201406 - Convection - Germany, The Netherlands, Belgium, France

 Status:Ongoing analysis Material from: Fernando, Linus

Discussed in the following Daily reports:

http://intra.ecmwf.int/daily/d/dreport/2014/06/09/sc/

http://intra.ecmwf.int/daily/d/dreport/2014/06/10/sc/

Picture

1. Impact

On 9 June severe convection affected western Europe. In Germany 6 people were killed, mainly by falling trees. Wind gusts up  to 42 m/s where reported from Duesseldorf airport.

http://www.bbc.co.uk/news/world-europe-27776189

2. Description of the event

The satellite imagery below (from late afternoon 9 June) shows convective activity occurring in France, NW Germany and Holland (also eastern England). The lightning reports indicate two major areas of strong activity; in France and Germany/Holland.

Satellite sequence from EUMETSAT:

https://www.youtube.com/watch?v=bf0uLDqdoc4

3. Predictability

3.1 Data assimilation

3.2 HRES

The figures below show the 24-hour precipitation (06-06UTC). The first plot shows the observations and the following HRES forecasts valid for the same period. In western Germany and Belgium several stations reported more than 30 mm. In the forecasts the band of convection was shifted somewhat to the west. For central France it seems like the convection was overestimated.

The figures below show the 24-hour maximum wind gusts (00-00UTC). The first plot is the observed values and the next is the HRES forecast for 9 june 00UTC. In general, no strong wind gusts are present in connection to the convection.

The  figure above shows animation of RGB product from EUMETSAT, the max CAPE for +(6-24)h period (top-right) and maximum CAPE blended with CIN (CAPE is removed where CIN >= 200, bottom-left) based on 09@00 run for the HRES. One can see a good agreement between the high values of CAPE and the regions where the convection took place in particular over France and Benelux region. The convection triggered ahead of a cold front crossing the Iberia Peninsula seems to be in contradiction with the relative low values of CAPE forecast. It is possible that a dynamical lifting process helped to trigger the convection in the region

3.3 ENS

70% ENS percentile total PPN in 6h (top-left). Vis image at 1500 UTC and 3hrly PPN from HRES based on the latest run (bottom).

CDF for Duesseldorf valild 9 June. The probabilities for extreme temperatures was well captured 5 days in advance. However, not signal for heavy precipitation and strong wind gusts where present.

The figures above show the EFI for CAPE (shades) and precipitation (green symbols) valid for 9 June. The hourglass symbol marks the location of Duesseldorf. Already in the forecast from 4 June had high EFI values for the region for CAPE. The extreme rainfall in the forecast is located on the western side of the high CAPE values, probably connected to the CIN values (see figure above).

3.4 Monthly forecasts

3.5 Comparison with other centres

The plots bleow shows the value of the maximum member for 18-hour precipiation (06-00UTC) for EC ENS (32km), COSMO-LEPS and COSMO-DE-EPS. All forecasts are initialised 9 June 00UTC.

4. Experience from general performance/other cases

5. Good and bad aspects of the forecasts for the event

6. Additional material