Good evening from Southern Connecticut Weather.
Extreme temperature regimes can trigger extreme atmospheric responses as the planet seeks balance. A high end blast of cold in both geographic scope and intensity is poised to trigger the development of a blockbuster storm that may be historic in parts of the south. While the overall pattern has been visible for a while now, we are getting into the range where we can project just how the dominoes will fall. For us, it means big cold and an increasing chance of big snow.
We're talking over double digits (10"+) statewide.
While there is still uncertainty over the overall track and evolution of the storm, it's time to take a first look at what we're seeing with more detail.
If the forecast holds, you can expect a first call forecast Friday and final call forecast Saturday.
Extreme temperature regimes can trigger extreme atmospheric responses as the planet seeks balance. A high end blast of cold in both geographic scope and intensity is poised to trigger the development of a blockbuster storm that may be historic in parts of the south. While the overall pattern has been visible for a while now, we are getting into the range where we can project just how the dominoes will fall. For us, it means big cold and an increasing chance of big snow.
We're talking over double digits (10"+) statewide.
While there is still uncertainty over the overall track and evolution of the storm, it's time to take a first look at what we're seeing with more detail.
If the forecast holds, you can expect a first call forecast Friday and final call forecast Saturday.
Above: the 12z European model depiction of the weekend storm. The trend has been your friend if you like winter weather, as the entire synoptic (large scale) pattern forces the development of this sprawling storm.
Overall Setup
It all starts with the cold. This is not run of the mill cold, as we've been saying for days now. This is extreme cold directly from the Arctic, and is barely modified as it gets displaced into the central United States.
Overall Setup
It all starts with the cold. This is not run of the mill cold, as we've been saying for days now. This is extreme cold directly from the Arctic, and is barely modified as it gets displaced into the central United States.
Above: the 12z European model depiction of 850mb temperatures. Note how the cold begins in the Arctic and plunges all the way down to the Gulf coast. This is the first step in triggering our storm.
As the big cold dome bulldozes its way into the U.S., the temperature contrast between the cold and Gulf warmth creates a baroclinic boundary. Overrunning is a typical thing that can happen in any season, but in this case, the extreme nature and scale of the cold means it won't take much to trigger a truly massive overrunning setup.
As the big cold dome bulldozes its way into the U.S., the temperature contrast between the cold and Gulf warmth creates a baroclinic boundary. Overrunning is a typical thing that can happen in any season, but in this case, the extreme nature and scale of the cold means it won't take much to trigger a truly massive overrunning setup.
Above: explanation of overrunning generally. Image courtesy of PNI Atlantic News.
Our trigger goes off on Friday, and then it's off to the races.
Our trigger goes off on Friday, and then it's off to the races.
Now, many will ask at this point: "we're expecting Arctic air this weekend, won't that make it too cold to snow?"
Normally, this kind of Arctic dome would be suppressive, and early on, the models (interestingly not the AI though) believed that this would be the case. However, there's more to this story. Yes, it looked like the cold press would be too much, but then we started seeing a trend at 500mb.
Normally, this kind of Arctic dome would be suppressive, and early on, the models (interestingly not the AI though) believed that this would be the case. However, there's more to this story. Yes, it looked like the cold press would be too much, but then we started seeing a trend at 500mb.
Above: European ensemble trend at 500mb. This is looking at the last couple days of runs.
It's subtle, but look at the energy over the southwest, and the energy in the northern Plains. Initially, the models on balance had these separated, creating more confluence over our region. That would have zipped this storm along and out to sea. However, the trend has emphatically tried to phase these two pieces. This is where the explosive potential for us comes into play, because if there is a full phase it triggers a bit coastal storm.
However, as it stands the imperfect interaction between these pieces of energy pumps heights in the east, forcing a further north track of a relatively weak coastal storm. The storm is enhanced by the overall setup. It doesn't need the phase to produce a major event from the south to Maine.
Below is the trend as we've seen the changes at 500mb. Big, big changes.
It's subtle, but look at the energy over the southwest, and the energy in the northern Plains. Initially, the models on balance had these separated, creating more confluence over our region. That would have zipped this storm along and out to sea. However, the trend has emphatically tried to phase these two pieces. This is where the explosive potential for us comes into play, because if there is a full phase it triggers a bit coastal storm.
However, as it stands the imperfect interaction between these pieces of energy pumps heights in the east, forcing a further north track of a relatively weak coastal storm. The storm is enhanced by the overall setup. It doesn't need the phase to produce a major event from the south to Maine.
Below is the trend as we've seen the changes at 500mb. Big, big changes.
Current Thoughts
With this change at 500mb across the guidance, there is higher than usual confidence that a major winter storm will hit the state. In fact, there is a cross guidance signal now that even puts some very robust totals in play on the ensembles. While a full phase would up the ante even more, the setup as it stands is high end.
Timing
Snow accumulation
Impact
To be clear, nothing is fully locked in at this time. While a storm is likely, there is still room for this storm to shift north, which could introduce mixing in southern CT after an initial thump of snow, or the storm could shift south, reducing totals. There's also the chance of more phasing of the two pieces of energy, which would raise the snow potential even more.
The bottom line is that a blockbuster storm is on the table for much of the east, and between the Sunday snow and Arctic blast this weekend, we have a highly disruptive period on tap.
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
With this change at 500mb across the guidance, there is higher than usual confidence that a major winter storm will hit the state. In fact, there is a cross guidance signal now that even puts some very robust totals in play on the ensembles. While a full phase would up the ante even more, the setup as it stands is high end.
Timing
- The current expectation is that the snow starts in the predawn hours on Sunday.
- The worst of the storm is possibly Sunday afternoon-Sunday night, with snow ending Monday morning or afternoon.
Snow accumulation
- Double digit snow statewide is increasingly likely.
- It's still too early for specific numbers, but this looks to be a higher end snowfall.
Impact
- The national scope of the storm means that there will be major travel disruptions from the weekend into early next week.
- This looks like a high impact event in Connecticut with widespread cancellations Sunday and Monday.
- Wind and power outages look to be low risk at this time.
To be clear, nothing is fully locked in at this time. While a storm is likely, there is still room for this storm to shift north, which could introduce mixing in southern CT after an initial thump of snow, or the storm could shift south, reducing totals. There's also the chance of more phasing of the two pieces of energy, which would raise the snow potential even more.
The bottom line is that a blockbuster storm is on the table for much of the east, and between the Sunday snow and Arctic blast this weekend, we have a highly disruptive period on tap.
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
