IPMA:
"Possibilidade de ocorrência de trovoada no fim do dia na região Norte." - Para Sábado
"Aguaceiros, que poderão ser de granizo e acompanhados de trovoada." - Para Domingo
Previsão do ESTOFEX:
A level 1 was issued for N Portugal, Spain portion of France and Balearic Islands mainly for the severe wind gusts and in lesser extent for tornadoes.
A level 1 was issued for N Portugal mainly for the excessive precipitation.
SYNOPSIS
Most of the N and CNTLR Europe is covered with a polar dry air mass where due to absent thermodynamic instability convection is unlikely. A wide jet stream stretches from N Atlantic through Iberian Peninsula, CNTRL Mediterranean and Turkey. Within this flow, a few shortwaves are forecast to produce high shear/low cape conditions where severe convective storms will be possible. In the end of the forecast period, a long wave over Iberian Peninsula will amplify and bring and advection of the cold air mass.
DISCUSSION
A shortwave is forecast to enter W part of the Iberian Peninsula in the afternoon hours and propagate eastwardly to reach Sardinia and Corsica in the end of the forecast period. Although a thermodynamic instability over the land surface will be small and produce mostly low-topped convection, a NWesterly advection of PV units and a significant airflow in mid and low troposphere may organize thunderstorms into low-topped mini supercells capable of producing severe wind gusts. It is worth to mention that vertical profile of the wind field (0-1km SRH locally up to 400-500 m2/s2) and moist boundary layer (mixing ratio up to 8-9 g/kg) will be conducive for the tornado occurrence. Therefore an isolated tornadic event cannot be ruled out, especially in the NW part of the Iberian Peninsula where the conditions are the most promising. A superimposing stratiform precipitation with the convective precipitation in the N Portugal pose a risk for excessive precipitation and thus local flash flooding. Lightning activity of the cells over the land areas should not be high. In the evening and nighttime hours, hunderstorms should receive more thermodynamic instability over marine areas and the lightning activity should increase. A cold front is forecast to pass Iberian Peninsula in the nighttime hours and a marginal lightning activity is possible in the cold sector.
