Good evening from Southern Connecticut Weather.
It has been quite a stretch. Winter 2022-23 never arrived and left much of the region with historic warmth and a near snowless season relative to climatology. That carried over into December 2023, which had no measurable snow and was the second warmest on record.
Like much of the northeast and Mid-Atlantic, both Hartford and Bridgeport official reporting stations have seen long snow droughts--periods without an inch (or two) of daily snowfall. For Hartford it's a top 10 recorded streak and for Bridgeport it's top two.
During that blowtorch December however we preached patience, and although it's understandable if snow lovers don't get excited until snow actually falls, a significant winter storm--statewide--is increasingly likely this weekend.
It has been quite a stretch. Winter 2022-23 never arrived and left much of the region with historic warmth and a near snowless season relative to climatology. That carried over into December 2023, which had no measurable snow and was the second warmest on record.
Like much of the northeast and Mid-Atlantic, both Hartford and Bridgeport official reporting stations have seen long snow droughts--periods without an inch (or two) of daily snowfall. For Hartford it's a top 10 recorded streak and for Bridgeport it's top two.
During that blowtorch December however we preached patience, and although it's understandable if snow lovers don't get excited until snow actually falls, a significant winter storm--statewide--is increasingly likely this weekend.
Above: European Ensemble depiction of the 500mb progression of the storm Saturday and Sunday. Note how the system scoots under New England, making it more likely this is a cold system with little mixing.
Heads Up for Thursday
Before talking about the weekend, we need to talk about tomorrow morning. If you recall, on Monday I flagged the potential for some light rain or snow Thursday as another system passes well to our south. I said that timing would be important for whether we'd see rain or snow, if anything.
Today the high resolution models and global models have moved back to the idea that there's enough moisture and forcing available to allow for light snow in parts of the state tomorrow morning. In fact, the latest European run shows the potential for a little minor accumulation with snow falling as most away from the shoreline are below freezing.
No matter where you are, watch out for potential light snow tomorrow morning between 5-10am. We don't expect much. If you get snow over you a coating to an inch is possible, but we've seen how the sneaky minor "events" become far more impactful because people aren't prepared. Be careful on the roads tomorrow morning if there's precipitation around.
The Euro and high resolution guidance showing a short term forecast of light snow falling in the upper 20s to low 30s as everyone is focused on the weekend has me perked up. Take note.
Heads Up for Thursday
Before talking about the weekend, we need to talk about tomorrow morning. If you recall, on Monday I flagged the potential for some light rain or snow Thursday as another system passes well to our south. I said that timing would be important for whether we'd see rain or snow, if anything.
Today the high resolution models and global models have moved back to the idea that there's enough moisture and forcing available to allow for light snow in parts of the state tomorrow morning. In fact, the latest European run shows the potential for a little minor accumulation with snow falling as most away from the shoreline are below freezing.
No matter where you are, watch out for potential light snow tomorrow morning between 5-10am. We don't expect much. If you get snow over you a coating to an inch is possible, but we've seen how the sneaky minor "events" become far more impactful because people aren't prepared. Be careful on the roads tomorrow morning if there's precipitation around.
The Euro and high resolution guidance showing a short term forecast of light snow falling in the upper 20s to low 30s as everyone is focused on the weekend has me perked up. Take note.
Above: the latest high resolution HRRR which has been consistent today in bringing a narrow stripe of snow over the state tomorrow morning. This is the depiction at 7am.
Below: the 18z Euro, which is even more robust, with most seeing light snow at 7am. Not much is expected, but note the blue line--virtually all of the state is below freezing and if this moves in pre sunrise it could get slick quickly.
Below: the 18z Euro, which is even more robust, with most seeing light snow at 7am. Not much is expected, but note the blue line--virtually all of the state is below freezing and if this moves in pre sunrise it could get slick quickly.
Weekend Winter Storm
Alright, now to the main attraction. Snow is coming. Aside from the novelty of a snowstorm during a period of literally historic lack of winter, this looks like a legitimate event.
Originally the signal for this storm appeared in late December, so we have been quietly tracking it for a while. This weekend the signal grew strong enough for us to consider the possibility of a storm, and now we're at the stage where it's time to start discussing details.
The overall setup
If you've been following the Facebook posts, the setup is fairly straightforward on a synoptic (global) scale. Our system is rocketing across the western US today, which may be helping the guidance start to converge on a solution. As it approaches the south on Friday and Saturday, the system will begin to transfer and organize off the east coast. It will start moving up the coast, impacting the Mid-Atlantic on Saturday. Unlike last year, cold will be in place for this one. We have a high pressure area to the north that will bring in colder air starting tomorrow night.
The main questions we had with this system were 1) how close does the surface low and associated lows aloft track to CT and 2) how strong/organized/dynamic is the system.
With last night's and today's model suites, we have a better sense of the environment and are starting to narrow the forecast down.
Timing--High Confidence
It looks pretty straightforward that the onset of the snow happens late Saturday from SW to NE. The guidance has been essentially in lockstep on this part and we have no reason to discount it. While it may start out as a mix in coastal CT, temperature profiles look robust for cold staying locked into the region during the duration of this event.
What does that mean? Snow probably begins between 7pm and 11pm from SW to NE. It may start off as a mix in coastal CT, but by early morning Sunday virtually everyone is snow. Because the vort (area of vorticity) doesn't look as organized a trailing piece of energy tries to phase or combine with the lead wave during the event. This is a complicated interaction but what's important to know is that it increases the likelihood that snow falls all day Sunday.
The snow departs Sunday night and Monday should be fine. Sorry teachers and students.
Here's the GFS and Euro depictions of the coming storm at approximately 7pm Saturday. The day and part of the evening should be fine for travel and events.
GFS
Alright, now to the main attraction. Snow is coming. Aside from the novelty of a snowstorm during a period of literally historic lack of winter, this looks like a legitimate event.
Originally the signal for this storm appeared in late December, so we have been quietly tracking it for a while. This weekend the signal grew strong enough for us to consider the possibility of a storm, and now we're at the stage where it's time to start discussing details.
The overall setup
If you've been following the Facebook posts, the setup is fairly straightforward on a synoptic (global) scale. Our system is rocketing across the western US today, which may be helping the guidance start to converge on a solution. As it approaches the south on Friday and Saturday, the system will begin to transfer and organize off the east coast. It will start moving up the coast, impacting the Mid-Atlantic on Saturday. Unlike last year, cold will be in place for this one. We have a high pressure area to the north that will bring in colder air starting tomorrow night.
The main questions we had with this system were 1) how close does the surface low and associated lows aloft track to CT and 2) how strong/organized/dynamic is the system.
With last night's and today's model suites, we have a better sense of the environment and are starting to narrow the forecast down.
Timing--High Confidence
It looks pretty straightforward that the onset of the snow happens late Saturday from SW to NE. The guidance has been essentially in lockstep on this part and we have no reason to discount it. While it may start out as a mix in coastal CT, temperature profiles look robust for cold staying locked into the region during the duration of this event.
What does that mean? Snow probably begins between 7pm and 11pm from SW to NE. It may start off as a mix in coastal CT, but by early morning Sunday virtually everyone is snow. Because the vort (area of vorticity) doesn't look as organized a trailing piece of energy tries to phase or combine with the lead wave during the event. This is a complicated interaction but what's important to know is that it increases the likelihood that snow falls all day Sunday.
The snow departs Sunday night and Monday should be fine. Sorry teachers and students.
Here's the GFS and Euro depictions of the coming storm at approximately 7pm Saturday. The day and part of the evening should be fine for travel and events.
GFS
Euro
Precipitation Type--High Confidence
As I mentioned above, this looks to be mostly to all snow. Why? High pressure. Originally, there were questions on how much high pressure influence we'd see. Higher influence would have suppressed this south, while the absence of a high would have torched the column and surface, allowing this to become another high precipitation rain event.
With more confidence on the mid-level setup, we see that for most of CT this looks like an all snow event. As is usually the case however, the immediate coastline may have some mixing at the start. Even so, the presence of a cold high to the north should keep the area mostly snow, as long as the track doesn't shift so far north as to warm the coast too much. Right now that looks like a low likelihood, but it's something we always watch.
Here is a GFS sounding of the Groton area at around 7am on Sunday. The GFS has been the warmest model and this sounding has snow falling all the way to the surface even with a marginal surface temperature. This is probably too warm at the surface, and if it's snowing in Groton, it's snowing everywhere else along the shoreline.
As I mentioned above, this looks to be mostly to all snow. Why? High pressure. Originally, there were questions on how much high pressure influence we'd see. Higher influence would have suppressed this south, while the absence of a high would have torched the column and surface, allowing this to become another high precipitation rain event.
With more confidence on the mid-level setup, we see that for most of CT this looks like an all snow event. As is usually the case however, the immediate coastline may have some mixing at the start. Even so, the presence of a cold high to the north should keep the area mostly snow, as long as the track doesn't shift so far north as to warm the coast too much. Right now that looks like a low likelihood, but it's something we always watch.
Here is a GFS sounding of the Groton area at around 7am on Sunday. The GFS has been the warmest model and this sounding has snow falling all the way to the surface even with a marginal surface temperature. This is probably too warm at the surface, and if it's snowing in Groton, it's snowing everywhere else along the shoreline.
The risk here is that a weaker and less organized low would bring lighter precipitation and warmer temperatures as we don't get dynamic cooling. That would be a fail mode for the shoreline but currently it doesn't look likely.
Snow Accumulation & Impact
This is what everyone cares about--how much snow in their backyard. With the caveat that there's still a lot to sort out in details like storm intensity, wind potential, banding, and snow ratios, this looks like a significant snowstorm. Even at the shoreline.
As a reminder, for most of Connecticut the threshold for a winter storm warning is generally 6" of snow and 7" in Litchfield County, which on average gets the most snow in the state because of elevation and favorable banding location.
Right now we are looking conservatively at 5-10" of snow statewide. The floor has been rising with this one, so when we make our first call snow map tomorrow it's more likely that the numbers are higher than it is we cut them.
The greatest chance for double digit snowfall looks to be in eastern CT at this time and minimum at the immediate shoreline, but both the maximum and minimum zones are still abstract for now.
Looking at the totality of the information, a significant to major snowfall is legitimately on the table.
Stay tuned for additional updates.
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
Snow Accumulation & Impact
This is what everyone cares about--how much snow in their backyard. With the caveat that there's still a lot to sort out in details like storm intensity, wind potential, banding, and snow ratios, this looks like a significant snowstorm. Even at the shoreline.
As a reminder, for most of Connecticut the threshold for a winter storm warning is generally 6" of snow and 7" in Litchfield County, which on average gets the most snow in the state because of elevation and favorable banding location.
Right now we are looking conservatively at 5-10" of snow statewide. The floor has been rising with this one, so when we make our first call snow map tomorrow it's more likely that the numbers are higher than it is we cut them.
The greatest chance for double digit snowfall looks to be in eastern CT at this time and minimum at the immediate shoreline, but both the maximum and minimum zones are still abstract for now.
Looking at the totality of the information, a significant to major snowfall is legitimately on the table.
Stay tuned for additional updates.
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
