern New England, as associated shortwave trough amplifies. This will cause a tighter pressure gradient with strong northwest winds, possibly gusting over 40mph. There may enough instability in the atmosphere to trigger some isolated snow showers or snow squalls as well on Monday.

More tranquil weather returns on Tuesday with lighter winds and seasonable temperatures. We are watching the potential for larger east coast storm for Wednesday and Thursday. However, latest guidance indicates a weaker and progressive solution, with less interaction between the northern and southern stream disturbance that would need to phase for a major snowstorm at this time. But some snow or mixed precipitation is still possible, from either disturbance. Stay tuned for more zone forecast updates as we try to iron out more details Sunday’s storm later today and tonight.