Approaching cirrus clouds from the southern quadrant due to a developing low pressure system over Algeria which became a mature comma-shaped mid-latitude cyclone by Saturday evening. In this case, the clouds were heralding the arrival of a warmer airmass. The first thumbnail shows the formation of cumulus clouds at dawn of the same day due to lingering polar maritime airmass contrasting with the warmer sea temperature. The second thumbnail shows upper-level moisture which sustained the cirrus cloud formation and the third thumbnail is the surface pressure chart.