An area of low pressure exiting off the Delaware and New Jersey coast this morning has already produced a surprise snowfall with 4 to 7 inches of snow accumulating over extreme southern New Jersey and Delaware this morning. Is another threat potentially evolving for Sunday? Possibly.
This morning’s moderate snowfall was driven by the disturbance currently over the Atlantic intensifying at just the right time, which by the way was faster than guidance had suggested. As a result a band of moderate to heavy snow rapidly developed over Delaware and southern New Jersey.
The next disturbance is currently over over the northern Plains and is expected to reach the New Jersey coastal waters by Sunday morning. As this disturbance reaches the New Jersey coastal waters, the 500 MB trough will become negatively tilted, which mean the orientation is from southeast to northwest. This orientation will slightly slow down the progression of the low pressure over the New Jersey coastal waters and align winds at the mid levels and lower levels to converge while the upper level winds diverge. This leads to the potential for an inverted trough to develop which can produce a band of moderate to heavy snow that rotates from Monmouth County, New Jersey to New York City, New York and then east towards Long Island, specially the south side of Long Island.
As a result, the following snow threat exists for this Sunday. For locations over the northern interior like northern Connecticut, the central Hudson River Valley, and northeastern Pennsylvania; only a trace to an inch of snow can be expected. The bulk of the lifting with this storm will be focused south and east of these locations. Closer to the coast and over much of the Philadelphia metropolitan area, snowfall amounts will reach as much as two inches as snow showers and periods of light snow work through the region. Along the central New Jersey coast up through the south side of Long Island is where the best potential for an inverted trough could develop. The majority of mesoscale models high light these locations and with a rather impressive snow band at that. Most locations can expect one to three inches, however there is potential for as much as six inches of snow if the band gets organized fast enough.
The best potential for snow will be from 10 AM through 10 PM on Sunday. I will keep an eye on this threat and will provide live coverage of this threat if needed.