Synoptic situation
On 1 August 2016, the Azores high was located over Azores and a thermal low was over Iberia and north-west Africa. Until 4 August, the Azores high moved towards the British Isles and intensified. This weather situation lead to warm and dry conditions over Madeira Archipelago and until 10 August the position of those systems allowed a dry and hot air mass from north-west Africa to reach Madeira (Fig. 3.1). On 4 August, at the middle and upper levels, Madeira started to be under the influence of a high pressure system and by 7 August, a low pressure system near the Canary Islands began moving westward until the 10th (Fig. 3.2). Throughout this period, the easterly or north-easterly winds prevailed at low levels and during some periods there were relatively large pressure gradients nearby Madeira, between the low over Canary Islands and the high pressure system near Azores. Fig. 3.3 shows values around 20/30kt (yellow barbs). Occasionally this area of strong winds extended from the surface up to 500 hPa level.
Figure 3.1: Surface analysis on 5 August 2016 at 06:00UTC by DWD. Red circle indicates the location of Madeira Island. Source: http://www1.wetter3.de/Archiv/archiv_dwd.html.
Figure 3.2: Geopotential height (damgp) and wind barbs (kt) at 500hPa (ECMWF) overlaid with Natural Color RGB on 8 August 2016 at 12:00UTC. Red circle indicates the location of Madeira Island. Source: ePort - EUMeTrain.
Figure 3.3: Geopotential height (dam) and wind barbs (kt) at 850hPa (ECMWF) overlaid with Natural Color RGB on 8 August 2016 at 18:00UTC. Red circle indicates the location of Madeira Island. Source ePort.
The south-east coast of Madeira Island, in the lee of the mountains, experienced warming and drying conditions from 4 to 10 August, with air temperature reaching 37 °C during the day and 34 °C during the night and relative humidity falling below 15% in Funchal Observatório. At this station, temperatures were observed to rise after sunset on 4 August, with a complementary decrease in relative humidity. From 8 to 10 August, the relatively warm and dry conditions persisted. Both events were accompanied by strong winds from the north-east.