In the image above a vertical cross section line is chosen which crosses the WV band at the rear side of the upper level low, the dry slot, the cloudiness over Ireland intensified by the PVA maximum in the left exit region of the jet streak and the southernmost part of the Warm Front Shield. Isentropes and IR + WV pixel values show a typical upper level low situation around 55N/14W where a peak in the WV signal identifies the rear side of the Upper Level Low. The WV minimum around 53N/10W corresponds to the Dark Stripe, while the broad maximum to the south represents the Warm Front Shield. Isentropes show a Baroclinic Boundary of the Upper Level Low; isentropes of 322K and 330K represent surfaces respectively within and above this Baroclinic Boundary. Relative streams on these surfaces show a lot of typical features for both the Upper Level Low and Rapid Cyclogenesis. At the lower surface of 322K (left image) a rising stream over the British Isles from south-east to north-west is a typical phenomenon on low surfaces for Rapid Cyclogenesis; however, the pronounced cyclonic circulation in the area of the Dark Stripe corresponds to the Upper Level Low. At the higher surface of 330K (right image) a typical frontal situation can be noticed over west Ireland with a strongly rising Warm Conveyor Belt accompanying the Warm Front Shield and the dry intrusion from north-west in the area of the Dark Stripe. This is again a situation which typically appears with Rapid Cyclogenesis.