Material from: Linus

1. Overview

 Around 7-8 April, Western Europe experienced unseasonal maximum temperatures (but still with cold nights). For example, 8 April became the earliest day of the year Reading hit 25 degrees. 

2. Analyses and Observations

2.1 Event Definition

Here we will focus on the 2-metre temperature on 8 April 12UTC around Orleans (France), in a 0.5x0.5 degree box centred on 48N, 1.8E.

2.2 Analyses

The plots below show analyses of z500 and T850 for the period 1 April to 1 9 April.

2.3 Observations

2.4 Climatological perspective

3. Forecasts

3.1 Data assimilation and observation usage

3.2 Single Forecasts for the event based on 00UTC forecasts (defined in Section 2.1)

Observations and analysis for the event

Control forecast (IFS 9-km resolution)

DestinE (IFS 4.4km resolution)

AIFS-single (AIFSv1.0 ~0.25 resolution)

AIFS-ENS control (~0.25 degree resolution)

AIFS-IFS Hybrid

The plot below shows forecasts from 7 April for Orleans from a selection of the models and nearby observations. While only having 6-hourly output, one can still see that the AIFS forecasts captured the daily maximum better.

3.3 Ensemble distribution

EFI (based on IFS 9-km ensemble)

The plots below show the AIFS for maximum 2-metre temperature on 8 April.

Forecast Evolution plot

The plot below shows the evolution of forecasts for 2-metre temperature on 12UTC on 8 April.

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

• AIFS captured the maximum temperature much better than IFS

6.2 Experience from general performance/other cases

202504 - Heatwave - Western Europe

7. Additional material