Good evening from Southern Connecticut Weather.
You know you've got a real storm on your hands when snow is forecast all the way down to Florida. A developing storm system along a deep trough moving into the eastern U.S. is increasingly likely to thread the needle and track just close enough to bring snow up the east coast.
While the last few days have provided high "will it or won't it" drama, today's last minute trend has been so strong that there is now increased confidence that a significant hit in Connecticut is likely. We don't like going from not really talking about a system to a final call less than a day before a storm arrives, but sometimes in weather you really don't know how things are going to shake out until late, and sometimes, not at all.
There will be drama all the way to the end. True to form in tracking this one, this is a low confidence forecast with bust potential in both directions.
You know you've got a real storm on your hands when snow is forecast all the way down to Florida. A developing storm system along a deep trough moving into the eastern U.S. is increasingly likely to thread the needle and track just close enough to bring snow up the east coast.
While the last few days have provided high "will it or won't it" drama, today's last minute trend has been so strong that there is now increased confidence that a significant hit in Connecticut is likely. We don't like going from not really talking about a system to a final call less than a day before a storm arrives, but sometimes in weather you really don't know how things are going to shake out until late, and sometimes, not at all.
There will be drama all the way to the end. True to form in tracking this one, this is a low confidence forecast with bust potential in both directions.
Overall Setup
The setup actually isn't much different from what I wrote last Sunday, but the timing ended up a bit different with the trough sweeping into the eastern U.S. sparking primary storm development. This isn't a massive storm, but it is a significant one. As today's storm departs and our trough moves east it will start to try amplifying, and a system will develop at its base in the south.
For the first time, I am going to use AI graphics, and the image below comes from the European Model AI. While the normal GFS and Euro are major elements of the forecast, this is the first time that we've seen AI guidance lead the way in identifying and sticking to the most likely forecast. They simply had an impact in the region while the other guidance did not.
The setup actually isn't much different from what I wrote last Sunday, but the timing ended up a bit different with the trough sweeping into the eastern U.S. sparking primary storm development. This isn't a massive storm, but it is a significant one. As today's storm departs and our trough moves east it will start to try amplifying, and a system will develop at its base in the south.
For the first time, I am going to use AI graphics, and the image below comes from the European Model AI. While the normal GFS and Euro are major elements of the forecast, this is the first time that we've seen AI guidance lead the way in identifying and sticking to the most likely forecast. They simply had an impact in the region while the other guidance did not.
This is looking at energy at 500mb. There is a deep trough quickly moving toward the coast tomorrow, and at the bottom of it you see energy (the storm) beginning to develop. However, up in the northern Plains there is another piece of energy. This is a "kicker" that will keep the southern storm from bombing out and will keep things moving fast.
However, there is just enough spacing between the two lobes of energy and enough of a "curl" of the southern system energy to keep this close enough to the coast for snow.
However, there is just enough spacing between the two lobes of energy and enough of a "curl" of the southern system energy to keep this close enough to the coast for snow.
To be sure, this is not the epic storm that some tried to hype a week ago, but with the AI guidance leading the way, in the last 24 hours we've seen a significant trend by the operational (regular) models toward the AI evolution bringing snow up the entire east coast.
Here's the 12z European model and looking at the amount of moisture available below it, the 24 hour trend. It's just close enough to bring a significant system.
Here's the 12z European model and looking at the amount of moisture available below it, the 24 hour trend. It's just close enough to bring a significant system.
Timing
Once again, timing is tricky. The guidance agrees that we see light snow break out from SW to NE as the storm approaches, but it may come in two batches just like today. The first batch likely arrives between 6-9am. The expectation is that it'll be light to moderate, but if it's heavier or lighter this will influence the overall snowfall total.
There may very well be a similar lull during the afternoon, before the surface low races up the coastline and brings snow as early as mid-afternoon (around 2-3pm) and continuing through the night. The heaviest snow is likely between about 5-10pm. Snow would end in the predawn hours Monday, and most of Monday should be clear and cold.
Once again, timing is tricky. The guidance agrees that we see light snow break out from SW to NE as the storm approaches, but it may come in two batches just like today. The first batch likely arrives between 6-9am. The expectation is that it'll be light to moderate, but if it's heavier or lighter this will influence the overall snowfall total.
There may very well be a similar lull during the afternoon, before the surface low races up the coastline and brings snow as early as mid-afternoon (around 2-3pm) and continuing through the night. The heaviest snow is likely between about 5-10pm. Snow would end in the predawn hours Monday, and most of Monday should be clear and cold.
Above: the 12z Euro depiction of the storm. While this doesn't explicitly show a lull, other high resolution guidance shows a lighter period before the surface low gets closest to the region.
Snow & Ice Accumulation
Above is the snowfall map once again. I seriously considered making that 3-6" zone a 4-8" zone, but I don't have high enough confidence in widespread 6-8" to raise the ceiling. This snowfall map is all about track. A further west track would push heavier snow and more precipitation into the state. Further east, and we're struggling to meet the lower bound of the forecast. The morning batch will matter a lot, as more accumulation before the peak would raise our potential. If that's a bust, the rest of the day could be in trouble.
The temperature profile is marginal with the absence of a high to the north, but we shouldn't have the same issue that we did today in SE CT with everything torching and only rain falling. There shouldn't be as much southerly flow, especially as the coastal low passes by the region tomorrow afternoon and evening. If there is a morning period where southeast areas are warmer, the shift in wind as the coastal passes should allow for a flip to snow, though I still think we are all virtually all snow.
Wind & Power Outages
Overall, although this is a significant storm it is not windy. We don't have a high to the north (which would have kicked this out to sea most likely) and that means we don't have a pressure gradient to account for clashing with a modestly strong developing coastal low. With temperatures more marginal, it may be another pasty system at times, with higher ratio snow possible in the morning. Power outages are not expected.
Overall Impact
With the lack of a high to the north, the temperature profile looks similar to today, meaning snow falling in above freezing temperatures for at least part of the day. However, the expectation of higher rates means that we will see periods where the roads are slick. As a result, expect a moderate to high impact on the roads when it is snowing, and lesser impact if we do get that lull during the day.
The Sunday timing makes this lower impact, and the storm ending early Monday morning means that Monday should be fine. Overall, expect a moderate impact.
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
Above is the snowfall map once again. I seriously considered making that 3-6" zone a 4-8" zone, but I don't have high enough confidence in widespread 6-8" to raise the ceiling. This snowfall map is all about track. A further west track would push heavier snow and more precipitation into the state. Further east, and we're struggling to meet the lower bound of the forecast. The morning batch will matter a lot, as more accumulation before the peak would raise our potential. If that's a bust, the rest of the day could be in trouble.
The temperature profile is marginal with the absence of a high to the north, but we shouldn't have the same issue that we did today in SE CT with everything torching and only rain falling. There shouldn't be as much southerly flow, especially as the coastal low passes by the region tomorrow afternoon and evening. If there is a morning period where southeast areas are warmer, the shift in wind as the coastal passes should allow for a flip to snow, though I still think we are all virtually all snow.
Wind & Power Outages
Overall, although this is a significant storm it is not windy. We don't have a high to the north (which would have kicked this out to sea most likely) and that means we don't have a pressure gradient to account for clashing with a modestly strong developing coastal low. With temperatures more marginal, it may be another pasty system at times, with higher ratio snow possible in the morning. Power outages are not expected.
Overall Impact
With the lack of a high to the north, the temperature profile looks similar to today, meaning snow falling in above freezing temperatures for at least part of the day. However, the expectation of higher rates means that we will see periods where the roads are slick. As a result, expect a moderate to high impact on the roads when it is snowing, and lesser impact if we do get that lull during the day.
The Sunday timing makes this lower impact, and the storm ending early Monday morning means that Monday should be fine. Overall, expect a moderate impact.
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
