SYNOPSIS
Moderate instability is forecast for most parts of Iberia in a warm and moist airmass ahead of an upper cut-off low. Some decent WAA and diurnal heating may lead to approx. 1500 J/kg MLCAPE over the western parts of Iberia which partly overlaps with enhanced 0-6 km deep layer shear.
DISCUSSION
...Iberia and N Maghreb States...
Deep layer shear increases from about 10 m/s in the northern half of Iberia to more than 20 m/s towards Morocco and N Algeria as an upper jet stream is located near the southern tip of the upper cut-off low. In contrast to the horizontal gradient in vertical shear, instability will likely reach its maximum over central Portugal where 0-6 km shear is rather low. GFS shows a slightly veering wind profile up to approx. 500 hPa which leads to some 100 - 150 m²/s² SRH3. If convection starts to develop, the evolution of isolated well-organised multicells and a few supercells will be likely. The main threat is expected to be large hail and some isolated severe wind gusts as LCL / LFC heights are quite high (around 2 km) and steep mid level lapse rates indicate a dry EML which is favourable for evaporative cooling. Flash floods and tornadoes are unlikely in such a situation, but they are not completely ruled out. The peak activity of severe thunderstorms is expected in the late afternoon / early evening.