Meteorologists are closely monitoring two storms that could potentially come together and yield a big snowstorm in the northeastern United States late this week -- or skip over coastal areas altogether once again, continuing the mostly snowless pattern this winter.
Two cities - Baltimore, Maryland, and Islip, New York - did not experience any snow during the entire month of February for the first time ever. A trace of snow snuck in right at the end of the month in other cities like Philadelphia, but seasonal snow totals in the City of Brotherly Love are still pacing well below normal at 0.3 of an inch, or 2% of normal. Washington, D.C., has only picked up 0.6 of an inch of snow this entire winter thus far, or only 4% of normal.
The potential storm will follow a spring preview in the Northeast during the first part of this week -- and regardless of the exact scenario that plays out, AccuWeather meteorologists are expecting a nosedive in temperatures that will bring a sudden return of winter's cold.
The two storms, one tracking into Pacific Canada and another storm over the southern-central United States on Tuesday, will eventually merge over the northwestern Atlantic Ocean late this week.
This image over the Pacific Ocean and the western United States was taken on Tuesday morning, March 3, 2020. Swirls of clouds near the southeastern arm of Alaska and the portions of northwestern Mexico and the southwestern U.S. represent the two storms being watched for possible phasing into one big storm along the Atlantic coast on Friday. (NOAA / GOES-West)
How fast and how close to the U.S. coast that merge occurs to form one powerful storm will determine how far west heavy, accumulating snow and strong winds extend in the northeastern U.S. and southeastern Canada.
The first scenario is that these two storms merge, but they would do so too late and too far away from the Northeast coast to produce a substantial snowfall. Even in this scenario, some snow would still sweep through parts of the Northeastern states as one weak storm shifts eastward.
The Pacific storm, which will essentially become an Alberta clipper system by midweek, is forecast to roll into the Great Lakes region on Thursday and then the Northeast on Friday.
"Regardless of how the two storms later merge, the clipper storm will produce snow showers as it moves along," AccuWeather Chief On-Air Meteorologist Bernie Rayno said.
The Upper Midwest to the central Appalachians and interior Northeast will face snow showers from the clipper, which may produce enough accumulation to create slippery travel, especially where snow falls from the late afternoon to the early morning hours.
The clipper storm will bring a batch of cold air with it, bringing an end to the spring preview the Northeast is feeling early this week, and winds will increase as the cold air infiltrates the region.
Temperatures will plunge by 15 to 20 degrees Fahrenheit Thursday into Friday.
The cold air and gusty winds will sweep in regardless of whether or not the two storms phase into one big storm. If it were not for the clipper storm in the first place, then air probably would not become cold enough for snow in the coastal Northeast.
"At this time, the most likely scenario is for snow showers to sweep from the Great Lakes toward the Interstate 95 corridor of the Northeast during Friday and Friday night," Rayno said.
"Steady snow may develop over southeastern New England, even with the delayed-phasing idea," he added.
In a second scenario, the storms could phase together quickly near the coast. This near-coast storm scenario could bring nor'easter conditions with high winds, coastal flooding and major travel disruptions.
In this case, heavy precipitation could be thrown westward to the I-95 corridor from Philadelphia to New York City and Boston, where a snow drought has kept a firm grip thus far.
"Even if the two storms stay relatively separate into Friday, an arm of precipitation, in the form of rain and snow, may extend westward from the storm at sea and could brush the upper mid-Atlantic and southeastern part of New England," Rayno explained.
In any case, the storms may produce significant snow over part of Canada from Nova Scotia to Newfoundland early this weekend.
AccuWeather meteorologists will continue to monitor both storms as they move across North America for any signs of phasing near the Atlantic coast this week.
One key component for the big, near-coast storm scenario has been missing all winter. That is the lack of an area of persistent high pressure at most levels of the atmosphere near Greenland. This setup, known as the Greenland block, when present, assists in explosive strengthening of storms close to the Northeast coast of the U.S. When not present, storms may still strengthen, but they tend to move along very quickly and may not have time to bring the big snow scenario to the I-95.
During most of this winter, the polar vortex has remained strong and contained near the Arctic Circle. It is during episodes when the polar vortex weakens that the jet stream becomes convoluted and patterns such as the Greenland block can develop. These same episodes can bring widespread severe cold weather outbreaks.
Even if this particular setup late this week does not bring about the big storm scenario, there may be another opportunity or two as the month progresses.
The upcoming pattern suggests that a similar setup could develop a week later as the jet stream develops large buckles over the Lower 48 states.
These big buckles, referred to as closed-off storms in the jet stream, are not uncommon during March and April and can produce heavy snow in localized areas. Such a pattern can occur even if the polar vortex remains strong and well to the north.
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