We’re still tracking a mixed bag of wintry weather for the state Tuesday afternoon into Tuesday night, with snow, sleet and freezing rain all in the cards. In this discussion we’ll go into more detail on the system and release our first call map.
Models and Trends
Guidance has remained consistent with the idea of a Miller B scenario, with an initial wave of low pressure running into the Great Lakes before running into a retreating high to the north and transferring its energy to a developing secondary low developing south of Long Island. The primary variable that we’re looking at is still the timing of that transfer and the placement of the high pressure to our north. A weaker high, or one placed further north, would allow for the primary low to push further into the lakes before redeveloping, allowing warmer air to move into the state and the eventual solution to be more wet than white. Conversely, a stronger, more southerly high would allow for the inverse to occur; warmer air is kept further south at the surface and is delayed in its arrival, and we see a more hefty front end thump of snow and ice. Given that the midlevels are likely to warm before the surface, I would expect a period of icing to occur in either scenario, especially away from the immediate shoreline.
Overall, the guidance is in pretty good agreement on the placement and strength of the various features. The trend over the past 24 hours has been perhaps slightly warmer, but I feel like we commonly see this in these types of systems where models underestimate the strength and influence of the high pressure until right before go-time, and as a result we often see a last minute trend colder. As such, we will carry a forecast that is slightly colder than the guidance consensus for this first call map, but may need to reduce amounts slightly tomorrow should that expected tick colder not materialize.
As far as the models go, the GFS is currently the snowiest model, while the NAM is the warmest, with the Euro as a good middle ground, but all seem within the envelope of possible solutions. As such, we chose to use a model blend for the forecast as I didn’t see any major outliers or red flags among the guidance suite. Unsurprisingly, the snowier solutions are also the faster ones as the system is able to outrun the warm air.
Here's a look at precipitation types from the GFS, RGEM and NAM for 1 PM and 7 PM Tuesday - notice the slight differences in timing and temperature but general consistency overall.
Here’s our forecast snowmap for this event.
For the northern portion of the state, the forecast is a bit trickier. While some of the guidance brings the mix line further north very quickly, the GFS (and to a lesser extent the Euro) has been steadfast on arguing for a longer period of snow across the state, especially across the far northern tier. While I’m hesitant to be too bullish given the number of red flags that point to a warmer solution, I do generally find that the colder outcomes often win in these sorts of events and the GFS notoriously has a warm bias, so the fact that it’s colder is definitely worth noticing. Should a GFS like solution verify, we could see warning level totals across some portions of the interior, especially in the far northern tier of the state. For now though, I’m going to stick closer to guidance consensus and go with 3-6” for the area, with the caveat that we may need to adjust totals in either direction tomorrow depending on where the system ultimately tracks. I think there will be a fairly sharp cutoff between a few inches of snow and warning level totals, and right now I think that will be just north of the state, but it wouldn’t take much to bring that further south into our area (or conversely for it to move further north and the net result being a similar forecast to the southern zone). Stay tuned.
For all zones, I expect a period of icing to occur in the changeover from snow to rain, with light accretions possible. I don’t expect enough icing to cause widespread power impacts, but some isolated issues could be possible related to weak branches or structures.
There is still a noticeable disparity in timing among the guidance, with the Euro holding off snow until early Tuesday evening while most of the other models bring it in earlier Tuesday afternoon (and the GFS and RGEM bring in snow Tuesday morning). I will lean towards the faster solutions for now, and expect snow to be breaking out across the state by late morning to early afternoon. This also moves up the timing of the mix line, meaning that we could be seeing a transition from snow to sleet to freezing rain during the PM commute (or, if you believe the warmer solutions, already seeing a wintry mix by the start of the rush). If you’re able to leave work early on Tuesday, it would probably be a good idea. The further north and east you are, the longer you’ll hold onto all snow. Eventually, wintry precipitation changes to plain rain overnight (except for possibly far NW areas), but the roads could still be a little bit slick into Wednesday morning depending on how much icing we see.
Unfortunately I don’t have the template for the SCW impact scale on this computer (I’m writing this from Montana, where I’m being impacted by this storm myself as it’s closed the highway on it’s way east to you all) but here’s what we’re expecting.
- Snow Accumulation: Low to Moderate
- Snowfall Rates: Moderate
- Wind: Low
- Power Outages: Low
- Timing: High
- Road Conditions: Moderate
All in all, it looks like another one of the events that we know and love around here in Connecticut (especially this season) ; a low confidence mixed bag of wintry “fun”. We’ll keep tracking on it and have a final call out tomorrow night. Until then, have a great start to your week and thank you for reading SCW!