Okay, let’s get right to it. A blizzard is on the doorstep, and will bring a whopper of a snow day to all of Connecticut tomorrow. Our final call is similar to our second call from yesterday, but due to a slight west trend overnight, we have upgraded the totals in the NW portion of the state, where the best mid-level banding should form and where the pivot will take place, and downgraded totals in the southeastern portion of the state to account for mixing that is likely as a result of the further west track. Regardless of these changes, the overall idea is the same; heavy snow moves in overnight, crippling the state for the morning rush and lasting through the afternoon before tapering off. Combined with strong winds, we will see coastal flooding, near-zero visibility, and significant power outages. A Blizzard Warning is in effect for the entire state except coastal New London and Middlesex counties, which have Winter Storm Warnings (In my opinion, they should have blizzard warnings as well).
Here is our new forecast map for this event. We’ll talk more about it a bit further down.
Here is our new forecast map for this event. We’ll talk more about it a bit further down.
Model Discussion and Preference
Since we last wrote yesterday, the trend has been west. The GIF below shows the MSLP on the GFS, which was once one of the most eastern most models, for the last eight runs over two days; 18z yesterday to 18z today.
Since we last wrote yesterday, the trend has been west. The GIF below shows the MSLP on the GFS, which was once one of the most eastern most models, for the last eight runs over two days; 18z yesterday to 18z today.
While the magnitude of the shift is relatively small, the impact on the ground is significant. We went from a SE jackpot yesterday to SE mixing today, and now have the heaviest snow in the northwest portion of the state. That’s shown on the surface output of the GFS below, valid for the same timeframes as above.
While the guidance has been in good agreement on moving west, some spread remains. The GFS, after being the furthest east, is now the western outlier, with mixing making it into most of the state. The hires NAM is the eastern outlier, which saves most of the state from mixing away from the immediate eastern shoreline. It’s important to note that even in the furthest west track, we still see a period of extremely heavy snow statewide, and with the heavy winds, blizzard conditions will verify along the coastline. There’s no escaping it no matter which model you chose. Here’s the 3km NAM (eastern envelope of solutions) and the GFS (western envelope of solutions) valid for 2 PM tomorrow.
The question then becomes how much of the rest of the state mixes. I do think that this is no longer an all snow event for most, as with the new track, there’s basically no way to avoid the taint being that close to the low center. However, outside of the southeast portion of the state, I think that the mixing is inconsequential; we may see a bit of freezing drizzle or a tenth or two of an inch of rain at the end of the event tomorrow afternoon, but that will be after a powerful thump of snow tomorrow morning. Given the QPF values that are showing up on guidance (2”+ for most of the state), you can lose some to mixing and still see very high snow totals. As such, favored a consensus blend, leaning towards the western solutions for both QPF (heavier) and mixing (more). This results in significant mixing in the southeastern portion of the state, a bit of mixing for most, and an all snow event for NW areas that are further from the low. For QPF, took a model average, yielding a blend of around two inches for most of the state, again, lowest amounts SE, highest NW. Modeled winds are also extremely impressive, with the Euro and GFS both showing wind gusts of over 50 MPH in parts of the state. Between the winds and heavy wet snow, I expect numerous power outages across the state tomorrow. Here’s the modeled wind gusts from the GFS (in knots – multiply by 1.15 to get to MPH) – the Euro is even higher.
The Forecast
For reference, here's the map once again.
For reference, here's the map once again.
Okay, now for the fun part. Let’s break down the map. Yesterday, we went with 12-18” for all as a baseline starting point. Now, with what we’ve seen on guidance, we can break that down a bit more into a little more detail.
Southeast Connecticut
First, we’re now confident in mixing in SE areas. This will limit snow totals there – depending on which model solution you believe, it could be relatively minor, or it could be two thirds of the QPF or more that is lost to rain. For now, we went with just under half of the QPF falling as a mix or rain, leaving us with about 1” of QPF as snow and approximately 10” based on a 10:1 ratio, which seems likely here. I went a little higher on the high end of the range as I wouldn’t be surprised to see the system tick slightly colder in the final hours, and also to leave some wiggle room for strong banding if it forms.
Central Connecticut
In the central portion of the state, not much has changed. We could see a bit of mixing towards the end of the storm, but the damage will have been done. While some models suggest higher totals in this area, I opted to stick with a widespread 12-18” and accept that some areas will likely get a bit more than expand the map to 20” or more, as I think those totals will be scattered and I don’t like hyping a big max number when few will hit it. 18” is a realistic high end expectation.
Northwest Connecticut
The northwest portion of the state is where this could be truly spectacular. Not only is the chance for mixing very low, the chance for being caught in the pivot point of the deformation banding is very high. Models are showing some amazing rates in this area, with the 3km NAM this afternoon showing 10” in one hour in the hills. That’s not going to happen, but some crazy numbers are certainly going to come in before the day is over. The banding, along with using a 12:1 ratio instead of a 10:1 ratio due to the colder temps and better lift in this area, makes me comfortable in some colossal totals, and as a result have upgraded to 18-24” with locally higher amounts possible where the best banding forms. Same caveats as above with the high end. We strongly considered adding the western shoreline to this zone, but figured that the ratios wouldn’t apply down there and that a bit of QPF could be lost to mixing, and to us, that was the difference between confidence in 16”ish and 20”ish that would have been needed to take those totals all the way to the shoreline.
Timing and Duration
We’re expecting snow to move in after midnight in the SW corner of the state and work its way NE through the overnight. By 4-5 AM, we should be snowing across the whole state. By daybreak, expect a few inches on the ground in the SW corner to just a coating or so in the NE corner. The fun starts around 8 or 9 AM as the main snow banding pushes north and east into the area. Visibilities will drop, winds will pick up, and travel conditions will go off a cliff. As a reminder, a travel ban begins at 5 AM tomorrow. Here’s the HRRR for 6 AM and 10 AM tomorrow – quite the uptick in intensity, and you can see even heavier snow south of the state that is moving in.
Southeast Connecticut
First, we’re now confident in mixing in SE areas. This will limit snow totals there – depending on which model solution you believe, it could be relatively minor, or it could be two thirds of the QPF or more that is lost to rain. For now, we went with just under half of the QPF falling as a mix or rain, leaving us with about 1” of QPF as snow and approximately 10” based on a 10:1 ratio, which seems likely here. I went a little higher on the high end of the range as I wouldn’t be surprised to see the system tick slightly colder in the final hours, and also to leave some wiggle room for strong banding if it forms.
Central Connecticut
In the central portion of the state, not much has changed. We could see a bit of mixing towards the end of the storm, but the damage will have been done. While some models suggest higher totals in this area, I opted to stick with a widespread 12-18” and accept that some areas will likely get a bit more than expand the map to 20” or more, as I think those totals will be scattered and I don’t like hyping a big max number when few will hit it. 18” is a realistic high end expectation.
Northwest Connecticut
The northwest portion of the state is where this could be truly spectacular. Not only is the chance for mixing very low, the chance for being caught in the pivot point of the deformation banding is very high. Models are showing some amazing rates in this area, with the 3km NAM this afternoon showing 10” in one hour in the hills. That’s not going to happen, but some crazy numbers are certainly going to come in before the day is over. The banding, along with using a 12:1 ratio instead of a 10:1 ratio due to the colder temps and better lift in this area, makes me comfortable in some colossal totals, and as a result have upgraded to 18-24” with locally higher amounts possible where the best banding forms. Same caveats as above with the high end. We strongly considered adding the western shoreline to this zone, but figured that the ratios wouldn’t apply down there and that a bit of QPF could be lost to mixing, and to us, that was the difference between confidence in 16”ish and 20”ish that would have been needed to take those totals all the way to the shoreline.
Timing and Duration
We’re expecting snow to move in after midnight in the SW corner of the state and work its way NE through the overnight. By 4-5 AM, we should be snowing across the whole state. By daybreak, expect a few inches on the ground in the SW corner to just a coating or so in the NE corner. The fun starts around 8 or 9 AM as the main snow banding pushes north and east into the area. Visibilities will drop, winds will pick up, and travel conditions will go off a cliff. As a reminder, a travel ban begins at 5 AM tomorrow. Here’s the HRRR for 6 AM and 10 AM tomorrow – quite the uptick in intensity, and you can see even heavier snow south of the state that is moving in.
By noon or so, we will have to start to watch for mixing along the southeast shoreline. The mix line could quickly push inland, or it could be confined south of us, depending on which model guidance verifies. We will also have to watch for a dryslot that could potentially lessen intensities in eastern areas, another reason for the lower totals there. Later in the afternoon, I expect the mix line to make another push northwest as intensities lessen somewhat and dynamics die off, but by then, the damage will be done and we’ll be digging out from an impressive system. Precipitation lightens and then moves out SW to NE starting around 5-6 PM, with areas that mixed potentially changing back to snow as the low pulls northeast. Snow should be out of the state by midnight.
Impacts
We’ll be updating live throughout the day tomorrow, with the first update by 7 AM. As always, we’re looking to see your reports and photos – send them to us on Facebook and on Twitter @SouthernCTWX and your photos could be featured as our Facebook and Twitter cover photos!
Finally, we’d really appreciate it if you’d share our discussion with your family and friends, not only to spread awareness about this event, but also to help us grow. We rely on word of mouth to get the buzz out about SCW, and it’s thanks to you all that we have been as successful as we have been so far. Help us get to the next level!
As always, ask any and all questions here. 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! From the entire forecast team, thank you for trusting SCW as your forecast of choice!
-SA
Impacts
- Heavy wet snow across the region. This will be a backbender to remove – I’d recommend keeping up with it as the storm progresses rather than waiting until the end if you’re going to be shoveling by hand. If you’re elderly or fragile, make a friendly neighborhood kid’s day and hire them to take care of it for you.
- Strong winds – 50+ MPH gusts are expected. Between the wind and the snow, trees and other infrastructure is at risk.
- Power outages are likely. Gas up your generator if you have one, and if you don’t, have flashlights and warm clothing/blankets ready. Know where food and water are in your house and have them easily accessible
- Travel will be near impossible across the state tomorrow morning. There is a travel ban starting at 5 AM. Don’t go out unless you absolutely need to.
- Schools will be closed tomorrow, and I would expect a smattering of delays and cancellations for Wednesday, especially in the NW zone.
We’ll be updating live throughout the day tomorrow, with the first update by 7 AM. As always, we’re looking to see your reports and photos – send them to us on Facebook and on Twitter @SouthernCTWX and your photos could be featured as our Facebook and Twitter cover photos!
Finally, we’d really appreciate it if you’d share our discussion with your family and friends, not only to spread awareness about this event, but also to help us grow. We rely on word of mouth to get the buzz out about SCW, and it’s thanks to you all that we have been as successful as we have been so far. Help us get to the next level!
As always, ask any and all questions here. 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! From the entire forecast team, thank you for trusting SCW as your forecast of choice!
-SA
