Meteosat-10 captured imagery of orographic roll clouds south of the Alpine ridge on 9 March 2019.
By HansPeter Roesli (Switzerland)
As shown by the profile over the gridpoint 46.2°N/8.8°E of Locarno forecast for 15:00 UTC, a strong vertical velocity shear was present in the west-northwesterly winds above 700 hPa.
The wind shear explains the presence of the orographic roll clouds observed from the ground (Figure 1), and by the Meteosat-10 high resolution visible channel in the rapid scanning mode (every 5 minutes) (Figure 2). The photograph was looking east-northeast.
The rapid evolution of the waves, partially hidden under a cirrus deck, may be followed in the animated High Resolution Visible HRV sequence between 14:10 UTC and 15:10 UTC (Figure 3).
Figure 3: Meteosat-10 HRV animation, 9 March 14:10 UTC–15:10 UTC