Status:Ongoing analysis Material from:
1. Impact
On 22-23 February windstorm Louis hit north-western Europe. Vinga Fyr outside Gothenbourg measured above 30 m/s in mean wind and almost 40 m/s in the gusts.
https://www.smhi.se/bloggar/vaderleken-2-3336/sammanfattning-av-stormen-louis-1.205378
2. Description of the event
On this evaluation we will focus on the maximum wind gusts 22 February 12UTC - 23 February 12UTC and mean wind at 06UTC on 23 February. The main location will be 0.5x0.5 degree around Vinga Fyr (57.6N, 11.6E).
The plots below show analyses of MSLP and 6 hour rainfall from 21 February 00UTC to 24 February 00UTC, every 12th hour. The cycone rapidly developed over the southern North Sea during 22 February.
Satellite image from 23 February 09.15UTC, around the time the maximum winds along the Swedish coast was measured.
3. Predictability
3.1 Data assimilation
3.2 HRES
The plots below show 24-hour maximum wind gusts (22 February 12UTC - 23 February 12UTC) in observations (first plot) concatenated short forecasts (second plot) and ENS control forecasts with different lead times.
The plots below 10-metre mean wind on 23 February 06UTC in observations (first plot - missing) analysis (second plot) and 30-hour forecasts from ENS control (9km), DestinE 4.4 km, AIFS, PanguWeather and Graphcast
3.3 ENS
The plots below show EFI for maximum wind gusts on 23 February from different lead times (note different period from other plots due to limitations in EFI).
The plot below shows the forecast evolution plot for 10-metre mean wind at Vinga Fyr on 22 February 12UTC 23 February 12UTC.
Analysis - green dot
ENS control–red
ENS - blue box-and-whisker
Model climate – cyan box-and-whisker
Ensemble mean as black diamonds. Triangle marks the maximum in the model climate based on 1400 forecasts.
The signal for the extreme winds (above 99th percentile of the climate) appear on the last day before the event for this location. But one could wonder it the control forecast on 19 February acted like a warning bell for the storm?
The plot below shows the same as above but for 10-metre mean wind over Vinga on 23 February 06UTC.
Observation - green hourglass
Analysis - green dot
ENS control–red
DestinE4.4km - purple dot
ENS - blue box-and-whisker
AIFS - pink
PanguWeather - cyan
Graphcast - grey
Model climate – cyan box-and-whisker
Ensemble mean as black diamonds. Triangle marks the maximum in the model climate based on 1600 forecasts - to be added.
3.4 Monthly forecasts
3.5 Comparison with other centres
4. Experience from general performance/other cases
5. Good and bad aspects of the forecasts for the event