Here is our new forecast map for this event. We’ll talk more about it a bit further down.
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.
For reference, here's the map once again.
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.
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.
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.
- 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!
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