Good evening from Southern Connecticut Weather.
It's crunch time. If we're going to get close to normal seasonal snowfall it's time to turn the model depictions of pattern change into production at the surface. So far, it has been much wetter than normal, warmer than normal, and below normal snowfall, especially at the shoreline.
As I said earlier in my update--if this were five years ago we'd be locking in a major snow storm all the way to the coast as we were in the midst of a historic period of big winter events. The tide turned in a dramatic way however over the last half decade, which on balance has allowed us to snatch defeat from the jaws of victory--if you are inclined to like winter.
This is one of those storms that looks good on paper, but has enough red flags that there's still a fair amount of uncertainty.
Before talking about the storm, let's recap where we are.
Hartford (BDL) Normals
February Snowfall: 14.8"/ Snowfall to date: 0" (0% of monthly normal)
February Precipitation: 3.13"/ Precipitation to date: 0.01" (0.3% of monthly normal)
Normal To Date snowfall: 41.2"/ Snowfall to date: 15.5" (37.62% of normal)
Normal December-February precipitation: 14.45"/Precipitation to date: 16.42" (113.63% of normal)
Bridgeport (BDR) Normals
February Snowfall: 10.7"/ Snowfall to date: 0" (0% of monthly normal)
February Precipitation: 3.12"/ Precipitation to date: 0.04" (1.28% of monthly normal)
Normal To Date snowfall: 25.7"/ Snowfall to date: 5.5" (21.40% of normal)
Normal December-February precipitation: 10.28"/Precipitation to date: 14.45" (140.56% of normal)
We have some work to do in the snowfall department, but we always expected a backloaded winter. The next four weeks are critical.
Let's dive in.
It's crunch time. If we're going to get close to normal seasonal snowfall it's time to turn the model depictions of pattern change into production at the surface. So far, it has been much wetter than normal, warmer than normal, and below normal snowfall, especially at the shoreline.
As I said earlier in my update--if this were five years ago we'd be locking in a major snow storm all the way to the coast as we were in the midst of a historic period of big winter events. The tide turned in a dramatic way however over the last half decade, which on balance has allowed us to snatch defeat from the jaws of victory--if you are inclined to like winter.
This is one of those storms that looks good on paper, but has enough red flags that there's still a fair amount of uncertainty.
Before talking about the storm, let's recap where we are.
Hartford (BDL) Normals
February Snowfall: 14.8"/ Snowfall to date: 0" (0% of monthly normal)
February Precipitation: 3.13"/ Precipitation to date: 0.01" (0.3% of monthly normal)
Normal To Date snowfall: 41.2"/ Snowfall to date: 15.5" (37.62% of normal)
Normal December-February precipitation: 14.45"/Precipitation to date: 16.42" (113.63% of normal)
Bridgeport (BDR) Normals
February Snowfall: 10.7"/ Snowfall to date: 0" (0% of monthly normal)
February Precipitation: 3.12"/ Precipitation to date: 0.04" (1.28% of monthly normal)
Normal To Date snowfall: 25.7"/ Snowfall to date: 5.5" (21.40% of normal)
Normal December-February precipitation: 10.28"/Precipitation to date: 14.45" (140.56% of normal)
We have some work to do in the snowfall department, but we always expected a backloaded winter. The next four weeks are critical.
Let's dive in.
Above: the current winter headlines issued by the NWS. Winter storm watches are up for all of CT, with the exception of the shoreline. Why? There is higher confidence of a 6"+ snowfall away from the coast than there is at the coast currently. As we get closer and the uncertainty diminishes, the coast will either see a winter storm watch/warning or winter weather advisory.
Overall Setup
You haven't seen us write much because there hasn't been much to talk about! The overall pattern evolution since late January has turned out as expected. After a series of big storms in early to mid January, the pattern, which has turned over quite frequently and rapidly this winter, quieted down through early February.
The overall evolution of El Nino suggested that we would have another period for winter between mid-February and perhaps into mid-March. The pattern is changing, and we have a system right at the front end of it.
That has implications for the state. First, the wintry pattern you'll feel later next week isn't going to be ripe by Tuesday. The storm is coming into a marginal airmass, which introduces the risk of a warmer solution at the shoreline.
Second, and related to this, the lack of true cold at least initially is due to the lack of a classic block to the north. This can (and likely will) be overcome, but it introduces the risk of northern shifts of the storm track which, you guessed it, put the coast and maybe even southern CT at risk of more rain before a change to snow.
This is a thread the needle type storm. This is one that more than five years ago would have brought snow to the coast with the luck we had, but would almost certainly fail to produce a major winter storm with in the last five years with the luck we have. Yes, sometimes these marginal events come down to fortune.
But let's get back to the science. There is quite a bit of discrepancy among the global and high resolution models, but among our two best, the European and GFS, there is strong consensus among the operational models and ensembles. This gives me confidence that at least for now I can focus on these two while just watching trends among the multitude of other guidance.
First, let's look at the GFS, which has been further south overall and colder as a result.
Overall Setup
You haven't seen us write much because there hasn't been much to talk about! The overall pattern evolution since late January has turned out as expected. After a series of big storms in early to mid January, the pattern, which has turned over quite frequently and rapidly this winter, quieted down through early February.
The overall evolution of El Nino suggested that we would have another period for winter between mid-February and perhaps into mid-March. The pattern is changing, and we have a system right at the front end of it.
That has implications for the state. First, the wintry pattern you'll feel later next week isn't going to be ripe by Tuesday. The storm is coming into a marginal airmass, which introduces the risk of a warmer solution at the shoreline.
Second, and related to this, the lack of true cold at least initially is due to the lack of a classic block to the north. This can (and likely will) be overcome, but it introduces the risk of northern shifts of the storm track which, you guessed it, put the coast and maybe even southern CT at risk of more rain before a change to snow.
This is a thread the needle type storm. This is one that more than five years ago would have brought snow to the coast with the luck we had, but would almost certainly fail to produce a major winter storm with in the last five years with the luck we have. Yes, sometimes these marginal events come down to fortune.
But let's get back to the science. There is quite a bit of discrepancy among the global and high resolution models, but among our two best, the European and GFS, there is strong consensus among the operational models and ensembles. This gives me confidence that at least for now I can focus on these two while just watching trends among the multitude of other guidance.
First, let's look at the GFS, which has been further south overall and colder as a result.
Above: 18z GFS surface look courtesy of Tropical Tidbits.
Looking at this surface, even without a classic block in place we get a rapidly developing system that is far enough south that it's almost all snow even down to the coastline. Specific snowfall amounts would vary based on banding, but verbatim that's probably a nice statewide 6-12" snowfall with some areas higher. The numbers don't matter here as much as the evolution. The surface track is south. The storm is strong. This allows for heavy banding that overcomes marginal temperatures particularly in southern CT.
Importantly, while the 700mb low--a critical element of any winter forecast--is close to the state, it's good enough for strong frontogenesis (read: banding) to deliver significant accumulating in a fast moving storm.
Looking at this surface, even without a classic block in place we get a rapidly developing system that is far enough south that it's almost all snow even down to the coastline. Specific snowfall amounts would vary based on banding, but verbatim that's probably a nice statewide 6-12" snowfall with some areas higher. The numbers don't matter here as much as the evolution. The surface track is south. The storm is strong. This allows for heavy banding that overcomes marginal temperatures particularly in southern CT.
Importantly, while the 700mb low--a critical element of any winter forecast--is close to the state, it's good enough for strong frontogenesis (read: banding) to deliver significant accumulating in a fast moving storm.
Above: the GFS depiction of the 700mb low Tuesday afternoon. I like seeing that it is strong, which allows for some wiggle room if the track is less than ideal for snow (further south).
Below is the 700mb frontogenesis. Just a slight tick southeast with the 700mb low would keep the state colder aloft to allow for greater snowfall statewide, but this would bring a period of heavy snow into CT though the best would probably be to our northwest.
Below is the 700mb frontogenesis. Just a slight tick southeast with the 700mb low would keep the state colder aloft to allow for greater snowfall statewide, but this would bring a period of heavy snow into CT though the best would probably be to our northwest.
The European model has been mostly aligned with the GFS, but shows what can happen if the low is further north.
Above: the 12z European model. The 18z is even further north.
This depiction shows why a significant snow is likely for northern CT, even with a further north track. With a closer surface (and 700mb low) track we introduce warmth into southern CT. That'd mean rain changing to snow on Tuesday.
However, the storm intensifies rapidly offshore, which allows the rain/snow line to crash back to the coast and verbatim, brings a plowable snow for coastal CT and widespread 12"+ amounts to the rest of the state.
The latest 18z Euro which I referenced above cuts back significantly (showing why we don't care about numbers yet) but still brings a significant to major storm to the state.
This depiction shows why a significant snow is likely for northern CT, even with a further north track. With a closer surface (and 700mb low) track we introduce warmth into southern CT. That'd mean rain changing to snow on Tuesday.
However, the storm intensifies rapidly offshore, which allows the rain/snow line to crash back to the coast and verbatim, brings a plowable snow for coastal CT and widespread 12"+ amounts to the rest of the state.
The latest 18z Euro which I referenced above cuts back significantly (showing why we don't care about numbers yet) but still brings a significant to major storm to the state.
Current Expectation
We are not putting out any numbers until our first call tomorrow. Given the uncertainty, we want to see if high resolution guidance begins to join the general consensus of the Euro/GFS. However, we don't need numbers to say the following.
Stay tuned for our first call discussion and snowfall map tomorrow afternoon.
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
We are not putting out any numbers until our first call tomorrow. Given the uncertainty, we want to see if high resolution guidance begins to join the general consensus of the Euro/GFS. However, we don't need numbers to say the following.
- A high impact event is increasingly likely, even at the shoreline, as we expect periods of moderate to heavy snow on Tuesday causing widespread cancellations.
- While snowfall totals are still TBD, we are looking at a significant to major snow event inland with more uncertainty along the shoreline (areas without a winter storm watch currently). Even there, a plowable snowfall is likely.
- It is a little too soon to have details on snowfall ratios and wind, but we are closely watching if a heavier wet snow in southern CT this could cause power issues. Wind does not look terribly strong, but it doesn't need to be if there's a lot of paste-like snow.
- This is a fast mover. Rain/snow likely starts in the pre-dawn hours Tuesday and is out of the area by approximately 7pm Tuesday night.
Stay tuned for our first call discussion and snowfall map tomorrow afternoon.
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
