Good evening to you from SCW!
Summary
We are gearing up for the largest snowstorm to hit the state since February of 2015, and the system has only continued to look more impressive throughout the day. While it will be a quick hitter, the snowfall rates will be extremely impressive, and combined with high snow ratios it will pack a significant punch. As such, we have upgraded snow totals by 4” across the board for the entire state, making the new forecast 10-16” statewide. Snow will begin in the pre-dawn hours across the state and taper off west to east over the course of the afternoon. While most snow will be gone by the evening commute, roads will be snowpacked and uncleaned, making the PM commute almost as much of a mess as the AM commute will be. Snowfall rates of 2”+ per hour are expected, with some locations likely seeing periods of over 3” per hour in the heaviest bands. Travel will be difficult to impossible across the state tomorrow, and I expect virtually every school district in the state to close (many already have). If you don’t absolutely have to go out tomorrow, stay home and enjoy the snow.
Here’s the latest forecast snowmap:
Summary
We are gearing up for the largest snowstorm to hit the state since February of 2015, and the system has only continued to look more impressive throughout the day. While it will be a quick hitter, the snowfall rates will be extremely impressive, and combined with high snow ratios it will pack a significant punch. As such, we have upgraded snow totals by 4” across the board for the entire state, making the new forecast 10-16” statewide. Snow will begin in the pre-dawn hours across the state and taper off west to east over the course of the afternoon. While most snow will be gone by the evening commute, roads will be snowpacked and uncleaned, making the PM commute almost as much of a mess as the AM commute will be. Snowfall rates of 2”+ per hour are expected, with some locations likely seeing periods of over 3” per hour in the heaviest bands. Travel will be difficult to impossible across the state tomorrow, and I expect virtually every school district in the state to close (many already have). If you don’t absolutely have to go out tomorrow, stay home and enjoy the snow.
Here’s the latest forecast snowmap:
Models and Trends
As mentioned earlier, the general trend in the guidance today has been to strengthen the surface low and bring it further west. This results in more precipitation making its way onshore and a general increase in QPF across the region. The GFS and the Euro are now in good agreement on a widespread ~1” of QPF statewide, a fairly significant increase from previous runs where the 1” amounts were limited to the areas that got under the best banding. This trend makes sense to me; as the storm has become stronger and better defined, it has allowed for more inflow to come in off the water and for more moisture to be drawn into the system. The signals for good snow growth and excellent frontogenesis is also there, making this a very dynamic system in the mid to upper levels. All of these factors should result in heavier bands of snow and stronger precipitation overall as the general circulation of the system becomes well defined. We have seen this trend on pretty much all guidance today, and I am reasonably confident that it is legitimate. As such, I am comfortable going towards the higher end of guidance for this forecast.
Here’s a look at low placement and total QPF from the 6z and 18z GFS from today. Notice the jump NW in the surface low and the corresponding increase in QPF.
As mentioned earlier, the general trend in the guidance today has been to strengthen the surface low and bring it further west. This results in more precipitation making its way onshore and a general increase in QPF across the region. The GFS and the Euro are now in good agreement on a widespread ~1” of QPF statewide, a fairly significant increase from previous runs where the 1” amounts were limited to the areas that got under the best banding. This trend makes sense to me; as the storm has become stronger and better defined, it has allowed for more inflow to come in off the water and for more moisture to be drawn into the system. The signals for good snow growth and excellent frontogenesis is also there, making this a very dynamic system in the mid to upper levels. All of these factors should result in heavier bands of snow and stronger precipitation overall as the general circulation of the system becomes well defined. We have seen this trend on pretty much all guidance today, and I am reasonably confident that it is legitimate. As such, I am comfortable going towards the higher end of guidance for this forecast.
Here’s a look at low placement and total QPF from the 6z and 18z GFS from today. Notice the jump NW in the surface low and the corresponding increase in QPF.
The other trend that is less quantifiable, yet potentially more significant to the forecast, is the trend for the computer generated algorithms to indicate very high snow ratios across the state. Traditionally, 10:1 is the standard ratio, meaning that 1” of QPF would translate into about 10” of snow. In a scenario like this one where there will be intense lift and heavy snowfall rates, I would expect that number to be on the low side. While there is no great way to forecast ratios, there are some algorithms, such as the Kuchera and COBB methods, that take a stab at it using modeled upper air temperatures at various points in the column. In this case, those algorithms are extremely bullish, suggesting snow ratios of 18-22:1. That would mean that our 1” of QPF would translate to 18-22” of snow, making this the most significant statewide snow event since the Blizzard of February 2013 (better known as Winter Storm Nemo or the Great Blizzard of 2013). Needless to say, I don’t buy those numbers. The algorithms are often too extreme on either end of the spectrum, and I think they are going a little bit crazy with the amount of lift and the rates that are modeled. For now, I’m going with ratios around 13:1, which fits in nicely with our 10-16” forecast. However, the bust potential with this is high; should the ratios verify as they are being modeled, we will see some 20”+ totals in the state. I would say the chances of that are less than 10%, but hey, you never know.
Forecast and Timing
As we said above, we have upgraded snow totals to 10-16” across the state. I do think that most reports will end up in the 10-14” range, but we decided to allow the maximum to be up to 16” to account for both any areas where banding persist and the possibility of snow totals being enhanced. While there will be some fairly strong bands and likely some subsidence zones around them, this storm should keep moving fairly quickly, and therefore most should get into the banding for a time. Therefore, totals will likely be fairly uniform across the state, with a bonus where the banding remains for an extended period of time. As far as snow rates go, they will be extremely impressive. Models are consistently spitting out areas of 2”+ per hour, and the latest NAM and GFS have fairly large areas of 3” per hour at the height of the storm. We will start out with a heavy, wet snow, but will quickly transition over to a light, fluffy snow for the majority of the event. Winds will also be an issue. While I don’t expect gusts high enough to hit blizzard criteria, it will definitely be a bit gusty, especially on the coastline.
For timing, snow will move into the state during the pre-dawn hours. By daybreak, snow should be falling statewide. Heavy snow will move in from west to east over the course of the morning rush, and will persist throughout the morning. I would expect that the heaviest band of snow will generally push eastward over the course of the morning, but even areas that are only seeing lighter rates will still be seeing rates that we’d usually consider “heavy”. Snow will begin to lessen in intensity and then taper off throughout the afternoon, with most snow out of the state by dark. Some scattered snow showers may persist through the evening, especially in eastern areas.
Impacts
The Bottom Line
A significant snowstorm is coming. While it’s nothing we haven’t seen before, it demands respect and attention. Don’t travel if you don’t have to, use extreme caution if you do have to, and above all, get out there and enjoy it! Send us your photos and reports tomorrow – we’ll be on Facebook and Twitter all day and your reports allow us to corroborate our forecast with what’s on the radar and what’s on the ground. We’ll be up bright and early watching the radar, with the first update of the day to come by 7 AM and rapid-fire throughout the day until the last flake has left the state.
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! All you have to do is click one of the buttons below! We’ll be here all evening answering your questions, so ask away!
Thank you for reading SCW!
-SA
Forecast and Timing
As we said above, we have upgraded snow totals to 10-16” across the state. I do think that most reports will end up in the 10-14” range, but we decided to allow the maximum to be up to 16” to account for both any areas where banding persist and the possibility of snow totals being enhanced. While there will be some fairly strong bands and likely some subsidence zones around them, this storm should keep moving fairly quickly, and therefore most should get into the banding for a time. Therefore, totals will likely be fairly uniform across the state, with a bonus where the banding remains for an extended period of time. As far as snow rates go, they will be extremely impressive. Models are consistently spitting out areas of 2”+ per hour, and the latest NAM and GFS have fairly large areas of 3” per hour at the height of the storm. We will start out with a heavy, wet snow, but will quickly transition over to a light, fluffy snow for the majority of the event. Winds will also be an issue. While I don’t expect gusts high enough to hit blizzard criteria, it will definitely be a bit gusty, especially on the coastline.
For timing, snow will move into the state during the pre-dawn hours. By daybreak, snow should be falling statewide. Heavy snow will move in from west to east over the course of the morning rush, and will persist throughout the morning. I would expect that the heaviest band of snow will generally push eastward over the course of the morning, but even areas that are only seeing lighter rates will still be seeing rates that we’d usually consider “heavy”. Snow will begin to lessen in intensity and then taper off throughout the afternoon, with most snow out of the state by dark. Some scattered snow showers may persist through the evening, especially in eastern areas.
Impacts
- A heavy snow for the entire state. 10-16” expected, locally higher amounts possible.
- Scattered power outages possible, especially along the shoreline.
- Difficult to impossible travel across the state tomorrow.
- Widespread school closings tomorrow, and delays/closings possible on Friday as well depending on the impacts from tomorrow and the speed at which crews are able to clear snows.
The Bottom Line
A significant snowstorm is coming. While it’s nothing we haven’t seen before, it demands respect and attention. Don’t travel if you don’t have to, use extreme caution if you do have to, and above all, get out there and enjoy it! Send us your photos and reports tomorrow – we’ll be on Facebook and Twitter all day and your reports allow us to corroborate our forecast with what’s on the radar and what’s on the ground. We’ll be up bright and early watching the radar, with the first update of the day to come by 7 AM and rapid-fire throughout the day until the last flake has left the state.
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! All you have to do is click one of the buttons below! We’ll be here all evening answering your questions, so ask away!
Thank you for reading SCW!
-SA
