Good evening from SCW!

We’re tracking a system for tomorrow evening that until recently has looked like predominantly a rain event for the state. However, in the last few model cycles, we have begun to see guidance trend this system a bit cooler, resulting in some wintry impacts to the state. This will be shorter than our usual discussions due to time constraints on my end, but please ask us any questions you have and we’ll get back to you ASAP!

Here’s a look at the system on the high-res NAM. At first, we see light snow across the entire state, but warming temps in the boundary layer flip most over to rain as the heavier rates arrive. The exception is the NW hills, where elevation and latitude hold on just enough for a mostly if not all snow event there, and it is there where we could see plowable amounts. ​

The guidance is generally in good agreement on QPF totals, with somewhere between a third and a half of an inch expected for most of the state. In areas where precip remains all snow, that translates to a 3-6” forecast, but rising boundary layer temps will likely keep snow amounts lower across the rest of the state. For most, I only am expecting a minor accumulation, with a coating to perhaps an inch or two possible before flipping to rain. The tricky zone is the foothills of NWCT and the hills of NECT. Verbatim on the guidance, they remain mostly rain as well, but I have a hard time believing that there won’t be at least some gradient zone, and so I’m going to go with 1-3” there for now. We’ll keep an eye on the models overnight and update tomorrow if needed.

Here’s that forecast in map form.

As far as timing goes, we’re generally looking at precipitation breaking out west to east across the state during the early afternoon hours. I expect most to start as snow away from perhaps the immediate coastline. Snow then mixes with and changes to rain by early evening for all except the NW hills, and that boundary remains in place until around midnight or so when things may flip back to snow as the precip moves out.

We’re also watching the possibility for some intense snow squalls on Wednesday afternoon with the passage of the cold front. While not likely to produce significant accumulations, these critters can pack a punch, and create near whiteout conditions for a short period of time. We’ll talk more about these tomorrow should the potential still remain, but keep in mind that travel may temporarily become difficult then.

Finally, the big headline behind this storm is the cold that’s coming in. Projected highs for Thursday look to be only in the upper single digits to mid teens, and overnight lows should drop below zero for much of the state on Wednesday night. Well below normal temps stick around through at least the middle of the weekend. More to come on this in a full update tomorrow!

Thanks for reading SCW,
-SA

​Good evening from Southern Connecticut Weather! Warm weather tomorrow looks to quickly move out by Thursday this week as another cold vortex of air will be with us through to the weekend. Not nearly as cold as what we experienced yesterday, but definitely nippy weather. Beside temperatures we have another frontal system on the cards for Thursday, but this storm looks like a rain event. 


​Current Setup:
High pressure is centered in upstate NY, and the resulting flow for the state is a northerly one, which explains the cold dry air and the clear skies for the day. Temperatures capped off around the mid 20s statewide with abundant sunshine. In Texas, there is a low pressure system that is associated with an upper level trough. This will be our weather maker for Thursday.
 

Here is the GFS run at 500 mb (vorticity). You an see a deep trough in the southwest weaken and split off into two separate systems through Thursday. One system heads northeast towards Canada and the other carries through towards New England. According to this there is a lack of upper dynamics to intensify this storm, which is why we don't expect a major storm to develop.


Wednesday:
Temperatures Wednesday will begin in the low 20s and climb to the mid 40s by midday. But in the late afternoon a warm front will pass through. High clouds will build and a resulting southerly flow will develop. This should keep temperatures from dropping into the 30s. Late Wednesday rain showers will develop heading into Thursday morning. 

​Thursday:
Early Thursday morning, light rain will become increasingly more steady. It is possible that the higher elevations of the Litchfield hills could see a light wintry mix at first before switching over to all rain early Thursday. Temperatures should rise into the upper 40s statewide, with models suggesting possible high temps in the 50s, but I remain skeptical. In terms of precip amounts, we are looking at a good inch to an inch for the state. Expect moderate to heavy rain in the second half of the day as an approaching cold front will provide more lift. Following the passage of the cold front by the late evening, the state will dry out and cold temperatures will build in overnight.
 

GFS run for Thursday indicates light rain in the morning, and moderate to heavy rain for the evening.

​Friday-Sunday:
A northwesterly flow will dominate for a 3-4 day period following the passage of the cold front. An arctic vortex stationed over eastern Canada will poke its head into the country, running the chance for flurries every day and very cold weather. Temperatures for this weekend will be sub-freezing and dry. Sunday evening a weak trough axis will try to develop off of the NW flow. This could pose the potential for a coating of snow Sunday afternoon and evening, but this far out it does not seem to be anything eye catching. 

500 mb heights indicate the polar vortex dropping in from Canada.

​
Monday - Tuesday:
A warm front will pass through Monday, allowing temperatures to climb above freezing. An approaching system from the west looks to bring rain and possibly some wintry weather for Tuesday, but nothing as of yet to watch out for.
 
The Dailies
 
Wednesday: Highs in the low 40s. Clouds building in over the afternoon. Chance for rain showers late. Chance of precip 50%.
 
Thursday: Rain, heavy in the afternoon and ending late. Highs in the upper 40s.
 
Friday: Cold and breezy. Highs in the low 30s.
 
Saturday: Cold. Highs in the 20s.
 
Sunday: Chance for snow in the afternoon. Highs in the low 30s. Chance of precip 50%.
 
Monday: Highs in the low 40s.
 
Tuesday: Chance for rain. Highs in the 30s and 40s.
 
 
 
 
Thank you for reading Southern Connecticut Weather and enjoy your evening!
-LD

Good morning from Southern Connecticut Weather. 

This is one frustrating forecast. A complex winter storm has been traversing the country, and its final act will arrive in New England later this afternoon and evening. This is a multi-hazard event that will bring snow, sleet, freezing rain, and rain to the state. Despite our best efforts, this is looking like a low confidence forecast, the last thing you want as we head toward gametime.

​Let's jump right in. 

We've taken the snowfall numbers down slightly for most, with a more significant cut for SE CT which never does well when we're on the line with temperatures. 

The icing threat remains, but this is by far the lowest confidence piece of a low confidence forecast. I think that there will be a zone of freezing rain inside the main zone that may see higher end freezing rain, and in that zone there may be significant power issues.

Do not look at this map as anticipating widespread .5+ ice accretion. It does not envision that.

It is best to be prepared if you are in central and south (western) Connecticut as just a few degrees can make the difference between freezing rain and sleet. 

The trend has clearly been toward more warming, even at the surface. 

Above is a trend gif of the high resolution NAM (3K), which has clearly shown the warming of the surface over the last few runs. To be clear, in an event like this, colder air tends to hold stronger, especially in the CT River Valley, but the trend from the NAM has been the trend among virtually all guidance.

That could make this storm a less impactful event, but my guess is that the surface will be colder, leaving the door open for freezing rain. 

Timing

Mid-Late Evening (5pm to 12am)
Everyone should start out as snow. That's where our best chance is for accumulation. Snow will move into the state between 5-9pm, and when it hits it will be a thump. We should see snow quickly go from light at onset to moderate/heavy during the late evening hours. Travel will quickly become hazardous. 

Early Morning (12am to 7am)
​This is the critical period as things begin to get tricky. A warm nose punches north and cuts off the snow, and we transition to mixed precipitation. Heavy precipitation will still be falling, and we could see a period of heavy sleet. One critical question is how long sleet lasts. If our snow is slow to transition to sleet, that would increase the snow totals on the front end. It's also possible we quickly change to sleet and then quickly change to freezing rain, which will increase the icing threat and reduce snow totals. 

Make sure you're out measuring your snow before the changeover because once the sleet/freezing rain starts, it will quickly consolidate your snow! 

As we get closer to sunrise, the guidance is now showing more significant plain rain for parts of the state. I think it's overdone, but along coastal and especially SE CT, it's possible we get above freezing and most down there wake up to a glaze of ice and not a whole lot of snow. 

Morning & Early Afternoon (7am-2pm)
The mixed precipitation and rain should dominate the early portion of this period, but as the storm departs colder air will rush in. That will change our rain and/or mixed precipitation to snow, but I doubt it adds much to our overall totals. Temperatures will drop like a rock during the day, and what hasn't been cleared or salted will freeze solid. We're looking at flash freeze potential here, so even if you end up with rain, you need to be careful on the roads in the afternoon as the temperatures crash. 

Monday is going to be frigid. We expect lows near zero statewide and wind chills that are well below zero. Take note. 

Summary

• With the combination of snow, mixed precipitation, and a flash freeze on Sunday, we are expecting a significant winter weather event for all of Connecticut. 
  
  
• There is high uncertainty over the amount of icing that we will receive. Higher confidence in snow and icing occurs the further north you are in the state, but everyone should be prepared for some level of icing Sunday morning. A prolonged freezing rain period may cause power issues. 
  
  
• Even in places that receive plain rain, sharp temperature drops on Sunday and early Monday will cause a freeze that will create hazardous road conditions. 

This is one of those storms that's going to require close monitoring in real-time. This is where we need your help! Please send us your photos and observations during the event as we try to provide forecast updates.

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 Southern Connecticut Weather!
 
After some snow in the overnight and early morning hours, a coating to around 1 inch of the white stuff accumulating statewide, we clear out and have a short period of tranquil weather with seasonable temperature, about 24 hours for us to collect our bearings after what looked to be a bit of an “appetizer” for the winter weather event to come later on this weekend. First things first, for today, expect cloudy to mostly cloudy skies with the chance for snow showers this afternoon. Temperatures will hold steady in the low to mid 30s. Heading into this evening, we will see the clouds break and temperatures slide back down into the low to mid 20s statewide.

​For Saturday morning, things start out calm and cold, with mostly sunny skies and dry conditions with temperatures in the 20s. Clouds and frozen precipitation will begin to roll back in during Saturday afternoon and evening with temperatures holding steady in the upper 20s to around 30. Then the forecast really starts to get tricky. The entire state looks to start as a period of snow, picking up what looks to be a plowable amount in all locations including the southeast portion of the state, which looks to be the “warmest” area, per usual, in this storm. What the real question right now is, how far inland do we see a warm surge in the mid-level temperatures, therefor changing snow to sleet and freezing rain? There will be an abundance of low-level, surface cold to work with, so the event being primarily frozen is not in question.

On a brief synopsis of the event, we will have low pressure moving in from the Texas Panhandle tracking through Kentucky and then off the mid-Atlantic coast, somewhere off the New Jersey coast, strengthening along the way. The question for us, as usual, where does the storm track as it heads off the mid-Atlantic coast, does it skirt Long Island and track southeast from there? Does it track little further south? This is a very important detail in how far north the mixing line makes it, and how much actual snow the state actually sees. Little 10-20 mile deviations in storm track could mean the difference between 6 inch of snow, seeing double digits of accumulation, or seeing more sleet and freezing rain. At this time we think somewhere in the middle. Not quite where the GFS has it where, it brings more mixing, and not quite the mesoscale NAM, which shows more in the way of snow accumulation across the state.

​Timing… effects of this storm will begin to be felt as early as Saturday afternoon with clouds and snow beginning to filter in. Snow, sleet, and or freezing rain will continue to fall through the overnight hours on Saturday through Sunday afternoon. Any sleet or freezing rain should transition back to snow, statewide, as we head through the day on Sunday as the tail end of the storm swings through the state. Clearing occurs later Sunday afternoon and evening, with bitter cold temperatures being ushered in Sunday night, I will get more into that later on in this discussion.

​Impacts…Impacts from this storm look to be mainly caused by wintry conditions themselves. Snow, heavy at times, will provide limited visibilities and very slick roadways for the entire state, especially early in the storm statewide. As the storm begins to track closer (off the NJ coastline) and really begins to strengthen, midlevel temperatures will warm and bring a sleet/freezing rain changeover line up through the state. At this time, I’m thinking everyone sees at least a little mixing, with a more prolonged changeover to sleet and freezing rain closer to the coast. Aforementioned sleet and freezing rain may end up being the biggest impact of this storm as these conditions on top of the snow that has already fallen could spell a real tricky, if not impossible time on the roadways. As far as wind, impacts will be a little more tempered, closer to the coasts could see gusts around 30-35 mph, still enough to cause loss of power, especially when coupled with the wintry precipitation. Also with storms like these, coastal flooding, even minor is to be expected. Overall snowfall/sleet from the event right now look to be 6-12 inches in the northwest and “hillier” terrain of the state, with 4-8 inches of snow predominantly in the middle of the state, basically north of the Parkway, and 3-6 inches of snow south of this zone, where freezing rain looks to be big concern. Overall a moderate impact event.

​A brief look at the long term, shows a pattern very much in flux. Earlier on in the discussion I discussed frigid temperatures being ushered in behind Saturday/Sunday’s storm. Temperatures will fall like a rock on Sunday night back through the single digits and even negative numbers further inland. Frigid temps look to stay with us through the middle of the week with temperatures moderating as another storm system looks to make its presence felt on Wednesday. At this time, it is far too early to speculate about that event, but it does look as though more wintry precipitation will impact the area in this time period. A further look ahead shows an active pattern continuing through the next 2 weeks, with the potential for a few prolonged frigid periods and ample opportunities for precipitation.

​Here’s a quick look at the next 5 days:
 
Today: Mostly cloudy, with scattered snow showers, clearing this evening… highs in the 30s
Tonight: Mostly clear, temps in the low to mid 30s
Saturday: Mostly clear in the morning, clouds and snow moving in during the late afternoon, temperatures steady in the 30s
Saturday night: Periods of snow, sleet, and freezing rain, temps at the shore rising to around 32, temps inland steady in the upper 30s
Sunday: Periods of snow, sleet, freezing rain, becoming all snow late in the morning, temps steady in the upper 20s and low 30s, falling through the afternoon.
Sunday night: Snow early then gradual clearing, temperatures falling through the entire night, bottoming out in the low single digits south, to negative single digits inland.
Monday (MLK Day): Clear and cold. Highs single digits and teens statewide, falling back into the single digits at night.
Tuesday: Mostly clear early, temperatures start off frigid, then rebound back into the 20s, increasing clouds toward evening, possible snow, lows in the teens.
 
As always, thank you for sticking with Southern Connecticut Weather and reading this discussion. We encourage you to stay with us throughout the storm for frequent updates. Have a great day!- TW

​Good evening from Southern Connecticut Weather! It looks like we have a mess on our hands for this weekend, as this is going to be CT’s first major storm of the season. This system has it all: snow, sleet, freezing rain, ice, and wind. This has the potential to be a very dangerous system, particularly due to the amounts of sleet and ice that are forecasted to fall here in New England. We will cover what we know, and what we are still monitoring to provide you all the necessary information for this weekend.
 
The Setup:
An upper level trough digs into the eastern portion of the country, and intensifies from Gulf moisture. 250 mb jet anaylsis indicates very strong divergence aloft for this weekend over New England, coupled with 500 mb positive vorticity values as well. This is indicative of intense lower level convergence and is supportive of strong vertical motion on the synoptic scale for New England, particularly Saturday night and Sunday. One aspect of this storm which is incredible is the warm and cold advection 850 mb and 700 mb. Incredibly strong warm and cold advection exist at these levels, and this is the result of a large thermal gradient across the system and cross-isobaric flow. A very cold arctic blast of air from Canada is associated with an upper level shortwave. This tries to phase with our trough, and the meeting of the warm Gulf air and freezing artic air is what is going to drive strong winds and intense convection associated with this storm. An important feature to note of this system is that it is not vertically stacked, or the center of pressure of the storm is not lined up vertically through the atmosphere. It is instead tilted, on an axis, and this allows for cold air and warm air to slide over one another. This “tilt” of the storm is an important aspect that I will talk about later on.

Here is the GFS run that shows the 500 mb phasing of the trough and the Canadian shortwave.

Here is the 250 mb wind maxes, and there is a max over New England which would support strong convection and convergence over the Northeast.



​The Timing and Precip:
The GFS and NAM models agree that snow will possibly start late Saturday afternoon, possibly the early evening. Snowfall will intensify as it nears midnight, as a switchover to sleet, wintry mix will occur sometime during the early morning Sunday. Strong convection will be evident with high omega values and intense vertical motions on the simulated soundings for early Sunday morning. Depending on when the switchover is, we could see some significant accumulations of snow across the state of more than 6”, higher in the northern portions of the state, and possibly less along the immediate SE coastline of the state. A lot of the times the models struggle with the thermodynamic aspect of a storm, and with this one, it is possible that cold air could hang around longer than expected and therefore prolong the period of snow. As a result, snowfall totals could potentially be significantly higher for the state, but we are treading a mighty fine line with this system’s track and the thermal features of this storm.  
 
By early morning Sunday, around 4 am, there will be a changeover to a wintry mix for the state, and freezing rain for the SE coastline. This is because of the “tilt” I had mentioned before. Warm air from this system will slide over the cold dense air at the surface, making for an inversion layer. This will cause widespread sleet, freezing rain, and ice for a majority of the state heading into Sunday. By midday temperatures along the SE coastline could climb above freezing, leading to a possible rain/freezing rain mix. But a very developed inversion seems to persist throughout most of the day Sunday, which would indicate sleet/freezing rain. By midafternoon Sunday, the cold arctic air with this system will begin to move into the state from the NW. A gradual change back to snow will occur before the tail end of the precip moves out by late Sunday evening.
 

Here is the NAM output for the storm. We can see a clear change from snow, to a mix, back to snow for the majority of the state. 

​What we are still watching:
The models vary slightly with the track of the storm. The GFS is keeping the system to our north slightly more than the NAM and the Euro, and this would indicate warmer temperatures across the CT shoreline, and could indicate a period of more rain than rain/sleet. While the NAM and Euro is more favorable for a prolonged period of snow, and a wintry mix/freezing rain for the majority of the state. The track of this storm determines on the phasing of the upper level trough and the Canadian shortwave. If the two phase better, we could see a northward track of the system, but if they do not, it could favor a southerly track which would support more snow. 

Here we can see the comparison between the NAM (up) to the GFS (below). Clearly the NAM is taking a more southerly track, which would in turn support more snow and a mix. The GFS supports a northerly track as of now, and is showing a more rain.

​Another aspect to watch is the dynamics of this system. A very cold artic high will be in place to the north, and this would favor cold air for the lower levels which could prolong the snowfall in the state and increase accumulations, particularly the northern portion of the state. Again, this depends on how strong the arctic high will be, and at what time the warm air aloft will move in to create an inversion. If cold air from the high remains intact through Sunday along the surface, we could see surface temps around freezing for the day Sunday or even below.
 
Precip Totals:
In terms of snow/sleet, depending on how long the snow period lasts we could see totals ranging from 4-10 inches across most of the state, and significantly less across the SE shoreline. Right now, I feel it is better to not underestimate this storm. Therefore, we decided to go for 6-10” for the NW corner of the state, 4-8” for the majority, and 2-5” for the SE coast. Ice accumulations could be up to half an inch on the high end. Rainfall is possible along the SE coast, and there could be a slight threat of flooding due to the accumulation of snow, rain, and ice for Sunday.

​The Impact:
For anyone who has plans on Sunday, it would be in your best interest to cancel. It will be a mess. Due to the strong thermal gradients winds will be 10-20 mph with gusts in excess of 20+. This coupled with snow, sleet, hail, and freezing rain will make for extremely dangerous driving conditions so be sure to stay off the roads as much as possible. Probably the most incredible part of this storm is the deep freeze that will occur after the cold arctic air has passed through the state Sunday night. Temperatures are expected to drop to or even below zero. Whatever snow, slush, or rain that has accumulated all day Sunday will freeze immediately, and that will make for tough travel Monday morning. This storm has all the makings for a dangerous storm, particularly the icing and sleet.
 
We will continue to provide you updates on the lead up to this storm so stay tuned in for updates. And don’t forget to share us on social media to let others know about the weather! Once again thank you for reading SCW and have a good evening!
 
-LD