Good evening from Southern Connecticut Weather. 

It's a quick turnaround, as we're already tracking the next storm. This is a brief look at our final forecast for our most recent storm. The first in ten weeks! 

Above: the final snow total map from our snowstorm. I used a mix of NWS reports and follower final totals. I tried to fit in as many as I can. None of the final reports came in lower than our 3" floor or higher than our 8" ceiling. That's as good as it gets. 

The Forecast

Timing 
We expected snow to begin between 6-10pm, and while that was generally a good call, I think there are some points lost because from what I could tell we didn't have flakes falling until the 7pm hour.

The heaviest snow did occur during the overnight hours, especially the early Tuesday timeframe. Snow continued for most through Tuesday morning and into the afternoon. As we expected the bulk of the snow fell by 8am and as temperatures warmed during the day, accumulation wasn't as efficient, especially in southern CT. In fact, one follower reported rain in coastal SE CT. 

Overall, great call. Points lost for being slightly off on start time in the west. 

Grade: A- 

Snow Accumulation
We had high confidence in a widespread 4-8 inches of snow. That worked out perfectly. The snow totals were pretty uniform in different regions of the state, and despite not a lot of reports in NW CT, I did see 6-7" reports on social media which were not included in the map. 

The biggest win was the shoreline zone. When the models were trying to throw out 7-9" totals along the coast late yesterday, we held with our 3-6" zone. While we didn't see as many 5-6" reports as I thought yesterday afternoon, only a few spots were near our 3" floor. Had we upgraded that zone to 4-8, or a done a statewide 5-10, which we were thinking about for a bit, we would have busted. We bet against the high totals of the models at short range yesterday and won that bet.  

Some will probably want to contest this, but everyone who follows knows I'm no nonsense with grading. This was about as good as it gets from SCW. 

Grade: A

Impacts 
We expected a moderate impact event and got one. We were accurate with our roads forecast, which called for messy conditions late Monday through Tuesday morning, but gradually improving during the day Tuesday. Importantly, we got the widespread cancellations call right. 

We weren't quite perfect though. We were ever so slightly warmer than expected, which led to more wet than fluffy snow. In the whole scheme of things, we weren't off by much at all, but off is off. It was probably the difference between widespread 5-7 and widespread 6-8. There were no power or wind impacts. 

Grade: A

Overall Grade
We did an excellent job. This is about as good as forecasters can do, especially given the back and forth of the guidance inside 72 hours. Snow accumulation, as always, is weighed heavier than the other factors. 

Final Grade: A

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. 

I have a confession to make: I'm nervous.

I'm not really nervous about the forecast itself. After an historic lack of winter thus far, it looks like we will see that period finally try to turn around. But it has to get here. 

It should. 
​
​The guidance has more or less stabilized, and it's time to make a final call. This will be a shorter discussion than our first call, but the grading will come from this forecast. Let's dive in. 

Above: our final call map for Monday-Tuesday. As I alluded to earlier, we have left most of the state in the 4-8" zone, and expect highest totals in the NW and western portion of the state. For the shoreline, with the trend toward colder temperatures during the peak of the storm holding through the day, we have increased the expected snow totals there from 2-4" to 3-6". For this zone, most will likely see total accumulations of 4-6", but we introduced a 3" floor for the immediate shoreline areas that may see lower ratios early Tuesday morning. 

The Forecast

Timing 
Again, most of Monday looks fine for travel. We expect to see snow develop from west to east, and the guidance has coalesced around a later start time. As a result, we now anticipate snow to begin between 6-10pm. This should leave the evening commute dry for virtually all of CT. 

The heaviest snow occurs during the overnight hours, especially the early Tuesday timeframe. Snow will continue through Tuesday morning, and perhaps into the afternoon. However, we expect the bulk of the snow to fall by about 7-8am on Tuesday, and as temperatures warm during the day, accumulation won't be as efficient, especially in southern CT.  

Snow Accumulation
There is high confidence in a widespread 4-8 inches of snow. The highest accumulation is likely to be in western Connecticut, especially the NW hills where a winter storm watch is in effect. For the shoreline zone, we took the numbers up and expect most to end up with 4-6". We added the 3" floor because the immediate shoreline is always at risk of slightly lower totals if ratios are lower. I doubt it happens, but I don't want to kick myself afterward in case it does. 

As I said last night, in the CT River Valley we always watch for dry slotting. Some guidance shows this. I'm watching NE CT too in case there is less precip squeezed out up there, but we do still expect a widespread 4-8".

Above: the 18z GFS depiction of the storm. It's all snow, for all of CT, on the frames that matter. 

Impacts 
We expect a moderate impact event. Roads will be messy late Monday through Tuesday morning, but will gradually get better during the day Tuesday. The timing makes it more likely that we see widespread cancellations on Tuesday.

With the continued cold trend, we may see higher ratio snow early Tuesday morning, which results in more fluffy snow. Along the shore, however, temperatures closer to freezing may mean some heavier (read: pasty) snow on Tuesday. We don't expect significant power outages and we don't expect particularly strong winds. 

Above: A quite bullish HREF mean for the storm, showing most getting 6-8". We're lower than this, but it increases confidence in our general forecast of a widespread 4-8". 

Overall
Overall, this has become a pretty straightforward forecast. We see snow begin in the state from west to east between 6-10pm on Monday, with the heaviest snow falling early Tuesday morning. Snow may linger into Tuesday afternoon, and we anticipate widespread cancellations for a broad 4-8" of snow inland and 3-6" in far southern CT, where most see 4-6". 

Moderate impact overall, and then we turn our attention to the end of the work week...

​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. 

The storm we've been tracking for the last few days continues to shift around a bit on the guidance, but it's time to issue our first call. Computer guidance is only a tool. At the end of the day, we have to look at the guidance in its totality, but we also have to analyze the overall pattern and environment to make a reasonable call for what's going to happen. 

We have enough confidence to issue our first call map, and as you will see in the detailed discussion, there's still a fair amount to sort out. For the first time in 10 weeks, let's analyze a snowstorm. 

Above: our first call snow map. We expect interior CT to see between 4-8" late Monday into Tuesday. As it stands, we expect most to be in the 4-6" range with the highest potential for more snow in western CT. For coastal CT, we have introduced a 2-4" zone. However, this is a lower confidence zone. We expect most in this zone to end up with 3-4" if you are away from the immediate shoreline. 

General Overview
As I said before, we're looking at our first legitimate wintry event in a while because the pattern has changed. Essentially, we are looking at the big storm in California. As it crosses the Rocky Mountains, it will de-amplify, or weaken, as it reaches the Great Lakes. A week or two ago, this would have cut to our west and brought us rain and warmth.

However, because there is a -NAO providing blocking in the Atlantic, rather than a straight cut to our west we will see just enough high pressure to our north as energy transfers, and we see a low develop along the coast, bringing in colder air throughout the column for snow. 

While the guidance has bounced around, it has held for the most part with this general evolution. As a result, we have high confidence that this one does not suddenly miss to the south or cut to the west bringing all rain.  

Above: a GFS 500mb loop showing the evolution of the California. Look at how it is strong in California, but gradually weakens as it heads east toward the Great Lakes. It then transfers enough energy off the coast to bring us our storm. 

The Forecast

Our grade will be based on the following factors in our final call, which will be issued late tomorrow or very early Monday. We have gotten questions about why the models have seemed all over the place. Here's why. 

Computer models are designed to take atmospheric data and make extremely complex calculations to project what the weather will be. It's more than just how much snow will fall or what the temperature will be at the surface. Guidance looks at everything from the upper level pattern to low level details. The upper level pattern drives our sensible weather. 

In the whole scheme of things, models can't be trusted with details until we're inside 72 hours of an event, and even then, things constantly change. A degree or two warmer at 850mb, above the surface, can make the difference between snow or something else. This happens at many levels near the surface. 

Overall, the models have shifted here because they have struggled with de-amplification. That has created a little chaos in temperature and total precipitation forecasts, along with the track. This is because of the interaction between the low pressure and the block in the Atlantic. That has more or less smoothed out, and as we get closer, I expect more alignment. Small changes aloft can still have big implications at the surface. 

Timing 
Most of Monday looks fine for travel. We expect to see snow develop from west to east around mid-afternoon, which is a little earlier than the guidance currently suggests. That may make the evening commute a little tricky but manageable as we look at things right now. 

The heaviest snow occurs during the evening and overnight hours. Normally, that would reduce the impact and it does to an extent, but we expect snow to continue into Tuesday morning and possibly early afternoon, if the system does not introduce enough warming to change things over in southern CT. 

Snow Accumulation
As the snow map shows, we expect most to see 4-8" with the shoreline seeing lower amounts. We need to break this down more, however. 

We have fairly high confidence that this is a 4-8 event inland. Looking deeper, it's western CT that is most likely to have the highest amounts, and that may even reach down to the shoreline. In the CT River Valley, we always watch for dry slotting, and in eastern CT, this time it looks like we may not get the best lift to continue the streak of jackpots from snow event. Famous last words. 

Bottom line, 4-8 is a good bet for interior CT. 

Where I really have caution flags up is far southern CT. I need those peeps to read carefully here. Despite the 2-4 zone, this looks impactful. For our first call, the SCW team decided to be more conservative in case there is poorly modeled warmth, which obviously has been an issue this year, that cuts down on snow accumulation. The trend today has been to shift the warmth further south, meaning more snowfall when the storm is really going. In fact, the latest GFS and Euro are in agreement for now that even if there is a mix, that happens Tuesday morning after a widespread 4+ has fallen even down there. 

As a result, for our first call we think it is reasonable to expect a floor of 2", but most will see snowfall of 3-4". These numbers may go up in the final call should we see a continued trend that keeps the warmth away and allows for less precipitation to be "wasted" on rain.

​I do not anticipate the final call lowering the floor to say an inch or so. This should be plowable across Connecticut, especially given the timing of the heaviest snow. 

Above: the 18z GFS. As you can see, it's looking colder than prior runs, which increases confidence for now that our floor of 2" won't be touched in coastal CT. We watch the immediate shoreline. The heaviest snow ends Tuesday morning, but lighter snow is possible into the afternoon.   

Impacts 
The timing of the heaviest snow happening overnight and early Tuesday actually cuts both ways here for impact. On one hand, the timing means that most will be off the roads. On the other, it increases snow accumulation potential on roads as we won't have daytime insolation available to warm up roads and sidewalks. This should mean that Tuesday sees widespread cancellations, even at the shoreline. This is the best chance yet for a snow day...for those that have an interest in that kind of thing. 

In addition, this is looking more like a paste than fluffy snow. That will have some impact as well in terms of shoveling. We don't expect significant power outages because we won't have a significant gradient or strong enough low to really crank the winds up. It'll be a little breezy at the coast, but nothing too bad. 

Below is the 18z Euro depiction of surface temperatures. As you can see for inland CT, this is all snow with plenty of cold in place. For the immediate shoreline, we do need to watch but even here it looks cold enough for plowable snow. Although the temperatures rise late morning into afternoon, the bulk of the snow has fallen by then. 

​This looks like a moderate impact event. 

Overall
For a winter that has essentially been the worst in recorded history, it's easy to feel like this one is going to fall apart right before it starts. If you need to see snow to believe it, I get it. I kind of do too.

However, given the data and our read of the pattern, this looks like a moderate impact event statewide, with plowable snow that likely turns Tuesday into a snow day. 

Stay tuned as we will continue to refine the forecast. For southern CT folks, don't let the 2-4 zone make you tune this one out. While 2" is the floor we expect most to end up with 3-4", and there's a legitimate possibility those numbers go up if we continue to look colder closer to the storm arriving. 

​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. 

It has been nearly three weeks since I last wrote a formal discussion, and with good reason. It has been a continuation of winter 2022-23 thus far: virtually snowless and far warmer than normal. It has been so quiet, this forecaster has begun longing for real spring. Doesn't a week of 70 and sunny sound wonderful?

We have seen a very long period of quiet, relative to winter weather threats this year. However, this is looking to change this week as we watch multiple opportunities for...something...

Let's dive in. 

Above: Another month, another torch. This winter has been historically warm and historically snowless relative to normal, thus far. 

Monday
A holiday for many, tomorrow looks like a decent, but cloudy day. It is likely our last truly warm day for a while. Expect highs in the low to mid 50s, which this time of year is 10-15 degrees above normal. 

Tuesday
Our active period starts as a weak wave passes to our north and tries to spawn redevelopment to our south. While the early morning looks quiet, we will likely see periods of rain that could change briefly to snow or a mix of rain and snow during the late morning and afternoon. Wintry precipitation is most likely in northern Connecticut, but temperatures are marginal. I am not expecting a significant event, but watching in case the redevelopment off the coast gets a little stronger. This is actually important for the more significant late week event, because a colder event will drive the temperature boundary a little further south for Thursday. 

Wednesday
Wednesday is a transition day, as we watch the primary weather maker of the week approach. It should start off quiet and sunny, with highs in the low to mid 40s. We will see increasing clouds into the afternoon and evening, and it's possible we start to see snow and mixed precipitation late in the evening as the storm approaches. 

Thursday
It's not quite a SCW Period of Interest, but it's close to it. This system, which has been on the computer guidance in various iterations for more than a week, is now looking like a fairly classic overrunning event, which is simply warmer air overrunning colder air at the mid and lower levels to produce precipitation. 

While still a bit skeptical of the impact, this is looking like a higher confidence winter weather event in at least northern CT.

Why? These kind of events tend to be simpler with less reliance on the broader pattern, which has without question been far warmer with storms cutting to the west. We don't have to think about storm track here.

The critical factor in this event is where the boundary of low level warm/cold air sets up, and whether there is a "cold tuck" during the event that allows for additional cold air to funnel in and prolong the wintry precipitation. The trend so far has been colder, even in southern CT. 

For now, northern CT should expect snow to change to mixed precipitation, which could be both sleet and freezing rain and result in icing. In southern CT, I currently see the potential for mixed precipitation to rain in southern CT.

​Note that there is still a fair amount to be sorted about how much cold filters in, but this looks increasingly unlikely to trend to an all rain event for CT, even if it trends warmer late. This is looking like our first legitimate winter weather event in a while in northern CT, and possibly southern CT if the trends continue. There may be widespread cancellations on Thursday. 

Above: the very latest GFS, which is a little warmer than the last run, but still has almost all of CT mixing throughout the event. That's something to watch for more impacts in southern CT. 
​
Friday
The models want to keep some precipitation around on Friday, but I think that's unlikely. As a result, I think Friday looks quiet and cold in the wake of the event, with highs in the 20s and 30s.  

Saturday-Sunday
The weekend will likely have another chance for wintry precipitation, but this one is tenuous. Cold air should be in place, but Saturday looks quiet. Sunday may bring another system like Tuesday, with a weak system to the north trying to spawn redevelopment. Not worth talking about much right now. 

The Dailies
Monday: Mostly cloudy and unseasonably warm. Highs in the low to mid 50s. 

Tuesday: Mostly cloudy with a chance of rain and snow. Highs in the upper 30s to low 40s. Chance of precipitation 80%. 

Wednesday: Mostly sunny early with increasing clouds and a chance of snow/mix late. Highs in the low to mid 40s. Chance of precipitation 40% late. 

Thursday: Snow (early)/rain/and mixed precipitation. Highs in the low to mid 30s. Chance of precipitation 90%. 

Friday: Partly sunny. Highs in the upper 20s to low 30s. 

Saturday: Mostly sunny. Highs in the upper 20s to low 30s. 

Sunday: Mostly cloudy with a chance of snow. Highs in the low to mid 30s. Chance of snow 30%. 

​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

Disc: A brief, but intense Arctic blast effects the state thru tomorrow, then we warm up, but winter may return at the end of the week or next weekend???

Currently: Arctic front well offshore.  Strong winds marking the arrival of CAA.  Winds have been very impressive, as we've had three gusts over 40 MPH here at the office!

Tonight: I went well under guidance, as core of Arctic air moves in.  My only concern is that the core of the cold is really here within a few hrs of midnight.  However, winds diminish a bit later at night, so that could be compensated for by radiational cooling We'll see.  Overall, I generally have most of the state painted in single digits BELOW zero! It is possible Tolland and Windham get to -10! It is also possible the immediate S coast does not get to zero, but even they'll be close!

Tomorrow: Went a touch above guidance.  Very rapid recovery, as high pressure slides offshore.  Howver, given our starting point, it will stay quite cold, with highs only in the mid to upper 20s.  Winds continue to diminish, so wind chills will be close to actual temps.

Tomorrow Night/Sun: I went below guidance by a couple deg, as NBM guidance appears to think cloud cover is very thin.  While this is possible, the sun angle is still pretty low.  There will also be some onshore flow off the cold LI sound in the afternoon on the S coast.  Highs generally near 40.  In the normally warmer (during the day) CT Valley locations, I went near guidance, and have low to mid 40s there.

Long Term: Mostly quiet period, things get more unsettled in the 2nd half of the period, and perhaps more interesting toward the end of the period.

Mon: W/wind flow turning more land-based and clearing skies, I felt safe going very close to guidance.  High temps generally in the mid to upper 40s.

Tue: Wind flow looks lighter.  That's the only major change I can see between Mon and Tue.  So I made one adjustment to the fcst for Tue, and that is to go a bit cooler than guidance along the immediate S coast, w/aftn sea breezes possible.  So highs generally mid to upper 40s, but 40-45 along the S coast.

Wed: I went a bit cooler than guidance everywhere.  A cold front approaches, so clouds increase ahead of it, along w/the chance for a brief shower.  I erred on the side of caution w/regards to temps.  if clouds are delayed, it could be warmer than my fcst, as we'd get into the warm surge ahead of the cold front.  But for now, just to be safe, I have the entire state painted in upper 40s.

Thu: The storm slated for this period has trended faster.  Faster means less wintry, as cold air really won't have a chance to dig in.  So we'll need to watch trends, as a slower storm could mean wintry wx prospects.  For now, I just broadbrushed rain Thu into early Fri.  

A few things could happen: This could be a mainly overnight and morning(s) event. where most of the day Thu is relatively dry.  However, even if this happens, Thu is drizzly, showery, and dank.  This could trend slower impacting more of Fri, which would introduce wintry wx into the area.  For now, I went w/the faster solution, since snow hasn't worked out much this season.

Long Range: Maybe it's my eyes after trying to find winter for so long, maybe it's Punxy Phil's prediction, but it kind of looks like winter wants to stay a bit in the longer range, but we'll see.  We could also kick it off w/some type of wintry event around Big Game Sun or early the next week.  Way too early to tell, esp the way we've gone this winter, but we'll see!

Only one graphic today- GFS temps at 12Z tomorrow.  Fcst lows from that model are a couple deg colder!

​

That's all for now! See you next week!

​-GP!