Good afternoon from Southern Connecticut Weather. 

There wasn't a lot of sleep in the last few weeks as winter gave us its best shot. This latest storm was the most impactful, with snow, ice, rain, and wind on the backside of it. How did our forecast hold up? We submit our final grade below, and illustrate why the social media hype you may have seen elsewhere for a possible storm on Thursday took off...and was wrong.

Above: the verification map for the winter storm. Note that this includes measured snow and sleet (which officially counts as snow) from published National Weather Service reports. 

Grading the Forecast
Timing
As I mentioned in the final call forecast, the timing was trickier than I would have liked, both for the start time and the evolution of the warm air. We were fortunately right that the morning and afternoon would be fine, so that's good, but the onset of the snow happened fast.

We had snow break out from 3-7pm. First flake reports started coming in at 2:30pm, which isn't bad but worth a minor deduction. What was the bigger issue with start time was that the snow rapidly moved across the state, hitting eastern CT faster than expected. Many were snowing by 5pm, so this range was too large. 

Now for the changeover to mixing. We did say that we expected mixing to occur in SW CT between 10pm and midnight, and the mixing happened between 9-10pm. Not bad. Not perfect. However, we did also say that most of southern CT would be rain by early Sunday morning. That was partly right--but there wasn't enough specificity about it.

For northern CT, we were spot on, even identifying the potential for a mesolow to lock in colder air. We were also spot on about the rain timing window and wind timing. 

As mentioned above, there needed to be some deduction for a faster onset of the snow and slower erosion of the cold in part of southern CT, but this was pretty good overall. 

Grade: A-

Snow & Ice Accumulation 
​As you saw with the accumulation map above, we were spot on. It was the best map of the season, and the fact that this was the highest impact and most tricky forecast makes me proud. I'm even proud of where we set up the dividing line, though I probably could have pushed it slightly north.  

We had plenty of cold to start as snow, and as expected the warm air aloft did erode the cold. The surface cold was hardest to dislodge in northern CT, and NW CT struggled along with much of northern CT to get above freezing. However, there was much more cold than expected in southern CT away from the immediate coast, and as a result there was more freezing rain there. 

For southern CT, we did anticipate a general 1-3" of snow and sleet, along with a glaze of freezing rain before a flip to rain. It would have been more helpful to be more specific with the freezing rain amounts, because as I look back, a glaze implies minimal icing and that was not the case. The trick here is, what's significant? For me, .1 or .2 of ice is essentially a glaze to me, while .25 and above is more meaningful. It's something to remember whenever we have another icing event on the table. 

For northern CT, the guidance was all over the place but we went with 2-5 rather than 2-4" or a general 1-3 statewide. Great call. As expected, few saw 5", but the high ceiling for a colder storm turned out to be right as we had an isolated number of reports above 5". What's most important in all of this is that I did communicate that ice, not snow, was the story of this storm. 

The map carries us here, which is all that folks care about I know. However, there needed to be some deduction for lack of clarity. I'm not sure we could have anticipated the amount of cold in southern CT at the time of the forecast given the data we had, but to our credit, we did put it in multiple live updates in advance of the storm--so it should not have been as much as a surprise to readers. 

Grade: A-

Wind & Power Outages
It was a good call saying that we wouldn't have many wind issues during the storm. That proved to be right given the wind reports we saw. We got our significant wind in the wake of the storm and today. Because of the ice, we saw isolated to locally scattered outages. While overall, we had maybe 1-2% of the state without power--isolated overall--we did have some communities with higher concentrations of outages. That worked well with the forecast. 

Not much else to add here. It was spot on. 

Grade: A

Overall Impact
This is another bright spot for the forecast. I considered saying that this would be moderate impact in southern CT, but stayed away from that given the colder storm potential and forecast this as a high impact event statewide. We had numerous events canceled during the weekend, and the combination of snow, sleet, freezing rain, and heavy rain causing localized flooding did make things a mess. The road conditions were mostly right--though I should have called for more icy roads into the morning in southern CT. Great job overall. 

Grade: A

Final Grade
You have no idea how good it does my heart to know that the toughest storm of the season so far had the best forecast of the season. On little sleep!

Yes, there are always ways that we can improve. That is why we do these reviews. There is no perfect forecast. I could have been more specific with expected freezing rain accumulations, and the onset timing could have been forecasted better, but everyone that read the final call forecast knew to expect a high impact event statewide Saturday and Sunday.

Although it doesn't get graded, the live updates continue to prove that they add enormous value, given that we needed to "nowcast" the erosion of the cold and several waves of precipitation. For once, having the snow accumulation forecast weighed twice helps rather than hurts the final grade! 

Final Grade: A-

Now let's talk about something not so good--the social media hype surrounding the next storm in the pipeline...

Above: one of the images that was circulating social media in recent days about the possibility of a historic storm this week. On this image, "snow potential" was for Hartford to have nearly 35" of snow by Friday! Oops. 

Hype Sells but is Often Wrong
SCW has built its reputation on no-nonsense weather forecasting and discussion, and as a practice, we don't take shots at others that forecast. It's hard stuff. We don't pay attention to what anyone else is doing really, with the exception of the National Weather Service because they issue watches and warnings (and have high resolution models that are helpful). 

However, we often quietly bat down the hype that we see on social media. When talking about hype here, we're not talking about a bad forecast--which happens. We're talking about people that are intentionally trying to rile people up and/or share information in bad faith.

This time, I want to take a look at why the image above and the other calls you may have seen for an epic event coming this week turned out to be wrong, and why at each step better decisions could have been made. 

The Hype Cycle

Step 1: Find the Kernel of Truth
Like most garbage on social media, it probably has some kernel of truth--or at least the appearance of it. If you've been following our forecasts, we noted on Friday, February 14, that there was storm potential for the coming week. We kept it vague as we usually do at this time range, because while you can see storm potential 6-10 days out, you cannot see details.

This is what we said in the final call forecast that we issued that Friday: 

There will be plenty of cold, which will lead us to the next storm in the pipeline.

There is zero reason to get excited about or dread a possible storm next week. At this time, we do have higher than usual confidence that something will develop. Because there is going to be cold air in place and likely blocking in the Atlantic, we know it is highly unlikely to cut like this weekend storm. We have moderate confidence that the timing for a storm would be late Wednesday or Thursday. We do not know track and storm evolution. This could easily miss because of a poorly timed phase--just like that blizzard we missed out on a month ago. This could be a messy phase that brings us another modest snowfall. It could be a big dog blizzard. There's no real reason to do anything other than look at next week with a casual eye and avoid the hype on social media and elsewhere. Let's see where we are Sunday before taking anything related to next week seriously.  

We intentionally don't show snow maps or the most extreme versions of these models because they are useless. A good forecaster knows not to use them--especially at this range. 

The signal that a storm likely developing somewhere was the kernel of truth. But that's not enough to go all in on a historic event. 

Step 2: Show Extreme Potential
Sometimes, there is legitimately extreme potential that should be communicated. Most of the time however, models are either over amplified or "overwhelmed" in analyzing the nuances and chaos of numerical weather prediction at longer or even medium range. They start out extreme, but naturally modify to something far more mundane more often than not.

Here, a good forecaster knows to wait to see if there's a shift in the fundamental elements of a forecast that make an extreme solution more or less likely. In our text above, we note the potential of a poorly timed phase or a messy phase, along with the big dog possibility (but note we don't talk about snow totals intentionally). We don't post a snow map with specific numbers and say it's not a forecast. In our opinion, sharing that kind of stuff does more harm than good, and should only happen when you're at high confidence for an event to hit. 

For others, those more likely scenarios don't get serious consideration. So what was a kernel of truth--a big storm is possible--gets twisted into the most extreme computer model run possible and becomes the only thing that is shared and seen because it's shocking to look at. 

And the result is what we would expect. 

Above: this was the extreme GFS operational model forecast for total snow by this Friday. This model run was 7.5 days in advance of Friday. This much snow in one storm is almost unprecedented, which is a red flag in itself. 

Here's a trend loop for that same snapshot in time. Look at how the snow forecast changes as we get closer to reality. It's basically zero now. Note that some of this included snow from the weekend storm, but the picture is all the same. 

Step 3: The Truth Arrives Too Late
By the time someone is sharing a computer model showing 35" of snow in a week, or a hurricane hitting New Haven, or super high end tornado parameters in Connecticut, real analysis and truth go into hiding. We're playing whack-a-mole with questions about what's actually going to happen. 

Eventually the truth arrives because there's no mega blizzard, or hurricane, or tornado outbreak, but not before a lot of people are left confused and concerned.

One of the fundamental things about weather forecasting is understanding that most people do not follow it the same way that we do. Concepts like phasing, tropospheric polar vortex, and teleconnections are not understood at a detailed level by a small business owner or family, nor should they be. It's our job to bring thoughtful analysis to the table to help people be informed. 

Just looking at the 500mb pattern should have told many that the mega blizzard idea up the Eastern Seaboard was going to be tough, especially if folks waited for more information. 

Above: the last 15 runs of the GFS model looking at the overall pattern at 500mb. Note all of the changes that happen run to run--these make a huge difference in what happens here.

Ok, so what's happening this week?
Now for some reality.

A mega blizzard is not happening this week--though you probably know that by now because there aren't any new computer models showing a blizzard being shared. The kernel of truth was in fact truth--a significant storm is likely to form, but because of a missed connection between the northern stream and southern stream of the Jet Stream, the storm slides well south of our region, and becomes a significant storm well out to sea.

As a result, the next storm in the pipeline is most likely a miss--with light snow on Thursday possible if an inverted trough develops. This gives us all a much needed break from stormy weather, though the Arctic cold will be with us for most of the week ahead. The pattern still looks active, but for now, not at the same pace as the last two weeks. 

The storm was real. The hype was wrong. 

A​s 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

Good evening from Southern Connecticut Weather. 

Winter weather advisories are up once again for all of Connecticut as the latest storm in our extremely active pattern approaches. This one, like most of the others, will be a mixed bag system, with snow, sleet, freezing rain, and rain for the state over most of the weekend. Let's get right to it. There's a lot to discuss, including a look at big wind potential Monday, another Arctic blast, and the next potential storm in the pipeline.

Above: the snow and ice map for our upcoming storm. For southern CT, I expect a general 1-3" of snow and sleet, followed by a glaze of ice especially inland. For northern CT it gets more tricky, with 2-5" of snow and sleet expected and a glaze of ice for most. In NW CT, really most of Litchfield County, there is a greater risk of modest ice accumulation via freezing rain on Sunday. 

Overall Setup
We've been watching this storm closely the last few days, and while the general setup is now relatively straightforward, the devil is in the details.

Unlike our last few systems of middling strength, this is a big dog. A low pressure system will eject from the south, and rapidly intensify as it tracks northeast. Because there is no real Atlantic blocking to shunt it out to sea up under our region, with will cut to our west as it intensifies. That means we rain eventually. 

However, there is a relatively deep level of cold air in place, and that will ensure that the front end of the system will produce snow and ice. Importantly, this storm will try to spawn a mesolow off the coast that would lock in colder air as precipitation runs over the region, but that is something we will need to watch for as the storm evolves. Rather than the original thought of two separate waves this weekend, there's really only one big storm. Note the surface pressure in the 975mb range over near Buffalo and the expanse of the snow on the NW side of the low. This is a sprawling and powerful storm, that will influence the wind potential after it departs Monday and drag in our latest Arctic blast. 

The GFS below illustrates the storm evolution and the cold air advection Monday morning. 

The Forecast
Timing
This is trickier than I'd like because there is a bit of a discrepancy in the high resolution models for when this starts. Tomorrow morning and early afternoon look fine statewide. If you have morning and even early afternoon activities or travel plans, they will be fine. However, snow will break out statewide tomorrow afternoon. I think we see snow start out light for the state from west to east between approximately 3-7pm. The earliest start time will be in western CT, with the start of the storm during the middle part of that time frame in central CT, and latter part of that time frame in eastern CT. 

The snow will be moderate at times, and given the cold that will be in place tomorrow expect road conditions to deteriorate as the snow continues. It will snow statewide most of tomorrow. As the cold air aloft erodes, we will see the mix line start to creep into CT. In southwest CT, it will happen the earliest, with a flip from snow to sleet likely between about 10pm to midnight. Once this mix line starts showing up, it will blast its way through much of southern CT, turning most of southern CT to rain by early Sunday morning. 

However, for northern CT, that mixing will be hard to dislodge during the early morning hours. That will give the area an extended period of sleet and then potentially freezing rain. In NW CT especially, surface cold will be hard to dislodge, so there's a chance icing continues into the day Sunday there, and across much of northern CT if the mesolow develops fast enough to lock in the cold for longer. 

At any rate, warmth eventually wins with this storm for most if not all of the state. By Sunday afternoon and night we will likely have periods of moderate to heavy rain moving through the state until the storm passes and winds start to ramp up in its wake. Monday will be clear, but it will be very windy. 

Snow & Ice Accumulation 
​If you look at the image below, this is basically how the storm will play out over time. 

We will start with cold air at the surface and aloft across the entire state. That's why we will start off as snow. Over time tomorrow, warm air aloft will erode the cold, changing us to sleet. As more warmth moves in as the storm intensifies to our west, then we will see freezing rain. The surface cold will be hardest to dislodge in northern CT, which is why freezing rain will likely last longer here than in southern CT. Once the warmth has overwhelmed the entire column, we rain.  

This makes the snow and ice accumulation forecast tricky. Along the coast, you honestly want more snow than ice, which means you want heavy enough precipitation to keep the column cool as long as possible before warmth arrives.

For southern CT, I anticipate a general 1-3" of snow and sleet, along with a glaze of freezing rain before a flip to rain. The lowest snow amounts are likely in coastal SW and SE CT, with more snow and sleet the further inland you are. 

For northern CT, the guidance is all over the place. My best call is a general 2-5". I doubt many see 5". I want a high ceiling for if this trends colder. I think most likely land in the 2-4" zone.

It's really important to note that I'm intentional in setting these ceilings and floors. It's not going to be a bust if most of the state is 1-2" of snow--that would likely mean that there's fairly substantial icing in the form of sleet (which accumulates much less efficiently like snow) and freezing rain. The ice is the story for this storm.

Less snow and more ice as I described above is probably the highest impact and worst case scenario. It is on the table, but I expect more cold in place for more measurable snow and some ice.

Below is the latest high resolution NAM depiction, showing the difficulty in getting the cold air in CT totally eroded. There will be places in southern CT on Sunday that rocket their way into the 40s, while parts of northern CT will be struggling to cross the freezing mark, especially early.

This is a very tricky setup.  

Wind & Power Outages
Overall, being on the warm side of this storm isn't going to cause a lot of wind issues early. In fact, for most of the storm I'm not expecting significant wind. However, in the wake of the storm we are likely to get a significant period of wind on Monday. That's going to be discussed later since it's post storm. 

With possible icing in interior CT however, wind on Monday will be something to watch. The ice by itself doesn't look to be major, but there could be some isolated to scattered outages on Sunday, and more scattered outages on Monday depending on whether we can get the higher winds to verify. 

Overall Impact
This is a high impact event. To be clear--it's not a let's panic and go get bread and milk storm, but it's high impact because most events will likely be canceled for later Saturday and into Sunday, even though it'll likely be fairly warm in southern CT eventually. Flights will likely get delayed between Saturday evening and Sunday early afternoon.

The snow by itself isn't bad, but the combination of snow (which could be moderate at times statewide on Saturday), sleet and freezing rain especially inland, and the prospect of heavy rain and snowmelt on Sunday that could cause some localized flooding issues, makes this a messy event.

Road conditions will not be great for northern CT on late Saturday afternoon/evening into much of Sunday. In southern CT, road conditions will not be great Saturday afternoon/evening into Sunday morning in terms of snow/ice. Wet roads will be a thing late Sunday morning and through the evening. 

Because of the timing of the storm and winds after, there is the chance of widespread delays Monday morning, but it's a little early to lock that in. I just need to note it here because the potential is there. 

Looking Ahead
I will do this very quickly, since the weekend storm is the main focus. We're nowhere close to being done with this active wintry pattern. It's likely to last until at least early March. There is no early spring likely this year. 

As I mentioned above, Monday we are likely to see a very windy day in the wake of our storm. Right now, I think we see wind advisories for gusts of 45-50mph statewide, but there is a signal for greater wind potential on Monday. If that happens, power outages will become more likely. Stay tuned to for additional updates as that comes into greater focus. 

One thing is a guarantee: we get Arctic cold in the wake of this big weekend storm. Expect high temperatures well below normal, with the chance we string together some days below freezing. This time of year, temperatures start to rebound. Believe it or not, the average high/low temperature in Hartford in mid February is 38/20, while it's 40/25 in Bridgeport.  

The Arctic blast will be much worse to our west, but it'll be plenty cold here. Below is a European ensemble 5 day averaged temperature departure next week. 

There will be plenty of cold, which will lead us to the next storm in the pipeline.

There is zero reason to get excited about or dread a possible storm next week. At this time, we do have higher than usual confidence that something will develop. Because there is going to be cold air in place and likely blocking in the Atlantic, we know it is highly unlikely to cut like this weekend storm. We have moderate confidence that the timing for a storm would be late Wednesday or Thursday. We do not know track and storm evolution. This could easily miss because of a poorly timed phase--just like that blizzard we missed out on a month ago. This could be a messy phase that brings us another modest snowfall. It could be a big dog blizzard. There's no real reason to do anything other than look at next week with a casual eye and avoid the hype on social media and elsewhere. Let's see where we are Sunday before taking anything related to next week seriously. 

Above: the GFS from this afternoon showing a miss next week. 

Below: the Euro showing a messy phase leading to a modest storm next week. ​

Nothing to be riled up about. At all.

Yet. 

​A​s 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

Good evening from Southern Connecticut Weather. 

Busy times. 

Tonight we're dealing with a close scrape from a storm to the south (Storm One) and the second storm this week (Storm Two) is already on its heels. A mixed bag is on tap for our Thursday, and because of the timing there is likely to be some impact. Storm Three is waiting this weekend. Let's dive in. 

Above: a snapshot of the high resolution NAM, showing mixed precipitation in northern Connecticut and rain in southern CT around 4am Thursday morning.

Storm Two (Late Wednesday-Thursday)
In this pattern you should expect some of everything: hits, misses, snow, rain, and mixed precipitation. Literally. The fast flow in the atmosphere moves storms along very quickly, while the oscillating temperature gradient between warm and cold makes precipitation type for each system tricky. 

Storm Two has trended weaker over the last few days, which has a big impact on conditions and impact. If it were stronger, we'd likely be able to hold more cold in place as warm air tried to erode the cold, but with a weaker storm and lighter precipitation, we can't get enough cooling to hold off the rain. 

There will still be enough cold late tomorrow for things to start off as snow, but that snow will be light and quickly change over. In southern CT, it will quickly go from snow (a coating) to mix to rain, while inland areas will hold onto mixing a little longer on Thursday. 

The NAM below depicts this well, showing a period of snow starting between approximately 8-10pm Wednesday night, followed by a change to mix and then rain Thursday morning. 

Because of the timing, this weak storm will have some impact, especially inland. Unlike last week, the cold is unlikely to hang on as long.

For southern Connecticut, expect a coating of snow and a light glaze of ice Wednesday night into early Thursday. By sunrise it will be a plain rain. As a result, the impact looks low, and while widespread delays are possible I do not think they are likely. 

For northern Connecticut, we could see a coating to an inch or isolated two spot before a glaze of ice. While some guidance shows a change to rain, it's possible that a dry slot moves in before there is meaningful rainfall. Because mixing could continue past sunrise in northern CT, widespread delays look likely, and cancellations are possible. 

This is a fast mover, so the PM commute although wet, shouldn't be too bad. 

Storm Three (Saturday-Sunday)
The final storm of the week continues to have the biggest potential, but there's a lot of uncertainty over whether it will be a significant rain event (1"+) or a wintry storm. 

This one is tricky, and it's a lot about timing. A piece of Arctic air is trying to move toward the region as the weekend storm develops. Recent guidance has backed off a significant cold press leading to another mixed bag to rain system. There is a lot that can still change with this, so it's not worth going into too much detail yet until some of the major features are more stable, but this looks to be a longer duration storm as a follow up wave tries to develop along the temperature gradient. 

With a colder press, the gradient and thus the low would sag further south, bringing significant snow and/or ice. Without that cold press from the polar vortex, the temperature gradient is further north, and the storm effectively cuts to our west, bringing heavy rain Saturday and Sunday. 

In terms of timing, it looks like onset wants to speed up. Right now, we're looking at snow breaking out early Saturday afternoon, with precipitation likely lasting through Sunday as the follow up wave develops. There are still significant differences between the GFS and Euro. At this time, I think this one brings a snow to mix to rain event. 

GFS, which is much more wintry with snow and potentially significant ice. 

The Euro on the other hand goes from snow to significant amounts of rain during the period. 

There's still a ton to sort out with the weekend. A storm is likely and we will likely have some snow, but how much snow before going to ice or possible rain remains highly uncertain. Stay tuned. 

A​s 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

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?

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.  

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 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. 

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. 

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. 

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. 

​A​s 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.
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Thank you for reading SCW and enjoy the Super Bowl! 

-DB

Good morning from Southern Connecticut Weather. 

I'll get right to it. A significant winter storm is on the way. Winter storm warnings are up for all of the state for the first time this season. Let's dive in. 

Above: the final call snow map, which was tweaked upward slightly. 

Overall Setup
There aren't any substantive changes from what I said in the first call forecast about the overall setup. The cold is in place this morning with everyone in the teens and 20s currently. While temperatures will rise, we should have the cold held in place much better than the last mixed bag event. Our storm will quickly take shape later this evening as a low develops and slides off the coast and travels near the "Benchmark" which is a key zone for significant snows in New England. It's not quite a perfect system, however, as a warm nose could creep in aloft, leaving the chance of some mixing toward the end of the storm.

The NAM, which for a while was the least aggressive model, continues to show this risk in southern CT even as it comes in line with other guidance. Its depiction is below. 

The Forecast
Timing
To my surprise, this looks like the onset has slowed down some. That's a bit unusual given how quickly the flow has been. The overall thoughts are not that much different however in the whole scheme of things. It's still a fast mover, and today the overwhelming majority of activities are fine. Now it does look like snow starts between about 7-10pm. Snow should start from SW to NE, and the heavy snow will get going pretty quickly after onset, meaning you will probably want to be off the roads before if not shortly after the snow starts in your area. Travel late tonight into early Sunday will be tough. 

The worst of the storm happens in the overnight hours, from about 10pm to 2am, with snow gradually diminishing in intensity after that. There is agreement that snow is done by late morning, so while the morning commute may be a little tricky, the afternoon should be fine and Super Bowl events should not be disrupted too much. 

Snowfall Accumulation
Like the last few storms, I am tweaking the forecast just a bit to take the floor and ceiling up. I am now going with a statewide 5-10" zone as opposed to the original 4-8" forecast. This is primarily because high resolution guidance has gotten on board that the storm develops fast enough to bring a dynamic period of heavy snow to most of Connecticut as the storm passes to our south. With a developing storm however, there are some risks. With banding, there will be proverbial winners and losers, with some towns ending up with higher totals and the next town over maybe ending a little low because of subsidence (read: dry slotting).

The other risk that is on my mind is the prospect of mixing late in the storm as a warm nose tries to creep in aloft. This could mean a period of sleet or freezing drizzle in southern CT as precipitation slackens on the backside of the storm. That would actually make the storm a little more impactful, even if it cut down on totals some. My expectation is that ratios stay relatively close to 10:1, but for a time, particularly during the heaviest snow, there may be some very efficient snow growth. I think that introduces the risk that some spots end up with slightly over 8". For the coast, I think that the mix risk (which looks fairly likely at some point near the end of the storm) is not enough to preclude widespread 5" minimum totals. I'll be extremely annoyed if somehow we see widespread 4" amounts haha. 

Here, I think the global models--the GFS and Euro are a good guide post. They bring in pretty significant precipitation overall with both showing a period of heavy snow. This is a better setup for significant snow than the mixed bag a few days ago, but folks need to keep expectations in check. I still think most places end up with between 5-8" of snow. Plenty significant considering that such a range represents half of what all of February usually produces. If the storm comes together a little faster or banding is oriented over CT better, there is a little upside. If it is slower to organize, the floor and ceiling are lowered. Simple as that. 

Above: this morning's GFS depiction of our fast moving system. Even with the mix line close to the coast, there is a period of heavy snow overnight for most of CT that produces significant snowfall totals. The Euro effectively mirrors this. 

Impact​
This still looks like a moderate impact event, mostly because of the timing. Most of Saturday is fine, and the worst of the storm is Saturday night into Sunday morning. Super Bowl parties are still a go Sunday afternoon and evening when the storm is long gone. That said, tonight and Sunday morning will not be smooth sailing. Expect bad road conditions, delayed flights, and poor visibility during the worst of the storm. If there is some mixing, that could leave a heavier crust on top of what should be more powdery/fluffy snow and icy conditions, especially in southern CT. I don't think we have significant wind or power issues. Overall, it's a significant but fast moving winter storm that's hitting at a time of minimum impact.

After this one, we turn our attention to Tuesday, which is the next opportunity for snowfall. It has trended south and less impactful, for now. 

​A​s 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.
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Thank you for reading SCW.

-DB