Director, Seasonal Forecasting
Atmospheric and Environmental Research
JANUS Research Group
March 2, 2026
Summary
The Arctic Oscillation (AO) is currently near neutral and is predicted to remain close to neutral to positive as pressure/geopotential height anomalies across the Arctic are currently mixed and are predicted to turn remain mixed to mosty negative the next two weeks. The North Atlantic Oscillation (NAO) is currently positive with negative pressure/geopotential height anomalies across Greenland, and the NAO is predicted to remain positive to neutral the next two weeks as pressure/geopotential height anomalies are predicted to remain mostly mixed to negative across Greenland the next two weeks.
Troughing/negative geopotential height anomalies across Greenland will support ridging/positive geopotential height anomalies across much of Europe the next two weeks. However starting next week troughing near the Urals will expand westward into Eastern Europe. This pattern will favor normal to above normal temperatures across most of Europe including the United Kingdom (UK) the next two weeks with the biggest exception being normal to below normal temperatures across Turkey the next two weeks and Eastern Europe Europe next week.
The general pattern across Asia over the next two weeks is ridging/positive geopotential height anomalies across Northern Europe and Eastern Siberia supporting troughing/negative geopotential height anomalies across Western Siberia and the Urals the next two weeks. This pattern favors mostly normal to above normal temperatures across much of Asia including Eastern Siberia with normal to below normal temperatures across Western Siberia and Western Russia and next two weeks but also Central Siberia into Northeast Asia this week.
This week the predicted atmospheric pattern across North America is troughing/negative geopotential height anomalies across Alaska, and much of Canada with ridging/positive geopotential height anomalies United States (US). However next week, strenghtening ridging/positive geopotential height anomalies in the Gulf fo Alaska will support lowering geopotential heights across the Central US. This patten will support normal to below normal temperatures in Alaska and much of Canda this week and the Central US next week with normal to above normal temperatures across the Western and Eastern US.
Polar vortex (PV) is undergoing one last stretched PV early this week followed but a PV split next week. My thoughts are below.
Plain Language Summary
Winter 2025/26 is officially over (meteorological winter that is), so on average for the entire winter cold temperatures have dominated Scandinavia, Northeastern Europe, much of Russia, Northeastern Asia, Alaska, much of Canada and the Northeastern US (see Figure). In contrast mild temperatures have dominated Western and Southern Europe, Western, Central and Southeastern Asia, Eastern Siberia, Northeast Canada and the Western and Southern US (see Figure). The forecast for the next two weeks can be summarized as more of the same with cold predicted from Russia into Northeast Asia, Alaska, Canada but milder in the entire US (see Figures 3, 6 and 9). The polar vortex (PV) has so far this winter been ping ponging between circular and strong or a Candian Warming, which favor relatively mild temperatures mostly in eastern North America and Asia and stretched or more elongated that favors cold temperatures in East Asia and eastern North America. At least one more stretched PV this week followed by something completely different - a split polar vortex or is it really?
Figure.
Estimate of the observed surface temperatures (°C; shading) from 01 Dec 2025 to 28 Feb 2026 based on GFS initializations and the GFS forecast from the 1 Mar 2026 run.
Impacts
I did finally make it to Germany but because of a busy routine today’s blog is a bit of a Frakenstein with plots mostly from today but also yesterday.
Our estimate of the winter surface temperature anomalies is complete and is shown above. I will provide a more in-depth recap of the winter forecast but overall I am very pleased how our winter forecast performed. And is often the case, when you compare the forecast to our competittiors (I am referring to the government forecast centers) it looks even more remarkable.
Jumping right in, I first discuss the two-week forecast for the mid-tropospheric circulation, which helps set the table for what I am expecting with the polar vortex (PV) and our weather. Once again, for most of the two weeks the mid-tropospheric circulation is characterized by low pressure centered near the North Pole and high-pressure ridging floating around the mid- to high-latitudes (see Figure i). This week once again the dominant high latitude blocking will be centered in the North Pacific sector. Currently the models have one blocking center in Eastern Siberia but eventually a second one sets up in the Gulf of Alaska. There is blocking in the North Atlantic sector one center along the US East Coast, bringing with it the first extended mild period in the Northeastern US since I believe Janaury. There is also a second blocking high center near Scandinavia, which I believe is the main catalyst for the PV split.
Figure i.
Initialized 500 mb geopotential heights (dam; contours) and decameter anomalies (dam; shading) across the Northern Hemisphere for 9 Feb 2026 and forecasted from 02 Mar 2026 and forecasted from 03 Mar 2026 to 17 Mar 2026. The forecasts are from the 00Z 02 Mar 2026 GFS model.
Figure ii presents the latest PV animation. Initially the PV is elongated or stretched from Western Asia to Canada, though I admit this is a sad looking stretch. The PV stretch does look a little better in Figure 12a. The PV stretch also looks much better at 100 hPa or in the lower stratosphere (not shown). This brief PV stretch is bringing one last and brief Arctic outbreak to the Eastern US. Then for most of the animation the PV splits into two centers one over Western Siberia and the other over Eastern Canada, Then at the end of the animation the two PV centers try to merge and reconstitute one PV center over the North Pole, likely ensuring the SSW is not the Final Warming like last March.
Figure ii.
Forecasted average 10 mb geopotential heights (dam; contours) and geopotential height anomalies (m; shading) across the Northern Hemisphere for 02 Mar 2026 and forecasted from 03 Mar 2026 to 17 Mar 2026. The forecasts are from the 00Z 02 Mar 2026 GFS model.
The PV split will result in a sudden stratospheric warming (SSW - defined as a reversal of the wind from westerly to easterly at 60N and 10 hPa) this week. Capping off a remarkable PV season starting off with an SSW in November in the form of a displacement, then three months of “rinse, lather repeat” or stretched PVs that just kept repeating for much of the winter punctuated or separated by a relatively strong PV and/or a Canadian warming. And for the crescendo another SSW in the form of a PV split. This will not be the Final Warming, which may wait until April to occur, but hard to predict the exact timing.
PV splits seem to generate the most excitement among the weather enthusaists on social media and for much of my career me as well. But with this PV split my enthusiasm is tempered. We all associate a prolonged period of severe winter weather following the PV split. But when and where are always open questions. In contrast what seems to be a garauntee is an extended mild period in the Eastern US right as the event occurs and the immediate ensuing period. So when a PV split occurs in the second half of winter it could be a winter slayer and when the pattern flips it is already spring. I love snow but damp, raw weather, not so much. And as as I get older I get more excited about PV stretches, the associated severe winter is immediate and dependable, though its duration can be short.
But this PV split does present some interesting lessons. Since the landmark papers of Bladwin and Dunkerton, we have come to associate with all SSWs the downward influence about two weeks later. So as the general thinking goes the impacts from the SSW descend from the stratosphere through the atmospheric column to the surface resulting in a negative NAO (Greenland blocking) and widespread severe winter weather across the Northern Hemisphere including the US, Europe and Asia. The impacts from the SSW on our weather arrives on average two weeks after the SSW. This downward influence would show up in the polar cap geopotential height anomalies (PCHs) plot presented in Figure 11. Even in two week’s time, the signal or downward influence from the SSW or PV split is stil hung up in the stratosphere and has not arrived in the troposphere. Yes the pattern is predicted to turn much colder across North America in that time period (see Figure 9) or before the arrival of the impacts from the PV split based on traditional diagnostics. So what is going on?
So once again, I present the wave diagnostics in Figure iii that I show every week and that I have grown very fond of. So once again this week, wave energy goes up and east over Asia, but this time instead of reflecting off of the stratospheric PV (or at least a reflective layer in the polar stratosphere) and head down and east over North America, the energy is absorbed in the polar stratosphere (see Figure iiia). In addition, the standing wave over North America, which has tilted eastward so often this winter is tilting westward (I drew in a blue line to make this more clear). Wave energy now also goes up and east over North America and into the polar stratosphere. Likely the tag team of upward wave energy over both Asia and North America results in a PV split, rather than a PV displacement. It seems to me the lack of wave reflection over North America, allows for temperatures to rebound across the Eastern US.
Figure iii.
a) Predicted longitude-height cross section of geopotential eddy height anomalies (shading) and wave activity flux (vectors) averaged 3 March through 7 March 2026 b) same as a) but forecast from 8 March through 12 March 2026. The forecast is from the 00Z 2 March 2026 GFS operational.
However for next week it does appear that wave reflection returns as seen in Figure iiib. As has occurred so often this winter, wave energy goes up and east over Asia, reflects off the stratospheric PV (or at least a reflective layer in the polar stratosphere) and then heads down and east over North America where the energy is re-absorbed amplifying the standing wave over North America and delivers cold air south across North America including the Eastern US. Also importantly the standing wave tilts to the west with height over Asia but tilts to the east over North America. Again I include a blue line to highlight the change in wave tilt over North America from this week to next week.
So if you are not paying close attention (highly likely if you are not reading the blog) you might just assume that we have a PV split, it turns colder a week later so that just must be from the typical downward influence from the PV split. But Figure 11 clearly shows that is not the case, instead it is our familiar friend - wave reflection. What is important to keep in mind is that both Canadian Warmings and SSWs are supportive of wave reflection. When doing scientific studies for publication we need to create averages over long periods of data but important details get lost. The weekly blog allows us to cut through the blizzard of data points and see clearly what is happening in real time.
I have officially retired my Monty Hall impression for the winter of 2025-26. So I will skip for this week.
Near Term
This Week
The AO is predicted to be near neutral this week (Figure 1) with mixed geopotential height anomalies currently across the Arctic and mixed geopotential height anomalies across the mid-latitudes of the NH (Figure 2). With predicted negative geopotential height anomalies across Greenland (Figure 2), the NAO is predicted to be postive this week.
Figure 1.
The predicted daily-mean AO at a) 10 hPa and b) 1000 hPa from the 00Z 2 Mar 2026 GFS ensemble. Gray lines indicate the AO index from each individual ensemble member, with the ensemble mean AO index given by the red line with squares.
Troughing/negative geopotential height anomalies across Gereenland will support widespread ridging/positive geopotential height anomalies across Europe (Figure 2). This pattern will support normal to above normal temperatures across much of Europe including the UK this week (Figure 3). This week the general pattern across Asia is ridging/positive geopotential height anomalies across Northern Europe and Eastern Siberia will support troughing/negative geopotential height anomalies centered on Western Siberia extending southwestward into the Middle East this week (Figure 2). This pattern favors normal to below normal temperatures across Western and Central Siberia into Northeast Asia and the the Middle East with normal to above normal temperatures across most of Asia including Eastern Siberia this week (Figure 3).
Figure 2.
Forecasted average 500 mb geopotential heights (dam; contours) and geopotential height anomalies (m; shading) across the Northern Hemisphere from 3 Mar 2026 to 7 Mar 2026. The forecasts are from the 00Z 2 Mar 2026 GFS ensemble.
The predicted pattern across North America this week is troughing/negative geopotential height anomalies Alaska and Canada with ridging/positive geopotential height anomalies across the US this week (Figure 2). This patten will favor normal to below normal temperatures across Alaska and much of Canada with normal to above normal temperatures across much of the US this week (Figure 3).
Figure 3.
Forecasted surface temperature anomalies (°C; shading) from 3 Mar 2026 to 7 Mar 2026. The forecasts are from the 00Z 2 Mar 2026 GFS ensemble.
Troughing and/or cold temperatures will support new snowfall across parts of Turkey the Tibetan Plateau, parts of Southern Siberia and Northeast Asia while milder temperatures will support snowmelt across the Alps, Scandinavia, the Baltic States, Eastern Europe, Western Russia and parts of Siberia this week (Figure 4). Troughing and/or cold temperatures will support new snowfall across the higher elevations of Western Canada, the Canadian Plains and the higher elevations of the Northwestern US while milder temperatures will support snowmelt across parts of Southern Canada and the Northeastern US this week (Figure 4).
Figure 4.
Forecasted snowfall (mm/day; shading) from 3 Mar 2026 to 7 Mar 2026. The forecasts are from the 00Z 2 Mar 2026 GFS ensemble.
Near-Mid Term
Next Week
With geopotential height anomalies remaining mixed to mostly negative across the Arctic and with mixed geopotential height anomalies across the mid-latitudes this period (Figure 5), the AO will likely be neutral to positive this period (Figure 1). With mostly negative pressure/geopotential height anomalies across Greenland (Figure 5), the NAO will likely be positive this period.
Figure 5.
Forecasted average 500 mb geopotential heights (dam; contours) and geopotential height anomalies (m; shading) across the Northern Hemisphere from 8 Mar 2026 to 12 Mar 2026. The forecasts are from the 00Z 2 Mar 2026 GFS ensemble.
The persistent troughing/negative geopotential height anomalies across Greenland will continue to support widespread ridging/positive geopotential height anomalies across Europe centered on Scandinavia this period (Figure 5). The pattern will support widespread normal to above normal temperatures across Europe including the UK with the exception of normal to below normal temperatures in Eastern Europe with induced northerly flow this period (Figure 6). Across Asia ridging/positive geopotential height anomalies centered over Scandinavia and Eastern Siberia will support troughing/negative geopotential height anomalies centered on Western Siberia bit extending southwestward towards the Middle East this period (Figure 5). This pattern favors widespread normal to above normal temperatures widespread across much of Asia especially Central and Eastern Asia including Eastern Siberia with normal to below normal temperatures across Western Siberiia into Western Russia and the Middle East this period (Figure 6).
Figure 6.
Forecasted surface temperature anomalies (°C; shading) from 8 Mar 2026 to 12 Mar 2026. The forecasts are from the 00Z 2 Mar 2026 GFS ensemble.
Strengthening ridging/positive geopotential height anomalies along the US East Coast and in the Gulf of Alaska will support deep troughing/negative geopotential height anomalies across Alaska and much of Canada this period (Figure 5). This pattern will favor normal to below normal temperatures across Alaska, much of Canada with normal to above normal temperatures across the US and Southeastern Canada (Figure 6).
Figure 7.
Forecasted snowfall rate (mm/day; shading) from 8 Mar 2026 to 12 Mar 2026. The forecasts are from the 00Z 2 Mar 2026 GFS ensemble.
Troughing and/or cold temperatures will support new snowfall in the Balkans, the Caucuses, parts of Siberia and the Tibetan Plateaus while milder temperatures will support snowmelt in parts of Scandinavia, Western Russia, parts of Siberia and Northeast Asia this period (Figure 7). Troughing and/or cold temperatures will support new snowfall in the higher elevations of the West Coast of Canada, the Northwestern US and the US Upper Midwest while milder temperatures will support snowmelt in Alaska, Central and Southern Canada and the Northeastern US this period (Figure 7).
Mid Term
Week Two
With predicted mixed to mostly negative geopotential height anomalies across the Arctic and mixed geopotential height anomalies across the mid-latitudes this period (Figure 8), the AO will likely be neutral to positive this period (Figure 1). With predicted mixed to negative pressure/geopotential height anomalies across Greenland (Figure 8), the NAO will likely remain near neutral to positive this period.
Figure 8.
Forecasted average 500 mb geopotential heights (dam; contours) and geopotential height anomalies (m; shading) across the Northern Hemisphere from 13 Mar to 17 Mar 2026. The forecasts are from the 00Z 2 Mar 2026 GFS ensemble.
Weak troughing/negative geopotential height anomalies across across Greenland will continue to support ridging/positive geopotential height anomalies widespread across Europe centered on Scandinavia with weak troughing/negative geopotential height anomalies to the south across Eastern Europe this period (Figure 8). This pattern should favor widepsread normal to above normal temperatures across much of Europe including the UK with with normal to below normal temperatures limited to Eastern Europe this period (Figures 9). Predicted ridging/positive geopotential height anomalies across Eastern Siberia and Scandinavia will continue to support troughing/negative geopotential height anomalies across Western Siberia and the Urals this period (Figure 8). This pattern favors normal to below normal temperatures across Western Siberia and Western Russia with normal to above normal temperatures widespread across Asia including Eastern Siberia, Central Asia and the Tibetan Plateau this period (Figure 9).
Figure 9.
Forecasted surface temperature anomalies (°C; shading) from 13 Mar to 17 Mar 2026. The forecasts are from the 00Z 2 Mar 2026 GFS ensemble.
Strengthening ridging/positive geopotential height anomalies over the Gulf of Alaska will support deepening troughing/negative geopotential height anomalies across the interior of North Ameirca with more ridging along the US East Coast this period (Figure 8). This pattern supports normal to below normal temperatures across Alaska, much of Canada and the Central US with normal to above normal temperatures across the Western and Eastern US this period (Figure 9).
Figure 10.
Forecasted snowfall (mm/day; shading) from 13 Mar to 17 Mar 2026. The forecasts are from the 00Z 2 Mar 2026 GFS ensemble.
Troughing and/or cold temperatures will support some possible new snowfall in the Alps, parts of Norway, parts of Siberia and the Tibetan Plateau while milder temperatures will support snowmelt in parts of Scandinavia, Western Russia and Southern Siberia this period (Figure 10). Troughing and/or cold temperatures will support new snowfall across across Southern and Eastern Canada and the Northeastern US while milder temperatures will support snowmelt in southern Alaska, Western and Central Canada this period (Figure 10).
Longer Term
30-day
Today’s polar cap geopotential height anomalies (PCHs) plot currently shows warm/positive PCHs throughout the stratosphere and the troposphere (Figure 11). Then next week warm/positive PCHs are predicted to persist in the stratosphere but transition to cold/negative PCHs in the troposphere.
Figure 11.
Observed and predicted daily polar cap height (i.e., area-averaged geopotential heights poleward of 60°N) standardized anomalies. The forecast is from the 00Z 2 Mar 2026 GFS ensemble.
The predicted warm/postive PCHs in the lower troposphere this week (Figure 11) are consistent with the predicted near neutral AO (surface temperature anomalies more than pressure fields are cosnsistent with warm/positive PCHs) this week (Figure 1). Then next week the forecast of cold/negative PCHs in the lower troposphere (Figure 11) are consistent with a near neutral to positive AO (Figure 1).
Figure 12.
Observed 10 mb geopotential heights (dam; contours) and temperature anomalies (°C; shading) across the Northern Hemisphere averaged from 3 Mar. (b) Same as (a) except forecasted averaged from 7 Mar to 11 Mar 2026. The forecasts are from the 00Z 1 Mar 2026 GFS ensemble.
This week the polar vortex (PV) is elongated in shape from the Urals to Central Canada with the main PV center over the Urals with relatively cold temperatures focused over Eastern Europe and Western Asia and with high pressure centered over the Dateline and relatively warm temperatures across the Canadian Arctic in the polar stratosphere (Figure 12a). Then during the second week of March, the PV is predicted to split into two PV centers with one center over the Urals and and a second center over Hudson Bay with high pressure centered in between centered over the Beaufort Sea with cold temperatures over Eastern Asia with relatively warm temperatures stretching across from Siberia to Canada and Greenland in the polar stratosphere (Figure 12b). This is a clear PV split. The stratospheric AO in Figure 1 this week is predicted to remain negative to strongly negative the next two weeks with the large PV disruption.
Figure 13.
Forecasted average 500 mb geopotential heights (dam; contours) and geopotential height anomalies (m; shading) across the Northern Hemisphere for Apr 2026. The forecasts are from the 00Z 1 Mar 2025 CFS.
I include in this week’s blog the monthly 500 hPa geopotential heights (Figure 13) and surface temperatures for April (Figure 14) from the Climate Forecast System (CFS; the plots represent yesterday’s four ensemble members). I do want to emphasize unless I say otherwise, I find the CFS forecasts of low confidence and most often don’t match my own thinking. The forecast for the troposphere is ridging across Greenland, the Urals, Eastern Siberia, the Gulf of Alaska and the Central US with troughing centered near the UK, across Northern and into Northeastern Asia, Eastern Canada into the Canadian Maritimes (Figure 13). This pattern favors seasonable to relatively warm temperatures across Europe, Northern Siberia, Southern, Central and Eastern Asia, including the Middle East, eastern China the Tibetan Plateau, Pakistan and Afghanistan, Eastern Siberia, Central Canada and the Western US with seasonable to relatively cool temperatures across Siberia, Northeast Asia, Alaska, Western and Eastern Canada and the Central and Eastern US (Figure 14).
Figure 14.
Forecasted average surface temperature anomalies (°C; shading) across the Northern Hemisphere for Apr 2026. The forecasts are from the CFS 00Z 1 Mar 2025.
Boundary Forcings
Artic Sea Ice
I am and will continue to watch Arctic sea ice. Current conditions are shown in Figure 15. It has been shown that less sea ice in the North Atlantic sector of the Arctic weakens the polar vortex while less sea ice in the North Pacific sector strengthens the polar vortex. Arctic sea ice anomalies continue to show a strong focus or weighting of negative anomalies towards the North Atlantic sector relative to the North Pacific sector and this is a robust signal of an overall weaker PV this winter. The negative anomalies are distributed between the Eurasian sector, i.e., Barents Kara Seas and the North American sector, now mostly in Baffin Bay (see Figure 15). Therefore, I do think that low sea ice in the Barents-Kara Seas has supported Barents-Kara Seas blocking this past January but low sea ice near Greenland could be supporting blocking in the region as well. Large negative sea ice anomalies have also developed in the Sea of Okhotsk and could be a result of but also supporting blocking in the region.
Figure 15.
Arctic sea ice cover extent for 1 Mar 2026. White depicts ice covered areas and the orange contour the climatological extent of Arctic sea ice for the date. Plot taken from: https://nsidc.org/sea-ice-today
SSTs/El Niño/Southern Oscillation
Equatorial Pacific sea surface temperatures (SSTs) anomalies are below normal, along the equatorial Pacific (Figure 15) consistent with La Niña conditions for much of the winter, however warming has appeared near the South American coast and could be a sign of a developing El Niño conditions. Observed SSTs across the NH remain well above normal especially in the North Pacific and much of the North Atlantic, though below normal SSTs exist regionally especially in the South Pacific. The very warm SSTs in both ocean basins could be supporting the predicted blocking in both basins.
Figure 16.
The latest daily-mean global SST anomalies for week ending 28 Feb 2026.
Madden Julian Oscillation
Currently the Madden Julian Oscillation (MJO) is currently weak where no phase is favored (Figure 17) and the forecasts are for the MJO to remain weak where no phase is favored (Figure 17). Therefore, it seems that the MJO is having little influence on North American weather this week and next week. But admittedly this is outside of my expertise.
Figure 17.
Past and forecast values of the MJO index. Forecast values from the 00Z 01 Mar 2026 ECMWF model. Yellow lines indicate individual ensemble-member forecasts, with the green line showing the ensemble-mean. A measure of the model 'spread' is denoted by the gray shading. Sector numbers indicate the phase of the MJO, with geographical labels indicating where anomalous convection occurs during that phase. Image source https://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/ecmf.shtml
