Material from: Linus
1. Overview
During the first week of January a low-pressure system named Floriane but MeteoFrance impacted various parts of north-western Europe (France - wind, UK - heavy rain and snow, Denmark - wind, Norway - snow, Sweden - wind and snow). In Sweden there was a lot in media about the weather warnings (amber) due to the combination of snow and wind during the travel days in the end of the festive period.
2. Analyses and Observations
2.1 Event Definition
Wind: 24-hour maximum wind gusts on 7 January for a 0.25x0.25 box around Vaderoarna, Sweden (58.6N, 11E).
Snow in Sweden: 72-hour snowfall starting on 5 January 00UTC for a 0.5x0.5 box centred on Lesjöfors, Sweden (60N, 14.2E)
2.2 Analyses
The plots below show analyses of MSLP and 6 hour rainfall from 4 January 00UTC to 8 January 00UTC, every 12th hour.
The plots below show analyses of T850 and z500 from 4 to 8 January.
2.3 Observations
Plots of snow depth in Sweden on 5 and 8 January (both 06UTC) from SMHI.
2.4 Climatological perspective
3. Forecasts
3.1 Data assimilation and observation usage
3.2 Single Forecasts
Wind event
Observations for the event
Note that observations are missing from most parts of Sweden, and among the few available I suspect the dark-orange dot to be wrong.
Control forecast
DestinE
AIFS deterministic
AIFS ensemble
3.3 Ensemble distribution
EFI for 1-day maximum wind gusts on 7 January
There as no strong signal in EFI for extreme wind gusts over Skagerak beyond two days before the event.
Forecast Evolution plot for the event
Note that no observation from Vaderoarna was found, but the SMHI page gave 33 m/s.
Legend:
ENS-CF - red dot
ENS distribution - blue
Dalmatian plots valid 7 January 12UTC, with dot coloured by 600km maximum wind at 1 km height.
3.4 Sub-seasonal forecasts