For the second time this winter season, a blockbuster storm is poised to impact our state. In this discussion, I encourage you to think beyond just snowfall accumulation. As I mentioned this morning in our update, the trend in the last 24-48 hours has been toward a more impactful storm for the state, and that has continued through this afternoon. We now have high confidence in a high impact event across Connecticut. Let's dive in.
Things have not changed too much in terms of the overall evolution. Perhaps the low is showing up a little stronger on the models, with a tighter upper level (non-surface) depiction, but overall we still expect the current low over the Mid Atlantic region to redevelop offshore late tonight/early tomorrow and begin the journey northeast. Things do seem to be moving a little faster, so don't be surprised especially in SW CT if you see some flurries or snow showers tonight. That's no big deal, as we now expect the accumulating snow to begin after 11pm in far SW CT and the rest of the state during the pre-dawn hours.
Below is the latest high resolution NAM model, which has done a decent job depicting the storm so far. I am posting for the purposes of showing the overall evolution, with snow starting late tonight and blossoming into bands of heavy snow tomorrow.
Once again, here are the details on the storm and our grading criteria.
We are taking the numbers up modestly from our first call forecast. As mentioned at the start of the forecast, this is where we have the highest confidence. We have 5-10" for the SE CT area. We think that mixing could cut down on snowfall in far SE CT, and we could see a situation where the immediate shoreline is lower while just a few miles inland we see totals closer to the high end of this range.
For inland areas, we think a general 8-14" is the best forecast, though we do note that there is higher potential in this zone, especially in SW and NE CT due to banding signals. The lower amounts relative to others may be in the CT River Valley between Hartford and the CT/MA border. That hasn't changed. This is due to potential dryslotting that is caused by downsloping into the valley from a strong easterly flow.
With regard to precipitation type, we think the storm is mostly snow for most of the state, even down into parts of SE CT. However, as the snow begins to taper to lighter returns late tomorrow and early Tuesday morning, we do think sleet is possible. It is most likely to be prevalent along the shoreline, but even some inland areas deeper into the southern four counties of CT, especially New London and Middlesex counties, could see some mixing. Be sure to measure before the mixing takes place to prevent undercounting!
Below are the depictions of the total precipitation that falls from the GFS (left) and Euro (right). Even if they're off (they will be) this gives us high confidence in a significant snowfall and a minima in the CT River Valley. Images courtesy of weathermodels.com.
We're now looking at snowflakes beginning to fly by later tonight in SW CT, though we are not expecting any accumulating snow to take place until after 11pm tonight. Snow will break out from SW to NE with most of the state dealing with light to moderate snow by daybreak. Things will quickly become moderate to heavy between 11am and 2pm, and the worst of the conditions are likely to be late tomorrow afternoon through the evening hours. We will then see the mixing begin in SE CT and perhaps other parts of the immediate shoreline as lighter snow occurs overnight and into Tuesday morning.
It's important to note that some guidance tries to string out the snow longer, with snow showers continuing through Tuesday and perhaps into early Wednesday. That's something to watch, and is still uncertain, but the storm as we see it will be occurring in earnest all of Monday through at least Tuesday morning.
As I mentioned this morning, the thing that may have stood out most in the last 12 hours has been the increase in wind potential. This is important, because wind has a significant impact on power outage potential and overall impact. We now see an increased likelihood of blizzard conditions in much of Connecticut, with the best chance of a blizzard verifying along coastal Connecticut. As a refresher, blizzard conditions are defined as:
- Three consecutive hours of 35+ mph wind gusts
- Visibility of 1/4 mile or less for 3 consecutive hours
That's easier said than done, so I am unsure if we see Blizzard Warnings without more confidence in strong wind.
For inland CT, we expect maximum wind gusts between 35-45mph, centered Monday afternoon into early Tuesday morning as the low passes to our south. As always, remember that gusts are gusts. Most of the time wind speeds will be lower here and at the shore.
For coastal CT, we expect maximum wind gusts between 45-55mph, also centered Monday afternoon into early Tuesday morning. If there's a place that could go higher with an isolated 60mph gust, it would be the Groton/New London area.
Which leads me to power outages. Last night, it looked like a heavier and wetter snow was likely, but looking at the data today, I think many inland areas have more of the lighter/fluffy type snow, especially during the height of the storm. This is because better mid-level dynamics should allow for higher ratio snow. Along the coast however, and especially in SE CT where the mix line could be lurking, a heavier wetter snow is still likely.
Combined with strong wind gusts, I think scattered outages are likely in southern CT with more isolated outages possible in inland CT. If you're in a place that loses power during wind events, be prepared. I am a little worried about far SE CT, but I'm not confident in calling for widespread outages.
With blizzard conditions possible during the afternoon and evening commute, expect road conditions to be awful across the state. If you don't have to be on the roads, I strongly recommend avoiding them tomorrow afternoon through early Tuesday during the worst of the storm. It won't be pretty Monday morning or Tuesday morning either. Expect widespread cancellations on Monday and Tuesday.
The combination of heavy snow, strong wind, coastal flooding and timing during most of the day Monday and at least part of Tuesday makes this a high impact event statewide. The worst impacts should occur tomorrow afternoon through early Tuesday morning. Coastal flood warnings are up for all of the CT shoreline, so if you are in a flood prone zone during noreasters take note.
As always, there are going to be "winners" and "losers" with regard to snow totals due to banding, but this has unusually high upper end snow potential, beyond what we are forecasting. We'll see if that potential is maximized, but as it stands we are looking at our most significant winter weather event since 2018. We will have updates as necessary during the storm.
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.