Good morning from Southern Connecticut Weather.
For those of you that have followed us a long time, you know that after big events we like to grade our forecasts, good, bad, or ugly. With the rapid succession at which we're having storms lately, we grade two in this post.
Grading ourselves does two things. First, it provides accountability. It's easy to throw out numbers and never look back, but we want to highlight our successes and failures because that's meteorology. There will be plenty of both. Second, it provides us with an opportunity to learn from our forecasts, so that we can be better in the future as we serve you.
Let's start with the January 6-7 storm.
January 6-7 Storm
For those of you that have followed us a long time, you know that after big events we like to grade our forecasts, good, bad, or ugly. With the rapid succession at which we're having storms lately, we grade two in this post.
Grading ourselves does two things. First, it provides accountability. It's easy to throw out numbers and never look back, but we want to highlight our successes and failures because that's meteorology. There will be plenty of both. Second, it provides us with an opportunity to learn from our forecasts, so that we can be better in the future as we serve you.
Let's start with the January 6-7 storm.
January 6-7 Storm
Above: our verification map with the NWS published snow totals across the state from our weekend winter storm.
As a recap, we grade on the major factors of our final call forecast. We weigh snowfall accumulation twice, because the truth is that people care more about how much snow falls in their backyard than anything else.
Timing
This was the highlight of the forecast. Despite some shifting from guidance at the last minute, we did an excellent job with timing. We predicted that snow would begin from SW to NE between 4-8pm. Our first snow reports had a start time just around 4:27pm. Virtually all of the state was snowing by 8pm. The progression was accurate, with heavier snow between 10pm and 4am.
We did predict a lull and the mixing, and by late morning as the second vort began interacting with the first we saw cold drain into the state. In fact, the cold drain happened a little faster than expected. Snow ended Sunday evening.
Overall, it's hard to do better than this for timing.
Grade: A
Wind/Power Outages
Timing was the best part of the forecast. This was the second best. We expected scattered outages but they were more isolated. The winds at the shore weren't bad as expected. The peak gust at Bridgeport was 28, while Groton was a little windier.
Grade: B
Snowfall Accumulation
Now to the toughest part of the forecast. There were some that were quick to call bust and then the forecast worked out in their backyard. There were many others that called bust and the bust was verified once the snow stopped falling. I'll never understand why some are so quick to call bust, but that's the business.
Originally, we considered a 5-10 zone inland but thought that was too low and went with a 6-12 zone. For the shoreline, we originally considered a 3-6" zone and went higher with a 4-8" zone. We thought the colder trend would be enough for significant snow even to the immediate coast, even with a significant snowfall gradient, which we did see in eastern CT.
A 3-6" zone would have been better, but honestly not by much and not for much of the central and eastern CT coast. We were wrong. Big.
Why we were off however isn't the reason you may think. The storm verified colder than the warmer models. The mixing line stayed south of the coast past midnight. The issue, as we see it, was the lack of heavy rates during the initial wave. When that happened, the coast was cooked. The forecast ended up wrong but not as wrong in SW CT where there was strong initial banding. For others, the dry slotting (or subsidence if we want to be technical) was too much to overcome.
Part two also took its time building a more consistent precipitation shield, but once it did some areas particularly inland were able to cash in.
Let's take a look at the radar from part of the initial wave.
As a recap, we grade on the major factors of our final call forecast. We weigh snowfall accumulation twice, because the truth is that people care more about how much snow falls in their backyard than anything else.
Timing
This was the highlight of the forecast. Despite some shifting from guidance at the last minute, we did an excellent job with timing. We predicted that snow would begin from SW to NE between 4-8pm. Our first snow reports had a start time just around 4:27pm. Virtually all of the state was snowing by 8pm. The progression was accurate, with heavier snow between 10pm and 4am.
We did predict a lull and the mixing, and by late morning as the second vort began interacting with the first we saw cold drain into the state. In fact, the cold drain happened a little faster than expected. Snow ended Sunday evening.
Overall, it's hard to do better than this for timing.
Grade: A
Wind/Power Outages
Timing was the best part of the forecast. This was the second best. We expected scattered outages but they were more isolated. The winds at the shore weren't bad as expected. The peak gust at Bridgeport was 28, while Groton was a little windier.
Grade: B
Snowfall Accumulation
Now to the toughest part of the forecast. There were some that were quick to call bust and then the forecast worked out in their backyard. There were many others that called bust and the bust was verified once the snow stopped falling. I'll never understand why some are so quick to call bust, but that's the business.
Originally, we considered a 5-10 zone inland but thought that was too low and went with a 6-12 zone. For the shoreline, we originally considered a 3-6" zone and went higher with a 4-8" zone. We thought the colder trend would be enough for significant snow even to the immediate coast, even with a significant snowfall gradient, which we did see in eastern CT.
A 3-6" zone would have been better, but honestly not by much and not for much of the central and eastern CT coast. We were wrong. Big.
Why we were off however isn't the reason you may think. The storm verified colder than the warmer models. The mixing line stayed south of the coast past midnight. The issue, as we see it, was the lack of heavy rates during the initial wave. When that happened, the coast was cooked. The forecast ended up wrong but not as wrong in SW CT where there was strong initial banding. For others, the dry slotting (or subsidence if we want to be technical) was too much to overcome.
Part two also took its time building a more consistent precipitation shield, but once it did some areas particularly inland were able to cash in.
Let's take a look at the radar from part of the initial wave.
Above: the radar from about 9:30pm to 2am. Note how there are consistent areas of weaker echoes show up across the southern four counties as a big band of snow rocks much of northern Connecticut, particularly west of the Connecticut River. Even though the mixing line stayed south of the state, the initial precipitation underwhelmed and with marginal temperatures that will not cut it.
As the bust was ongoing in the southern four counties, Litchfield and Hartford counties were rocking under an intense band.
As the bust was ongoing in the southern four counties, Litchfield and Hartford counties were rocking under an intense band.
As a result, looking back at the map there was only one observation in the entire shoreline zone that hit the mark. Approximately 30% of the observations were within 1". Truly awful.
The only thing that saves this forecast from being a big fat F is the northern four counties. To be clear, we were too high throughout all of southern CT, even in the 6-12 zone, but if you were in the northern four counties, you hit the mark. Had we went with 5-10, we would have been too low. To be so wrong in southern CT kills the grade, however. Maybe I'm being harsh given how much of the state we actually got right, but to bus this much leads me to given one of the worst snowfall accumulation grades I can recall.
Grade: D-
Overall Impact
We thought schools would be fine Monday given the Sunday end but surprisingly they were not. Despite the snowfall bust in the south, it was still the biggest storm in a few years across the state. Even at the shore, Bridgeport received 3.0" for the first time in years. It didn't seem particularly high impact, and obviously it wasn't in southern CT. Minor to moderate to moderate impact would have probably been best. Given the information at the time, moderate would have been the forecast.
Grade: C
Final Grade
People only really care about snowfall in their backyard, but we forecast for the state and for other factors. We have to take the totality of that into account. Given how it turned out with snowfall, the grade is dragged down to a level that's just unacceptable for us. It happens, and hopefully won't happen for a long time.
Grade: C
On to the next one...
January 9-10 Storm
The only thing that saves this forecast from being a big fat F is the northern four counties. To be clear, we were too high throughout all of southern CT, even in the 6-12 zone, but if you were in the northern four counties, you hit the mark. Had we went with 5-10, we would have been too low. To be so wrong in southern CT kills the grade, however. Maybe I'm being harsh given how much of the state we actually got right, but to bus this much leads me to given one of the worst snowfall accumulation grades I can recall.
Grade: D-
Overall Impact
We thought schools would be fine Monday given the Sunday end but surprisingly they were not. Despite the snowfall bust in the south, it was still the biggest storm in a few years across the state. Even at the shore, Bridgeport received 3.0" for the first time in years. It didn't seem particularly high impact, and obviously it wasn't in southern CT. Minor to moderate to moderate impact would have probably been best. Given the information at the time, moderate would have been the forecast.
Grade: C
Final Grade
People only really care about snowfall in their backyard, but we forecast for the state and for other factors. We have to take the totality of that into account. Given how it turned out with snowfall, the grade is dragged down to a level that's just unacceptable for us. It happens, and hopefully won't happen for a long time.
Grade: C
On to the next one...
January 9-10 Storm
Above: The Hockanum River in East Hartford on January 10. The river at the time was approximately 2.75x its normal height and had 10x greater flow than normal. This river was only at action stage, while other rivers across Connecticut were at moderate to major flood stage. The Yantic River saw its third highest crest in recorded history.
Everyone cares about snow, but these big rain events with wind potential have far higher impact sometimes. That was the case here, and after the rough forecast for the 6-7th we quickly had to come up with a forecast for a truly high impact storm of national scale.
Timing
We were a little off on how quickly the cold would be scoured out, which led to a little more flakes flying in interior CT, but that was minor. The timing was also slightly off, with a start that was a little faster than anticipated. Again, minor as we weren't off by more than an hour. We were very close with our worst impacts forecast, as the storm was at its worst between midnight and 5am for most of the state with far SW CT seeing the squall line come in just before midnight. The line moved through quickly and the heavy rain was done by sunrise.
Grade: A-
Rainfall/Flooding
We said this would most likely be the headline of the storm and it was. Easily. The rainfall forecast was spot on according to rainfall analysis, but we did have some locations over 4" of rain. We did call for that so no points off as that was relatively isolated as expected. That combined with rapid snowmelt created significant flooding issues.
Grade: A
Everyone cares about snow, but these big rain events with wind potential have far higher impact sometimes. That was the case here, and after the rough forecast for the 6-7th we quickly had to come up with a forecast for a truly high impact storm of national scale.
Timing
We were a little off on how quickly the cold would be scoured out, which led to a little more flakes flying in interior CT, but that was minor. The timing was also slightly off, with a start that was a little faster than anticipated. Again, minor as we weren't off by more than an hour. We were very close with our worst impacts forecast, as the storm was at its worst between midnight and 5am for most of the state with far SW CT seeing the squall line come in just before midnight. The line moved through quickly and the heavy rain was done by sunrise.
Grade: A-
Rainfall/Flooding
We said this would most likely be the headline of the storm and it was. Easily. The rainfall forecast was spot on according to rainfall analysis, but we did have some locations over 4" of rain. We did call for that so no points off as that was relatively isolated as expected. That combined with rapid snowmelt created significant flooding issues.
Grade: A
Coastal Flooding
This was also a pretty easy forecast admittedly given the southerly and southeasterly flow, and we saw minor to moderate coastal flooding along the shoreline. Interestingly, areas further northeast saw major coastal flooding, with some areas ending up with top 5 or top 10 coastal flood events. Fortunately, nothing like that here in Connecticut.
Grade: A
Wind
This was the hardest part of the forecast, and we hit this nicely as well. The inversion held around the state, and even where snowmelt was rapid in interior CT we saw the highest gusts stay aloft. That roar you heard most frequently was the wind above the ground, which was unable to mix down in a high end way, even with the development of an intense squall line.
We had our wind forecast a little more muted than it might otherwise be and that was a good call.
We expected maximum wind gusts inland to peak between 40-50mph. Hartford peaked at 41mph while Willimantic peaked at 47 and Danielson at 46. Interestingly, BDL barely gusted.
Along the coastline and interior New London County, we expected peak gusts between 50-65mph. We could have went lower, but it was fine. Stamford had a maximum gust of 60mph, while Fairfield was at 57 and Groton/New London peaked at 56. Bridgeport and New Haven peaked in the mid-40s, so that takes a little off the grade.
We also said with peak wind gusts in this range, scattered to localized widespread power outages were possible. Outages remained low.
Grade: A-
Overall Impact
This was certainly a high impact storm, particularly with flooding. To have three rivers at major flood stage and a mandatory evacuation for a partial dam failure is enough, but we had localized flooding across different parts of the state. The wind potential was moderate, and I'm glad to have us be wrong about scattered to locally widespread power outages. Wednesday did bring some delays and cancellations as well.
Grade: A
Final Grade
Overall, after a less than stellar forecast for the winter storm, it was wonderful to get right back to our usual standard for an even higher impact storm, on short rest no less. We overestimated the impact of wind on the power grid, but virtually everything else was spot on.
Grade: A-
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 SCW.
-DB
This was also a pretty easy forecast admittedly given the southerly and southeasterly flow, and we saw minor to moderate coastal flooding along the shoreline. Interestingly, areas further northeast saw major coastal flooding, with some areas ending up with top 5 or top 10 coastal flood events. Fortunately, nothing like that here in Connecticut.
Grade: A
Wind
This was the hardest part of the forecast, and we hit this nicely as well. The inversion held around the state, and even where snowmelt was rapid in interior CT we saw the highest gusts stay aloft. That roar you heard most frequently was the wind above the ground, which was unable to mix down in a high end way, even with the development of an intense squall line.
We had our wind forecast a little more muted than it might otherwise be and that was a good call.
We expected maximum wind gusts inland to peak between 40-50mph. Hartford peaked at 41mph while Willimantic peaked at 47 and Danielson at 46. Interestingly, BDL barely gusted.
Along the coastline and interior New London County, we expected peak gusts between 50-65mph. We could have went lower, but it was fine. Stamford had a maximum gust of 60mph, while Fairfield was at 57 and Groton/New London peaked at 56. Bridgeport and New Haven peaked in the mid-40s, so that takes a little off the grade.
We also said with peak wind gusts in this range, scattered to localized widespread power outages were possible. Outages remained low.
Grade: A-
Overall Impact
This was certainly a high impact storm, particularly with flooding. To have three rivers at major flood stage and a mandatory evacuation for a partial dam failure is enough, but we had localized flooding across different parts of the state. The wind potential was moderate, and I'm glad to have us be wrong about scattered to locally widespread power outages. Wednesday did bring some delays and cancellations as well.
Grade: A
Final Grade
Overall, after a less than stellar forecast for the winter storm, it was wonderful to get right back to our usual standard for an even higher impact storm, on short rest no less. We overestimated the impact of wind on the power grid, but virtually everything else was spot on.
Grade: A-
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 SCW.
-DB
