TORRO have update their facebook page. I can’t link to it but they say:
“TORRO CONVECTIVE DISCUSSION 2017/003
A TORRO CONVECTIVE DISCUSSION has been issued at 14:50GMT on Wednesday November 22nd 2017
Valid from/until: 14:50 – 07:00GMT on Wednesday/Thursday November 22nd/23rd 2017 for the following regions of the
United Kingdom & Ireland:
Wales
Central and southern England
Channel Islands
THREATS
Isolated tornadoes; gusty winds; isolated CG lightning
SYNOPSIS
A broad warm sector covers the region at the moment, with an area of low pressure forming across central Ireland. This will move NE through the next 6-12 hours, with a synoptic cold front pushing eastwards across Ireland, and then much of England and Wales overnight.
Ahead of the synoptic cold front, an upper trough will overspread the warm sector and is likely to cause areas of convection to develop, due to upper lifting/cooling. A lack of decent dry air aloft may limit the overall convective potential, and some of the convection may be elevated above the boundary layer, at least initially. The warm sector is strongly sheared, including impressive low-level wind fields (12Z Camborne ascent shows 0-1km SREH of 450K/Kg) - however, convection will need to root into the boundary layer to take advantage of this.
However, enough signals exist in hi-res modelling of lines of convective activity, including the potential for waves to develop on these lines, to suggest that at least some convective enhancement of wind gusts is possible. In addition, any convection which can root into the boundary layer has the potential to produce a few brief tornadoes. The highest chance of this is probably across the southern half of the area.
The lack of more robust instability precludes the issuance of a tornado watch - this is a convective discussion, which is a level below a watch, due to the more uncertain, and also somewhat marginal nature of this event.
Forecaster: RPK”