18 UTC...the secondary low "Gernot" lies over Wales with a low pressure center of 991mb (around 3mb deeper than forecasted).

As you can see by the meteocentre analysis from Toulouse, the core is situated in the left exit region of the upperlevel jet which contributes to strong cyclonic shear vorticity advection. Additionally, a weakly curved trough axis to the west of Ireland provides weak cyclonic curvature vorticity advection Both combined with shortscale (time and space) warm air advection allow for strong cyclonic vorticity advection and upward motions.

Compared with GFS 12z run, the surface pressure is a little bit deeper (as mentioned), but the position is exactly realized. Upstream, hardly defined waves are following. To the north of the secondary wave, a small low-pressure system is moving eastward. Both the wave (as baroclinic leaf) and the small low (as cloud head) are expected to form a pronounced intense low-pressure system as a result of rapid cyclogenesis (> 24mb pressure fall in 24h) that is very likely to affect the British Isles with severe winds and heavy rain on Sunday.

Looking at the 500mb geopotential+temperature charts...you see the jet axis (red line), the trough axis (blue) and the ridge axis (black). The low pressure center is depicted as a white circle. The latter one is situated in the left exit region where isohypses are densely packed. Hence, a stronger flow predominates ahead of the trough axis. The stronger the flow, the stronger the cyclonic vorticity advection. As a result, the secondary low still will deepen moving further eastward. Lying on the cold side of the jet axis and combined with the fact, a well-curved upper ridge has built up downstream, one can explain the given cold conveyor belt that formed the occlusion front.

At the same time, the warm conveyor belt develops on the warm side of the jet axis embodied by the baroclinic leaf you'll see in satellite imagery below. I took all images from here and here. I would like to add I'm not sure if a draw all frontal boundaries in proper style.

The coloured image from Eumetsat shows a well-defined dryslot over Wales overrunning the low pressure center, but also triple point and parts of warm and cold front (that's a point to be discussed, perhaps the triple point lies somewhat more southerly). Thus, both cold and warm front have significantly warmed cloud tops that appear darker than in the range of the baroclinic leaf where the warm conveyor belt advections very moist and relatively warm air masses eastnortheastward. The fact the dryslot is very pronounced could explain the stronger pressure fall than expected.

IR-image illustrates a more confusing situation because the cloud-free region stretches up to Northern France. One could suppose the occlusion front reaches from Wales across Southeastern England up to Western Benelux and Northeastern France. However, surface analysis doesn't support this assumption. Instead, cold front crosses the English Channel where scattered cloud structures are present east of the low center (marked by "L"). Cold front character is hardly developed due to the lack of an upper cold pool and weak surface temperature contrasts.

Water vapour image depicts the dryslot coinciding with the secondary low center. The next hours the low is forecast to peak out over Benelux developping a strong wind field on its south side with 50-60 Kts in 850mb over Eastern France and most parts of central and southern germany. Upperlevel trough should rapidly intersects the area with enhanced thetaE values leading to maybe to some low-end instability release with showers and isolated thunderstorms. However, upperlevel jet directs more southward across the Alps while highest windspeeds will be restricted to lower levels. Therefore, some linear convective bands, maybe with embedded bowing segments, can be expected with the (back-bent) occlusion front and cold front, capable of producing some severe wind gusts. A tornado is also not ruled out but that risk not warranted at the moment due to lack of instability. Another scenario could be a more stratiform precipation riddled with convective cells not being discrete and hence no really chance of mesocyclones to be formed. Moreover, solar insolation should be capped due to the large cirrus shield coming with the warm conveyor belt. Right now, there are a lot of incertitudes...

Latest Estofex Update proposes a more agressive assessment with some chance of tornadoes.