A well developed cut-off low stays nearly stationary for the next 24 hours just west of Portugal and Spain, while another cold-core depression approaches the cut-off from the NE and both start to interact . I do not want to use the Fujiwhara effect as an explanation, because both features start to merge quite fast, but it is a quite interesting evolution anyway.
... An area west of Portugal...
Latest modified IR images already indicated a broad area of cooling cloud tops just west of Portugal as warm conveyor belt gets better organized. For the next 24 hours, best shear and instability are displaced and the only region, where both agee is out of our area of responsibility.
Despite those negative facts, we went with a low-end level-1 area, including the coastal areas of SW Portugal. As mid-levels start to cool down significantly during the night hours, traces of instability are also forecast along the coast, where LL shear is signficantly enhanced. Right now the main risk will be an isolated waterspout report, as 0-3km instability further offshore is pronounced . Otherwise strong to severe wind gusts are possible along the coast as winds at 850hPa increase to 25-30m/s.
Latest thoughts are that a few thunderstorms are embedded in a more stratiform rain shield.
The area has to be monitored for more robust thunderstorm development than currently anticipated, but weak lapse rates as a result of the strengthening WAA should keep thunderstorm activity in the level-1 area quite limited.
Avisos da meteorologia não prevêem perigos para a população
