Good evening from Southern Connecticut Weather!
We're still digging out after yesterday's blizzard, but with an active pattern it's more important than ever to get this grade out while things are still fresh.
For new followers, we grade our major forecasts. We do this for a few reasons. First, it's tradition. You don't see a lot of places grade their forecasts, and we're proud of doing something that while painful at times, sets us apart.
Second, it provides accountability. Longtime followers know that core to what we do is avoiding hype. We always aim to provide calm, fact-based, well-reasoned analysis to give you the information you need without having you feel impending doom every time you want to know how bad a storm might be.
Of course, we want to do this by maintaining a certain standard of accuracy. As a reminder, I'm not a meteorologist by training. While we have one "on staff" the majority of the team has no formal training. By publicly releasing grades of our forecasts, you get to see just how accurate our big forecasts are, and learn what went right and what went wrong. While we don't follow what others do, we know that online especially a lot of weather accounts are only good for yapping and engagement farming.
We aim to be helpful.
Third and perhaps most important, it makes us better. No forecast is perfect. It doesn't matter who you are. The key to getting better at anything is to learn from your mistakes. To provide the highest level of service to you, we need to know where our biases are so we can limit them when writing a forecast. A review also helps us track over time which models are best for certain situations.
Ok, with that out of the way, how did we do with the biggest storm of the season?
It's grading time. Let's dive in.
We're still digging out after yesterday's blizzard, but with an active pattern it's more important than ever to get this grade out while things are still fresh.
For new followers, we grade our major forecasts. We do this for a few reasons. First, it's tradition. You don't see a lot of places grade their forecasts, and we're proud of doing something that while painful at times, sets us apart.
Second, it provides accountability. Longtime followers know that core to what we do is avoiding hype. We always aim to provide calm, fact-based, well-reasoned analysis to give you the information you need without having you feel impending doom every time you want to know how bad a storm might be.
Of course, we want to do this by maintaining a certain standard of accuracy. As a reminder, I'm not a meteorologist by training. While we have one "on staff" the majority of the team has no formal training. By publicly releasing grades of our forecasts, you get to see just how accurate our big forecasts are, and learn what went right and what went wrong. While we don't follow what others do, we know that online especially a lot of weather accounts are only good for yapping and engagement farming.
We aim to be helpful.
Third and perhaps most important, it makes us better. No forecast is perfect. It doesn't matter who you are. The key to getting better at anything is to learn from your mistakes. To provide the highest level of service to you, we need to know where our biases are so we can limit them when writing a forecast. A review also helps us track over time which models are best for certain situations.
Ok, with that out of the way, how did we do with the biggest storm of the season?
It's grading time. Let's dive in.
Above: the verification map for our blizzard. Figuring out which reports to use was tough because there is substantial variation (as we thought) in snow totals. To make it as objective as possible we used 1) follower reports that followed our measuring/reporting instructions; 2) National Weather Service public reports--but only after noon on February 23. Earlier reports, which would likely have under count snow totals as snow really ended around 5pm on the 23rd, were not counted here. I also used a handful of reports from folks I know around the state that can be trusted to measure accurately.
Forecast Grades
Timing
This did end up feeling like the toughest part of the forecast, and as I was watching the storm roll in that feeling didn't change.
What made this most difficult was the pre-storm snow that was and wasn't related to the storm. We were inundated with questions about whether Sunday morning and afternoon activities would be fine, and so we needed to accurately predict when things would get bad more so than when things would start--since light snow was around the state even in the morning.
We were right that the light snow in the morning would not impact morning activities. Good.
We were right with the general timing of the storm. It did truly arrive between about 4-8pm. Excellent.
We were only partially right in how the snow advanced in the state. We said it would arrive from west to east, and while it did start out that way in SW CT, the storm really arrived from south to north. That may seem small, but it rendered our bullet points that broke down when western/central/eastern CT would see snow irrelevant. That's worth a deduction. Fortunately, we had a bit of a backdoor cover with the general timing being clearly stated and accurate.
From there, the timing forecast was excellent on balance. We were right that conditions would quickly deteriorate. Station reports generally had locations go from high visibility light snow to much lower visibility light to moderate snow within an hour of onset. We said that would be the time to get off the roads and that was critically on point.
We said that the worst of the storm would be 8pm Sunday to 8am on Monday. That was mostly right but slightly off. On Monday the worst of the conditions really started winding down between 10am and noon. The forecast for the worst wind, which was from midnight to noon Monday was spot on. The coastal flood forecast was also accurate.
The only other thing that was off was the timing of the end. The lighter snow came in earlier than 4pm, and the storm was effectively done hours before 10pm.
While not perfect, the timing forecast was still pretty solid, especially where it mattered. Deductions on missing the direction of approach and those few hours at the end of the storm.
Grade: B+
Snowfall Accumulation
Forecast Grades
Timing
This did end up feeling like the toughest part of the forecast, and as I was watching the storm roll in that feeling didn't change.
What made this most difficult was the pre-storm snow that was and wasn't related to the storm. We were inundated with questions about whether Sunday morning and afternoon activities would be fine, and so we needed to accurately predict when things would get bad more so than when things would start--since light snow was around the state even in the morning.
We were right that the light snow in the morning would not impact morning activities. Good.
We were right with the general timing of the storm. It did truly arrive between about 4-8pm. Excellent.
We were only partially right in how the snow advanced in the state. We said it would arrive from west to east, and while it did start out that way in SW CT, the storm really arrived from south to north. That may seem small, but it rendered our bullet points that broke down when western/central/eastern CT would see snow irrelevant. That's worth a deduction. Fortunately, we had a bit of a backdoor cover with the general timing being clearly stated and accurate.
From there, the timing forecast was excellent on balance. We were right that conditions would quickly deteriorate. Station reports generally had locations go from high visibility light snow to much lower visibility light to moderate snow within an hour of onset. We said that would be the time to get off the roads and that was critically on point.
We said that the worst of the storm would be 8pm Sunday to 8am on Monday. That was mostly right but slightly off. On Monday the worst of the conditions really started winding down between 10am and noon. The forecast for the worst wind, which was from midnight to noon Monday was spot on. The coastal flood forecast was also accurate.
The only other thing that was off was the timing of the end. The lighter snow came in earlier than 4pm, and the storm was effectively done hours before 10pm.
While not perfect, the timing forecast was still pretty solid, especially where it mattered. Deductions on missing the direction of approach and those few hours at the end of the storm.
Grade: B+
Snowfall Accumulation
Above: a repost of the verification map.
We weigh snow accumulation double because that's what people care about. As you see above, our forecast was for a general 16-24" of snow across the state. As we said in the forecast, this was heavily dependent on how close the storm tracked to us, which would determine how much moisture got pushed into the state.
At the end of the day, the storm ticked just southeast of where the models were at the time if the final forecast. That's not a surprise, as that happens often with coastal storms. We accounted for that.
We don't get points for this, but we accurately highlighted the risk of a bust (in this case, snow totals below 12") in the CT River Valley. From our final call forecast:
You will note though that there is this shadowing effect in the CT River Valley. This happens when you have massive easterly flow downsloping into the valley, limiting the amount of moisture wrung out. All this could be overcome with banding over the area, but watch out in places like Hartford and Windsor Locks. The risk is higher for a "bust" here.
Sure enough, a narrow corridor between Enfield to South Windsor ended up in the "sucker zone" and busted low. There are other parts of the state that saw general totals below our 16" floor, but if you note, even in the pockets of lower snow you saw some reports that were on par with the forecast in northern CT. Part of that for sure is lower snow. Another part of that may be measuring difficulty given the wind.
Southern CT has had one heck of a winter. They cashed in once again with widespread 18+ totals. For southeast CT, this winter has been a dream for snow lovers. We had several reports above 24" and 30" totals in far SE CT. Amazing.
Before the grade this leads me to the big takeaway. Some people whine about having large snowfall ranges but that's literally how these storms often work. I'm intentional with "whine" because I'm angry at myself for letting it get to me haha. Here's what we said in the final call forecast:
Elsewhere, there's always the risk of subsidence (read: dry slotting) when you have extreme banding. Anything lower than 12" would be a bust in my book, and while the forecast is for 16-24" statewide, someone could very well end up with a lollipop of 30" if they get under extreme banding for longer than anticipated. Most probably end up in the 16-22" range, but we have ranges for a reason here. The bigger the storm, the bigger the range due to the unpredictable nature of banding.
Exactly!
In Greenwich alone we had credible 18" and 13" reports. In New Milford, we had credible reports that ranged from 14" to 19". In the Vernon area we had a measurement of 16" that was done meticulously, and the next town over had 11". By far the greatest example came in far SE CT, where we had one credible report of 20.5" right next to the predicted "lollipop" of 30" and 30.8"!
A 12-24" snowfall forecast would not have been perfect because of what happened in the northern CT River Valley corridor, but it would have been better than trying to do a more narrow range. So the next time we have a blizzard and you see a wider range than normal (if the data calls for it of course, we don't want to game the system), if you complain I am sending this discussion!
Ok, now to the grade. Yes, a 12-24" map would have been better, as uncomfortable as it would be for some followers and yours truly, but forecasting 16-24" wasn't bad. Southern CT did a lot of heavy lifting for us as northwest and north central CT fell short of expectations. A narrow stripe of northern CT was an outright bust with 5 towns in bust territory.
On the Good, Better, Best scale, this one fell right in the middle. Annoying, but that's just us grading hard.
Grade: B+
Wind & Power Outages
This may not have felt as difficult a forecast as the timing forecast, or as weighty as the snow accumulation forecast, but this was easily the highest stakes part of the whole forecast. This storm definitely wasn't like anything we've seen recently.
Before the National Weather Service had enough confidence to issue the warnings statewide, we were calling this a blizzard. That designation was officially achieved in coastal locations, and while it looks like it fell just short of the three consecutive hour criteria in interior CT, there's no doubt that we saw blizzard like conditions even if not officially a blizzard.
We were right about the snowfall consistency and ratios oscillating with the banding, and it seems that while the snow had weight to it, it wasn't pure past or pure fluff, meaning we landed in the middle as forecast.
In northern CT, our forecast was for maximum wind gusts of 40-50mph. Impressively, Hartford (city) gusted to 51, while BDL gusted to 54. Willimantic gusted to 49mph. That's within the range of acceptability so we're very happy with that.
In southern CT, especially coastal sections, our forecast was for maximum wind gusts of 50-65mph. The highest gust came out of Groton, with a 68mph report. Bridgeport, Fairfield, Middletown, Meriden, New Haven all gusted over 50. Meriden put up an impressive 56mph report. Again, well within the range of acceptability.
Scattered to locally widespread power outages were anticipated and that's what happened. Here's what we wrote:
Locally widespread means that some towns may have significant parts without power, while another town does not. We don't currently expect heavy wet snow, but along the coast it's always tricky, and with higher end winds that means if we see more paste down there we will have big power outages. This is definitely something to watch. The greatest risk for widespread outages is in southern and coastal CT, especially SE CT and our friends in Westerly.
When checking the reports, this is exactly what happened. While some towns had 20+% of the community without power, many many others were just fine with more scattered to isolated outages. While there was fear of a high end power outage event, we didn't feel that was going to happen on a widespread basis around the state and the overwhelming majority of communities kept their power. I think at the peak we had about 15,000 customers or so without power which is very good in the whole scheme of things.
Proud of this part of the forecast.
Grade: A
Overall Impact
Not much to say here. We said a bona fide blizzard was coming and it did. It was an upper echelon storm, with part of SE CT getting 24-30" of snow, and high winds in every part of the state, which rarely happens. Bridgeport tied #2 all time in biggest snowstorm.
Impacts on the roads were extreme and Monday things did grind to a halt. There were widespread school cancellations on Monday and Tuesday. Roads were impassable for a time and thanks to the plow crews out there we're digging out at a good pace now. Snow was not on the wetter side so we didn't get those "tens of thousands" of power outages. That's a line I wish I didn't use, but overall, the impacts were spot on. This was probably the worst winter storm statewide since about 2018. We expected this so be a high impact to locally extreme impact event and it was.
Grade: A
Overall Grade
Taking everything above, this was a very good forecast. To be sure, not the best, and the other blockbuster storm overall probably was a better forecast. Going back, I'd probably use a 12-24" snow forecast zone, and would have anticipated the possibility that the trajectory of the storm would have snow break out from south to north rather than SW to NE, but when that's your nitpick rather than "man, I thought we'd have 200,000 outages" or "you know, a 16" floor really undersold the potential here", that's a good day in the office.
Grade: B+
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 and trusting SCW.
-DB
We weigh snow accumulation double because that's what people care about. As you see above, our forecast was for a general 16-24" of snow across the state. As we said in the forecast, this was heavily dependent on how close the storm tracked to us, which would determine how much moisture got pushed into the state.
At the end of the day, the storm ticked just southeast of where the models were at the time if the final forecast. That's not a surprise, as that happens often with coastal storms. We accounted for that.
We don't get points for this, but we accurately highlighted the risk of a bust (in this case, snow totals below 12") in the CT River Valley. From our final call forecast:
You will note though that there is this shadowing effect in the CT River Valley. This happens when you have massive easterly flow downsloping into the valley, limiting the amount of moisture wrung out. All this could be overcome with banding over the area, but watch out in places like Hartford and Windsor Locks. The risk is higher for a "bust" here.
Sure enough, a narrow corridor between Enfield to South Windsor ended up in the "sucker zone" and busted low. There are other parts of the state that saw general totals below our 16" floor, but if you note, even in the pockets of lower snow you saw some reports that were on par with the forecast in northern CT. Part of that for sure is lower snow. Another part of that may be measuring difficulty given the wind.
Southern CT has had one heck of a winter. They cashed in once again with widespread 18+ totals. For southeast CT, this winter has been a dream for snow lovers. We had several reports above 24" and 30" totals in far SE CT. Amazing.
Before the grade this leads me to the big takeaway. Some people whine about having large snowfall ranges but that's literally how these storms often work. I'm intentional with "whine" because I'm angry at myself for letting it get to me haha. Here's what we said in the final call forecast:
Elsewhere, there's always the risk of subsidence (read: dry slotting) when you have extreme banding. Anything lower than 12" would be a bust in my book, and while the forecast is for 16-24" statewide, someone could very well end up with a lollipop of 30" if they get under extreme banding for longer than anticipated. Most probably end up in the 16-22" range, but we have ranges for a reason here. The bigger the storm, the bigger the range due to the unpredictable nature of banding.
Exactly!
In Greenwich alone we had credible 18" and 13" reports. In New Milford, we had credible reports that ranged from 14" to 19". In the Vernon area we had a measurement of 16" that was done meticulously, and the next town over had 11". By far the greatest example came in far SE CT, where we had one credible report of 20.5" right next to the predicted "lollipop" of 30" and 30.8"!
A 12-24" snowfall forecast would not have been perfect because of what happened in the northern CT River Valley corridor, but it would have been better than trying to do a more narrow range. So the next time we have a blizzard and you see a wider range than normal (if the data calls for it of course, we don't want to game the system), if you complain I am sending this discussion!
Ok, now to the grade. Yes, a 12-24" map would have been better, as uncomfortable as it would be for some followers and yours truly, but forecasting 16-24" wasn't bad. Southern CT did a lot of heavy lifting for us as northwest and north central CT fell short of expectations. A narrow stripe of northern CT was an outright bust with 5 towns in bust territory.
On the Good, Better, Best scale, this one fell right in the middle. Annoying, but that's just us grading hard.
Grade: B+
Wind & Power Outages
This may not have felt as difficult a forecast as the timing forecast, or as weighty as the snow accumulation forecast, but this was easily the highest stakes part of the whole forecast. This storm definitely wasn't like anything we've seen recently.
Before the National Weather Service had enough confidence to issue the warnings statewide, we were calling this a blizzard. That designation was officially achieved in coastal locations, and while it looks like it fell just short of the three consecutive hour criteria in interior CT, there's no doubt that we saw blizzard like conditions even if not officially a blizzard.
We were right about the snowfall consistency and ratios oscillating with the banding, and it seems that while the snow had weight to it, it wasn't pure past or pure fluff, meaning we landed in the middle as forecast.
In northern CT, our forecast was for maximum wind gusts of 40-50mph. Impressively, Hartford (city) gusted to 51, while BDL gusted to 54. Willimantic gusted to 49mph. That's within the range of acceptability so we're very happy with that.
In southern CT, especially coastal sections, our forecast was for maximum wind gusts of 50-65mph. The highest gust came out of Groton, with a 68mph report. Bridgeport, Fairfield, Middletown, Meriden, New Haven all gusted over 50. Meriden put up an impressive 56mph report. Again, well within the range of acceptability.
Scattered to locally widespread power outages were anticipated and that's what happened. Here's what we wrote:
Locally widespread means that some towns may have significant parts without power, while another town does not. We don't currently expect heavy wet snow, but along the coast it's always tricky, and with higher end winds that means if we see more paste down there we will have big power outages. This is definitely something to watch. The greatest risk for widespread outages is in southern and coastal CT, especially SE CT and our friends in Westerly.
When checking the reports, this is exactly what happened. While some towns had 20+% of the community without power, many many others were just fine with more scattered to isolated outages. While there was fear of a high end power outage event, we didn't feel that was going to happen on a widespread basis around the state and the overwhelming majority of communities kept their power. I think at the peak we had about 15,000 customers or so without power which is very good in the whole scheme of things.
Proud of this part of the forecast.
Grade: A
Overall Impact
Not much to say here. We said a bona fide blizzard was coming and it did. It was an upper echelon storm, with part of SE CT getting 24-30" of snow, and high winds in every part of the state, which rarely happens. Bridgeport tied #2 all time in biggest snowstorm.
Impacts on the roads were extreme and Monday things did grind to a halt. There were widespread school cancellations on Monday and Tuesday. Roads were impassable for a time and thanks to the plow crews out there we're digging out at a good pace now. Snow was not on the wetter side so we didn't get those "tens of thousands" of power outages. That's a line I wish I didn't use, but overall, the impacts were spot on. This was probably the worst winter storm statewide since about 2018. We expected this so be a high impact to locally extreme impact event and it was.
Grade: A
Overall Grade
Taking everything above, this was a very good forecast. To be sure, not the best, and the other blockbuster storm overall probably was a better forecast. Going back, I'd probably use a 12-24" snow forecast zone, and would have anticipated the possibility that the trajectory of the storm would have snow break out from south to north rather than SW to NE, but when that's your nitpick rather than "man, I thought we'd have 200,000 outages" or "you know, a 16" floor really undersold the potential here", that's a good day in the office.
Grade: B+
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 and trusting SCW.
-DB
