Status: Finalized Material from: Linus, Lorenzo, Thomas H. Ivan, Nevena Zivanovic (Republic Hydrometeorological Service of Serbia)

Discussed in the following Daily reports:


 1. Impact

During the last weekend of January massive precipitation hit southern Europe. Several cities in northern Italy were flooded (e.g. Pisa) and Austria, Croatia and Serbia experienced severe snowfall. Slovenia experienced a severe ice storm in connection to the event (see additional material from Ivan). In connection to the same cyclone, Serbia recorded extreme winds (see additional material from Serbia).

http://www.bbc.co.uk/news/world-europe-25992800

2. Description of the event

z500 and t850 from 12-hour forecasts

The plot series above show the z500 and t850 short (12 hour) forecasts valid from 30 January to 4 February. During the period a trough was located over south-western Europe. leading to a south-westerly flow hitting Italy and the southern Alps for the days.

MSLP and percipitation from 12-hour forecasts

The plots above show precipitation forecasts (accumulated between step 6 and 18) for the same dates as above. Here the strong precipitation is apparent for the period.

3. Predictability

 

3.1 Data assimilation

 

3.2 HRES

Precipitation verification and HRES forecast

The figures above show the verification for the 24-hour accumulated precipitation for day 2-3 forecasts.

4-day accumulated precipitation
1. 30 Jan 06UTC - 3 Jan 06UTC
2. HRES 30 Jan 00UTC
3. HRES 29 Jan 00UTC
4. HRES 28 Jan 00UTC

The figures above show the 4-day precipitation accumulation (30 Jan 06UTC -3 Feb 06UTC) from HRES. The first figure shows the observed values from the same period. The maximum over the southern Alps was well captured for the forecast from 30 Jan 00UTC, but the heavy precipitation for the Rome region was clearly missed. The heavy rainfall for the southern tip of Italy was captured by the forecast but not in the exact location. For earlier forecasts, the maximum precipitation was lower for the Alps and still missed for Rome.

3.3 ENS

EFI from 29 Jan 00UTC for 31 Jan to 5 Feb (day 1-5).

3.4 Monthly forecasts

Weekly precipitation anomalies

The figures above show the weekly anomaly of the precipitation for the 27 January to 2 February, from the monthly forecast system. For the central Mediterranean a wet anomaly is present 15-21 day forecast but for the northern Italy the anomaly first appear in the 5-11 day forecast.

3.5 Comparison with other centres


3.6 EFAS flood forecasts

See below the forecasts of EPIC, the flash flood component of EFAS, issued on the 29, 30 and 31 January 2014 at 00 UTC. A rather large area in the Central and North of Italy showed a significant probability to exceed the three warning threshold, corresponding to 2, 5, and 20 years.

The forecast on the 31st also detected the severe event that caused widespread flooding in Rome, the Lazio and the Calabria region on the 2-3 February. (http://floodlist.com/europe/deadly-floods-italy)

For Italy, an EFAS partner exists only for the Po River Basin but not for other river basins. For this series of events, three EFAS flash flood watches were sent, one for the Oglio River on the 30/01/2014 (Northern Italy) and two for the Drava River (Southern Austria), on the 31/01/2014. See image below.

Discharge observations are available at some stations in the North of Italy. The comparison in the following figures show that forecasts in the Po River slightly underestimated the observed peak discharge (in red), though no flooding was caused by the river.


On the other hand, results show a clear underestimation in smaller river basins, partly due to model resolution issues. Indeed for EFAS hydrological forecasts, no flood alert is issued in river basins with upstream area lower than 4000 km2. See for example a comparison between EFAS forecasts and discharge observations in the Secchia River (1300 km2), where severe river flooding occurred.

4. Experience from general performance/other cases

 

5. Good and bad aspects of the forecasts for the event

  • Good forecast for precipitation amounts for southern Alps.
  • Missed extreme precipitation for Rome area
  • Good early warning for wind gusts in Serbia (see additional material)

6. Additional material

  • Ivans presentation on the FD/RD meeting DJF2013-2014 with evaluation of the icestorm over Slovenia and snowfall over Austria ivan.ppt
  • Presentation from UEF2104 by Nevena Zivanovic (Republic Hydrometeorological Service of Serbia) about severe winds serbia_wind.pdf
  • In Austria, the winter 2013/14 has been exceptionally warm and rather extreme in terms of the precipitation distribution to the south and north of the Alps. More information can be found here: ExtremeWinter_2013-14_Austria.pdf