WEATHER

NJTV News Weather: Potential for Major Snowstorm Friday-Sunday

The 7 p.m. Friday 500mb map shows the upper level low "cut off" over Kentucky, identified by the anomalous closed black contours. Notice the winds do not follow their normal west to east progression across the country as they reach the cutoff low. This feature will slow and stall the surface low, resulting in a long duration snowstorm for the East Coast.

The 7 p.m. Friday 500mb map shows the upper level low “cut off” over Kentucky, identified by the anomalous closed black contours. Notice the winds do not follow their normal west to east progression across the country as they reach the cutoff low. This feature will slow and stall the surface low, resulting in a long duration snowstorm for the East Coast.

By John Cifelli
NJTV News Meteorologist

Almost exactly one year ago, New Jersey was bracing for a “historic” snowstorm, primed to cripple the state for days under mountains of wind-driven heavy snow. We can recall what actually happened — the storm developed later and further north. Northern New Jersey saw double digit snow totals and Boston caught the brunt of it, having a pile of removed snow so large that it didn’t melt until mid-summer. Statewide, however, the predictions of snow to be measured in feet fell woefully short, and the historic snowstorm was replaced by a historic busted forecast.

One year later, we find ourselves in a similar situation. The warning flags are up. A major East Coast snowstorm likely qualifying as a blizzard is expected to thrash New Jersey beginning Friday night, and lasting through Sunday. Although the ghost of January 2015 still haunts the corners of this forecaster’s mind, there are some important differences in the set-up that preclude this system from not delivering a wintry wallop worthy of the “historic” moniker once again.

As we speak, our weekend storm is plowing into the Pacific Northwest, busting California’s drought like it was everybody’s business. As the low pressure center slides across the Rocky Mountains tomorrow, a “Pacific/North American” ridge will develop in its wake. This strong ridge of high pressure over the West Coast will shunt the emerging surface low into a downstream trough over the southern Plains by Thursday morning. This marks the main contrast between this weekend’s scenario and January 2015. Last year, we were waiting for the storm to develop and strengthen off the East Coast. This time around, the beast is already born days in advance. All that’s left is to figure out where it tracks, which is always the critical question for New Jersey snowstorms.

The potent upper level trough deepens to the point that the upper level low embedded within will become “cut off” from the flow late Thursday. This phenomenon can be thought of like a rush of water in a stream — the burst of strong flow can create an eddy that will drift off, spiraling on its own into deeper water until it dissipates. Friday, the same scenario plays out aloft over the mid-Atlantic, and the resulting surface weather will be a powerful coastal cyclone, nearly stalled in its movement, affecting a large swath of the eastern United States. When and where the upper level low cuts off will dictate the surface low placement, as well as the duration of the event. An earlier cutoff and the storm will struggle to lift north and exhaust its best dynamics over the lower mid-Atlantic. This would spell less snow and wind for northern New Jersey and points north. A later cutoff and the surface low creeps further north, but this scenario may introduce precipitation type issues in southern New Jersey and along the coast.

For now, the likelihood of a major snowstorm to impact New Jersey this weekend is about as high as it gets being three and a half days out. Snow will be heavy at times as early as Friday evening, and linger past nightfall on Saturday. Winds will be noticeable statewide and strong along the coast. Coupled with a full moon, there is a real threat of coastal and back bay flooding, as well as coastal erosion. High tide is around 7 a.m. and p.m. on Saturday, and those times will bear careful watching.

My first snowfall map will be issued tomorrow, but for now, I’ll just say that the possibility of measuring over a foot of snow when day breaks on Sunday is in the cards. Being this far out, it is inappropriate to commit any further. There are good reasons that 12+ inch snowstorms don’t happen more than a couple times a decade. It’s really difficult to get them to come together, even when there is strong model consensus and a favorable pattern four days out. Tune the snow blower, make sure you have your emergency materials accessible and ready and avoid the food store on Friday if at all possible!