First, a walk down memory lane. Thirty-nine years ago, Connecticut was experiencing one of the most exceptional winter weather events in its history. The Blizzard of 1978 stands in the Pantheon of Connecticut blizzards, along with the Great Blizzard of 1888, Great Blizzard of 2013 and the October Bomb of 2011. The Blizzard of 1978 stood out because of the incredibly strong winds of the storm, creating massive drifts and crippling the state for days. What a winter.
Traveling back to the present, we’re not looking at anything like that this week, but a potentially active week is ahead, with the chance for multiple winter weather events. Let’s start with tomorrow…
Tuesday
Our first winter weather event arrives tomorrow. It fits the mold of many of our winter weather events so far this season. The overall setup is straight forward. We have a strong low that will cut well to the west of the region, but we have cold air in place at the start which will bring the potential for a mixed bag tomorrow morning into the afternoon. Here’s what we know:
Tuesday
Our first winter weather event arrives tomorrow. It fits the mold of many of our winter weather events so far this season. The overall setup is straight forward. We have a strong low that will cut well to the west of the region, but we have cold air in place at the start which will bring the potential for a mixed bag tomorrow morning into the afternoon. Here’s what we know:
A Winter Weather Advisory is up for all of Northern Connecticut. They start as early as 4am (Litchfield) and last until 7pm.
A Freezing Rain Advisory is up for northern Fairfield, New Haven, Middlesex, and New London Counties from 3am to 1pm.
These types of setups always make me uneasy because a degree or two of difference for an hour or two can make the difference between a significant event for commuters or a minor one. Everyone should take it easy on the roads tomorrow morning if you have to be out. The short term guidance is in agreement for a period of icing away from the shore.
A Freezing Rain Advisory is up for northern Fairfield, New Haven, Middlesex, and New London Counties from 3am to 1pm.
- The first precipitation is expected to arrive in Connecticut between 4-8am.
- The earlier the precipitation begins, the more likely areas will see frozen precipitation, especially freezing rain.
- Little to no snow accumulation is expected, but there will be enough icing during the morning to cause problems.
- Widespread delays are expected tomorrow across the state, but delays and cancelations are most likely in northern Connecticut.
- By afternoon, freezing rain and mixed precipitation will transition to rain for most of the state. In the typical cold spots, frozen precipitation may hang on a bit longer.
These types of setups always make me uneasy because a degree or two of difference for an hour or two can make the difference between a significant event for commuters or a minor one. Everyone should take it easy on the roads tomorrow morning if you have to be out. The short term guidance is in agreement for a period of icing away from the shore.
4km NAM surface depiction (above) and RGEM (below). Note that the RGEM is a bit more aggressive with the intensity and amount of frozen precipitation.
Looking a bit deeper let me show you why we end up with freezing rain and mixed precipitation. Let’s look at the surface first.
The surface temps on the NAM show below freezing temperatures at onset. If you’re new to weather you may think “that means snow!” but in reality you have to look further up to really get a sense of what’s going to happen.
This is the temperature at 850mb, a bit further up in the atmosphere. Here, it is abundantly clear that snow ain’t happening at this time. Temperatures above the surface are above freezing, while the surface is below. This is a time where soundings are vital to get a sense of what will happen throughout the entire column above us. I won’t post one, but this graphic helps to explain how warm layers give us mixed precipitation.
The early stuff will get much of the coverage, but this is a rain maker. I expect this to be a system that brings us decent rains off and on tomorrow afternoon, and showers early Wednesday. Have an umbrella ready!
Wednesday
Wednesday is an intervening day between winter weather events. It is also a day that we torch. With a brief period of westerly and southwesterly flow, expect highs to top out in the 50s for many locations. That’s well above normal this time of year. As the day progresses however, we start to see a snap back to winter as colder air filters in. This sets the stage for Thursday.
Wednesday
Wednesday is an intervening day between winter weather events. It is also a day that we torch. With a brief period of westerly and southwesterly flow, expect highs to top out in the 50s for many locations. That’s well above normal this time of year. As the day progresses however, we start to see a snap back to winter as colder air filters in. This sets the stage for Thursday.
GFS 850mb depiction for early Wednesday morning. Note where the freezing line is and the wind direction. That is only temporary however, as cold air rushes into the state as the day progresses.
Thursday
Thursday is really the day that I’m watching. Over the last week, the guidance has been toying with a shortwave way out over the Pacific and western US. For a while, it looked like any potential chance of even clouds was nonexistent, but the system has come back with a vengeance on much of the guidance. Just take a look at this analysis of the GFS runs over the last few days, all showing the same time period—Thursday around 7am.
Thursday
Thursday is really the day that I’m watching. Over the last week, the guidance has been toying with a shortwave way out over the Pacific and western US. For a while, it looked like any potential chance of even clouds was nonexistent, but the system has come back with a vengeance on much of the guidance. Just take a look at this analysis of the GFS runs over the last few days, all showing the same time period—Thursday around 7am.
If you notice, there are a couple of frames in there with heavy snow. I’m not ready to bite on that yet. This is a classic case of a short lead forecast where there’s legitimately little confidence. No one knows what is going to happen yet. The European model and others have waffled between a bigger hit and a glancing blow. The GFS has also waffled, and I think we’re just too far out at this point—even under 72 hours at this point—to have much confidence in what will happen. Here’s what I do know right now though:
For Thursday, it is best to stay tuned. We may have a first call out as early as tomorrow.
Friday & the Weekend
Whatever happens Thursday is gone by Friday. In its wake, we get cold and head into another period of uncertainty. With a deep trough over the region, we could see another area of low pressure, a clipper, approach by Saturday. That could bring snow.
We may also see another low pushing toward the region from our west on Sunday or Monday. That would likely be a rain maker as it puts us in the warm sector, but with cold air around we may be staring down another mixed bag event.
The Dailies
Tuesday: Early mix of snow, rain, and freezing rain, transitioning to all rain by afternoon. Rain may be heavy at times. Highs in the low to mid 30s. Chance of precipitation 100%.
Wednesday: Showers early giving way to partly cloudy and breezy conditions. Highs early in the 50s dropping throughout the day. Chance of rain early 40%.
Thursday: SCW period of interest. Snow. Highs in the upper 20s to low 30s. Chance of snow 50%.
Friday: Partly cloudy, cold and breezy. Highs in the mid to upper 20s.
Saturday: Mostly cloudy with a chance of snow. Highs in the upper 20s to low 30s. Chance of snow 30%
Sunday: Mostly cloudy with a chance of rain/snow. Highs in the mid to upper 30s. Chance of precipitation 20%
Monday: Mostly cloudy with a chance of rain. Highs in the mid to upper 30s. Chance of precipitation 20%
Overall—a busy week is ahead for SCW.
As always, don’t forget to like us on Facebook and share our discussions, and follow us on Twitter @southernctwx and retweet our posts!
Thanks for reading SCW.
-DB
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There is potential for a significant winter storm on Thursday.
- Currently, I’d place the chances of a warning level (6”+) event statewide at 25%.
- I’d place the chances of a glancing (3”-6”) event at 40%.
- I’d place the chances of a whiff (coating-2”) at 35%.
- Temperatures will likely be cold enough for all snow statewide.
- The timing of the event would make delays and cancelations possible.
For Thursday, it is best to stay tuned. We may have a first call out as early as tomorrow.
Friday & the Weekend
Whatever happens Thursday is gone by Friday. In its wake, we get cold and head into another period of uncertainty. With a deep trough over the region, we could see another area of low pressure, a clipper, approach by Saturday. That could bring snow.
We may also see another low pushing toward the region from our west on Sunday or Monday. That would likely be a rain maker as it puts us in the warm sector, but with cold air around we may be staring down another mixed bag event.
The Dailies
Tuesday: Early mix of snow, rain, and freezing rain, transitioning to all rain by afternoon. Rain may be heavy at times. Highs in the low to mid 30s. Chance of precipitation 100%.
Wednesday: Showers early giving way to partly cloudy and breezy conditions. Highs early in the 50s dropping throughout the day. Chance of rain early 40%.
Thursday: SCW period of interest. Snow. Highs in the upper 20s to low 30s. Chance of snow 50%.
Friday: Partly cloudy, cold and breezy. Highs in the mid to upper 20s.
Saturday: Mostly cloudy with a chance of snow. Highs in the upper 20s to low 30s. Chance of snow 30%
Sunday: Mostly cloudy with a chance of rain/snow. Highs in the mid to upper 30s. Chance of precipitation 20%
Monday: Mostly cloudy with a chance of rain. Highs in the mid to upper 30s. Chance of precipitation 20%
Overall—a busy week is ahead for SCW.
As always, don’t forget to like us on Facebook and share our discussions, and follow us on Twitter @southernctwx and retweet our posts!
Thanks for reading SCW.
-DB
