Material from: Linus

1. Overview

 On 27 December the windstorm Johannes affected northern Europe causing a lot of fallen trees and power cuts in e.g Sweden. A couple of days later the blizzard from Storm Anna affected the same region making the situation more problematic.

2. Analyses and Observations

2.1 Event Definition

The evaluation will focus on the 24-hour maximum mean wind on 27 December 00UTC to 28 December 00UTC in the box 0.5x0.5 degree box centred on Orskar, Sweden (60.5N, 18.4E)

2.2 Analyses

The plots below show analyses of MSLP and 6 hour rainfall from 25 December 00UTC to 28 December 00UTC, every 12th hour.

The plots below show analyses of z500 and T850 from 21 December to 29 December (all 00UTC).

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-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 gusts on 28 December.

Forecast Evolution plot

The plot below shows the forecast evolution for the 24-hour maximum mean wind around Orskar in Sweden on 28 December.

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

6.2 Experience from general performance/other cases

7. Additional material