Good evening from Southern Connecticut Weather!
System #1 was good for providing much needed rainfall, but was a bit of a dud when it came to wintry precipitation, even by the low bar our forecast set.
Our next system is on the way, and while the setup is fairly similar to System #1 we do expect this one to be more impactful. This forecast will be quick and to the point. Let's dive in.
System #1 was good for providing much needed rainfall, but was a bit of a dud when it came to wintry precipitation, even by the low bar our forecast set.
Our next system is on the way, and while the setup is fairly similar to System #1 we do expect this one to be more impactful. This forecast will be quick and to the point. Let's dive in.
Above: the snowfall map for our coming system. In far northern CT we should see all frozen precipitation, which should lead to minor snowfall and a glaze of ice. In most of CT we expect minimal snow with a glaze of ice/sleet possible. Along the coast, while we may start out with some mixed precipitation, or end as snow on Saturday, this is a rain event.
Overall Setup
Much like System #1, this storm is the result of energy being ejected from a sprawling low from the Midwest. Unlike System #1, there should be colder air in place at the start, and with a stronger storm we should be able to keep some marginal cold in place over the region.
This means that we will have a mixed bag event in what is a southwest flow event. That means that warmer air from the southwest will move over the region, flipping the column aloft from below freezing to above at some level. While temperatures throughout the column will be too warm for accumulating snow or ice in coastal CT, the level of cold available will determine how much snow and mixing occurs in interior CT.
As the storm departs on Saturday, residual moisture may flip everyone back to snow as colder air advects into the state.
Overall Setup
Much like System #1, this storm is the result of energy being ejected from a sprawling low from the Midwest. Unlike System #1, there should be colder air in place at the start, and with a stronger storm we should be able to keep some marginal cold in place over the region.
This means that we will have a mixed bag event in what is a southwest flow event. That means that warmer air from the southwest will move over the region, flipping the column aloft from below freezing to above at some level. While temperatures throughout the column will be too warm for accumulating snow or ice in coastal CT, the level of cold available will determine how much snow and mixing occurs in interior CT.
As the storm departs on Saturday, residual moisture may flip everyone back to snow as colder air advects into the state.
Above: the 18z GFS depicting the surface evolution of our storm. As you can see, the Midwest low effectively ejects energy that spurs a coastal storm, but for us the southwest flow from the primary low in the Midwest warms the column up.
The Forecast
Timing
In writing this forecast, timing has been the most difficult part to predict. Some of the global models have pushed back the start time of the precipitation to the afternoon, but we still think that a morning start time is most likely. The AM commute looks ok, with precipitation moving into the state toward the end of it--between about 9am and noon from west to east.
While there may be a little mix early in the coastal areas, I don't anticipate that lasting long and things should flip very quickly to rain there. Inland, you will likely start out as a mix of sleet or freezing rain, especially in elevation areas. In the CT River Valley, you will be close to freezing rain and we really need to watch what the surface temperatures are in the morning. If surface temperatures are too warm, you will go from rain to mixing.
Mixed precipitation continues during the afternoon and evening inland, with plain rain further south. Overnight as the storm pulls away we cool off and whatever moisture is left over should change to snow. This may be how a lot of people verify the snowfall forecast, though the bar is low to begin with.
The high resolution NAM, which tends to be very good with depicting warmth aloft in these setups, provides a general evolution that we agree with.
The Forecast
Timing
In writing this forecast, timing has been the most difficult part to predict. Some of the global models have pushed back the start time of the precipitation to the afternoon, but we still think that a morning start time is most likely. The AM commute looks ok, with precipitation moving into the state toward the end of it--between about 9am and noon from west to east.
While there may be a little mix early in the coastal areas, I don't anticipate that lasting long and things should flip very quickly to rain there. Inland, you will likely start out as a mix of sleet or freezing rain, especially in elevation areas. In the CT River Valley, you will be close to freezing rain and we really need to watch what the surface temperatures are in the morning. If surface temperatures are too warm, you will go from rain to mixing.
Mixed precipitation continues during the afternoon and evening inland, with plain rain further south. Overnight as the storm pulls away we cool off and whatever moisture is left over should change to snow. This may be how a lot of people verify the snowfall forecast, though the bar is low to begin with.
The high resolution NAM, which tends to be very good with depicting warmth aloft in these setups, provides a general evolution that we agree with.
Some guidance does have snow showers lingering on Saturday in the wake of our storm, but for now, we limit the potential of that in this forecast.
Snow Accumulation
Given the temperature profile, the snow is not the story of this event. It's the mixing. Many inland locations should see a period of sleet and freezing rain, which may lead to minor accumulation in northern CT. It doesn't take much to put down a glaze, though marginal surface temperatures will make accretion of ice less efficient.
In far NW CT and some towns along the CT/MA border, we expect 1-2" of snow/sleet (yes, sleet officially counts as snow). In most of interior CT, we're expecting a coating of snow at best, though some towns could see a little more. Here icing is the biggest hazard, with minor accumulation possible. A coating of snow/sleet to 2" of the same are possible, noting again that some may not verify snowfall until late Friday/early Saturday.
Wind & Power Outages
Although we're expecting whatever snow to fall to be on the wetter side, and minor icing, that's not enough for a significant power outage kind of storm. We shouldn't see strong winds with this either.
Overall, any power outages should be isolated.
Overall Impact
Despite the overall minor amounts of snow and ice, the timing makes this a much more impactful event than it'd otherwise be. The end of the morning commute may be impacted, especially in western CT with the earlier start time of precipitation, but the evening commute should be impacted for all. As a result, we could see scattered to even widespread school cancellations tomorrow, if not early dismissals, in interior. That alone is worthy of a moderate impact event for interior CT, with a low impact in coastal CT.
Bonus Discussion
For those of you that read to the end, let's talk about the weekend.
There's a lot of hype out there about this one, but we've kept our powder dry because a lot of the model solutions suggest a miss. The setup is actually pretty straightforward: in the wake of System #2, energy will dive down from Canadian Plains and Midwest, and spurred by a big ridge over the western U.S. this should force the energy offshore and allow for some level of storm development.
Snow Accumulation
Given the temperature profile, the snow is not the story of this event. It's the mixing. Many inland locations should see a period of sleet and freezing rain, which may lead to minor accumulation in northern CT. It doesn't take much to put down a glaze, though marginal surface temperatures will make accretion of ice less efficient.
In far NW CT and some towns along the CT/MA border, we expect 1-2" of snow/sleet (yes, sleet officially counts as snow). In most of interior CT, we're expecting a coating of snow at best, though some towns could see a little more. Here icing is the biggest hazard, with minor accumulation possible. A coating of snow/sleet to 2" of the same are possible, noting again that some may not verify snowfall until late Friday/early Saturday.
Wind & Power Outages
Although we're expecting whatever snow to fall to be on the wetter side, and minor icing, that's not enough for a significant power outage kind of storm. We shouldn't see strong winds with this either.
Overall, any power outages should be isolated.
Overall Impact
Despite the overall minor amounts of snow and ice, the timing makes this a much more impactful event than it'd otherwise be. The end of the morning commute may be impacted, especially in western CT with the earlier start time of precipitation, but the evening commute should be impacted for all. As a result, we could see scattered to even widespread school cancellations tomorrow, if not early dismissals, in interior. That alone is worthy of a moderate impact event for interior CT, with a low impact in coastal CT.
Bonus Discussion
For those of you that read to the end, let's talk about the weekend.
There's a lot of hype out there about this one, but we've kept our powder dry because a lot of the model solutions suggest a miss. The setup is actually pretty straightforward: in the wake of System #2, energy will dive down from Canadian Plains and Midwest, and spurred by a big ridge over the western U.S. this should force the energy offshore and allow for some level of storm development.
Above: the 500mb depiction of the 18z GFS. Note the big ridge over the western part of the country. How amplified this is and where it sets up will be big for how explosive this potential is and the track of the storm.
So far, the majority of guidance has kept this one as either a middling storm that slides east and out to sea once leaving the coast (Euro), while other guidance like the GFS has an explosive system that either provides a glancing blow or direct hit.
So far, the majority of guidance has kept this one as either a middling storm that slides east and out to sea once leaving the coast (Euro), while other guidance like the GFS has an explosive system that either provides a glancing blow or direct hit.
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Above is a lot of information, but here are surface depictions of the GFS (top left), Euro (top right) and their respective AI models underneath them. These are Monday morning. For the first time, we've really seen the Euro move toward a more impactful system. Each of the depictions above would bring snow to the state. The AI models have been more bullish on a big system just offshore from the beginning, though not all were hits.
What does this tell us?
Well, one model run doesn't make a trend, so I need to see a lot more consistency to latch onto what you see above. That said, we're getting into the short range soon, so each model cycle becomes increasingly important. Tomorrow it will definitely be time to talk about the Sunday/Monday potential, especially if the models "hold" tonight.
For now, there are three scenarios:
Blockbuster Hit--20%
Glancing Blow--60%
Total Miss--20%
Stay tuned.
What does this tell us?
Well, one model run doesn't make a trend, so I need to see a lot more consistency to latch onto what you see above. That said, we're getting into the short range soon, so each model cycle becomes increasingly important. Tomorrow it will definitely be time to talk about the Sunday/Monday potential, especially if the models "hold" tonight.
For now, there are three scenarios:
Blockbuster Hit--20%
Glancing Blow--60%
Total Miss--20%
Stay tuned.
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Thank you for reading SCW.
-DB
Thank you for reading SCW.
-DB
