Good evening from Southern Connecticut Weather.
After our winter "thaw" the cold has returned to the region. Along with it comes the return of our fast flow regime, which is responsible for very fast moving systems that are unable to fully develop and intensify because the flow aloft is moving so fast. If the atmosphere were a highway, our storms would be going 30-40mph over the speed limit.
That makes for very tricky forecasting. Let's get right to it.
After our winter "thaw" the cold has returned to the region. Along with it comes the return of our fast flow regime, which is responsible for very fast moving systems that are unable to fully develop and intensify because the flow aloft is moving so fast. If the atmosphere were a highway, our storms would be going 30-40mph over the speed limit.
That makes for very tricky forecasting. Let's get right to it.
Above: the final call snowfall map. For most of the state, we expect a coating to 2" of snow. For parts of central, NE, and western CT, we expect 1-3". For parts of NW CT, we expect 2-5" but there is certainly a chance some areas could end up with 6".
Overall Setup
Fast flow. Lead wave on an amplifying trough (that will interfere with Sunday/Monday becoming a big storm). Very fast mover. That's been the general theme of the season so far minus the amplifying trough, and it doesn't really change here.
Overall Setup
Fast flow. Lead wave on an amplifying trough (that will interfere with Sunday/Monday becoming a big storm). Very fast mover. That's been the general theme of the season so far minus the amplifying trough, and it doesn't really change here.
Above: the GFS depiction of tomorrow's snow. This is the general evolution across guidance.
Note how quickly this weak system moves, and interestingly, how it brings a brief period of heavier snow over western CT while a good portion of southern and eastern CT are rain in the afternoon/evening. The timing is almost ideal in western CT with the initial burst of snow in the morning and early afternoon, while the track of this make it less than ideal in eastern CT. This is how you get a significant snowfall gradient.
Timing
If you are in western or central CT, basically the 2-5" and 1-3" zones, I would be prepared for snow to break out in the predawn hours of Saturday, likely between 2-6am. Because of the direction of the precipitation however, although this is a fast mover it will feel very slow moving if you are in eastern CT. Out there, snow probably arrives between 6-8am and then quickly departs. How far east the accumulating snow gets before weakening and how fast in the morning will help determine who the "winners and losers" are with this one in the accumulation department.
But for travel, timing gets even more tricky. The models generally show two distinct batches of precipitation. The first batch happens in the period noted above in the morning. Then in the late morning and early afternoon (10am to 2pm) the second batch arrives and moves from west to east.
Not only does this introduce warming in much of the state (especially the C-2" zone) it also means that folks may very well wake up between 8-10am and ask "is this it?" only to see more precipitation move in during the afternoon. Plan accordingly, especially in western CT.
In NW CT the break is most brief, but for the rest of the state, rain and/or snow will creep back in over the course of the afternoon and fully depart by about 7pm. Tricky to say the least.
Below is the 18z Euro depicting timing between approximately 1am and 7pm.
Note how quickly this weak system moves, and interestingly, how it brings a brief period of heavier snow over western CT while a good portion of southern and eastern CT are rain in the afternoon/evening. The timing is almost ideal in western CT with the initial burst of snow in the morning and early afternoon, while the track of this make it less than ideal in eastern CT. This is how you get a significant snowfall gradient.
Timing
If you are in western or central CT, basically the 2-5" and 1-3" zones, I would be prepared for snow to break out in the predawn hours of Saturday, likely between 2-6am. Because of the direction of the precipitation however, although this is a fast mover it will feel very slow moving if you are in eastern CT. Out there, snow probably arrives between 6-8am and then quickly departs. How far east the accumulating snow gets before weakening and how fast in the morning will help determine who the "winners and losers" are with this one in the accumulation department.
But for travel, timing gets even more tricky. The models generally show two distinct batches of precipitation. The first batch happens in the period noted above in the morning. Then in the late morning and early afternoon (10am to 2pm) the second batch arrives and moves from west to east.
Not only does this introduce warming in much of the state (especially the C-2" zone) it also means that folks may very well wake up between 8-10am and ask "is this it?" only to see more precipitation move in during the afternoon. Plan accordingly, especially in western CT.
In NW CT the break is most brief, but for the rest of the state, rain and/or snow will creep back in over the course of the afternoon and fully depart by about 7pm. Tricky to say the least.
Below is the 18z Euro depicting timing between approximately 1am and 7pm.
Snow & Ice Accumulation
The timing and evolution of the system make this very tricky in the snowfall accumulation department. With that lull and track of the storm to our west that introduces warmth that should cut down on snowfall accumulation. However, in NW CT where the best dynamics are you could be in store for a significant event.
In the 2-5" zone we expect things to be all snow. The snow may vary between paste and lighter high ratio snow when it is heaviest. Some spots could very well end up with a localized 6".
In the 1-3" zone we expect mostly snow, but in that lull when precipitation is lightest we may warm up enough to briefly change to rain until heavier precipitation moves in and flips you back to snow.
In the C-2" zone we expect snow to fall, but rain is likely as temperatures are most likely to rise above freezing here. The further west you are, and further north, the more likely you see accumulating snow.
Wind & Power Outages
We won't grade on this but for continuity sake let's talk about it. For most this is probably more on the pasty side of snowfall but we don't expect any significant wind with the system being so weak and power outages are not a concern at all.
Overall Impact
The timing makes this tricky. In NW CT, be prepared for widespread cancellations and delays. In the 1-3" zone, there will be periods where the roads may be slick, especially in the morning, but overall this looks fairly low impact. In the C-2" zone although some roads will be slick, this is nothing out of the ordinary in a Connecticut January. Take your time on the roads, give extra space between cars, and overall it should be low impact. Definitely shovel because in the wake of this system tomorrow night gets below freezing.
Then we watch Sunday...
As always, please like, share, and interact with us on our social media--on Facebook to share our discussions, and follow us on Twitter @southernctwx to retweet our posts. Hit the buttons below to join.
Thank you for reading SCW.
-DB
The timing and evolution of the system make this very tricky in the snowfall accumulation department. With that lull and track of the storm to our west that introduces warmth that should cut down on snowfall accumulation. However, in NW CT where the best dynamics are you could be in store for a significant event.
In the 2-5" zone we expect things to be all snow. The snow may vary between paste and lighter high ratio snow when it is heaviest. Some spots could very well end up with a localized 6".
In the 1-3" zone we expect mostly snow, but in that lull when precipitation is lightest we may warm up enough to briefly change to rain until heavier precipitation moves in and flips you back to snow.
In the C-2" zone we expect snow to fall, but rain is likely as temperatures are most likely to rise above freezing here. The further west you are, and further north, the more likely you see accumulating snow.
Wind & Power Outages
We won't grade on this but for continuity sake let's talk about it. For most this is probably more on the pasty side of snowfall but we don't expect any significant wind with the system being so weak and power outages are not a concern at all.
Overall Impact
The timing makes this tricky. In NW CT, be prepared for widespread cancellations and delays. In the 1-3" zone, there will be periods where the roads may be slick, especially in the morning, but overall this looks fairly low impact. In the C-2" zone although some roads will be slick, this is nothing out of the ordinary in a Connecticut January. Take your time on the roads, give extra space between cars, and overall it should be low impact. Definitely shovel because in the wake of this system tomorrow night gets below freezing.
Then we watch Sunday...
As always, please like, share, and interact with us on our social media--on Facebook to share our discussions, and follow us on Twitter @southernctwx to retweet our posts. Hit the buttons below to join.
Thank you for reading SCW.
-DB
