Meto aqui tambien la prevision de ESTOFEX.
A situation, we saw so often this summer. Ahead of a slowly eastward progressing upper trough, an extensive frontal boundary forms from Spain all the way to Poland, separating a warm/humid airmass to its south/east from much cooler and drier air to its west. This boundary becomes active as scattered thunderstorms evolve, although environment is not favorable everywhere for organized thunderstorms. Hot and dry conditions continue over SE / E-Europe.
DISCUSSION
... NE-Spain and S-/SE France ...
A cold front arrives over NE Spain during the late morning hours from the NW, moving slowly southeastwards, before stalling somewhere over extreme NE-Spain. Combined with a weakening, eastward progressing vorticity lobe, enough lift will be present for scattered initiation, advancing from the NW to the SE already during the midday/early afternoon hours.
Ahead of the cold front, daytime driven onshore flow, fostered by falling surface pressure over SE Spain should advect a very moist BL airmass well inland, maximizing mixing ratio ahead/just along the front. In addition, the Spanish pulme overspreads the area of interest with steep mid-level lapse rates, which will be present during the afternoon hours. This will help to boost MLCAPE values to near 1500 J/kg with even higher MCUAPE values over a small area over extreme NE Spain. Warmer LL and hence capping should not be a problem as diabatic heating and strengthening convergence should break the cap easily.
Along the positive tilted upper trough, a broad belt of strong wind maxima covers E-Spain, including our area of interest and 25m/s 0-6km bulk shear and up to 200 m^2/s^2 SRH3 overlap,
resulting in an enhanced large hail/ severe wind gust threat with the highest severe wind gust risk more inland, where LCLs are well above 1.5km (strong downbursts). A few significant hail events are likely and hence a small level-2 was issued. LCLs drop rapidly during the late afternoon hours/next to the coastline and as GFS hints on strong LL CAPE release,
an isolated tornado event will be also possible. Thunderstorms, although diminishing in organisation, go on during the night hours along the coast.
ESTOFEX ve posible que se formen tornados, sin descartar granizo de tamaño considerable y vientos severos... Todo debe terminar esta noche segun ellos.
Hay que estar atentos a Cataluña a partir de esta tarde.