A new storm system will bring impacts to the Northeast from Friday into Saturday, but similar to past storms this winter season, little to no wintry precipitation is expected. That’s because there hasn’t been a perfect setup for a winter storm. Sure, there’s been significant snows that has impacted the interior Northeast, but near the coast and across the I-95 corridor, snowfall has been lacking.
During a typical winter storm event for the Northeast, and especially for the I-95 corridor, you need a low pressure to form near the Southeast coast under a “digging” trough of low pressure. In this week’s setup, there will instead be a low pressure over the Gulf Coast states. There will be an upper-level trough above that low, but it won’t “dig” (when the trough becomes oriented from northwest to southeast). Instead, it will remain neutral while weakening, bringing the low to the north and east.
The track of the low pressure will also determine the placement of the warm and cold air. Typically, when a low pressure or nor’easter tracks offshore the East Coast, the low will just be far enough from the coast for the mild air from the ocean to not infiltrate, therefore allowing for snow to fall. Since this weekend’s low will track right over the coastline, too much mild air will flow in from the Atlantic Ocean.
Lastly, you need a cold air source. Sure, you may have a low pressure tracking over an optimal region, favorable for significant Northeast snow, but without cold, freezing air, the storm will be snow-less. The main source for this cold air is when there’s a high pressure over northern New England or southeastern Canada, directly north of the low pressure. Since high pressure rotates clockwise, that allows for the cold air to flow from south to north. This way when that cold air mixes with the precipitation from the low pressure near the coast, snow falls.
Now let’s talk specifics with this snow-less weekend storm: impacts will begin on Friday, especially in the afternoon and evening, as moisture begins to overspread into the Mid-Atlantic, bringing a light to moderate rain to areas south of the Mason-Dixon Line.
By overnight, however, we’ll see that steady rain impact more of the Mid-Atlantic and even southern New England. Most of this rain will be on the lighter side of the spectrum but some localized flash flooding cannot be ruled out given the saturated soil already in place. On the northern fringe of this precipitation, a pocket of a wintry mix cannot be ruled out across portions of central New York and New England, but impacts should be minimal and brief.
On Saturday, the low pressure will pull away from the coast thanks to the weakening trough in the upper levels of the atmosphere. Lingering rain showers can still be expected near the Mid-Atlantic coastline. In southern New England, it will be a pretty wet day with a moderate, steady rain lasting most — if not all — of the day. Also watch for some snow in parts of central New England, especially in the southern Green and White Mountains as well as along the coastline of Maine.
By Sunday, dry weather can be expected across most of the Northeast. As cooler temperatures flow in from the north and west, occasional light snow showers may be possible across interior portions of the region.