Material from: Linus
1. Overview
In the end of April 2025 Western Europe experienced unseasonally high temperatures.
2. Analyses and Observations
2.1 Event Definition
Currently based on the 2-metre temperature on 30 April 12UTC for a 0.25x0.25 degree box centred on Troyes, France (48.3N, 4E). An evolution plot is also available for the 3-day mean temperature (29 April -1 May).
2.2 Analyses
The plots below show analyses of T850 and z500 from 26 April to 2 May.
2.3 Observations
2.4 Climatological perspective
3. Forecasts
3.1 Data assimilation and observation usage
The plots below show the observation statistics for assimilation of 2-metre temperature (left) and 2-metre relative humidity (right), for the box 45-50N, 0-7E.
3.2 Single Forecasts for the event based on 00UTC forecasts (defined in Section 2.1)
Observations for the event
SYNOP observations (left) and ECMWF analysis (right).
Control forecast (IFS 9-km resolution)
Compared to the ECMWF analysis, one can note the colder temperatures over France. In the short-range forecasts one can see the sign of a heat-island over Paris and London.
DestinE (IFS 4.4km resolution)
AIFS -single (AIFSv1.0 ~0.25 resolution)
The warm temperatures over France is better captured in AIFS.
AIFS ensemble (AIFS diffusion ensemble ~1 degree resolution)
3.3 Ensemble distribution
EFI (based on IFS 9-km ensemble)
The plots below shows the EFI for 3-day mean temperature 29 April 1 May. The event was well captured at least from 24 April and onwads.
Forecast Evolution plot
The plot below shows the evolution plot for the 2-metre temperature on 30 April 12UTC for Troyes, France. The prediction was extremely good from AIFS-single. The IFS forecasts were much colder than AIFS-single and AIFS-CRPS, which were in line with the observation.
Legend:
Observation - green hourglass
Analysis - green dot
ENS CF - red dot
DestinE - dark-green dot
AIFS-single - cyan dot
ENS distribution - blue
AIFS-ENS-CRPS distribution - pink
ENS m-climate - cyan
ENS m-climate maximum - black triangle
The plot below shows the evolution plot for 3-day mean temperature for Troyes, France (see event definition). Same legend as above.
3.4 Sub-seasonal forecasts
3.5 Comparison with other centres
4. Hazard Forecasts
5. Dedicated Experiments
6. Event Summary
6.1 Good and bad aspects of the forecasts for the event
- Extremely good prediction by AIFS-Single more than 7 days in advance
- Good predictability for the event overall
- Too cold temperatures in IFS over France