​Good afternoon from Southern Connecticut Weather!
 
   Hope you all enjoyed a nice Thanksgiving Day with friends and family and were able to stay warm! As you may have noticed, brutally cold temperatures have taken the state by storm. Unseasonable cold remains in place through early Saturday morning with ‘warmer’, closer to normal temperatures returning to the state as winds shift from a northerly, north-westerly direction to a southwesterly wind starting on Saturday afternoon, ahead of our next weather maker. Temperatures this afternoon will range from the low to mid 20s inland to the upper 20s to around 30 at the shore, as Long Island Sound temperatures are still relatively warm, influencing temperatures at the shore.

   For your Saturday, I previously mentioned that frigid temperatures will subside and head to more normal numbers, this is due to a storm system moving in from the Midwest switching wind direction to a southwesterly flow. It looks as though, outside of the initial snow squalls on Wednesday night, this “Arctic intrusion” will bear no major snow events. Temperatures should be warm enough that when the precipitation it will be all wet, and no white.  Early on Saturday morning, temperatures will range from the low teens into the 20s statewide, but will moderate very quickly as we head through the rest of Saturday. In fact, our high temperature will be had during Saturday evening in the middle of the rain event. Temps inland top out around the mid 40s, with low 50s to be found in southern CT, as you get closer to the shore. As far as the rain, there could be some minor flooding during at the height of the event during the overnight hours of Saturday. Total rainfall statewide looks to be between .75 and 1.5 inches of rain, not quite just a nuisance event, but not quite a widespread major flooding event either. Rain continues through Saturday night into Sunday, but the good news is, rain should end by the middle of the morning on Sunday, with temperatures again rising through the 40s statewide. As you can see, we do get a respite from those frigid temperatures, and wintry precipitation will be held to a minimum, at the expense of some rain. You take the good with the bad.

​   Now I know most of you are thinking, “yeah, the cold air ends and there isn’t any wintry precipitation expected over the next 2 to 3 days, but when should we expect winter conditions again?” Well, I will answer this question very cautiously. I don’t see any “Arctic intrusions” to hit the state for a solid part of the next week, if at all. As for snow, I will also cautiously say that snow through next week looks unlikely. Right now we are tracking a storm system for Monday into Tuesday, and as of now, it looks as though it will track into the Great Lakes promoting ‘mild’ temperatures and liquid precipitation for the region. As with weather though, this is all still 3 to 4 days away and the situation remains fluid. Beyond the Monday/Tuesday storm system, the weather looks tranquil from next Tuesday through early next weekend, with daytime highs in the 40s dropping back into the upper 20s and low 30s at night.

​A brief look at the next 2 weeks shows that storm tracks may not be so favorable for snowfall, and our cold air supply looks to be all but shut-off in this period. Storm tracks look to put Connecticut in the warm sector for the most part, outside of some onset or backside snow or sleet, I am not expecting very much in the way of wintry precipitation over the next 2 weeks. 

Now a look at the extended forecast:
 
Today: Sunny and unseasonably cold, highs struggling to get out of the 20s.
Tonight: Mostly clear and frigid, temperatures in the upper single digits to teens statewide
Saturday: Cold and mostly clear early, clouds move in during the afternoon, temperatures moderate into the 40s.
Saturday night: Cloudy early, rain moves in. Temperatures 40s inland, approaching 50 at the shore.
Sunday: Rain early, then clearing, highs 40-45 statewide.
Sunday night: Mostly clear, temperatures in the low to mid 30s statewide, some of the colder spots in NWCT move back into the upper 20s.
Monday: Clear early, clouds move in during the afternoon and evening, highs in the 40s.
Monday night: Cloudy with rain, temperatures in the upper 30s and 40s.
Tuesday: Rain early, clearing starts mid-morning, highs in the low to mid 40s.
Tuesday night: Mostly clear. Temperatures upper 20s and 30s.
Wednesday through Friday (11/30): Partly cloudy, highs in the low to mid 40s. Nighttime temperatures ranging from the upper 20s through the low 30s.

As always, thank you for continuing to read and support Southern Connecticut Weather! Have a great rest of your day and stay warm!- Tim

Good morning from SCW. 

I know it's early, but perhaps winter is showing us its hand. After our first winter weather event turned out to be a big one, the week of Thanksgiving is looking wintry as well, with well below normal cold and a few opportunities for wintry precipitation. Let's dive in. 

Early Sunday morning is bringing us a mix of clouds and sun. Image courtesy of GOES-E satellite. 

Sunday
Today is looking pretty good. We're starting the day with a mix of clouds and sun, and with high pressure in charge we will see a mostly dry day. Today is certainly a good time to finish up Thanksgiving shopping. Clouds will begin to increase over the course of the afternoon and evening as a boundary begins to sag south. 

As we go into the later afternoon hours, we will likely see some snow showers or a period of light now in northwest and northern CT. After highs in the upper 30s to near 40, temperatures will fall to near freezing in some of the northern towns. Although we are expecting mostly rain as the boundary continues to push south tonight and early Monday, we could see mixed precipitation in the colder spots of northern Connecticut during this time. 

Monday
Precipitation will continue into Monday. Folks in northwest CT should be prepared for a light accumulation of snow/mixed precipitation, with little to no accumulation elsewhere. There could be some delays in the hill towns with some slick spots. Otherwise, other places will see wet conditions with rain showers that diminish in coverage over the course of the afternoon. Monday will be the warmest day of the shortened work week, but still below normal with highs in the 40s. 

Below is the high resolution NAM showing the potential for mixed precipitation for northern towns just after midnight. We could see a period of snow showers or light snow in northern CT earlier than that, with rain showers further south. 

Tuesday
Here we go again? I'm declaring Tuesday a Period of Interest for the potential of accumulating snow. The boundary that brings us a mix of rain and snow on Monday pushes south, and it becomes a focal point for development of a low pressure system. The low looks to be pretty weak, but with cold air in the region (highs will be in the 30s) guidance is beginning to converge on a snowy day Tuesday. It's not a lock yet though. There are still some important details that need to come into focus, most importantly, how far south the low tracks and how much cold is in the state at the time the precipitation arrives. If the low tracks over us, it's a rain event. 

Unlike last storm, the airmass in place here is more marginal. Parts of southern Connecticut could see plain rain. For northern Connecticut however, accumulating snow is looking more likely, again depending on the track of the low. It's still a bit too soon to discuss totals, but this is worth watching.  

Should the guidance trend hold, we could see delays and cancellations in northern Connecticut on Tuesday. Stay tuned. 

Above is a high resolution NAM depiction of the next few days. You can see the mixed precip chance later tonight and Monday, followed up with potential snow in parts of Connecticut on Tuesday. Below is a European model depiction of 8am Tuesday. Temperatures are more marginal so we have to watch the trends to see if this is a more impactful event or less impactful. Either way, the rare white Thanksgiving could be in the cards this year. 

Wednesday
​The Arctic hammer begins to drop on Wednesday. Things should clear out and Wednesday looks like a nice day. However, as an Arctic front pushes through the state, we could see some snow showers and snow squalls. Right now, it looks isolated, but it's worth flagging given the heavy travel expected the day before Thanksgiving. 

Thanksgiving Day
Can you believe that Thanksgiving is just around the corner? I can't. The winter theme continues on Thanksgiving, with a big Arctic blast that will challenge records. The day looks nice, but it will be windy and frigid. Morning lows will be in the single digits and teens, with highs in the 20s. For perspective, the average high is around 50 degrees. This could be the coldest Thanksgiving since the 1800s. With the wind, it will feel like the teens or colder all day. 

Friday & Saturday
The end of the week looks cold as well, but we begin to moderate temperatures. Friday will start out cold and will stay cold with highs in the 30s, but by Saturday we begin to break the cold pattern and return to seasonably cool conditions. Although the weekend could be wet, the signal is a bit muddled right now. Traveling in the region looks ok, but we'll hone in on that forecast as we get closer. 

The Dailies
Sunday: Partly cloudy and seasonably cool early, with a chance of snow by the late afternoon/evening for northern CT. Highs in the upper 30s to near 40. Chance of snow in northern CT 40%. Chance of rain elsewhere 40%. 

Monday: Mixed precipitation in colder spots of northern CT, otherwise mostly cloudy with showers. Highs in the low to mid 40s. Chance of precipitation 50%. 

Tuesday: SCW Period of Interest. Snow in northern CT and mixed precipitation/rain in southern CT. Highs in the 30s. Chance of precipitation 70%. 

Wednesday: Partly cloudy and cold, with a chance of snow showers or squalls. Highs in the low to mid 30s. Chance of snow 20%. 

Thursday: Nice and frigid. Morning temperatures in the single digits to teens with wind chills near zero and single digits. Afternoon highs in the low to mid 20s with wind chills in the teens. 

Friday: Partly sunny and cold. Highs in the low to mid 30s. 

Saturday: Increasing clouds. Highs in the upper 30s to low 40s. Chance of rain 20%. 

​As always, please like, share, and interact with us on our social media--on Facebook to share our discussions, and follow us on Twitter @southernctwx to retweet our posts. Hit the buttons below to join.

Thank you for reading and trusting SCW. 

-DB​

Good evening from Southern Connecticut Weather. 

Our first snowstorm is in the books, and to the surprise of everyone, it ended up being a warning level event--meaning widespread 6" or more of snow outside of far southeast Connecticut. Although the storm wasn't unusual in its evolution, the timing of such a large snowfall was, as well as the severe impact on the roads. 

As we have done in the past, we want to be transparent about our forecasts with you, and learn from every event. This year, we will be working with clear criteria to grade ourselves after certain events. The average from the criteria will determine our final score. Moving forward, we will be grading ourselves using the criteria from our SCW Impact Scale: Snowfall Accumulation, Snowfall Rate, Wind, Power Outages, Timing, Road Conditions. In addition, we will also consider lead time, the amount of time we provide warning for potential events. 

Snowfall Accumulation: B
It is always a team effort here at SCW, but as the forecaster on call the day of the event/final call, I am giving myself a B for the snow accumulation forecast. I'm not happy about it. Compared to some other outlets, we did pretty well, highlighting higher snowfall totals statewide when the general forecast consensus was a way too low 2-5 inches. However, I didn't trust my gut. The team considered making a general 4-8" or 5-10" map, but I hedged more conservative thinking the guidance was too aggressive. Overall, even a general 4-8 would have probably kept this part of the forecast from being in the A range. The saving grace is that in a lot of instances, we were only off by 1-2 inches. That's not bad, and for that reason the forecast map get a B. 

Snowfall Rate: B-
Sadly, I'm not particularly enthused about this part of the forecast either. We were sure to hammer home the thought that we would see heavy snow during the event, but again I hedged conservative and only mentioned snowfall rates topping an inch an hour. There were locations that had 2" an hour rates, and that's significant. At least we were consistent in calling for heavy snow, which provided a lot of notice for commuters. 

Wind: A
Not much to say here. We didn't think wind would be a big factor and it wasn't. 

Power Outages: A
Same as the wind forecast, we didn't think we would see significant power outages from this event and we were on target. 

Timing: A-
Timing is one of those things where if you get it wrong, your forecast can end up being a disaster. I called for a bit of an earlier start time, and that worked out for folks in SW CT. The kids didn't have much trouble getting home overall and that's a good thing, because by the evening things were terrible. The heavy snow period was accurate, and the transition from snow to mixed precipitation worked out well despite some early jitters on our end as we saw the waves of snow continue to roll into the state during the evening. The only thing I think I missed was the time it took for snow to start everywhere. Some locations in northern and eastern Connecticut saw snow begin outside of our 2-5pm window. 

Road Conditions: C-
This was the worst part of the forecast. Although we discussed the snowfall potential, in my morning forecast I wasn't nearly specific enough about the evening commute impact. I should have been clearer and saw the writing on the wall about the timing and snowfall rate equating to truly severe conditions on the roads. In the future, I'll try be much clearer about what specific road condition impacts may be, particularly if the worst weather falls during a commute. 

Lead Time: A-
This is a tricky category to grade, because all storms are different. Sometimes, you know a week or two that something is coming and sometimes it is a total surprise. Here, we had a signal for something, and we did well to mention it early without going crazy. In fact, we declared a period of interest five days before the onset of the event. Looking back at the initial thoughts, it ended up being a good first assessment. That's pretty good. You don't have to worry about hype with SCW.  

Final Grade: B
Overall, the first big forecast of the year was solid but could have been better. As always, we learn a lot. There will be plenty of other chances to improve our grade in the future. 

As always, please like, share, and interact with us on our social media--on Facebook to share our discussions, and follow us on Twitter @southernctwx to retweet our posts. Hit the buttons below to join.

Thank you for reading and trusting SCW. 

-DB​

Good morning from SCW. 

The Winter Storm Watches from yesterday in northern Connecticut have been changed to Winter Weather Advisories, but a minor to moderate winter weather event is still forecasted to impact our state later today into early Friday. 

Image courtesy of the NYC National Weather Service

Key Impacts

Snowfall Accumulation
The low level cold and potential for heavy snow to overspread the state during the evening hours are the reasons I am adjusting our final forecast up slightly. 

As always, it is important to remember that these are ranges, and not everyone will see the same amount, even in the same town in some instances. In addition, there is the potential for icing as we transition from snow to mixed precipitation. At the shoreline, sleet will eventually mix in before turning to rain, and in interior CT, particularly in the valley locations and NW hills, we could see lingering cold result in sleet and freezing rain, creating a glaze of ice during the overnight hours. Be careful on the roads. 

Snowfall Rate & Road Conditions
Later this evening we will see a real thump of snow overspread the state. All of the indications are that we will see a period of heavy snow, with snowfall rates potentially topping 1 inch an hour. In those conditions, road hazards will increase. If you are out this evening, take your time. 

Wind 
It hasn't been discussed much, but winds will be breezy, particularly at the shoreline. We do not anticipate any major winds however, and no significant power outage risk. 

Timing
We expect snow to begin between 2-5pm in CT, with the earliest start time along the coast. Kids should be able to get home from school ok. During the evening hours we expect the heaviest snow, and during the later evening into early Friday morning time frame we will transition from snow to mixed precipitation to rain. There are some indications that there will be a flip back to snow in northern CT during the Friday morning hours. If that happens, it would likely impact the morning commute. We will be watching that potential. 

Above, NAM 3km depiction over the duration of the event. It also depicts the potential "flashback" to snow tomorrow morning. If that happens, the Friday morning commute would be impacted. 

​Overall, we're looking at a minor to moderate event, with the potential for heavy snow during the evening hours and some icing in interior CT during the late evening and overnight. We'll be here to provide updates as warranted. 

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​

Good afternoon to you from SCW!

It’s hard to believe, but we’re already tracking our first snow event of Winter 2018-2019. We’re expecting a minor to moderate snowfall across the state tomorrow, and it’s time to put our first call map out.

The Big Picture

Low pressure moves northeast into the area Thursday afternoon and rams into a departing area of high pressure, creating some initial warm air advection snows followed by a warming of the mid levels and surface and eventually a flip to rain. A light to moderate snowfall is expected for most of the state, and there is the potential for moderate icing in the interior as well. Everything should flip to rain by Friday morning except for possibly the far interior, and the storm winds down by mid-day Friday.

Here’s an overview of the system on the GFS.

Key Variables

I thought I’d try something new with this discussion and instead of looking at the individual models, look at some of the key variables that will drive how much snow we’ll get. We’ll use models to illustrate those variables, but I think it provides a more informed picture to see the ingredients behind the forecast instead of just the model forecast itself. Let us know what you think!

1. Arrival Time and Intensity of Precipitation
​
The guidance has been going back and forth a bit on the arrival time of this system, with the consensus yesterday being through the afternoon and having snow by the evening rush hour. The later runs though have pushed that back a bit, with snow not fully overspreading the state until the early evening hours. Generally, we’re seeing that a later start means less precipitation falls as snow as the temperatures warm at about the same time on all of the guidance. Furthermore, the models that are showing a later start are doing so because of less warm air advection driven precipitation - this is initial QPF out ahead of the main system that has the benefit of falling in the colder air mass that we have in place to start before the main system pushes it out - hence it would be all snow for everywhere in the state. The trend to cut back on the amount of WAA and hence the amount of initial precipitation means generally less snow for the state, and of course if the trend were to reverse we’d see more wintry precipitation and have a better chance of significant impacts to the evening commute.

To show this, here’s a look at yesterday's 12z GFS vs todays 12z GFS for 7 PM tomorrow night. You can see that on yesterday's run, we’ve got snow across all of the state with the mix line just starting to work its way up into SWCT, while on today's run, the snow is much lighter in the north and the mix line is already up into central CT.

2. Surface temperatures
​
It’s pretty simple - colder surface temps = more snow. The guidance differs a bit on how well the cold air is able to remain in place. Some models, like the Euro, keep the cold air locked in right down to the coastline and as a result allow for several inches of snow to fall across the entire state, with warning criteria for interior areas. The warmer solutions however quickly warm up the boundary layer at the shoreline and eventually further inland as well, with only a quick burst of snow on the shore and a couple of inches further inland. With November climo, I feel that you need to favor the warmer solutions, but that said, strong Canadian high pressure like we’re seeing here provides a lot of opportunity for staying colder and often allows us to remain on the colder side of a storm for longer than you’d expect.
To show the point, here are surface temps on the GFS and the RGEM For 7 PM tomorrow, along with the forecast snow amounts from each model. Don’t take those snowmaps as the gospel here since they tend to over do amounts significantly in marginal events, plus they use a fixed 10-1 ratio where I expect snow ratios to be lower here (sorry - I don't think 11" of snow is going to happen with this event :) ). That said, they do illustrate the differences between the models well, although some of the difference can also be attributed to the RGEM bringing in heavier precipitation sooner. 

3. Mid-level temperatures

Finally, we need to look at the mid-level warmth that this system will bring in. Even if we get strong cold air damming at the surface (which is common with high pressure like we’re going to see), it means nothing if the mid levels warm. The result in that case could be an icy mix for a time before things fully flip over to cold rain - we’ll have to watch for that in the typically colder hollows and valleys of the interior. Here’s a look at the NAM that shows the warm tongue and the surface temps - that area in NWCT where temps are above freezing aloft but below freezing at the surface would mean an icing event for them. The consensus that the warm air aloft will move northwards is fairly strong, but heavy precip rates could result in it pushing north slower than expected - we’ll have to keep an eye on that for a possible increase in snow amounts.

Forecast and Timing

Here’s a look at our forecast snowmap for the event.

In general, we’re looking at a light to moderate snowfall for the event. We’ll see precipitation come into the state during the late afternoon hours, and I do expect the evening commute to be impacted, especially along the coast. While the shoreline will quickly change to rain, just inland away from the marine layer I expect snow to hold on for several hours before changing over. Throughout the evening, I expect a change from snow to mixed precipitation to rain, with the period of mixed precip being very short in the warmer areas but potentially providing significant icing in the evening and overnight hours for the sheltered valleys and higher elevations. Should be over to plain rain by the morning commute.

I do think there is bust potential on both sides, but I’m leaning more towards the possibility of busting low rather than busting high. If we get a solid burst of precipitation in the late afternoon and early evening, I think we’ll quickly be able to pick up a few inches of snow, and then it’ll be up to the changeover to see if we pass the high end of the forecast. The key reason for busting low would be weaker WAA meaning less precip before a changeover, but given the trend over the last few model cycles I think that’s less of a possibility.

Impacts


Here’s the SCW impact scale for this event.​

Depending on icing overnight, could see some delayed openings Friday morning, but I don’t expect to see widespread school impacts from this event. Thursday evenings commute could be tricky, especially since it’s the first snowy one of the season, so if you’re able to leave work a bit early and beat the snow home that could be a good strategy. If not, take it easy, drive slowly, and leave plenty of space around you on the roads!

We’ll be back tomorrow morning with a final call and updated map if needed, until then, ask us any questions you have on our Facebook and Twitter pages (use the buttons below to follow and like us), and thank you for reading SCW!

-SA