For over two weeks now, we have suggested in our Sunday Storm article how a significant pattern change will take place during the mid- to late- January time period. Often with a pattern change of this magnitude, a significant storm will be involved, that is certainly the case for this weekend. The forecast confidence in this storm has gone up, meaning that we have a better idea of how this storm will evolve, but as with every forecast, the outcome is never 100% clear. Nevertheless, let’s take a dive into our current analysis of this exciting, and significant, winter storm.
Low pressure will begin to form tonight on the leeward side of the Colorado Rockies. Known as ‘Lee Cyclogensis,’ the leeward side of the Rockies is a common region where we see the formation of low pressure. It’s this low that will be responsible for this weekend’s weather from the Plains through the Northeast. Along with the development of this low pressure will be some moisture and cold air, therefore making for a swath of light to moderate snow across the Colorado Rockies and in parts of the northern Plains Thursday night.
On Friday, we’ll watch the same low pressure track in a general eastward direction. As more moisture coming all the way from the Gulf of Mexico and even the eastern Pacific Ocean interacts with the cold air being drawn down from the north by the strong high pressure, more snow will break out. Snow is forecast to fall during the day Friday from the northern Plains through portions of the Midwest, including parts of Minnesota, Iowa, Missouri, Wisconsin, and Illinois. The best risk for heavier snow will be in the greater Omaha and Des Moines areas.
Now overnight Friday, our storm will continue to intensify. We expect a light to moderate snow to work into the southern Great Lakes region and southern parts of the Midwest, well north and west of the Ohio River Valley. Based on the latest model data, there is the possibility for a band of heavier snow affecting the area from central Missouri through northern Ohio. There will also be some gusty winds mixed with this snow, so lowered visibility can definitely be expected among various locales. Just to the south of that heavy band will be the rain/snow line, where some freezing rain will be possible (see map below for details).
What will be interesting to watch on Saturday is the cold air trying to take over the backside of the low pressure, thus causing some areas to the south to experience a drastic change from rain to a period of snow. That includes the southern Plains (as far south as the Red River Valley) and the Mid-Mississippi River Valley.
Now overnight Saturday is when our attention shifts to the Northeast. We want to make clear that the exact track of this low pressure is still not completely set in stone, so if the low pressure were to track farther south than currently expected, then that will shift the snowfall area a bit.
Saturday night, snow will expand into northern portions of the Mid-Atlantic and all of New England, although Cape Cod may deal with a wintry mix or rain due to its close proximity to the ocean. The snow will be coming down quite heavily northern Pennsylvania through northern New England during this time period. Snowfall rates will exceed 1 inch per hour, and perhaps 2(!) inches per hour at times. This is why we expect a fairly widespread area of 20-30 inches of snow in northern New England and 14-20 inches in the northern Mid-Atlantic. Yes, you read that correctly.
Meanwhile closer to the coast, we currently anticipate a significant icing event from southern and eastern Pennsylvania through most of southern New England Saturday night, especially just inland and away from the imminent coastline. The icing that this region may experience could be very troublesome, with 7/10 of an inch of ice accretion forecast. Roads quickly become impassable with ice accretion, and if too much ice accretes, power lines and tree branches begin coming down, thus this will be perhaps the most serious (and less talked about) threat associated with this storm.
In the I-95 corridor, from generally central New Jersey southward, this will mainly be a rain event. We cannot rule out a brief changeover to snow early-Sunday morning through the first few daylight hours of Sunday, however.
By Sunday, the worst of this storm should be over for most areas, but parts of the northern New England may still be getting slammed with heavy snow and gusty winds, which may knock out power for some. Meanwhile in southern New England and even parts of the New York City Tri-State Area, freezing rain may still be falling. Please avoid travel and just hunker down in your house because conditions outside could be very dangerous. We’ll also see lingering snow showers across the northern Mid-Atlantic before it ends by the evening.
Sunday night, New England may still be dealing with impacts from this major winter storm. As the cold air comes crashing in from the north and west, a final round of snow could be possible throughout the region. Occasional light snow showers will remain in the forecast in New England through Monday while near the Great Lakes the cold air will fuel lake-effect snow.
A big story behind this storm will be the cold air, so if the power goes out, this will make the situation even worse because of low temperatures. Monday morning will be sub-zero or in the single-digits for much of the Northeast. Stay safe out there! We’ll be sure to update our analysis in tomorrow’s Morning Briefing (which you should totally subscribe to here).