Material from: Erin, Linus

1. Overview

 Storm Goretti hit south-western tip of England and Northern France late on 8 January.. In the UK 99 mph was observed on the Isle of Scilly, and maybe 123 mph in Cornwall. On the other side of the Channel in France, up to 213 kmh was observed in Normandy.  

2. Analyses and Observations

2.1 Event Definition

We will mainly focus on the 10-metre mean wind at 18UTC on 8 January in a 0.5x0.5 box centred on Isle of Scilly (49.9N, 6.3W). The observed mean wind was 27 m/s.

2.2 Analyses

The plots below show analyses of MSLP and 6 hour rainfall from 6 January 00UTC to 9 January 00UTC, every 12th hour.

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)

All forecasts initialised at 00UTC (step 18h, 42h, 66h and 90h).

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)

The plots below show EFI and SOT for 24-hour maximum wind gust on 8 January.

Forecast Evolution plot

The plot below shows the forecast evolution for 10-metre mean wind around Scilly at 18UTC on 8 January.

The mean winds in the short range IFS based forecasts (IFS-control and ensemble, Hybrid and Destine) were much higher (~35m/s) than observed (~27m/s).

The plot below shows the forecast evolution for 24-hour maximum wind gusts around Scilly at on 8 January.

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

• Sting Jet like feature over the Channel.
• The extreme wind around Scilly only predicted 1-2 days in advance. Earlier forecasts had the strong winds shifted to the south.
• Much higher mean wind in short-range IFS forecasts than the observation. Could be due to the station being on land while the model grid point is sea point, but worth to look further into.

6.2 Experience from general performance/other cases

• 202510 - Windstorm - Amy

7. Additional material