Floods in Serbia and Bosnia

I have been abroad for two weeks and was off-line. Sadly, the recent weather development over Serbia and Bosnia (weather history was covered by two posts, a couple of weeks ago; here and here) was severe. I want to briefly cite a statement of the German Weather Service as of May 16:

Schwere Unwetter in Südosteuropa – Das Satellitenbild zeigt die Wolkenspirale eines für die Jahreszeit ungewöhnlich heftigen Sturmtiefs über dem Balkan. Warme und feuchte Mittelmeerluft schiebt sich über kalte Polarluft. Die Folge waren extreme Regenfälle in Serbien, in der Region um Belgard sowie im Nordosten von Bosnien-Herzegowina. Die Karte zeigt die 24-stündigen Niederschlagsmengen. Gebietsweise sind innerhalb von 2 Tagen über 180 Liter/qm Niederschlag gefallen, die zu Erdrutsche und Überschwemmungen führten. Normal sind dort Niederschlagsmengen von etwa 70 Liter/qm im ganzen Mai. Das Regengebiet ist nach Nordwesten abgezogen. Derzeit konzentrieren sich der Niederschlag auf den Nordstau der österreichischen Alpen von Salzburg bis zur Rax. Dort kamen ebenfalls bereits über 100 Liter/qm Niederschlag zusammen.

Here are some images, illustrating the situation:

Surface pressure distribution from GFS analysis as of May 15.

Surface pressure distribution from GFS analysis as of May 16.

Satellite image showing the low-pressure system.

Satellite image showing the cyclone as of May 15, 15:00 UTC.

Total Precipitation in mm , May 11-17, 2014, computer generated contours, based on preliminary data. Source: NOAA.

Total Precipitation in mm , May 11-17, 2014, computer generated contours, based on preliminary data. Source: NOAA.

24-hrs rainfall sums as of May 15, 06:00 UTC.

24-hrs rainfall sums as of May 15, 06:00 UTC. Source: DWD.

In a former post, I had a look at gauge Veliko Selo in Serbia. Here is an update:

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Stage hydrograph for gauge Veliko Selo/Mlava as of May 23, 2014. Source: Republic Hydrometeorological Service of Serbia.

For some areas of Serbia, the was the third major event in 2014 (April, first decade of May, mid-May). Whereas the event in the first May decade was quite locally, the recent event hit large areas of Serbia and Bosnia and was much more devastating than the April event (which was also a bit more focussed on smaller catchments).

As a consequence, also the large stream systems (e.g., the Sava) featured a major (~100-year) flood flow:

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Stage hydrograph for gauge Sabac/Sava as of May 23, 2014. Source: Republic Hydrometeorological Service of Serbia.

Here are two well-written Wikipedia articles with further information: http://de.wikipedia.org/wiki/Balkantief_Yvette and http://en.wikipedia.org/wiki/2014_Southeast_Europe_floods.

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Octave 3.8 released (with GUI)

Octave is approaching Version 4. On the way to that major build, Version 3.8 was released recently and features a GUI, which is something many users were waiting for. A Windows build (which is also available as portable version (!)) can be found here.

Octave 3.8 GUI.

Octave 3.8 GUI.

However, there are still some flaws which should be fixed with the next major release. For instance, I was not yet able to tell Octave how to use Ghostscipt for graphics export properly.

On the other hand, to me, everything feels right and with a strong Matlab-IDE flavour. In other words: I am quite enthusiastic about the new GUI (which is a giant improvement compared to qtOctave, which is dead yet).

A look at Serbia

Actual rainfall was not that high than predicted (see recent post) and mainly hit Serbia where 50 to 75 mm were recorded (see Fig. 1), which is quite a lot, though.

Rainfall May 3 to 5 over Serbia.

Rainfall May 3 to 5 over Serbia.

Although regional floods occurred (or are ongoing; see Figs. 2 and 3), the flooding was not that intense than that of end of April (link).

Ongoing floods in Serbia as of May 7, 2014.

Ongoing floods in Serbia as of May 7, 2014. Gauge Veliko Selo is marked with a red dot.

Stage hydrograph for gauge Veliko Selo as of May 7, 2014.

Stage hydrograph for gauge Veliko Selo as of May 7, 2014.

 

Data was provided by the Republic Hydrometeorological Service of Serbia (link).

Note: is it just me or does the alert-level colouring coincide with the colours of Serbia’s flag?!?

Some updates on the further weather development

48 hrs ago, GFS showed a Genoa low signal for May 11 to 13 which would have had an impact on Germany/Saxony (see my recent post). Although being not that strong than the low causing the Central European floods of May/June 2013, the predicted general circulation pattern was quite comparable to that of 2013 (compare first and second column of Fig. 1).

Atmospheric pressure development during May 2013 compared to two GFS runs (initialized April 30 and May 2).

Figure 1: Atmospheric pressure development during May 2013 compared to two GFS runs (initialized April 30 and May 2).

At this time, the signal disappears for the mid-range (May 8 to 13) as the third column in Fig. 1 shows.

However, as of today, GFS shows the formation of a quite strong Genoa low, going on right now (see Figures 2 and 3) with heavy rainfall being expected for Slovenia, Croatia, Serbia, Hungary and Romania within the next three days.

GFS-predicted atmospheric pressure distribution for the next couple of days (initialized May 2).

Figure 2: GFS-predicted atmospheric pressure distribution for the next couple of days (initialized May 2).

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Figure 3: GFS-predicted precipitation distribution for the next couple of days (initialized May 2).

The same story is told by COSMO-LEPS (for details see here), showing a high probability for heavy precipitation over the aforementioned area between May 4 and 5 (see Fig. 4).

Figure 4: Probability of rainfall sums larger than 50 mm in 24 hrs for the period May 4 to 5 from COSMO-LEPS.

Figure 4: Probability of rainfall sums larger than 50 mm in 24 hrs for the period May 4 to 5 from COSMO-LEPS.