Introduction
Connecticut is a state filled with winter lovers and winter haters, and both have been spoiled. In the 2010s, winter lovers had a run for the ages, with BIG snow events in 2011 (all time event), 2013 (all time event), 2015, 2017, and 2018. There were several huge snow seasons as well all the way to the coast during that decade.
But now, winter haters are on a heater, literally and figuratively, with some of our warmest winters on record in the 2020s. In fact, despite the big snow events of the 2010s, last winter was the first time since 2015 that we had a below normal temperature winter season. That's an incredible period of warmth, which has also resulted in winter 2020-21 being the only season this decade anywhere close to normal in the snow department.
You have heard me repeat this a lot, but what we really need is a return to normal. Our environment is resilient to be sure, but it's also delicate. Too much of anything in either direction has an impact. Normal temperatures help slow the expansion of invasive species. Invasive insects like some of the recent tick populations we've seen can bring disease, while invasive plants can harm the population of native species. Normal precipitation and yes, even snowfall, helps our farming community in spring planting, and helps us avoid some of the droughts we've seen in recent years by adding reserves to our water table that get our wells through drier periods.
It's easy to be inconvenienced or even harmed by the weather in any season, but it's important to remember that our atmosphere is always trying to restore balance.
Will we see balance this winter? This winter forecast aims to give you the basics of what we're looking for this winter in a readable and educational format. Expect a lot of explanatory graphics!
Our big caveat is that there are others that spend a ton of time going into more detail. If you are looking for a deep dive on how sun cycles and Siberian snow cover may or may not impact our winter, this forecast won't do that. We try to focus on the biggest factors in our view.
We begin with what you're looking for most. In past forecasts, we showed snowfall as a percentage of normal. This year, it just makes more sense in our visual world to show you what that means in a map as well. Our final grade is NOT just based on snow, though it will be graded with extra weight, just as we do during our winter storm forecasts. For us, the snowfall forecast covers all snow that falls. If we're still frigid in April and winter is holding on, snow that falls then counts too.
Connecticut is a state filled with winter lovers and winter haters, and both have been spoiled. In the 2010s, winter lovers had a run for the ages, with BIG snow events in 2011 (all time event), 2013 (all time event), 2015, 2017, and 2018. There were several huge snow seasons as well all the way to the coast during that decade.
But now, winter haters are on a heater, literally and figuratively, with some of our warmest winters on record in the 2020s. In fact, despite the big snow events of the 2010s, last winter was the first time since 2015 that we had a below normal temperature winter season. That's an incredible period of warmth, which has also resulted in winter 2020-21 being the only season this decade anywhere close to normal in the snow department.
You have heard me repeat this a lot, but what we really need is a return to normal. Our environment is resilient to be sure, but it's also delicate. Too much of anything in either direction has an impact. Normal temperatures help slow the expansion of invasive species. Invasive insects like some of the recent tick populations we've seen can bring disease, while invasive plants can harm the population of native species. Normal precipitation and yes, even snowfall, helps our farming community in spring planting, and helps us avoid some of the droughts we've seen in recent years by adding reserves to our water table that get our wells through drier periods.
It's easy to be inconvenienced or even harmed by the weather in any season, but it's important to remember that our atmosphere is always trying to restore balance.
Will we see balance this winter? This winter forecast aims to give you the basics of what we're looking for this winter in a readable and educational format. Expect a lot of explanatory graphics!
Our big caveat is that there are others that spend a ton of time going into more detail. If you are looking for a deep dive on how sun cycles and Siberian snow cover may or may not impact our winter, this forecast won't do that. We try to focus on the biggest factors in our view.
We begin with what you're looking for most. In past forecasts, we showed snowfall as a percentage of normal. This year, it just makes more sense in our visual world to show you what that means in a map as well. Our final grade is NOT just based on snow, though it will be graded with extra weight, just as we do during our winter storm forecasts. For us, the snowfall forecast covers all snow that falls. If we're still frigid in April and winter is holding on, snow that falls then counts too.
Above: The Official SCW Seasonal Snowfall Forecast. We expect near normal snowfall across the state with 25-35" in southern CT (lowest in SE CT), 35-45" for most of interior CT, 45-60" in the eastern CT hill towns and far north central CT (including BDL), and 50-65" in the NW hill towns. The snow ranges are weighed toward approximately 80-100% of normal snowfall and the wider ranges in far northern CT accounts for the changes in snowfall climatology based on elevation.
Winter Forecasting
Before we get too deep the seasonal forecast, let's talk about winter forecasting generally. For winter systems, you can't forecast the way you can in the summer. The general pattern aloft is different, and the temperature contrasts between the warmer air in the south and cold to frigid air in the north can lead to explosive storms, blowtorches that feel like early spring, and Arctic blasts that plunge our temperatures below zero. Aside from our standard updates that may cover daily conditions, as we forecast there will be two general types of conversations we're having:
1. Pattern Discussion--This is a 7-14+ day look at the mid/upper level features that influence our general weather. For example, a discussion of teleconnections that could lead to colder/warmer temperatures or more/less stormy weather.
This is easier to view and forecast with accuracy in the longer range because we are looking at fundamental mid/upper level features such as ridges and troughs.
This is where you would see many of our 500mb height images.
Winter Forecasting
Before we get too deep the seasonal forecast, let's talk about winter forecasting generally. For winter systems, you can't forecast the way you can in the summer. The general pattern aloft is different, and the temperature contrasts between the warmer air in the south and cold to frigid air in the north can lead to explosive storms, blowtorches that feel like early spring, and Arctic blasts that plunge our temperatures below zero. Aside from our standard updates that may cover daily conditions, as we forecast there will be two general types of conversations we're having:
1. Pattern Discussion--This is a 7-14+ day look at the mid/upper level features that influence our general weather. For example, a discussion of teleconnections that could lead to colder/warmer temperatures or more/less stormy weather.
This is easier to view and forecast with accuracy in the longer range because we are looking at fundamental mid/upper level features such as ridges and troughs.
This is where you would see many of our 500mb height images.
Above: An EPS (European Ensemble) forecast at 500mb for December 8.
2. Storm Discussion--This is a short to medium range look at a specific "threat", regardless of whether it is rain/mixed precipitation/snow. For example, a discussion of a possible low pressure inside 5 days.
What's important here is that we're looking at medium to short range here, when things are in better view. This is where you may see us use graphics showing surface or mid level cold, or surface depictions.
What's important here is that we're looking at medium to short range here, when things are in better view. This is where you may see us use graphics showing surface or mid level cold, or surface depictions.
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Above: Examples of the operational GFS being used to depict surface cold and surface conditions, with perhaps an easter egg for those tracking next week's storm ;).
Now, we know that often times it's easy to get caught up in long range computer models, but when we are forecasting, we're generally using a tried and true timeline for forecasting and discussion. I figured it was time to put it in graphical form!
Expect to see this a few times this winter.
Now, we know that often times it's easy to get caught up in long range computer models, but when we are forecasting, we're generally using a tried and true timeline for forecasting and discussion. I figured it was time to put it in graphical form!
Expect to see this a few times this winter.
The bottom line is that at certain ranges, the snow maps and discussion you see elsewhere isn't always based in reality. If you see snow maps outside of the short range (with some exceptions) DO NOT BITE.
Even if something turns out to be real (think Great Blizzard of 2013 which was predicted on some models more than a week out) it's not worth taking seriously unless there's a serious ensemble signal. Even then...grain of salt to say the least.
Forecast Factors
As we've noted before, seasonal forecasting is extremely difficult. Folks have been trying to predict seasons in America since the Farmer's Almanac. The methods today may be more technologically advanced, but there will always be parts that will be right, close to right, and painfully wrong. Here are the major factors we're using this time around. Not much different than what we've done before.
Even if something turns out to be real (think Great Blizzard of 2013 which was predicted on some models more than a week out) it's not worth taking seriously unless there's a serious ensemble signal. Even then...grain of salt to say the least.
Forecast Factors
As we've noted before, seasonal forecasting is extremely difficult. Folks have been trying to predict seasons in America since the Farmer's Almanac. The methods today may be more technologically advanced, but there will always be parts that will be right, close to right, and painfully wrong. Here are the major factors we're using this time around. Not much different than what we've done before.
- ENSO (30%): ENSO stands for the El Nino Southern Oscillation, and it represents sea surface temperature anomalies that determine whether an El Nino or La Nina is present. ENSO influences global atmospheric conditions, hemispheric weather patterns, and downstream that means our sensible weather. This is often the biggest factor in what our season will look like. Our changing climate has changed how we use ENSO to forecast seasons, as we see tropical forcing and other factors we're not discussing here muddy the waters, but the fundamentals are still the same.
- Teleconnections (30%): ENSO in its own way influences teleconnections, which are always there. There are many indices measuring current conditions in different parts of the world, from upper level features to regional ocean temperatures. While ENSO is global, teleconnections are regional. These are the conditions that drive the overall hemispheric pattern and are critical to how frequently we get cold or warm and how stormy it is.
- Seasonal Guidance (15%): These models are longer range versions of some models, monthly or even seasonal looks. This area also includes climate models. We look at the overall averages when reviewing these, such as the average 500mb pattern, rather than specific output such as total snowfall. They have some skill, but not enough to hug tightly.
- Current Conditions (15%): This takes into account the general trend in the seasonal transition that happens every year. Some parts of the upper level pattern in the fall have a strong correlation to what the baseline weather pattern is during the winter months.
- Analogs (10%): We look at past years that have similarities to this year, whether it's conditions observed through the year, ENSO state, or teleconnections. Again, this brings some skill, but no two years are alike.
Above: The latest sea surface temperature anomalies across the globe. The area to the west of South America is our ENSO region, and with cooler temperatures extending westward, we still have a La Nina, though its hold is becoming more tenuous.
ENSO
As the image and text above shows, we're still in a La Nina. Generally speaking, anything within .50 degrees of normal for what is effectively a three month period is a neutral ENSO, with colder temperatures being a Nina and warmer temperatures being a Nino. One of the most important regions we look to is the 3.4 region, and as you can see we are squarely in Nina territory.
ENSO
As the image and text above shows, we're still in a La Nina. Generally speaking, anything within .50 degrees of normal for what is effectively a three month period is a neutral ENSO, with colder temperatures being a Nina and warmer temperatures being a Nino. One of the most important regions we look to is the 3.4 region, and as you can see we are squarely in Nina territory.
A La Nina usually brings a relatively fast start to winter in the east, followed by a winter thaw, oscillations between warmer and colder, and sometimes, an early spring. However, that's only if you have Nina conditions throughout the winter.
Above: A typical La Nina winter, image courtesy of NOAA. The variable jet stream usually means that can have periods of significant cold early followed by significant warmth in the middle to latter part of the season. It also often means that our region is the battle zone for storms, with several mixed precipitation and rain events depending on where the baroclinic zone (area where warmth and cold contrast) sets up. If that zone is further offshore, it usually means that storms take a track offshore, increasing the odds of snowier weather. If the zone is over us, that means expect mixed bag events and rain events.
This season La Nina is expected to persist through part of the winter, but we may revert to neutral conditions sometime in early 2026.
This season La Nina is expected to persist through part of the winter, but we may revert to neutral conditions sometime in early 2026.
Above: The computer model forecast for the 3.4 region SST anomalies. Note how the models move toward a cool neutral state by January.
Below: The result is we see that possibility reflected by the official Climate Prediction Center (CPC) forecast for ENSO. By January, odds are greater than 50% that we are in a neutral regime.
Below: The result is we see that possibility reflected by the official Climate Prediction Center (CPC) forecast for ENSO. By January, odds are greater than 50% that we are in a neutral regime.
So what does all this mean? I agree that at some point in the winter we go from a La Nina to a neutral position. Given the atmospheric lag time in translating the change in the ocean to change in the atmosphere, I think it means that we do have some sort of winter thaw--a multi-week period of above normal warmth, but that it does not lead to an early spring, meaning snow chances continue later into the season.
Teleconnections
There's been a lot of recent talk about Sudden Stratospheric Warming (SSW) leading to big cold in the east in December. That was not quite accurate in reality for reasons we don't need to discuss here. A SSW event would have an impact on teleconnections, and we think folks jumped the gun in forecasting the influence of a SSW event. Given the reflection event that is likely underway, we think the impact on teleconnections is more muted early in the season, with more impact later in December and January that may be reinforced with an actual SSW--furthering the odds that we do not have an early spring. If you like more reading, this is a great technical paper on reflection events.
Teleconnections
There's been a lot of recent talk about Sudden Stratospheric Warming (SSW) leading to big cold in the east in December. That was not quite accurate in reality for reasons we don't need to discuss here. A SSW event would have an impact on teleconnections, and we think folks jumped the gun in forecasting the influence of a SSW event. Given the reflection event that is likely underway, we think the impact on teleconnections is more muted early in the season, with more impact later in December and January that may be reinforced with an actual SSW--furthering the odds that we do not have an early spring. If you like more reading, this is a great technical paper on reflection events.
Above: An image from the cited paper showing how a reflection event in the stratosphere generally occurs.
Given the image above, we are entering "Phase B" which is showing up in the 500mb depictions as cold from the pole starts moving into the central U.S. and will propagate east into our region in early December.
Below is a discussion on the major teleconnections we look at. If you are a longtime follower, much of this you've seen before.
Atlantic Teleconnections
Arctic Oscillation (AO)
The Arctic Oscillation, or AO, measures pressure anomalies in the Arctic, and is strongly correlated with temperatures in our area for the winter months. A positive phase of the AO consists of below average geopotential heights. A negative phase consists of the opposite. In a negative phase of the AO, the polar vortex over the Arctic is more prone to being stretched and displaced, allowing Arctic air to penetrate further south. With a positive AO, the opposite is true. Stronger upper level winds keep the polar vortex in check, making it less likely for deep cold air intrusions and ideal storm tracks.
We start this winter with the AO in a negative regime, but by mid-month, the expectation is that the AO rebounds to neutral or positive. That said, I think this winter we see a fair amount of fluctuations of the AO, with a possible return to negative on balance in February.
Below is an image showing what a strong AO looks like. The image is merely illustrative, but note how the heights are well below average in the polar region. That’s a warm period.
Given the image above, we are entering "Phase B" which is showing up in the 500mb depictions as cold from the pole starts moving into the central U.S. and will propagate east into our region in early December.
Below is a discussion on the major teleconnections we look at. If you are a longtime follower, much of this you've seen before.
Atlantic Teleconnections
Arctic Oscillation (AO)
The Arctic Oscillation, or AO, measures pressure anomalies in the Arctic, and is strongly correlated with temperatures in our area for the winter months. A positive phase of the AO consists of below average geopotential heights. A negative phase consists of the opposite. In a negative phase of the AO, the polar vortex over the Arctic is more prone to being stretched and displaced, allowing Arctic air to penetrate further south. With a positive AO, the opposite is true. Stronger upper level winds keep the polar vortex in check, making it less likely for deep cold air intrusions and ideal storm tracks.
We start this winter with the AO in a negative regime, but by mid-month, the expectation is that the AO rebounds to neutral or positive. That said, I think this winter we see a fair amount of fluctuations of the AO, with a possible return to negative on balance in February.
Below is an image showing what a strong AO looks like. The image is merely illustrative, but note how the heights are well below average in the polar region. That’s a warm period.
North Atlantic Oscillation (NAO)
The North Atlantic Oscillation, or NAO, is a close relative of the AO. Here, forecasters look at two pressure centers in the Atlantic--an area of low pressure near Greenland, and a high pressure system near the Azores. Generally, during the winter we’re paying close attention to heights around Greenland. The strength and exact placement of these features tend to have a significant impact on the placement of the jet stream--absolutely critical for cold air placement and storm track in tandem. During a negative phase, we see higher heights over the Greenland area, and below average heights over the western Atlantic and (usually) the eastern US. The opposite generally occurs with a +NAO, which means more progressive tracks and more warm storm tracks.
While a persistently negative NAO is not necessary for a cold and snowy winter, having a -NAO, even if transient, can be a major factor in producing some of our biggest winter weather events, as a -NAO usually implies more blocking is available, while a +NAO represents a faster pattern with less room for storms to amplify. Further complicating matters is the position of the heights. A west based -NAO is more likely to produce a cold and stormy period than an east based -NAO. Too much -NAO can also lead to suppressed storms, leaving us cold and dry. Last year is a good example of that for some of our missed events.
Much like the AO, I expect a mostly neutral regime during the season, with transient periods of -NAO in tandem with the AO. This is in line with a EPS forecast below that takes us into January. NAO blocking in December correlates significantly with Atlantic blocking the rest of the season and the signal here is more neutral than strongly leaning one way or another.
The North Atlantic Oscillation, or NAO, is a close relative of the AO. Here, forecasters look at two pressure centers in the Atlantic--an area of low pressure near Greenland, and a high pressure system near the Azores. Generally, during the winter we’re paying close attention to heights around Greenland. The strength and exact placement of these features tend to have a significant impact on the placement of the jet stream--absolutely critical for cold air placement and storm track in tandem. During a negative phase, we see higher heights over the Greenland area, and below average heights over the western Atlantic and (usually) the eastern US. The opposite generally occurs with a +NAO, which means more progressive tracks and more warm storm tracks.
While a persistently negative NAO is not necessary for a cold and snowy winter, having a -NAO, even if transient, can be a major factor in producing some of our biggest winter weather events, as a -NAO usually implies more blocking is available, while a +NAO represents a faster pattern with less room for storms to amplify. Further complicating matters is the position of the heights. A west based -NAO is more likely to produce a cold and stormy period than an east based -NAO. Too much -NAO can also lead to suppressed storms, leaving us cold and dry. Last year is a good example of that for some of our missed events.
Much like the AO, I expect a mostly neutral regime during the season, with transient periods of -NAO in tandem with the AO. This is in line with a EPS forecast below that takes us into January. NAO blocking in December correlates significantly with Atlantic blocking the rest of the season and the signal here is more neutral than strongly leaning one way or another.
Pacific Teleconnections
Pacific/North American Pattern (PNA)
If we've learned anything in recent years, it's that the Pacific is king. The Pacific is vital to determining the whether we are flooded with warmer air or Arctic cold, and whether storms cut to our west or will be able to amplify off the coast. The PNA is one of the most important teleconnections, with a massive influence over North America. A positive PNA phase occurs when there are higher heights over the Pacific and western US. This correlates to ridging over the western US and a trough (transporting colder air) over the eastern US. In a negative phase, the opposite occurs.
Pacific/North American Pattern (PNA)
If we've learned anything in recent years, it's that the Pacific is king. The Pacific is vital to determining the whether we are flooded with warmer air or Arctic cold, and whether storms cut to our west or will be able to amplify off the coast. The PNA is one of the most important teleconnections, with a massive influence over North America. A positive PNA phase occurs when there are higher heights over the Pacific and western US. This correlates to ridging over the western US and a trough (transporting colder air) over the eastern US. In a negative phase, the opposite occurs.
To hammer home the point, here's what that would look like on the models. This is the EPS depiction of 500mb heights nearing mid December. Note the ridge in the west, and trough in the east. That pattern below is good for cold delivery but not necessarily ideal for storm track. The ridge being centered further east over the Rockies would be more favorable, though this as it stands is favorable.
Last winter, we had frequent periods of a PNA favoring normal temperatures, but not storminess, with frequent events burying a trough in the west, forcing storms to either cut to our west or get suppressed/shredded as they approached in a fast and compressed flow. That's really important to repeat: the position of the western ridge matters a lot. Too far west and storms can cut to our west, bringing rainy systems or nothing at all. Too far east and storm tracks could develop too far offshore to bring significant precipitation events.
This winter I think the PNA is less hostile, and while blockbuster events don't look particularly favorable, I do think there will be one or two windows as a favorable Pacific links with blocking from the Atlantic (likely in transition) from a -NAO to +NAO.
East Pacific Oscillation (EPO)
The East Pacific Oscillation, or EPO is a major driver in allowing Canada to develop cold air that feeds into the U.S., or shutting off any mechanism to deliver cold to much of Canada or the United States. Here, we’re looking at heights over the northeast Pacific and Alaska. Higher heights over this region brings warmer than normal weather over that region, but it serves up an almost ideal mechanism for cold air delivery in the continental U.S., as a resulting Arctic high in northwest Canada and trough over the US work in tandem to funnel cold into the region. At times, we can see a sprawling enough -EPO to develop what is called “cross-polar flow”. This is the extreme cold that comes straight from the polar region without much moderation. That's part of how we got the brief Arctic plunge in early February 2023, a historic cold shot in the second warmest winter on record.
With a positive EPO phase, we potentially see extended fall. In a +EPO, we get a persistent low (vortex) in the northeast Pacific and Alaska, which creates favorable conditions for the Pacific jet to inundate Canada and much of the continental U.S. with warm Pacific air. If you have this kind of pattern persist, you can almost guarantee little cold and snow. In recent years, we've had a raging Pacific jet minimize the cold that could build in Canada. That has reversed so far this fall, with a strong jet remaining but focusing more equatorward, avoiding the disruption of cold loading in Canada.
Here's a look at the positive and negative phases of the EPO and their effects on our sensible weather.
This winter I think the PNA is less hostile, and while blockbuster events don't look particularly favorable, I do think there will be one or two windows as a favorable Pacific links with blocking from the Atlantic (likely in transition) from a -NAO to +NAO.
East Pacific Oscillation (EPO)
The East Pacific Oscillation, or EPO is a major driver in allowing Canada to develop cold air that feeds into the U.S., or shutting off any mechanism to deliver cold to much of Canada or the United States. Here, we’re looking at heights over the northeast Pacific and Alaska. Higher heights over this region brings warmer than normal weather over that region, but it serves up an almost ideal mechanism for cold air delivery in the continental U.S., as a resulting Arctic high in northwest Canada and trough over the US work in tandem to funnel cold into the region. At times, we can see a sprawling enough -EPO to develop what is called “cross-polar flow”. This is the extreme cold that comes straight from the polar region without much moderation. That's part of how we got the brief Arctic plunge in early February 2023, a historic cold shot in the second warmest winter on record.
With a positive EPO phase, we potentially see extended fall. In a +EPO, we get a persistent low (vortex) in the northeast Pacific and Alaska, which creates favorable conditions for the Pacific jet to inundate Canada and much of the continental U.S. with warm Pacific air. If you have this kind of pattern persist, you can almost guarantee little cold and snow. In recent years, we've had a raging Pacific jet minimize the cold that could build in Canada. That has reversed so far this fall, with a strong jet remaining but focusing more equatorward, avoiding the disruption of cold loading in Canada.
Here's a look at the positive and negative phases of the EPO and their effects on our sensible weather.
Much like the other teleconnections, I expect this to remain near neutral for the balance of the season, increasing confidence in a more normal season than what we've seen in recent years. That may sound blah, but having near neutral indexes means that there's enough ridging to blunt the warm weighted extremes that we've seen when left unchecked.
Western Pacific Oscillation (WPO)
The Western Pacific Oscillation, or WPO, is a teleconnection we haven't talked about much, but we're recognizing its importance after recent years of Pacific domination on our weather pattern. This analyzes the heights in the Bering Sea (west of Alaska) and northwest of Hawaii. The atmosphere is a fluid, and the ridges/troughs we see in the central and western Pacific influence the amplitude and orientation of ridges and troughs over North America.
The Western Pacific Oscillation, or WPO, is a teleconnection we haven't talked about much, but we're recognizing its importance after recent years of Pacific domination on our weather pattern. This analyzes the heights in the Bering Sea (west of Alaska) and northwest of Hawaii. The atmosphere is a fluid, and the ridges/troughs we see in the central and western Pacific influence the amplitude and orientation of ridges and troughs over North America.
Once again, we're expecting less pronounced extremes either way with this teleconnection. I do think that this one looks a little more favorable for warmth in the longer term, given the historic warmth in the western Pacific that may lead to more ridging in that index region, and that's reflected in the final temperature forecast to blunt a bias toward colder conditions than we would otherwise expect.
Seasonal Guidance
With ENSO and Teleconnections covering 60% of what defines our winter forecast, there's not much to be said about the rest before getting to the final numbers. The seasonal guidance is kind of all over the place, with some showing a very quick flip to spring, and others leaning more toward a normal-ish year. The guidance giving us an early spring are cause for some pause and give confidence in some sort of winter thaw at some point, but not enough to significantly impact the forecast.
Seasonal Guidance
With ENSO and Teleconnections covering 60% of what defines our winter forecast, there's not much to be said about the rest before getting to the final numbers. The seasonal guidance is kind of all over the place, with some showing a very quick flip to spring, and others leaning more toward a normal-ish year. The guidance giving us an early spring are cause for some pause and give confidence in some sort of winter thaw at some point, but not enough to significantly impact the forecast.
Above: The November CFS showing monthly heights December, January, February, and March. That quick animation shows a more favorable orientation of heights for wintry weather in December, some return of warmth in January, and a rebound to more troughing in the east leading to cooler weather in February and March.
Below: The late October CanSIPS, showing a likely wintry December followed by gradual southeast ridging and warming which would possibly "end" winter sometime in February.
Below: The late October CanSIPS, showing a likely wintry December followed by gradual southeast ridging and warming which would possibly "end" winter sometime in February.
Current Conditions
We've had a trend this fall that has made me pause when looking at some of the warmer guidance later in the winter. We've had a normal transition through fall so far, with temperatures either near normal or below during the fall months. Now, that by itself doesn't mean much, but we've seen a persistent pattern of guidance reversing course with eastern ridging and warmer temperatures throughout the fall. One of the benefits of such a late winter forecast is that we can also see into the early part of December, which shows a similar pattern showing up. A fast start to winter is on tap, and while that doesn't mean much in the whole scheme of things, what we're seeing in the upper level pattern, especially with the Pacific jet and Pacific pattern, is more favorable for winter weather than we've seen in a few years, even with last year being our first colder winter in a decade.
We've had a trend this fall that has made me pause when looking at some of the warmer guidance later in the winter. We've had a normal transition through fall so far, with temperatures either near normal or below during the fall months. Now, that by itself doesn't mean much, but we've seen a persistent pattern of guidance reversing course with eastern ridging and warmer temperatures throughout the fall. One of the benefits of such a late winter forecast is that we can also see into the early part of December, which shows a similar pattern showing up. A fast start to winter is on tap, and while that doesn't mean much in the whole scheme of things, what we're seeing in the upper level pattern, especially with the Pacific jet and Pacific pattern, is more favorable for winter weather than we've seen in a few years, even with last year being our first colder winter in a decade.
Above: An example of the model trend of reducing ridging in the long range. This has been a consistent trend for months, and it shows no sign of slowing down. It's not everything, but it is something.
Analogs
Finally, let's talk analogs. I almost didn't add them. They matter least in the whole forecast, and with good reason in my opinion. No two years are alike, and in our warming climate looking at past climatological periods (which run 30 decades at a time) gets real risky real fast. Analog years of near normal/below normal temperature 2024-25, 2021-22, snowy 2017-18, and 2007-08 (even though this year was a strong Nina) lead the way.
The Forecast (Finally!)
Analogs
Finally, let's talk analogs. I almost didn't add them. They matter least in the whole forecast, and with good reason in my opinion. No two years are alike, and in our warming climate looking at past climatological periods (which run 30 decades at a time) gets real risky real fast. Analog years of near normal/below normal temperature 2024-25, 2021-22, snowy 2017-18, and 2007-08 (even though this year was a strong Nina) lead the way.
The Forecast (Finally!)
Above: The seasonal snowfall map reposted.
Snowfall
Once again, we expect near normal snowfall across the state with 25-35" in southern CT (lowest in SE CT), 35-45" for most of interior CT, 45-60" in the eastern CT hill towns and far north central CT (including BDL), and 50-65" in the NW hill towns. Given everything above, you can see that we lean toward slightly below normal to normal snowfall, mostly because excessive warmth/cold/precipitation looks to be checked in either direction. However, with a Pacific that has been hostile the balance of this decade, there's no reason to hedge snowier, especially with uncertainty on how ENSO transitions.
Our primary storm type will be southwest flow events (SWFEs), which usually start as snow before mixing and either turning to rain or precipitation shutting off. That's a result of the predominant trough being just west enough to run warmth into the region at least aloft, but our source region for cold in southeast Canada being legitimately cold for the first time in quite some time.
The second predominant storm type is likely to be redeveloping Miller B storms, which can be prolific snow producers...if timed right. The fast flow of the Pacific jet has me doubting we see many windows of opportunity for that this winter.
Remember, each month has its own snowfall average. You are least likely on average to see significant snow in December, with more in January, a peak in February, and some snow during the first 20 days of March.
Snowfall Forecast
December: 100% to 120% of normal
January: 70% to 90% of normal
February: 90% to 110% of normal
March: 80% to 100% of normal
Winter Snowfall: 80%-100% of normal across Connecticut
Temperatures
In recent years, it has been a given that we're warmer than normal DJFM (December, January, February, March). Not so this season. I think December looks near normal, with a cold start, mid-month thaw, and perhaps more cold in the last third of the month. January is when I think we're most likely to see a thaw, especially in the first 2/3 of the month. By mid-month we may be seeing a SSW event take place, but remember that there's usually a lag in what happens in the upper atmosphere and the surface, and there's no guarantee that the Polar Vortex gets displaced on our half of the globe. That said, with ENSO in transition, I expect that by the time we're moving into February we are looking at a wintry pattern returning. That puts January in near to slightly above normal territory. February and March look near normal, with a possible lean later in February and into March on the colder side.
Temperature Forecast
December: -1 to +1 (note that we consider anything inside a degree of normal as near normal)
January: 1 to 2 degrees above normal
February: -1 to +1
March: -1 to +1
Winter Composite: -1 to +1
Once again, we expect near normal snowfall across the state with 25-35" in southern CT (lowest in SE CT), 35-45" for most of interior CT, 45-60" in the eastern CT hill towns and far north central CT (including BDL), and 50-65" in the NW hill towns. Given everything above, you can see that we lean toward slightly below normal to normal snowfall, mostly because excessive warmth/cold/precipitation looks to be checked in either direction. However, with a Pacific that has been hostile the balance of this decade, there's no reason to hedge snowier, especially with uncertainty on how ENSO transitions.
Our primary storm type will be southwest flow events (SWFEs), which usually start as snow before mixing and either turning to rain or precipitation shutting off. That's a result of the predominant trough being just west enough to run warmth into the region at least aloft, but our source region for cold in southeast Canada being legitimately cold for the first time in quite some time.
The second predominant storm type is likely to be redeveloping Miller B storms, which can be prolific snow producers...if timed right. The fast flow of the Pacific jet has me doubting we see many windows of opportunity for that this winter.
Remember, each month has its own snowfall average. You are least likely on average to see significant snow in December, with more in January, a peak in February, and some snow during the first 20 days of March.
Snowfall Forecast
December: 100% to 120% of normal
January: 70% to 90% of normal
February: 90% to 110% of normal
March: 80% to 100% of normal
Winter Snowfall: 80%-100% of normal across Connecticut
Temperatures
In recent years, it has been a given that we're warmer than normal DJFM (December, January, February, March). Not so this season. I think December looks near normal, with a cold start, mid-month thaw, and perhaps more cold in the last third of the month. January is when I think we're most likely to see a thaw, especially in the first 2/3 of the month. By mid-month we may be seeing a SSW event take place, but remember that there's usually a lag in what happens in the upper atmosphere and the surface, and there's no guarantee that the Polar Vortex gets displaced on our half of the globe. That said, with ENSO in transition, I expect that by the time we're moving into February we are looking at a wintry pattern returning. That puts January in near to slightly above normal territory. February and March look near normal, with a possible lean later in February and into March on the colder side.
Temperature Forecast
December: -1 to +1 (note that we consider anything inside a degree of normal as near normal)
January: 1 to 2 degrees above normal
February: -1 to +1
March: -1 to +1
Winter Composite: -1 to +1
Above: Using our analogs, this is about what we'd expect in DJFM temperature. Right near normal, with a degree of wiggle room between below and above normal and dead center normal.
Precipitation
Much like our temperature forecast, I think we are near normal in overall precipitation, with each month likely being near normal in precipitation. We do not foresee a high end high precipitation winter, but some months may be above given the more neutral Pacific pattern. We doubt the spigot will go dry given the predominant variable northern stream jet, but during periods of more southeast ridging (like January) we may be dry.
Precipitation Forecast
December: 100% to 120% of normal
January: 80% to 100% of normal
February: 90% to 110% of normal
March: 90% to 100% of normal
Winter Composite: 90% to 110% of normal
Precipitation
Much like our temperature forecast, I think we are near normal in overall precipitation, with each month likely being near normal in precipitation. We do not foresee a high end high precipitation winter, but some months may be above given the more neutral Pacific pattern. We doubt the spigot will go dry given the predominant variable northern stream jet, but during periods of more southeast ridging (like January) we may be dry.
Precipitation Forecast
December: 100% to 120% of normal
January: 80% to 100% of normal
February: 90% to 110% of normal
March: 90% to 100% of normal
Winter Composite: 90% to 110% of normal
Above: Using our analogs, this is about what we'd expect in DJFM precipitation. Unlike the temperature forecast, I think there's more precipitation in the north Central U.S. and western U.S. than this map shows, giving respect to the variable jet stream we're likely to see.
Overall, to us it looks like we are on the path toward a season that balances out as normal. Will we see a continuation of normalcy after a pretty normal fall? Will we see two winters in a row with cooler temperatures? Will we get normal snowfall for the first time in half a decade?
We shall see.
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
Overall, to us it looks like we are on the path toward a season that balances out as normal. Will we see a continuation of normalcy after a pretty normal fall? Will we see two winters in a row with cooler temperatures? Will we get normal snowfall for the first time in half a decade?
We shall see.
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
