Good evening and merry Christmas from Southern Connecticut Weather!
Hopefully, everyone has had a wonderful day. If you are a winter weather lover, it looks like Santa has brought more digital snow to the state for the coming storm!
We thought there would be adjustments given the highly sensitive environment ahead of this one, and the adjustment has been in the direction of a more impactful event. Now, we're taking the numbers up statewide, and a significant to potentially major snowfall is on tap.
For reasons stated below, this forecast is a little more on the aggressive side than what we usually do, and while most will likely end up in the lower to middle part of this snowfall range, I wanted to use a higher ceiling for the potential that some last minute shifts or a slightly more robust/longer lasting period of banding leaves a stretch of an area with higher totals.
Hopefully, everyone has had a wonderful day. If you are a winter weather lover, it looks like Santa has brought more digital snow to the state for the coming storm!
We thought there would be adjustments given the highly sensitive environment ahead of this one, and the adjustment has been in the direction of a more impactful event. Now, we're taking the numbers up statewide, and a significant to potentially major snowfall is on tap.
For reasons stated below, this forecast is a little more on the aggressive side than what we usually do, and while most will likely end up in the lower to middle part of this snowfall range, I wanted to use a higher ceiling for the potential that some last minute shifts or a slightly more robust/longer lasting period of banding leaves a stretch of an area with higher totals.
Above: Our new snowfall map. We took the snow forecast up across the board, and expanded the highest zone further east into NW CT and more of western CT. We also adjusted the eastern zone to cover more of southern CT because of questions over banding.
Overall Setup
Not much has changed. We knew it was a sensitive forecast, and the trend yesterday and today has been toward a more significant early burst of snow and snowfall expanding further northeast. It's already breezy out there, and as another Arctic front passes we will get cold air put in place overnight tonight. Tomorrow will be colder than normal, which is obviously critical in advance of our storm.
While more adjustments are possible, there is high enough confidence now to put up these snowfall zones and make a final call forecast.
Overall Setup
Not much has changed. We knew it was a sensitive forecast, and the trend yesterday and today has been toward a more significant early burst of snow and snowfall expanding further northeast. It's already breezy out there, and as another Arctic front passes we will get cold air put in place overnight tonight. Tomorrow will be colder than normal, which is obviously critical in advance of our storm.
While more adjustments are possible, there is high enough confidence now to put up these snowfall zones and make a final call forecast.
Above: GFS depiction of the coming storm. The general evolution is now agreed upon by the guidance with a burst of snow initially followed by a period of lighter snow across the state. With cold in place and a track far enough south, it looks like we will remain virtually all snow. There may be a chance of some brief sleet in extreme SW CT, but this is a snow storm.
Timing
In our fast flow regime quick moving systems have been the rule and this is no different. Most of the day tomorrow looks absolutely fine for travel in Connecticut. Conditions will deteriorate tomorrow between 6-10pm from west to east as the storm moves into the region. It may start out as virga briefly as the column moistens enough for snow to fall, but once that happens snow will quickly go from light to moderate and possibly heavy, especially in western and central CT.
The 12z Euro below shows this nicely. We quickly move the banding of heavier snow into western and central CT early in the storm and it will be a thump. From there as the storm deamplifies we will see the intensity of the snow diminish before the storm exits fully Saturday morning, likely before 9am.
Timing
In our fast flow regime quick moving systems have been the rule and this is no different. Most of the day tomorrow looks absolutely fine for travel in Connecticut. Conditions will deteriorate tomorrow between 6-10pm from west to east as the storm moves into the region. It may start out as virga briefly as the column moistens enough for snow to fall, but once that happens snow will quickly go from light to moderate and possibly heavy, especially in western and central CT.
The 12z Euro below shows this nicely. We quickly move the banding of heavier snow into western and central CT early in the storm and it will be a thump. From there as the storm deamplifies we will see the intensity of the snow diminish before the storm exits fully Saturday morning, likely before 9am.
The worst of the storm is essentially from onset through the early morning hours. If you are traveling for a flight, there may be delays and cancellations Friday evening into Saturday morning, especially if you are flying in or out of a New York City area airport.
Snow & Ice Accumulation
Above is our final call map again. Much like I said yesterday, the further southwest you are the better odds you have of a major snowfall. The band of heavy snow is now projected to cross the state, especially the western and central portions of the state. One thing to acknowledge here is that when we have strong frontogenesis we often end up with banding further north than guidance signals and warm air advection like this can push precipitation further northeast than we'd otherwise see.
Above is our final call map again. Much like I said yesterday, the further southwest you are the better odds you have of a major snowfall. The band of heavy snow is now projected to cross the state, especially the western and central portions of the state. One thing to acknowledge here is that when we have strong frontogenesis we often end up with banding further north than guidance signals and warm air advection like this can push precipitation further northeast than we'd otherwise see.
Above: The 18z GFS showing 700mb frontogenesis. Note how there is strong frontogenesis over western CT. This is a good signal for moderate to heavy snow further northeast in the state.
This band of heavy snow is still pretty narrow geographically. Lighter snow will be present further northeast and folks on the edge of the snow may struggle as banding usually creates subsidence (read: dry slots). It is still the case that even a 25-50 mile shift makes this more or less significant. Given the overall trend toward a more amplified system, I think a more aggressive track is reasonable here. Things hinge on how strong the initial burst is, and while most likely fall on the lower to middle part of the range there's going to be spots that over perform. The speed of the system and its rate of deamplification caps the ceiling for this, but some folks could see a major snowfall.
Wind & Power Outages
Much like last night's expectation, I don't think this is a windy storm. Snow should be on the fluffy side and the storm is weakening as it rolls into the region, There may still be some sort of pressure gradient so it may be breezy, but I don't anticipate significant power outages.
Overall Impact
With the snow totals coming up the impact comes up. Even with the timing and it being a weekend this is a moderate to high impact event. The banding signal suggests heavy snow tomorrow night that will make travel hazardous, and during the storm we may have widespread flight delays/cancellations and hazardous travel conditions. Eastern CT is most likely to have a lower impact event, but even there travel is likely to be rough for a bit late Friday into early Saturday.
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
This band of heavy snow is still pretty narrow geographically. Lighter snow will be present further northeast and folks on the edge of the snow may struggle as banding usually creates subsidence (read: dry slots). It is still the case that even a 25-50 mile shift makes this more or less significant. Given the overall trend toward a more amplified system, I think a more aggressive track is reasonable here. Things hinge on how strong the initial burst is, and while most likely fall on the lower to middle part of the range there's going to be spots that over perform. The speed of the system and its rate of deamplification caps the ceiling for this, but some folks could see a major snowfall.
Wind & Power Outages
Much like last night's expectation, I don't think this is a windy storm. Snow should be on the fluffy side and the storm is weakening as it rolls into the region, There may still be some sort of pressure gradient so it may be breezy, but I don't anticipate significant power outages.
Overall Impact
With the snow totals coming up the impact comes up. Even with the timing and it being a weekend this is a moderate to high impact event. The banding signal suggests heavy snow tomorrow night that will make travel hazardous, and during the storm we may have widespread flight delays/cancellations and hazardous travel conditions. Eastern CT is most likely to have a lower impact event, but even there travel is likely to be rough for a bit late Friday into early Saturday.
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
