Status:Finalized Material from: Ivan, Mohamed, Linus
Discussed in the following Daily reports:
http://intra.ecmwf.int/daily/d/dreport/2015/03/03/sc/
http://intra.ecmwf.int/daily/d/dreport/2015/03/04/sc/
http://intra.ecmwf.int/daily/d/dreport/2015/03/05/sc/
http://intra.ecmwf.int/daily/d/dreport/2015/03/06/sc/
Picture
1. Impact
Around the 6 March severe weather affected south-eastern Europe including heavy snowfall over Bulgaria.
Winter scenes of deep snow covering the town of Troyan, Northern Bulgaria (red marker on the map) where the snow cover reached about 50 cm. The most affected area in Southern Bulgaria is denoted with the red oval; in some parts in the mountain the new snow cover was more than 1 m in height. Heavy wet snow damaged power lines, closed roads and blocked the access to many parts of the region. A sate of emergency was declared.
24-hour total precipitation ended at 06UTC of the day displayed on the maps analysed by the LAM ALADIN and high density observational network of rain gauge stations. These maps show that in the most affected region in the southern parts of Bulgaria the snowfall didn't stop for about 4 days. The heaviest snow fell on the 6th and in the morning of the 7th March.
The maps below show snow depth analysis at 06 UTC on the specified dates. The orography is also shown. The country was snow free on 5 March and the snow started accumulating on the 6 March and reached more than 1 metre in some southern parts of the country.
2. Description of the event
A cyclone formed on 5 March over the Western Mediterranean and remained quasi-stationary over the Central Mediterranean during the following few days. An active quasi-stationary weather front associated with this cyclone lay over the southern Balkans creating a long-lasting precipitation episode.
METEOSAT 10 IR imagery and ECMWF MSLP analysis show the evolution of the surface pressure and clouds every 6 hour from 6 March 00UTC till 9 March 06UTC. The heaviest precipitation episode over Bulgaria was between Friday afternoon, 6 March and Saturday afternoon, 7 March but in the most affected areas in Southern Bulgaria snowfall continued on the following day, 8 March as well.
Before the event hit Bulgaria, Italy experienced strong winds. The plot below shows the time-series of observations at Florence Airport and the corresponding forecast.
The next figure shows the verification of 24-hour maximum winds gusts for 5 March.
Later, the system caused heavy precipitation on the Balkans as seen in the plot below.
3. Predictability
3.1 Data assimilation
3.2 HRES
3.3 ENS
The EFI for snowfall gave some signal 6 days in advance becoming quite strong (large EFI) 1-2 days before the event.
EFI snowfall VT: 06/03/2015
EFI snowfall VT: 07/03/2015
3.4 Monthly forecasts
3.5 Comparison with other centres
4. Experience from general performance/other cases