Good evening from SCW!
Our first winter event in a while is on its way for tomorrow afternoon through the wee hours of Sunday, with accumulating snow statewide transitioning to rain Saturday night as temps warm. Overall, we’re expecting a moderate event, with mainly advisory levels of accumulation, but there’s some uncertainty on either end of the spectrum – should we see a colder than modeled solution play out, we could approach warning level totals in some areas, while dry air or a weaker/warmer storm could lead to an event that’s more wet than white.
Model Discussion
Here’s a look at the setup on the hires NAM.
Our first winter event in a while is on its way for tomorrow afternoon through the wee hours of Sunday, with accumulating snow statewide transitioning to rain Saturday night as temps warm. Overall, we’re expecting a moderate event, with mainly advisory levels of accumulation, but there’s some uncertainty on either end of the spectrum – should we see a colder than modeled solution play out, we could approach warning level totals in some areas, while dry air or a weaker/warmer storm could lead to an event that’s more wet than white.
Model Discussion
Here’s a look at the setup on the hires NAM.
The low goes well to our west and brings warm air into the state, but there is a good deal of precipitation out ahead of the warmth that’s running into the cold airmass that’s in place now. How strong that initial band comes in will likely be a big determinant in how much snow we get; a strong first band like the NAM shows will quickly saturate the column (minimizing the amount of QPF we lose to virga) and also help keep temps down, while a weaker solution will result in a good chunk of the QPF lost to dry air and also a quicker changeover. Eventually, warmer air moves in from the south and starts flipping areas over to rain from south to north, but at the same time, a dryslot moves in as the main low passes to our north and precipitation becomes very light or shuts off entirely.
The other main determinant will be how long the cold air can hold on at the surface before the warmer air moving in from the SW wins out. Generally, a more intense system will hold cold air in longer while still bringing more QPF, and as the changeover period is during the height of the precipitation, even a variation of an hour or two will make a big difference in snow totals. To show this, here is surface temps at 8 PM tomorrow from the Euro and the GFS as well as the final snowmaps from these models. I wouldn’t take either of the snowmaps as gospel, but the point is clear – a small shift towards colder temps has a big impact in overall snow totals. Generally, the guidance has been trending a bit stronger and a bit colder, and so we’re a bit more confident in higher totals than we were yesterday.
The other main determinant will be how long the cold air can hold on at the surface before the warmer air moving in from the SW wins out. Generally, a more intense system will hold cold air in longer while still bringing more QPF, and as the changeover period is during the height of the precipitation, even a variation of an hour or two will make a big difference in snow totals. To show this, here is surface temps at 8 PM tomorrow from the Euro and the GFS as well as the final snowmaps from these models. I wouldn’t take either of the snowmaps as gospel, but the point is clear – a small shift towards colder temps has a big impact in overall snow totals. Generally, the guidance has been trending a bit stronger and a bit colder, and so we’re a bit more confident in higher totals than we were yesterday.
Guidance is generally in good agreement, so with no major outliers, I took a consensus blend of the models for the forecast and adjusted it a bit based on analogs and a gut feeling to drag things a little warmer and therefore a bit quicker of a changeover, but any adjustments were minor.
Forecast and Timing
Here’s our forecast map for this event.
Forecast and Timing
Here’s our forecast map for this event.
I expect the highest totals in the NW hills, and I expect totals to decrease as you head SE, with the largest drop-off being along the immediate SE coastline where warm air will arrive first. I think the biggest wildcards here are the NE hills and SWCT. I could see both overperforming for different reasons (the NE hills because of cold air holding longer and SWCT for a quicker onset of precipitation) but for now I’m not confident enough in either scenario to boost up totals. With QPF being generally in the 1/3”-1/2” range and shaving a little off for rain, I’m comfortable with totals for most of the state in the 2-4” range, with some isolated 5” spots where heavy bands form. In the NW hills, I think cold air will last the longest, so I went with a 3-6” range, and along the far SE coast the combination of delayed arrival of precip and being the first to change over to rain will mean lower totals in the 1-3” range.
Look for snow to overspread the state starting in the mid afternoon, with western areas seeing snow as early as 2 PM ish while eastern areas will need to wait until around dark. Changeover to rain from south to north begins around dinnertime, but by midnight or so we’ll see a dryslot move in and shut off most precipitation. Could see some mixed rain and snow showers around through the overnight into the early morning hours, but I think by sunrise any lingering precip should be gone.
Impacts
Snowfall Accumulation--Moderate
This is an advisory level event for most and the impacts reflect that. Could call it low impact in the SE corner, but 2-3” ish is still plowable and I think that’s a legitimate possibility there. We have Winter Weather Advisories out from the NWS for all of the state except northern Litchfield County where there is a Winter Storm Warning.
Snowfall Rate--High
Although snowfall accumulations will be relatively low, I do expect a period of moderate to heavy snow centered around dinnertime or so. That will make road conditions an issue, and I exepct things to go downhill fast as heavy precipitation moves in. Plan your travels early in the day if you can!
Icing--None
This should be a rain/snow event and no icing is expected.
Wind--Low
I do not expect much wind with this storm.
Power Outages--Low
I don’t think snow will be all that wet, and amounts aren’t enough to do serious damage given the banal winds.
Timing--Moderate
Luckily it’s a weekend and there’s no school/work to worry about, but if you’ve got plans Saturday afternoon or evening you should definitely be aware of the forecast and be ready to modify your travels if necessary.
Road Conditions—Moderate/High
The totals won’t be all that crazy, but a quick period of heavy snow is all it takes to gum up the roads. The crews will be out there doing what they do best, and I expect that major roadways will still be moving (albeit slowly), but secondary and tertiary roads will be challenging. Sunday is the much better travel day of the weekend if you can swing it.
All in all, a pretty textbook moderate event for the state. We’ll have live updates on our social platforms as needed tomorrow, and please send us your reports on Facebook, Twitter, or by email – we really appreciate them. Thanks for reading SCW, enjoy the snow, and have a great long weekend!
-SA
Look for snow to overspread the state starting in the mid afternoon, with western areas seeing snow as early as 2 PM ish while eastern areas will need to wait until around dark. Changeover to rain from south to north begins around dinnertime, but by midnight or so we’ll see a dryslot move in and shut off most precipitation. Could see some mixed rain and snow showers around through the overnight into the early morning hours, but I think by sunrise any lingering precip should be gone.
Impacts
Snowfall Accumulation--Moderate
This is an advisory level event for most and the impacts reflect that. Could call it low impact in the SE corner, but 2-3” ish is still plowable and I think that’s a legitimate possibility there. We have Winter Weather Advisories out from the NWS for all of the state except northern Litchfield County where there is a Winter Storm Warning.
Snowfall Rate--High
Although snowfall accumulations will be relatively low, I do expect a period of moderate to heavy snow centered around dinnertime or so. That will make road conditions an issue, and I exepct things to go downhill fast as heavy precipitation moves in. Plan your travels early in the day if you can!
Icing--None
This should be a rain/snow event and no icing is expected.
Wind--Low
I do not expect much wind with this storm.
Power Outages--Low
I don’t think snow will be all that wet, and amounts aren’t enough to do serious damage given the banal winds.
Timing--Moderate
Luckily it’s a weekend and there’s no school/work to worry about, but if you’ve got plans Saturday afternoon or evening you should definitely be aware of the forecast and be ready to modify your travels if necessary.
Road Conditions—Moderate/High
The totals won’t be all that crazy, but a quick period of heavy snow is all it takes to gum up the roads. The crews will be out there doing what they do best, and I expect that major roadways will still be moving (albeit slowly), but secondary and tertiary roads will be challenging. Sunday is the much better travel day of the weekend if you can swing it.
All in all, a pretty textbook moderate event for the state. We’ll have live updates on our social platforms as needed tomorrow, and please send us your reports on Facebook, Twitter, or by email – we really appreciate them. Thanks for reading SCW, enjoy the snow, and have a great long weekend!
-SA
