Severe storm with radial Ci clouds over Cyprus

By Jochen Kerkmann, HansPeter Roesli, Anna Eronn (EUMETSAT) and Stelios Pashiardis (Meteorological Service, Nicosia, Cyprus)

The Meteosat-8 images below show a case of severe convection over the Eastern Mediterranean. On this day (13 October 2006), western Cyprus reported thundery showers associated with strong winds and hail (size of walnut) and total precipitation (24 hours) of 70.0mm (Pegia), 74.0mm (Mavrokolymbos) and 68.0mm (Ayios Neophytos).

Figure 1 shows three major convective systems over and around Cyprus identified by cold cloud tops in this IR10.8 image. The most interesting feature in this infrared image is the cold-U shape of the storm over western Cyprus, which is a typical satellite indicator of severe convective storms (see also Mesoscale Convective System hits Genoa, Liguria, 28 July 2006).

Other indicators for severe storms are the overshooting tops and the above-anvil plume seen in the high-resolution visible (HRV) image (Figure 2). In addition, thanks to the relatively large viewing angle and the low Sun elevation, the vertical structure of the various parts (base, tower, anvil) of the Cb clouds is revealed (see RGB HRV, HRV, IR10.8 close-up look).

Both images also show fibre-like cirrus clouds on the northern and eastern side of the convective storms, which seem to radiate out from the fringes of the anvils. The cause of these radial cirrus clouds is not exactly known. Certainly it indicates a strong upper-level divergence, as in the case of Hurricane Isabel. The regular spacing of the cloud streaks evokes a sense of wave-related motion, but it is unclear which type of wave could be responsible for this phenomenon (gravity waves?).

Additional content

HRV image, 13 October 2006, 7:00 UTC (source: HP. Roesli)
HRV image, 13 October 2006, 7:45 UTC (source: HP. Roesli)
RGB composite VIS0.8, IR3.9r, IR10.8 (13 October, 06:45 UTC)
RGB composite WV6.2–WV7.3, IR3.9–IR10.8, NIR1.6–VIS0.6 (13 October, 06:45 UTC)
RGB composite HRV, HRV, IR10.8 (13 October, 06:45 UTC)
Severe convective storm with radial Cirrus over France (Met-8, 28 June 2005, 19:15 UTC, HRV, source: M. Setvak)
Convective storm with radial Cirrus over Italy (NOAA-6 AVHRR, 17 July 1982, 08:00 UTC, VIS0.8, source: M. Setvak)
Convective storm with radial Cirrus over Italy (NOAA-6 AVHRR, 17 July 1982, 08:00 UTC, RGB 01-02-04, source: M. Setvak)
Radial Cirrus produced by Hurricane Isabel (Met-8, 10 September 2003, 06:00–18:00 UTC, IR10.8, source: J. Kerkmann)