SYNOPSIS
A disturbed weather pattern will persist over most parts of Europe with a strong upper-level low pressure just west of Portugal and a strengthening high pressure area west of Ireland. An active polar front jet will continue to steer depressions towards Norway and Sweden.
Hot and dry conditions prevail over the central and eastern Mediterranean.
DISCUSSION
....Portugal and Spain....
A strengthening, closed upper-level low ( centered just west of Portugal ) will be the main player for the next 24 hours and widespread thunderstorm activity can be expected.
We split the broad forecast area into 2 separate discussions to alleviate the overview.
... SW / NW Spain and Portugal ...
The general model pool coincides in the general evolution of this thunderstorm event. A well defined cyclonic vortex just west of Portugal will be nearly stationary during the next 24 hours. Attendant mid-/upper-level wind field favors a region of intense upper-level divergence over Portugal, which is forecast to shift slowly towards the N / NNW.
In addition, GFS allows small pieces of energy to cross the region from the south, which should also enhance the forcing. As mid-level lapse rates steepen somewhat during the forecast period and mixing ratio increases to at or above 10g/kg, a weakly capped atmosphere will be present with up to 1000 J/kg MLCAPE.
Widespread thunderstorm development over SW Spain and S / central Portugal will be underway during the morning hours and a cluster of storms should evolve with a NNW- movement.
Shear is not that strong with DLS of 15-20m/s but should support multicell storms and isolated supercells ( mid-level rotation could be supported by intense cyclonic vorticity ). LCLs are quite low and an isolated tornado is possible although the main risk will be a hail risk ( possible large ).
A better environment for tornadoes could evolve over N-Portugal and NW Spain during the evening / night hours, if latest model trends of GFS area right as LL shear increases to more than 20m/s and 400 J/kg SRH1will be present ! This looks reasonable regarding the intense veered flow .