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The plot below shows the 2-metre temperature anomaly from ERA5 for 3 to 5 January. Northern Sweden, Finland and Estonia saw cold anomalies larger than 15 degrees for this 3-day period.
The plot below show daily mean (based on 00 and 12UTC) temperature over northern Sweden (land points inside 60-65N, 10-20E) based on ERA5. Daily values (thin), 7-day running mean (thick) and daily climatology (dashed). The time series starts 3 August and ends 8 January. Since the beginning of October, almost all 7-day running mean have been colder than normal for this region.
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The plots below show analysis of 3-day temperature 3-5 January and forecasts from 1 December from IFS with 9 km resolution the the DestinE run with 4.4 km resolution. The 4.4 km forecast has a smaller area with below -30C (brown).
The plots below show 24-hour forecasts (IFS with 9 km and 4.4 km) from 3 January 00UTC and observations. For this time instance one can also see that the 4.4km forecast was fewer extremely cold areas.
The plots below show analysis of 3-day temperature 3-5 January and forecasts from 30 December from IFS (ENS control), and machine-learning forecasts from AIFS, PanguWeather and Graphcast. The box outlines a region between Vidsel and Alvsbyn. All machine-learning models are much warmer than the IFS control forecast.
3.3 ENS
The plots below show EFI for 3-day temperature 3-5 January. All forecast from 28 December and onwards captured the general structure of the cold event.
3.4 Monthly forecasts
The plots below show forecasts of weekly temperature anomalies for 1-7 January.
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