Material from: Linus, Mohamed

1. Overview

 During the last days of June and the beginning of July a heatwave affected large parts of Western Europe and also Morocco. In Spain and Morocco, several maximum temperature records for June was broken.

The Morocco part of the event is covered on the page: 202506 - Heatwave - Morocco

2. Analyses and Observations

2.1 Event Definition

Here we will focus on the 3-day temperature in Frankfurt am Main on 30 June-2 July, keeping in mind that it was a lot of places that were affected. The choice of Frankfurt is to see how well the forecasting system captured the northerly extent of the event.

2.2 Analyses

The plots below show analyses of T850 and z500 from 27 June to 3 July.

2.3 Observations

2.4 Climatological perspective

An article about the climatological perspective from C3S can be found here: https://climate.copernicus.eu/heatwaves-contribute-warmest-june-record-western-europe

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-CRPS ensemble (~0.25 degree resolution)

3.3 Ensemble distribution

EFI (based on IFS 9-km ensemble)

Forecast Evolution plot

The plot below shows the forecast evolution for 3-day mean temperature for Frankfurt am Main.

The signal from AIFS-single was quite exceptional, with all the single forecasts being above the 99th percentile of (IFS) model climate from 19 June and onwards.

Legend:

Observation - green hourglass
Analysis - green dot
ENS CF - red dot
AIFS-single - cyan dot

ENS distribution - blue
AIFS-ENS distribution - pink
ENS m-climate - cyan
ENS m-climate maximum - black triangle

3.4 Sub-seasonal forecasts

  The plots below show ensemble mean weekly average of 2-metre temperature 30 June - 6 July in forecasts from different initial dates (all Mondays).

Also the week-3 forecast captured the structure of the anomalies over Europe. Longer ranges also included a warm anomaly south-western to Central Europe, but the question is how much that is due two the global warming signal when we compare to the 20-year reforecast period.

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

• Exceptional signal in AIFS-single
• Some signal in the sub-seasonal range

6.2 Experience from general performance/other cases

7. Additional material