Moderate Risk of Scattered Thundery Showers UK and Ireland 09Z-21Z
Slight Risk of Funnel Cloud/ Weak Tornado Development as per map below (experimental)
A relatively low level risk regarding severity though a moderate risk spatially.
UKMO fax chart forecast a developing surface trough stretching from central UK through to central Ireland. Relatively deep for time of year, breakaway upper trough moves SE through period increasing lift and lapse rates. Fairly moist boundary layer expected to build with resulting good ratio of dew points to surface heating. The combination of weak vertical shear, moist mid levels and weak PVA aloft suggests updrafts unlikely to be sustained for any length of time. Any convection will likely become rather disorganised though with the potential for isolated sferics. I have added two FC/ TN boxes as per map below (experimental). Particular attention regarding the region of Anglesey where some local convergence looks possible to the lee of topography. The yellow boxes added primarily based on a combination of instability, dynamic forcing and convergence.
All in all convection likely to be sparsely populated over a very broad area. As such, many places will stay rain free. There is some risk of small hail with these showers though the Freezing Level doesn't look particularly low ATM.
This post has been edited by Tony Gilbert: 12 June 2012 - 19:30