Status: Finalised Material from: Ivan
Picture
1. Impact
Weekly temperature anomalies over SE Europe were between 6 and 10C. The evolution of the heat wave can be seen on daily mean temperature anomalies.
Weekly mean temperature anomalies derived from observations with respect to 20-year climatology.
Daily mean temperature anomalies.
Temperatures in some places exceeded 40C.
Maximum temperatures in 1st July 2017.
The end of the heatwave was followed by an outbreak of severe thunderstorms that started on 2nd July and continued on the 3rd July affecting Bulgaria and southern Romania. A lot of lightning activity, large hail, strong wind gusts and excessive rain accompanied severe convective storms. Hail stones of up to 5 cm caused damage in few places in central northern Bulgaria.
Air mass RGB animation of the severe convective outbreak over the Balkans, 2-3 July 2017.
ATDnet lightning flashes, animation.
Convective hazards on 2nd July (left) and 3rd July (right). Combination of ATDnet lightning density and European Severe Weather Database (ESWD).
More than 100 mm in less than 48 hours were measured in some places in Northern Bulgaria and in the high valleys of Western Bulgaria, causing flash flooding. The worst affected regions were Samokov in western Bulgaria and Pleven and Lovech districts in Northern Bulgaria.
Rainfall totals 02/07/17 6Z-03/07/17 6Z (left), 03/07/17 6Z-04/07/17 6Z (middle) and 02/07/17 6Z-04/07/17 6Z (right). Credit to the National Institute of Meteorology and Hydrology in Bulgaria for providing high-density rainfall observations from its synoptic and climatological network.
2. Description of the event
An extreme heatwave occurred over south-east Europe in the last week of June. The peak of the heatwave was at the beginning of July when a ridge built from northern Africa towards SE Europe.
Z500 weekly anomalies for the week started on 26 June 2017.
Z500/T850 0/12Z analyses valid for the week started on 26 June 2017.
3. Predictability
3.1 Data assimilation
3.2 HRES
HRES forecast of 48-hour rainfall totals valid from 06Z, 02/07/2017 to 06Z, 04/07/2017. From top left to bottom right HRES represents the following steps: t+30-78h, t+54-102h, t+78-126h, t+102-150h, t+126-174h, t+150-198h, t+174-222h. Observations are represented by the circles.
3.3 ENS
The EFI for 2-metre maximum temperature was pretty high for the hottest day, 1st July even 10-days in advance especially positive SOT which indicate a possibility of extreme heat.
The EFI/SOT for 2-metre maximum temperature, day+7 to day+10.
3.4 Monthly forecasts
Positive temperature anomalies over SE Europe are in the right place 2 weeks in the medium range, up to day+15 and although the signal goes further in the forecast at least for a part of the region affected by the heat wave. Another interesting finding is that observed anomalies (with respect to 20-year climatology) differ significantly from the analysed anomalies (with respect to ERA-Interim) in some regions. The heat wave in the analysis looks less extreme compared to the observed anomalies.
Monthly forecast weekly temperature anomalies.
The EFI for weekly mean temperature provided a strong signal for week 1 and week 2. Positive SOT values were present up to week 2.5 forecast which is an indicator that some really extreme temperatures were present in the forecast.
EFI for weekly mean 2t v. observations.
1 Comment
Meral DEMIRTAS
The heat wave affected south eastern Europe, including Greece and Turkey. I think it would be more appropriate to change the title as "Heat wave of south eastern Europe". Initial analysis and maps are very informative and interesting. Although the heat wave was not as intense as the heat wave of 2007, it was still very remarkable which caused forest fires.