State-of-the-European-climate: September 2019

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Cut off low bringing heavy precipitation over Eastern Spain



In the week of 9 September a cut off low pressure system was formed that brought heavy precipitation in southeastern Spain. Between 11 and 13 September more than 400 mm rain fell in parts of the Valencia region. The town of Ontinyent, 50 kilometer southwest of Valencia, recorded 296.4 millimeter of rain in 24 hours, which is the second highest daily rainfall on record. The precipitation led to local flooding and at least six deaths. The low pressure system originated from a cold through over Ireland on 9 September (Figure 1a) that was cut off from the jet stream, which then moved southward as a cut off low (Figures 1b-e). On 11-13 September the highly instable easterly flow from the warm Mediterranean brought heavy convective and orographic rainfall. The arrival of cold air originating from north of the jet stream caused what in Spain is called a gota fría, literally a cold drop (Figure 2a-e).



Figure 1a-e. 500 hPa height and precipitation from 9 to 13 September 12 UTC. Source: ECMWF/KNMI.



Figure 2a-e. Sea level pressure and 2 meter-temperature from 9 to 13 September 12 UTC. Source: ECMWF/KNMI.

Specific climate indicators for September 2019



The heavy precipitation over eastern Spain can also be seen in Figure 3 with the number of heavy precipitation days (more than 10 mm precipitation). Also the west coast of Norway, Denmark and England experienced 3-5 more heavy precipitation days than on average (1981-2010).



Figure 3: Heavy precipitation (>10 mm) days in September 2019 (left) and anomaly w.r.t. 1981-2010 (right)

The minimum of daily minimum temperature was lower than the 1981-2010 average in large parts of the Benelux, Germany, France and eastern Europe (Figure 4). Also the number of cold nights (Figure 5) was much higher than normal in Germany and parts of northern and eastern Europe.



Figure 4: TNn: Minimum of daily minimum temperature in September 2019 (left) and anomaly w.r.t. 1981-2010 (right)



Figure 5: TN10p: Days with TN < 10th percentile (cold nights) in September 2019 (left) and anomaly w.r.t. 1981-2010 (right)

Eastern Europe did not only experience low minimum temperatures but also high maximum temperatures, with the maximum of daily maximum temperatures up to eight degrees Celsius higher than on average (Figure 6).



Figure 6: TXx: Maximum of daily maximum temperature in September 2019 (left) and anomaly w.r.t. 1981-2010 (right)

The weather in September 2019

Temperature deviations and extremes



Daily minimum temperatures were above the 1981-2010 average in Italy and in southeast Europe (Figure 7). In North Africa the average temperature was lower than normal which might be explained by the torrential rain episode in the beginning of September.



Figure 7: September 2019 minimum (left), average (middle), and maximum (right) temperature differences from reference period 1981-2010 (E-OBS)



Figure 8: Areas with exceptional low and high monthly averaged minimum temperature (left), mean temperature (middle), and maximum temperature (right) in September 2019 (Based on E-OBS). The qualifications "exceptionally above (below) average", much above (below) average, slightly above (below) average and normal relate to the percentile ranges >90 (<10), 75-90 (10-25), 60-75 (25-40) and 40-60 as calculated from the climatological period 1981-2010.



Figure 9: Lowest minimum temperature (TNn, left), and highest maximum temperature (TXx, right) in September 2019. (Based on E-OBS)



Figure 10: Areas with exceptionally low temperatures of the coldest night (TNn, left), and exceptionally warm temperatures of the warmest day (TXx, right) in September 2019 (Based on E-OBS)



Evolution of the European land-surface temperature

Figure 11 (left panel) shows the European-averaged temperature from 1950 onward, where blue bars show temperatures which are below the 1981-2010 average and red bars above this mean value. The green bar is the provisional 2019 estimate, based on data until the end of September and climatological means for the remaining months. The grey bars in the panel indicate the estimated uncertainties which take into account the errors introduced by spatial interpolation over areas without observation stations, inhomogeneities in the temperature data that result from station relocations / changes in measurement instruments etc., and biases due to urbanisation, as documented in Van der Schrier et al. (2013) and Chrysanthou et al. (2014). The uncertainties tell us that although we are not 100% certain about the ranking of individual years, the overall positive trend since the 1980s is very pronounced.

The right panel of Figure 11 shows the daily temperature, averaged over Europe, for the past 12 months.



Figure 11: European land surface temperature (30W - 50E, 25N - 75N): annual anomalies with the current year in green. The grey bands show the uncertainty in the averaged temperature (left). Daily anomalies with respect to the seasonal cycle until the end of September 2019 (right). (Based on E-OBSv20.0e)

Precipitation

The heavy precipiation in the Valencia area is recognized in the E-OBS data (Figure 12) and it can be regarded as exceptional above the average (Figure 13). Note that also North Africa received rain amounts of 60 mm which is also rated as above the average. Central, north and west Europe were also wetter than average. Romania and Bulgaria were dry and the rainfall was under the 30-years average.



Figure 12: Monthly average precipitation sums over Europe and highest 1-day (RX1day) and 5-day sums (RX5day) in September 2019 (Based on E-OBS).



Figure 13: Areas with exceptional amounts of precipitation per month (RR sum, left), maximum in 1 day (RX1day, middle) and maximum over 5 days (RX5day, right) in September 2019 (Based on E-OBS)





Figure 14: Precipitation fraction in September with respect to 1981-2010 per year. Top row: Northwest Europe, Central Europe, Northeast Europe. Bottom row: Southwest Europe, Region definitions, Southeast Europe. (Based on E-OBS)

Radiation and Cloudiness



The global radiation anomaly based on E-OBS (Figure 15) is under the average. The incoming surface radiation based on Seviri/Mviri data (Figure 16) reveals an anomaly which is under the average. The monthly cloud cover (Figure 17) is 40 percent in southern Europe which is slightly under the average.





Figure 15: Monthly map of global radiation (left) and its anomaly (right, with respect to 1981-2010) (Based on E-OBS)





Figure 16: Monthly map of surface incoming shortwave radiation (left) and its anomaly (right, with respect to 1983-2005) (METEOSAT Seviri/Mviri product, source CM SAF)





Figure 17: Monthly maps of cloud cover (left) and its absolute anomaly (right, with respect to 1982-2009) (AVHRR, source CM SAF)

About the Copernicus State of the European Climate

Monthly and yearly State of the European Climate bulletins are prepared for audience of mainly non-meteorologists/climatologists interested in impact of weather and climate. In these bulletins, the main features of the most recent calendar month is shown, with a focus on extremes and significant deviations from climatology. The information is provided within their historical context, and includes references to addional information. The bulletin is based on Copernicus products, but also contains information from other sources as appropriate.

van der Schrier, G., van den Besselaar, E. J. M., Klein Tank, A. M. G., and Verver, G. ( 2013), Monitoring European average temperature based on the E-OBS gridded data set, J. Geophys. Res. Atmos., 118, 5120 5135, doi:10.1002/jgrd.50444.

Chrysanthou, A., van der Schrier G., van den Besselaar E. J. M., G. Klein Tank, A. M., and Brandsma, T. ( 2014), The effects of urbanization on the rise of the European temperature since 1960, Geophys. Res. Lett., 41, 7716 7722, doi:10.1002/2014GL061154.

News

24 October 2019
10 October 2019
Monthly E-OBS update released
7 October 2019
E-OBS v20.0e has been extended with global radiation fields
7 October 2019
E-OBS v20.0e released
30 September 2019
NGCD v19.09 released
23 September 2019
12 September 2019
Monthly E-OBS update released
26 August 2019
21 August 2019
Tables with observed temperature extremes have been added
21 August 2019
Monthly E-OBS update released
22 July 2019
15 July 2019
Monthly E-OBS update released
8 July 2019
Figures for Indices based on APGD have been added
25 June 2019
24 June 2019
13 June 2019
Monthly E-OBS update released
29 May 2019
Access page for the long-term Alpine precipitation reconstruction (LAPrec) has been created
29 May 2019
13 May 2019
Monthly E-OBS update released