Good afternoon from Southern Connecticut Weather.
Wow.
Our latest storm has departed and we already have another possible one about 48 hours away. Things are moving fast here, so this discussion will take a look at the storm that was and briefly talk about the three additional winter storms that are in the pipeline in the next week. I told you it would be active...but how snowy and icy will it get?
Wow.
Our latest storm has departed and we already have another possible one about 48 hours away. Things are moving fast here, so this discussion will take a look at the storm that was and briefly talk about the three additional winter storms that are in the pipeline in the next week. I told you it would be active...but how snowy and icy will it get?
Above: the verification map for our latest storm. I used a combination of NWS published observations and follower reports! Locations are approximate.
Grading the Storm
Welp, the snow has passed, the measuring is done, and it's time to grade. This is where we set aside the emotions and look at the data, in an effort to understand what went right, what went wrong, and how to get better.
Timing
This was a tricky part of the forecast. The timing shifted around in the lead up to the storm. In the whole scheme of things, the forecast was good. I expected snow to start between 7-10pm, and that happened, though in western CT the start time was closer to 8pm and in central CT the start time was closer to 9. That requires a deduction. It was a fast mover, the heavy snow got going quickly after onset, and the worst of the storm happened in the window I forecasted. Ending was good too, which is heartening considering that the Euro (which struggled along with the GFS on this overall) had snow lasting into the early afternoon.
Grade: A-
Snowfall Accumulation
Alright. The toughest part of the forecast. As a reminder, snowfall accumulation counts double toward the final grade. You really need to see the numbers on a map to understand what happened. First of all, in hindsight the 4-8 forecast would've been better. That's very disappointing, No reports ended up going into the higher ceiling. High resolution guidance got on board with a more dynamic system, but then led by the HRRR it cut back as the storm really evolved over us, sniffing out a significant dry slot that ended up pushing into northern CT which 1) killed effective snow growth (meaning the kind of snowflakes that efficiently accumulate, and 2) significantly reduced the intensity of the precipitation.
Anything starting with a 3 is a bust in my opinion here, while anything starting with a 4 is off the forecast, but not by a terrible margin.
Welp, the snow has passed, the measuring is done, and it's time to grade. This is where we set aside the emotions and look at the data, in an effort to understand what went right, what went wrong, and how to get better.
Timing
This was a tricky part of the forecast. The timing shifted around in the lead up to the storm. In the whole scheme of things, the forecast was good. I expected snow to start between 7-10pm, and that happened, though in western CT the start time was closer to 8pm and in central CT the start time was closer to 9. That requires a deduction. It was a fast mover, the heavy snow got going quickly after onset, and the worst of the storm happened in the window I forecasted. Ending was good too, which is heartening considering that the Euro (which struggled along with the GFS on this overall) had snow lasting into the early afternoon.
Grade: A-
Snowfall Accumulation
Alright. The toughest part of the forecast. As a reminder, snowfall accumulation counts double toward the final grade. You really need to see the numbers on a map to understand what happened. First of all, in hindsight the 4-8 forecast would've been better. That's very disappointing, No reports ended up going into the higher ceiling. High resolution guidance got on board with a more dynamic system, but then led by the HRRR it cut back as the storm really evolved over us, sniffing out a significant dry slot that ended up pushing into northern CT which 1) killed effective snow growth (meaning the kind of snowflakes that efficiently accumulate, and 2) significantly reduced the intensity of the precipitation.
Anything starting with a 3 is a bust in my opinion here, while anything starting with a 4 is off the forecast, but not by a terrible margin.
Above is a radar loop taken between about 10:30-11:30pm. This is all snow, and as you can see it is heavy around the state. However, the heaviest is in southern CT, and we have a dry slot that is opening up to the west. The hope was that the slot would fill in somewhat as the storm intensified and resaturated the column, and while that happened to an extent, it was not nearly enough to save most of northern CT.
Above is a radar loop taken between about 12-1am. Note how there is still moderate to heavy snow in much of southern CT, but very light precipitation in northern CT. This is the dry slot failing to resaturate. My theory for this is that we didn't have a mature enough storm system, and that we had intense banding to the southeast (note the heavy echoes and gravity waves) that reinforced subsidence (drying aloft) to kill snow growth. At any rate, it wasn't expected to be like that. Areas to our north and south did better in terms of precipitation--the forecast just got unlucky.
The mixing was talked about, and it didn't have much to do with what happened, even though the mix did end up much further north than expected. In fact, the soundings on the HRRR, which did show snow instead of mixing, were wrong. That's just very odd.
The forecast came closest to verifying in southern CT because of the prolonged nature of the heavy snow. Even an hour or two of holding the dry slot off could have made a big difference everywhere. Alas, it was not to be. I said I would have been extremely annoyed if somehow we saw widespread 4" amounts. How about widespread 3" amounts in northern CT. Ugh.
It's important to note that even a 3-6" forecast (which didn't seem reasonable at the time) would have been tough in the snow hole of the state. I thought most would end up with between 5-8" of snow. I was close to the floor in southern CT, but it was a bust in much of northern CT.
Grade: C-
Impact
The impact forecast was good. This was a moderate impact event for most given the timing. Saturday was fine and most of Sunday will be fine. Super Bowl parties will not be disrupted today. I even called the crust of ice on top (though I didn't expect it to reach as far north as it did). Totally fine impact forecast here.
Grade: A-
Overall Grade
Look, this is hard work regardless of whether everything is right or wrong. We want to be the best. That's why we hold ourselves accountable and to a high standard. There were tricky parts of the forecast that were hit nicely, like the timing and overall impact, but for the thing that most care about--it mostly missed. Fortunately, the near miss in southern CT helped the grade given the bust in northern CT.
Grade: B-
The mixing was talked about, and it didn't have much to do with what happened, even though the mix did end up much further north than expected. In fact, the soundings on the HRRR, which did show snow instead of mixing, were wrong. That's just very odd.
The forecast came closest to verifying in southern CT because of the prolonged nature of the heavy snow. Even an hour or two of holding the dry slot off could have made a big difference everywhere. Alas, it was not to be. I said I would have been extremely annoyed if somehow we saw widespread 4" amounts. How about widespread 3" amounts in northern CT. Ugh.
It's important to note that even a 3-6" forecast (which didn't seem reasonable at the time) would have been tough in the snow hole of the state. I thought most would end up with between 5-8" of snow. I was close to the floor in southern CT, but it was a bust in much of northern CT.
Grade: C-
Impact
The impact forecast was good. This was a moderate impact event for most given the timing. Saturday was fine and most of Sunday will be fine. Super Bowl parties will not be disrupted today. I even called the crust of ice on top (though I didn't expect it to reach as far north as it did). Totally fine impact forecast here.
Grade: A-
Overall Grade
Look, this is hard work regardless of whether everything is right or wrong. We want to be the best. That's why we hold ourselves accountable and to a high standard. There were tricky parts of the forecast that were hit nicely, like the timing and overall impact, but for the thing that most care about--it mostly missed. Fortunately, the near miss in southern CT helped the grade given the bust in northern CT.
Grade: B-
The Week Ahead
There's not time to look back much, as we have a very active week ahead. Let's take a quick look.
Monday-Tuesday
Tomorrow is looking fine. It's a seasonably cold, but nice day.
Tuesday also looks good for the most part but then we have the first storm of the period that will make a close approach. This storm will be a big one for the Mid-Atlantic, and it is likely to slide to our south by later in the evening and into early Wednesday. The guidance keeps the heavy snow south, but there is a chance that we see some light snow if the storm gets far enough north. For now, the Euro has been most aggressive bringing this north, with the NAM getting on board for some light snow too lately. This is a tough call, but for now I would say expect light snow with a minor accumulation late Tuesday into early Wednesday. It's too early to say for sure if Wednesday morning will have delays but for now it looks unlikely.
Here are the GFS and Euro surface depictions for late Tuesday via Tropical Tidbits.
There's not time to look back much, as we have a very active week ahead. Let's take a quick look.
Monday-Tuesday
Tomorrow is looking fine. It's a seasonably cold, but nice day.
Tuesday also looks good for the most part but then we have the first storm of the period that will make a close approach. This storm will be a big one for the Mid-Atlantic, and it is likely to slide to our south by later in the evening and into early Wednesday. The guidance keeps the heavy snow south, but there is a chance that we see some light snow if the storm gets far enough north. For now, the Euro has been most aggressive bringing this north, with the NAM getting on board for some light snow too lately. This is a tough call, but for now I would say expect light snow with a minor accumulation late Tuesday into early Wednesday. It's too early to say for sure if Wednesday morning will have delays but for now it looks unlikely.
Here are the GFS and Euro surface depictions for late Tuesday via Tropical Tidbits.
Above is the GFS which is a near miss, while the Euro below is a scrape that would bring some light snow late Tuesday into early Wednesday.
This one is far from locked into place so stay tuned for updates tomorrow.
Wednesday-Thursday
Wednesday looks fine with another seasonable transition day as we wait the next storm. This one is coming, and the track is very important to what kind of storm we see. Right now, there is general agreement that this is another mixed bag system, similar to last Thursday. With cold air in place initially, we start out with snow statewide either very late Wednesday night or early Thursday morning. That will flip to a mix of sleet and freezing rain. It's unclear if this will also flip to rain later in the day on Thursday. There doesn't look to be a lot of precipitation with this one, but you don't need much liquid to produce a high impact system with minor snow and moderate amounts of ice. Thursday looks like it could bring widespread delays or cancellations.
Here's the latest GFS, which is pretty cold and would bring a decent winter storm. The Euro, which was way too warm with last Thursday's mixed bag, is warmer this time around too.
Wednesday-Thursday
Wednesday looks fine with another seasonable transition day as we wait the next storm. This one is coming, and the track is very important to what kind of storm we see. Right now, there is general agreement that this is another mixed bag system, similar to last Thursday. With cold air in place initially, we start out with snow statewide either very late Wednesday night or early Thursday morning. That will flip to a mix of sleet and freezing rain. It's unclear if this will also flip to rain later in the day on Thursday. There doesn't look to be a lot of precipitation with this one, but you don't need much liquid to produce a high impact system with minor snow and moderate amounts of ice. Thursday looks like it could bring widespread delays or cancellations.
Here's the latest GFS, which is pretty cold and would bring a decent winter storm. The Euro, which was way too warm with last Thursday's mixed bag, is warmer this time around too.
Again, there's a lot to sort out with this one even as it's not terribly far out in time. This could trend warmer or colder, but I do think that there will be enough of a mess Thursday morning to cause travel and school delay/cancellation issues.
Friday-Sunday
Friday is another transition day in the wake of Thursday's storm. More cold tries to press in on Friday and Saturday in advance of the next one, which is also likely to hit us. That cold press is absolutely critical. The weekend storm has major potential, but this far out we don't know how much the cold will press in, which will impact the track. A low that is further south and east will lock in a lot more cold and potentially lead to a strong storm offshore. This is what the GFS has been toying with, with its ensembles showing an offshore (read: cold) system.
Friday-Sunday
Friday is another transition day in the wake of Thursday's storm. More cold tries to press in on Friday and Saturday in advance of the next one, which is also likely to hit us. That cold press is absolutely critical. The weekend storm has major potential, but this far out we don't know how much the cold will press in, which will impact the track. A low that is further south and east will lock in a lot more cold and potentially lead to a strong storm offshore. This is what the GFS has been toying with, with its ensembles showing an offshore (read: cold) system.
Meanwhile, the Euro and its ensembles show what could happen if you have the cold press a little weaker, with a further west track that brings significant rainfall in a warmer system.
The most important takeaway for next weekend is that a storm is likely, but the track is unclear and that means that it's going to be a while until we have clarity on the precipitation type.
A lot of activity in the week ahead.
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 and enjoy the Super Bowl!
-DB
A lot of activity in the week ahead.
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 and enjoy the Super Bowl!
-DB
