Good afternoon everyone! The time has come for me to publish my first weather forecast blog in nearly a year (1 year tomorrow was my last). Since I am putting together my forecast thoughts into a blog, that must mean that something exciting is in the cards right?
The image below is the upper atmospheric setup from 7 am this morning. The packet of energy that will evolve to become the Thursday storm system is located just off the Pacific west coast circled in blue. Over the next 2-3 days, this storm system will traverse the lower 48 states follow approximately along the red arrow. By the time that the storm reaches our New England it will evolve into a fast moving, power house of a storm system.
12-27-16 7:00 am 500 mb Heights & Vorticity
Fast forwarding to Wednesday evening at 7:00 pm, the very beginning of the storm system is just beginning to show up over western Tennessee. Meanwhile the original low pressure center that impacted the pacific northwest is slowly dying and drifting eastward across southern Canada.
12-28-16 7:00 pm Surface Depiction
Fast forwarding another 24 hours and what started as only a couple showers over western Tennessee has blossomed into a mature storm system over Cape Cod.
12-29-16 7:00 pm Surface Depiction
Now with a storm track of over Cape Cod to east of Boston harbor to the mid-Maine Coast, the dreaded rain/snow line is going to come in to play and will be the key factor in determining who gets the most snow. Someone located a few miles to the west of the rain/snow line is going to end up with a lot of snow.
Possible Timeline:
12-29-16 1:00 pm Simulated Radar w/precipitation type
Rain/snow moves into Southern New England from west to east Thursday mid-morning and early afternoon (Danbury, CT around 11 am; Boston, MA around 1 pm).
12-29-16 7:00 pm Simulated Radar w/precipitation type
By 7:00 pm the storm system is really starting to strengthen south of Montauk Point, Long Island and the precipitation rates across the region will follow suit. Between approximately 6 pm Thursday evening and 3 am Friday morning, rain and snow should fall at a rather intense clip.
Now the key to the whole forecast is how far north and west the rain/snow line progresses. Climatologically speaking, Routes 128 and 495 were constructed in such locations that these two road ways make for good markers of where the northwest progression of the rain/snow line often stops. It is in this region that the forecast will be the most difficult. A town such as Billerica could see 4″ of snow if the rain/snow line were to progress to 495 or the town could see 14″ if the rain/snow line halts at 128.
12-30-16 1:00 am Simulated Radar w/precipitation type
By 1:00 am on Friday the storm center has strengthened significantly into the low 970s mb and most locations outside of the Cape and Islands have flipped from rain to snow as cold air is wrapped into the system. It is around this period that we will have to watch for some potentially damaging wind gusts as the storm continues to strength and areas flip over to heavy wet snow. The image below is one model’s depiction of what the winds could look like around 1 am Friday morning.
12-30-16 1:00 am Winds
Very early Friday morning as the storm passes just east of Boston harbor we will have to keep an eye out for winds across eastern Southern New England on the order of 25-30 mph; with gusts up to 50 mph. These winds combined with the potential for heavy wet snowfall could cause a power outage or two. Just something to keep an eye out for.
12-30-16 7:00 am Simulated Radar w/precipitation type
By approximately 7 am Friday morning that storm system has pulled away to our northeast and the process of digging out will begin for many locations. Now those locations that remain all snow throughout the duration of the event will have a lot more to dig than others. Right now, this is my best guess of precipitation type:
Precipitation Type
And finally for my initial thoughts for how much:
Potential Snowfall Thursday afternoon into Friday morning
Very vague at the moment due to uncertainty of the rain/snow line and just how far north and west the heaviest precipitation gets. I will say that someone in the eastern half of the blue 8″+ category is going to see 18″ of snow from this. Just a matter of figuring out who.
-Chris
Chris Hampton Weather 