Exciting times ahead as we quickly approach this holiday weekend. An appetizer system moves through Friday, followed by the main course Sunday and for dessert on Monday, near zero temperatures. Let’s get right to it!
Below is a water vapor loop showing the current atmospheric pattern over most of the North American continent. Friday’s storm system is slowly organizing over southern Illinois, Indiana and Kentucky as it pushes east through the Ohio River valley. Looking a bit further west, Sunday’s storm is coming ashore along the northern California coastline. Note the key contrast between the two….which one looks more impressive? Hopefully you picked Sunday.
Thursday Morning Satellite – College of DuPage
Friday
Friday’s system fails to organize very well and is starved for moisture as it traverses the northeast. A light round of snow and rain will impact the region and potentially the Friday AM commute. Note: Sunday’s system is forming lee of the Rocky Mountains, even in its infant stages, it is already much more impressive than Friday.
Friday System Progression
I’m going to lean on the fine folks at the National Weather Service for the snowfall forecast. Friday’s storm is the appetizer anyway and let’s be real, appetizers are an afterthought when you’ve ordered prime rib for the main course.
Friday Snowfall – National Weather Service
Saturday
As Friday’s system departs, arctic high pressure will drop in from the northwest. This will act to establish a fresh supply of cold air. A cold air mass is much more stubborn and is very difficult to move. This will be key to the forecast for Sunday.
In the image below, high pressure drops in from Hudson’s Bay as low pressure organizes in the southern states.
Arctic High Pressure Moves In – WeatherBELL
As the system moves from west to east across the southern half of the United States, it will draw north a significant plume of Gulf of Mexico moisture. The loop below highlights available moisture in the atmosphere. Note how the plume of dark greens and blues is drawn north and makes its way all the way into southern New England.
Storm System Gather Moisture – PivotalWeather
Saturday Night -> Sunday
Saturday Night/Sunday Storm Progression – PivotalWeather
Snowfall will overspread the region from southwest to northeast during the evening hours Saturday night as the low pressure center moves through the Ohio River valley and off the New Jersey coastline. All locations start as snow.
During the early morning hours on Sunday, warmer air from the south will try to move in to New England. It’s progress will be slow as the cold air being reinforced by the arctic high pressure will put up a fight. Surface temperatures will likely stay below freezing longer than the air aloft; at or above 5,000 ft. Meaning that the snow will transition to sleet or freezing rain for a time. Eventually those locations in southern Connecticut, Rhode Island, and southeast Massachusetts will warm above freezing at the surface and transition to rain.
In terms of the progression of precipitation type during the storm, here is my current thinking:
Precipitation Type Forecast
Blue: All Snow
Red: Mainly Snow -> Sleet -> Ice -> Snow
Orange: Snow -> Sleet -> Ice -> Rain -> Snow
Green: Snow -> Sleet -> Rain -> Snow
Ok. Time for the main course. In terms of accumulated snowfall, here is what I am currently expecting:
Snowfall Forecast
Being that we are still 2-3 days away from the meat of the event, I’ve opted to paint a broader brush than usual. Small iterations in storm track could lend to large swings in ranges, particularly in southern New England. Compared to my counterparts at the National Weather Service, who continue to perform exemplary work despite the government shutdown, I may be a bit conservative.
National Weather Service Snowfall Forecast
Within that battle zone between cold air and warm, there is the chance for significant sleet & freezing rain to occur. This will likely fall on top of 6-12″ of snow, so the snow pack will develop a thick crust. Please be careful.
National Weather Service Ice Forecast
Monday
And on this weekends menu for dessert, near zero temperatures for Monday. Shoveling out Monday will likely not be the most enjoyable task ever. In addition to the foot of snow, temperatures near zero with wind chills even colder than that.
Surface Temperatures Monday AM – WeatherBELL
Update to forecast likely again tomorrow!
-Chris
Chris Hampton Weather 