Good evening from Southern Connecticut Weather.
This has been one heck of a roller coaster ride, and we're just getting started. On Monday, in my forecast for the week ahead, I first used the term "explosive"
"What significantly adds intrigue is the AI version of these models. The AI has done very well in identifying medium range patterns this winter, and here, with more ridging in the west leading to better amplification of a storm this coming weekend, the result is explosive.
The AI GFS has been fairly consistent in developing a big storm that tracks over southern New England. This would bring a very significant storm with all precipitation types.
The AI Euro, which has also been excellent at identifying patterns and storm tracks so far this winter, also has an explosive setup. This model keeps the low off the coast, bringing another blockbuster storm to the region.
So what's right? Well, at this stage there's nothing to worry about or get excited about, yet.
It's too early to say what models have a better handle, but with the AI version of these models and legacy model ensembles showing the potential for a significant storm, I currently lean more toward a storm than a miss like last weekend. This one is worth watching."
From there, many of the models did the equivalent of sticking a finger in the air and waiting to see which way the wind blows. Well maybe not that bad, but the lack of any kind of consensus had us with "zero concern".
Then something remarkable happened.
Once there was a definitive trend, it was an all-timer of a trend. We went from miss to glancing blow to a blizzard in the meteorological equivalent of a snap of the fingers.
Now we have stabilized the trend and it's time for a final call.
This has been one heck of a roller coaster ride, and we're just getting started. On Monday, in my forecast for the week ahead, I first used the term "explosive"
"What significantly adds intrigue is the AI version of these models. The AI has done very well in identifying medium range patterns this winter, and here, with more ridging in the west leading to better amplification of a storm this coming weekend, the result is explosive.
The AI GFS has been fairly consistent in developing a big storm that tracks over southern New England. This would bring a very significant storm with all precipitation types.
The AI Euro, which has also been excellent at identifying patterns and storm tracks so far this winter, also has an explosive setup. This model keeps the low off the coast, bringing another blockbuster storm to the region.
So what's right? Well, at this stage there's nothing to worry about or get excited about, yet.
It's too early to say what models have a better handle, but with the AI version of these models and legacy model ensembles showing the potential for a significant storm, I currently lean more toward a storm than a miss like last weekend. This one is worth watching."
From there, many of the models did the equivalent of sticking a finger in the air and waiting to see which way the wind blows. Well maybe not that bad, but the lack of any kind of consensus had us with "zero concern".
Then something remarkable happened.
Once there was a definitive trend, it was an all-timer of a trend. We went from miss to glancing blow to a blizzard in the meteorological equivalent of a snap of the fingers.
Now we have stabilized the trend and it's time for a final call.
Above: the final call snowfall map. We are going with a general 16-24" statewide. Honestly, a good 12-24" forecast would have worked perfectly but my tired eyes wouldn't have been able to handle all the grief I would have gotten haha.
In all seriousness, however, we are going with an 8" range because we know from history that extreme banding can do extreme things. The Connecticut River Valley in northern CT is most likely to end up with the least amounts. Eastern CT, including SE CT, is most likely to reach the upper end of the forecast.
Overall Setup
I'm not going to spend too much time on the setup, but I do want to show you the trend gifs of how this changed.
Overall, our main piece of energy dives down from Canada and the Midwest. A ridge in the western U.S. and just enough upstream blocking will allow for disparate pieces of energy to phase, triggering truly explosive development once the phased energy moves off the coast.
As I said yesterday, previously guidance had projected a flatter ridge out west and more confluence to our north which would work in tandem to kick our storm out to sea or deliver a glancing blow. Those models were wrong in the medium range, and corrected massively in the short term. The exception here was the AI models, which did an exceptional job sniffing out this potential accurately.
The best way to see the change is by looking at the Euro legacy model, which has struggled. Here are approximately the last 2.5 days of runs. In the medium range it has nothing to a glancing blow, then you suddenly see it has a storm, and then eventually it agrees with the blizzard idea.
In all seriousness, however, we are going with an 8" range because we know from history that extreme banding can do extreme things. The Connecticut River Valley in northern CT is most likely to end up with the least amounts. Eastern CT, including SE CT, is most likely to reach the upper end of the forecast.
Overall Setup
I'm not going to spend too much time on the setup, but I do want to show you the trend gifs of how this changed.
Overall, our main piece of energy dives down from Canada and the Midwest. A ridge in the western U.S. and just enough upstream blocking will allow for disparate pieces of energy to phase, triggering truly explosive development once the phased energy moves off the coast.
As I said yesterday, previously guidance had projected a flatter ridge out west and more confluence to our north which would work in tandem to kick our storm out to sea or deliver a glancing blow. Those models were wrong in the medium range, and corrected massively in the short term. The exception here was the AI models, which did an exceptional job sniffing out this potential accurately.
The best way to see the change is by looking at the Euro legacy model, which has struggled. Here are approximately the last 2.5 days of runs. In the medium range it has nothing to a glancing blow, then you suddenly see it has a storm, and then eventually it agrees with the blizzard idea.
The Forecast
Timing
This may still be the toughest part of the forecast. I want to outline it very clear so everyone can understand the evolution of the storm. Let's start with the general start time:
Snowfall Accumulation
Timing
This may still be the toughest part of the forecast. I want to outline it very clear so everyone can understand the evolution of the storm. Let's start with the general start time:
- There may be light snow in the morning as we see some pre-storm convergence over the area. This should be light and not impact any morning activities around the state.
-
The storm truly arrives between 4-8pm from west to east
- If you are in western CT, expect a start time between about 4-6pm
- If you are in central CT, expect a start time between about 5-7pm
- If you are in eastern CT, expect a start time between about 6-8pm
- It looks like conditions will quickly deteriorate, meaning that you should expect moderate to heavy snow within an hour of the time it starts where you are. That is the time to get off the roads.
-
The worst of the storm looks to be from about 8pm on Sunday to 8am on Monday
- The worst wind will occur between about 12am Sunday and 12pm (noon) Monday. Wind will gradually diminish as the storm pulls away.
- The worst coastal flooding will coincide with the strongest wind gusts. Expect moderate flooding in the Coastal Flood Warning zone between 11pm Sunday and 5am Monday.
- Snow will continue through the day on Monday with snow transitioning to light snow around 4pm and snow fully exiting the state by around 10pm. This could be a few hours earlier if the storm moves a bit faster than expected.
- It is going to take a long time to dig out. Expect blowing and drifting snow and power outages to impact Tuesday and maybe even Wednesday for school and work.
Snowfall Accumulation
Above: the 18z GFS showing 700mb frontogenesis (banding) evolution over the storm. There is a huge signal for intense snowfall rates early Monday.
As you saw above, our forecast is for a general 16-24" of snow across the state. This is heavily dependent on how close the storm tracks to us, which will determine how much moisture gets pushed into the state. As of now, the numbers are extremely impressive.
As you saw above, our forecast is for a general 16-24" of snow across the state. This is heavily dependent on how close the storm tracks to us, which will determine how much moisture gets pushed into the state. As of now, the numbers are extremely impressive.
Above is the GFS, which took a step back at 18z in the CT River Valley, but still has 1.5 to over 2" of moisture coming from the storm. That would easily put everyone in the 1-2 foot range.
The National Blend of Models below has something similar.
The National Blend of Models below has something similar.
You will note though that there is this shadowing effect in the CT River Valley. This happens when you have massive easterly flow downsloping into the valley, limiting the amount of moisture wrung out. All this could be overcome with banding over the area, but watch out in places like Hartford and Windsor Locks. The risk is higher for a "bust" here.
Elsewhere, there's always the risk of subsidence (read: dry slotting) when you have extreme banding. Anything lower than 12" would be a bust in my book, and while the forecast is for 16-24" statewide, someone could very well end up with a lollipop of 30" if they get under extreme banding for longer than anticipated. Most probably end up in the 16-22" range, but we have ranges for a reason here. The bigger the storm, the bigger the range due to the unpredictable nature of banding.
Elsewhere, there's always the risk of subsidence (read: dry slotting) when you have extreme banding. Anything lower than 12" would be a bust in my book, and while the forecast is for 16-24" statewide, someone could very well end up with a lollipop of 30" if they get under extreme banding for longer than anticipated. Most probably end up in the 16-22" range, but we have ranges for a reason here. The bigger the storm, the bigger the range due to the unpredictable nature of banding.
Above: the AI GFS, which has by far been the best so far, showing how heavy banding moves into the state from our rapidly intensifying low pressure.
Folks, this is a blockbuster event. Thundersnow and snowfall rates that meet or exceed what we saw in the other huge winter storm this season is entirely possible.
Wind & Power Outages
Folks, this is a blockbuster event. Thundersnow and snowfall rates that meet or exceed what we saw in the other huge winter storm this season is entirely possible.
Wind & Power Outages
This storm is not going to be like anything we've seen recently.
Above you can see the high resolution NAM from earlier predicting incredibly strong sustained winds offshore and strong wind extending inland. The wind offshore will not fully translate on land. As we've already said, this is a blizzard. Don't get caught up in whether inland CT gets warnings officially, this is a blizzard if the winds verify. That means consistent winds over 35mph (need 3 consecutive hour observations of it), and visibility less than a quarter mile. Winds should easily top that.
Now I know this is the scariest part of the forecast for a lot of people, and I wish I could say our analysis suggests that wind won't be a problem, but I can't.
Snowfall consistency and ratios will probably oscillate with the banding, but remain in between true paste and pure fluff. With that in mind, the combination of snow on power lines and trees and high winds will be highly problematic.
We have two things working against us here. First, we have a rapidly intensifying low pressure. Visible satellite sometime Monday will reveal our storm looking more like a hurricane than any of the weak low pressures we've had this season with pressures expected to potentially drop into the 960s. That's incredibly powerful.
The second is the pressure gradient. There will be a very strong and sprawling high pressure to the north that will clash with our storm. That will produce big amounts of wind.
This is the GFS pressure anomaly below. Note how strong our low is (blue) and how strong our high is (1049mb in Canada). That's a massive gradient.
Above you can see the high resolution NAM from earlier predicting incredibly strong sustained winds offshore and strong wind extending inland. The wind offshore will not fully translate on land. As we've already said, this is a blizzard. Don't get caught up in whether inland CT gets warnings officially, this is a blizzard if the winds verify. That means consistent winds over 35mph (need 3 consecutive hour observations of it), and visibility less than a quarter mile. Winds should easily top that.
Now I know this is the scariest part of the forecast for a lot of people, and I wish I could say our analysis suggests that wind won't be a problem, but I can't.
Snowfall consistency and ratios will probably oscillate with the banding, but remain in between true paste and pure fluff. With that in mind, the combination of snow on power lines and trees and high winds will be highly problematic.
We have two things working against us here. First, we have a rapidly intensifying low pressure. Visible satellite sometime Monday will reveal our storm looking more like a hurricane than any of the weak low pressures we've had this season with pressures expected to potentially drop into the 960s. That's incredibly powerful.
The second is the pressure gradient. There will be a very strong and sprawling high pressure to the north that will clash with our storm. That will produce big amounts of wind.
This is the GFS pressure anomaly below. Note how strong our low is (blue) and how strong our high is (1049mb in Canada). That's a massive gradient.
So what does that mean for us?
In northern CT, our forecast is for maximum wind gusts of 40-50mph.
In southern CT, especially coastal sections, our forecast is for maximum wind gusts of 50-65mph.
Scattered to locally widespread power outages are anticipated.
Locally widespread means that some towns may have significant parts without power, while another town does not. We don't currently expect heavy wet snow, but along the coast it's always tricky, and with higher end winds that means if we see more paste down there we will have big power outages. This is definitely something to watch. The greatest risk for widespread outages is in southern and coastal CT, especially SE CT and our friends in Westerly.
Overall Impact
A high impact event is a lock, but the real question here is whether we see extreme impacts.
A bona fide blizzard is coming, and while we get those from time to time, the combination of high end snow, wind, and timing--especially since a lot of people still have significant snowpack from the last big storm just a few weeks ago, has me wondering if this is going to be an upper echelon storm.
The impact will be extreme on the roads. The only saving grace here is that the worst is overnight Sunday into Monday morning. The state will grind to a halt on Monday. The combination of drifting snow and high winds will make roads impassible statewide for a time Sunday night into Monday, and clean up will make Tuesday and even potentially Wednesday bad.
Power outages as mentioned above will be scattered to locally widespread. We're not expecting October 2011, so let's put that to rest, but there will likely be tens of thousands of outages, especially is snow is on the wetter side.
I also cannot emphasize enough how much high amounts of snow removal can impact the body and make generator use dangerous. Make sure you are using proper techniques when shoveling and do not take shoveling related cardiovascular issues lightly. If you use a generator, make sure you have it properly ventilated.
This is a serious storm. Do I think it'll be like 1978 or 2013, no, but this could easily be the worst winter storm for us in over a decade.
With the totality above, we expect this to be a high impact to locally extreme impact event.
Stay tuned and stay safe.
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
In northern CT, our forecast is for maximum wind gusts of 40-50mph.
In southern CT, especially coastal sections, our forecast is for maximum wind gusts of 50-65mph.
Scattered to locally widespread power outages are anticipated.
Locally widespread means that some towns may have significant parts without power, while another town does not. We don't currently expect heavy wet snow, but along the coast it's always tricky, and with higher end winds that means if we see more paste down there we will have big power outages. This is definitely something to watch. The greatest risk for widespread outages is in southern and coastal CT, especially SE CT and our friends in Westerly.
Overall Impact
A high impact event is a lock, but the real question here is whether we see extreme impacts.
A bona fide blizzard is coming, and while we get those from time to time, the combination of high end snow, wind, and timing--especially since a lot of people still have significant snowpack from the last big storm just a few weeks ago, has me wondering if this is going to be an upper echelon storm.
The impact will be extreme on the roads. The only saving grace here is that the worst is overnight Sunday into Monday morning. The state will grind to a halt on Monday. The combination of drifting snow and high winds will make roads impassible statewide for a time Sunday night into Monday, and clean up will make Tuesday and even potentially Wednesday bad.
Power outages as mentioned above will be scattered to locally widespread. We're not expecting October 2011, so let's put that to rest, but there will likely be tens of thousands of outages, especially is snow is on the wetter side.
I also cannot emphasize enough how much high amounts of snow removal can impact the body and make generator use dangerous. Make sure you are using proper techniques when shoveling and do not take shoveling related cardiovascular issues lightly. If you use a generator, make sure you have it properly ventilated.
This is a serious storm. Do I think it'll be like 1978 or 2013, no, but this could easily be the worst winter storm for us in over a decade.
With the totality above, we expect this to be a high impact to locally extreme impact event.
Stay tuned and stay safe.
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
