Strelec, Natasa (Meteorological and Hydrological Service, Croatia)
In the Mediterranean numerous cyclones appear every year, some of them bringing heavy rain to the Mediterranean countries. In some cases early detection and forecast of cyclogenesis can be of great importance.
Satellite images in water vapour (WV) spectrum combined with vorticity advection field seem to be very promising tool for the detection of cyclogenesis in its early stage. By means of the examples it is shown that in most cases, as the beginning of cyclogenesis, a long dark band appears in the WV image, accompained by a leaf-formed region of higher WV radiance on one end. If the satellite image is compared with parameter fields, usually a jet-streak can be observed along the dark region in the WV image, while a vorticity advection maximum corresponds with the region of higher WV signal. In most cases within the next few hours the formation of the cyclonic vortex will be observed in both IR and WV imagery. This possibility of analysing cyclonic development in its early stage emphasises the importance of WV satellite images in everyday synoptic work.