Good evening from Southern Connecticut Weather.
First, I want to take a moment to say THANK YOU to all of those who liked, shared, asked questions, and decided to follow SCW during and after the Blizzard of 2017. It was and always will be an honor to serve you and give you the information you need to make informed decisions.
Now, to business. When I wrote my two week outlook at the start of the month, I mentioned that week two could be more active but I had no idea which direction things would go. For those snow starved nutmeggers, what a turnaround!
First, I want to take a moment to say THANK YOU to all of those who liked, shared, asked questions, and decided to follow SCW during and after the Blizzard of 2017. It was and always will be an honor to serve you and give you the information you need to make informed decisions.
Now, to business. When I wrote my two week outlook at the start of the month, I mentioned that week two could be more active but I had no idea which direction things would go. For those snow starved nutmeggers, what a turnaround!
Connecticut is set to see more snow overnight tonight, but in this discussion, I am focusing on the potential for another major storm to impact much of Connecticut by the latter half of the weekend. The setup for this one is more complicated, and many factors are yet to be resolved.
What we know right now:
What we know right now:
- A significant winter weather event is becoming increasingly likely for Sunday into early Monday for much of the state.
- Unlike the last storm, precipitation type issues are more likely with snow, mix, and rain for various parts of the state.
- With a rapidly developing low, I am concerned about the wind potential Sunday into Monday.
Our first call reflects the fact that I think northern Connecticut is able to hang onto snow the longest, with colder temperatures from the surface and into the column above. The greatest confidence in a significant event is there. In the second zone, there is a battle between warmer solutions and colder ones, but the consensus thus far is for a moderate to significant snow event with mixing as well. Along southern Connecticut, we have our lowest zone, as the area goes from snow to mix to rain on most guidance.
Technical Discussion
This ain’t going to be an easy one to forecast. Unlike the last setup, where things were straight forward in the larger scheme of things, we’re talking about a lot of moving pieces here. I want to break it down piece by piece.
We get an area of low pressure that forms to the west of the region. It is a very weak low at first overall, but as it gets closer it begins to strengthen, especially in the upper levels.
This ain’t going to be an easy one to forecast. Unlike the last setup, where things were straight forward in the larger scheme of things, we’re talking about a lot of moving pieces here. I want to break it down piece by piece.
We get an area of low pressure that forms to the west of the region. It is a very weak low at first overall, but as it gets closer it begins to strengthen, especially in the upper levels.
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Note here, on the latest run of the GFS, how temperatures in advance of the low are marginal in the 850mb layer. This is a signal for problems with precipitation type, as there isn’t a really good cold air mass in place. Ahead of the low, precipitation breaks out. This is warm air advecting into the region and overrunning colder air at the surface. The result is precipitation...snow.
By Sunday afternoon, the GFS has snow falling in much of Connecticut. Note the mix and rain in southern Connecticut though. Temperatures matter. The faster the low develops and the further south the low goes the better in terms of getting a longer duration of snow.
As the low continues its slide east, the upper level lows explode. For the second time in a few days, we’re looking at a low to experience bombogenesis, a very fast intensification that happens sometimes as lows take advantage of favorable upper level and surface conditions. These upper level lows, at 500 and 700mb respectively, cause the development of a surface low on Sunday. This low pulls in cold air, changing many back to snow before precipitation shuts off Monday morning.
As the low continues its slide east, the upper level lows explode. For the second time in a few days, we’re looking at a low to experience bombogenesis, a very fast intensification that happens sometimes as lows take advantage of favorable upper level and surface conditions. These upper level lows, at 500 and 700mb respectively, cause the development of a surface low on Sunday. This low pulls in cold air, changing many back to snow before precipitation shuts off Monday morning.
If it happened sooner, cold air would rush in faster, resulting in a faster changeover. If that happened we would be talking about an even bigger event. The GFS shows bombing, but the Euro is more explosive.
That’s incredible. Probably even more impressive than our most recent storm. The Ukmet (fondly known as the Ukie to me) has a similar solution.
Ukie showing the pressure of this low going from 999mb to 970 in 12 hours. Incredible.
With a split in the guidance, it’s best to blend and look at the overall setup. Right now, I lean toward a more impactful event for more people--especially in north and central Connecticut. Very slight shifts in the track of the low and the temperatures at and just above the surface will make the difference in how impactful this becomes.
The last thing, which shouldn’t be ignored, is wind. With rapid intensification of this low, by Sunday night and Monday we may see very strong wind gusts. Some of the guidance show the strongest winds after precipitation falls. We’ll have to watch closely to make sure that is the case.
Currently, I think snow breaks out in Connecticut early on Sunday, with snow becoming more widespread and heavy by Sunday afternoon. Depending on the track and rate of strengthening by the low, the rain/mix/snow line will creep north during the day and evening hours before changing back to snow for most as the storm passes to our south and east. Overall, this is one to watch. This could be a moderate to high impact event across much of Connecticut.
Current odds—remember that this will change. I went to low odds to blizzard with the last storm!
With a split in the guidance, it’s best to blend and look at the overall setup. Right now, I lean toward a more impactful event for more people--especially in north and central Connecticut. Very slight shifts in the track of the low and the temperatures at and just above the surface will make the difference in how impactful this becomes.
The last thing, which shouldn’t be ignored, is wind. With rapid intensification of this low, by Sunday night and Monday we may see very strong wind gusts. Some of the guidance show the strongest winds after precipitation falls. We’ll have to watch closely to make sure that is the case.
Currently, I think snow breaks out in Connecticut early on Sunday, with snow becoming more widespread and heavy by Sunday afternoon. Depending on the track and rate of strengthening by the low, the rain/mix/snow line will creep north during the day and evening hours before changing back to snow for most as the storm passes to our south and east. Overall, this is one to watch. This could be a moderate to high impact event across much of Connecticut.
Current odds—remember that this will change. I went to low odds to blizzard with the last storm!
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Thank you for reading SCW!
-DB
Thank you for reading SCW!
-DB
