Status:Ongoing analysis Material from: Linus
1. Impact
Around New Year 2022-2023 large parts of Europe was under a strong positive temperature anomaly, with several records being broken. It followed from a period with colder than normal temperatures in the middle of December.
2. Description of the event
The plots below show analyses of z500 and T850 for 28 December to 3 January.
3. Predictability
3.1 Data assimilation
3.2 HRES
3.3 ENS
The plots below show EFI for 3-day 31 December to 2 January, from different initialisation times.
The plot below shows the forecast evolution plot for 3-day temperature valid 31 December 00UTC -2 January 00UTC for the box over Germany and Poland. Concatenated 6-hour forecasts - green dot, HRES –red, ENS blue box-and-whisker, Model climate – red box-and-whisker. Ensemble median as black box and ensemble mean as black diamonds. Triangle marks the maximum in the model climate based on 1200 forecasts.
The forecast from around 19 December was for slightly colder than normal (persistence of cold wave?), but gradually picked up the signal for warmer than normal conditions in the forecasts from the following days.
3.4 Monthly forecasts
The plot below shows the verification of 2-metre temperature anomalies for the week starting 26 December. Consistent with the forecast evolution plot, one can see that the forecast from 19 December predicted a cold anomaly for north-western Europe, opposite to what was observed.
