January 2025 is underway and has already brought cold winter weather and snowfall across large parts of the United States and Canada. The pressure anomaly forecasts show a continued stream of cold polar air to descend into North America, but a potential pattern shift is starting to appear in early forecasts for February.
The continuous high-pressure area over the Arctic helped to initiate large-scale cold air transport from the Arctic into the United States and Canada, now also aided by an east Pacific ridge.
Below is the average forecast for the rest of January or at least one of the forecast scenarios. A persistent low-pressure area over the central and eastern United States, driving the northerly flow down into the United States. This is a remarkable pattern, putting January 2025 as one of the coldest in recent years or even decades.
WINTER WEATHER UNDERWAY
We have already entered into the second week of January. Below, you see the 5-day pressure pattern forecast. You can see the strong low-pressure anomaly just off the east U.S. coast, with a low-pressure extension back into the eastern and southern United States.
You can also see two strong high-pressure areas, one over Greenland and northeast Canada and a strong ridge over the east Pacific. That Pacific ridge helps to drive the northern flow and cold air down across the central, southern, and eastern United States.
You can see the 5-day temperature anomaly forecast below, which shows the spread of the cold airmass across the southern, central, and eastern United States. But over the far northern United States, the Pacific Northwest, and far eastern Canada, the temperatures will be far above-normal for this time of year.
Of course, in January the average temperatures in those areas are far below freezing, so even a strong positive anomaly does not mean warm temperatures. But it is interesting to see the effects of strong high-pressure anomalies, while the low-pressure drives cold down to the far southern United States.
Below is the temperature anomaly forecast for tomorrow, which shows the spread of cold air across the whole eastern half of the United States, down to the deep south. You can also see the far above-normal temperatures over western and eastern Canada.
Forecast images in this article were provided by WeatherBell, using a professional/commercial user license.
The movement of the pressure systems drives these strong temperature patterns and changes. Pairs of pressure systems are also known as Rossby Waves. You can see an example of Rossby waves in the image below by NOAA and how they are all connected and function with the jet stream.
The purple line connecting these pressure systems is called the jet stream. This rapid stream of air is found around 9 to 14 kilometers (6 to 9 miles) above sea level.
We produced a high-resolution video that shows the whole 15-day forecast of the airmass movement over North America. This way, you can see how the cold air is being transported down from the north like it has its own “cold highway”, driven by the Rossby waves of highs and lows.
The cold air airmass will also bring widespread snowfall to the United States and Canada, from the northern plains across the Midwest and into the northeastern United States. But the most significant event of the week will be the snowfall event over all of the southern states.
As the winter period continues into the mid-month, we are looking at a potential quick pause in the third week of January before the winter continues. That is sometimes known as a winter pattern “reset”.
WINTER PATTERN RESET
Looking into the third week of January, the pressure anomalies don’t look too different than the week before. The 5-day average forecast for next week shows a deep and broad low-pressure area over the eastern United States, extending into the Atlantic. This will keep the cold air locked over the eastern United States, with a brief break over the western half of the U.S.
Below is the jet stream forecast for later next week. You can see it is bending down across the United States. As the low-pressure area spins counter-clockwise, that creates a northerly flow across the United States when the low is over the eastern United States or eastern Canada. A ridge over the west pushes the jet stream higher up, bringing along a warmer airmass.
We can see that if we look at the temperature at the 850mb level (1500m/5000ft). This way, we can understand the overall airmass movement. The image below is for the same period as the jet stream forecast. You can see the cold air descending into the eastern United States, while over the west, the higher jet stream and the ridge bring a milder airmass.
You can also see the connection of the cold airmass far back to the north into the polar circle. This persistent northern flow from the Arctic is sometimes known as the “Polar Express”.
Below is the surface temperature anomaly, averaged for the whole next week. Most of the eastern United States will experience persistent cold air mass. But you can see the strong above-average area over Canada and the northern United States, brought in briefly by the high-pressure ridge.
Below is a single-run forecast from the ECMWF model. It shows the temperature anomalies for mid-next week. You can see a persistent cold area over the eastern United States while above-average surface temperatures move over the northern U.S. and southern Canada.
We usually look at anomalies, which reveal areas of above/below normal temperatures. But we can also look at actual temperatures in the image below for mid-next week. You can see that most of the United States is near or below freezing temperatures, especially the whole eastern U.S.
But you can also see a gap in the cold across the plains and into deep southern Canada. If you look closely, you can actually see that the temperatures in south Texas or northern Florida will be the same as over southern Canada. This is the effect of airmass and jet stream movement.
We can also look at some snowfall scenarios for the third week of January. Below is a single-run forecast that shows snowfall next week will mostly spread across the northern half of the United States and Canada. Some snowfall will also spread into the central plains, with the highest amount over the northeastern U.S. and the Great Lakes.
Of course, this is just a single model scenario, but we can look at these forecasts to evaluate the potential for cold and snow.
Going into the last days of week 3 of January, we can see another pattern shift. A new wave of arctic cold will replace the warm anomalies over western Canada and the northwestern United States. This is a “loading” pattern, which usually means that a cold airmass is gathering and is then usually released over the northern, central, and eastern United States.
To look into the final week of January and beyond, we need the extended range forecasts, which were very good in detecting this current cold period week ahead.
A COLD WAVE REPEATS
Looking at the extended-range forecast trend for the final week of January, you can see the main low-pressure area is now over the northern United States and southern Canada. This is the first time in a while that we see the low-pressure zone shifting further west.
This, for now, seems like a pattern reset, where the main low-pressure anomaly can be found further west. It then drops into the central United States and moves towards the east, bringing along the cold Arctic airmass.
The temperature forecast trend below shows a negative anomaly over much of the United States and southern Canada. This is an average forecast for the whole 7-day period at the end of the month. It indicates the cold air will spread from western Canada down and across the United States.
The ensemble forecast for the start of week 4 shows the cold air anomaly to spread throughout the United States from southern Canada. This is just the start of week 4, but this shows to be the time when this cold wave will start to spread across the continent.
We can also look at a single-run forecast to get an idea of the potential scenarios. The ECMWF operational forecast below indicates a very cold airmass to already spread beyond the east coast by January 21st. This scenario is faster than the trend average but is a low-confidence forecast as it’s just a single calculation.
The snow forecast trend for the final week of January shows snowfall over the western elevations of North America. You can also see some snowfall over the central and northern Plains. But in this period, more snowfall is currently indicated over the Midwest, the eastern United States, and the eastern half of Canada.
Overall, the current trends show January ending with the same colder weather that persists over the whole month. But as we look into the long-range projections for February 2025, signs of a new weather pattern emerge.
FEBRUARY 2025 EARLY TRENDS
Looking at the first week of February, you can see the low-pressure area pulling further back to the northwest. This keeps a northerly flow over the northwestern and northern United States. But depending on the strength of the ridge over the eastern United States, it usually brings a mild airmass into the central and eastern U.S.
This can be seen in the surface temperature forecast below. You can first see the cold airmass that remains over the western United States and the Pacific Northwest. But with the high-pressure starting to push back into the central and eastern United States, we see first indications that milder temperatures are trending to return in February.
We decided to also add the latest long-range forecast for February 2025, which was just released by the ECMWF. In the pressure forecast below, you can see a very similar pattern as in the early month trends above. A low-pressure area pulls back over the Pacific Northwest, with a ridge returning to the eastern United States and Canada.
The long-range temperature forecast for February shows the main cold airmass to remain over western Canada and the Pacific Northwest. The monthly forecast does show an extension of the cold air into the northern United States and the upper Midwest. This can potentially indicate that despite the low-pressure returning back west, there is still a window for a cold air release into the central and eastern U.S. as the pattern resets.
We will keep you updated on the developing weather trends in the coming weeks, so make sure to bookmark our page. Also, if you have seen this article in the Google App (Discover) feed, click the like and follow button there to see more of our forecasts and our latest articles on weather and nature in general.
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