Tornadoes, excessive rainfall and severe wind gusts forecast across Portugal and western Iberia
Valid: Wed 18 Dec 2019 06:00 to Thu 19 Dec 2019 06:00 UTC
Issued: Tue 17 Dec 2019 21:34
- A level 2 was issued across Portugal mainly for tornadoes, excessive rainfall and severe wind gusts.
- A level 1 was issued across western Iberia mainly for tornadoes, excessive rainfall and severe wind gusts.
- A level 1 was issued across northern Algeria and eastern Sardegna and Corsica mainly for excessive rainfall.
Synopis and discussion
Stable weather conditions prevail over much of Europe underneath an extensive high pressure system centered over the Czech Republic, Austria and Slovakia. More active weather pattern is forecast across parts of southern and southwestern Europe, associated with a deep trough over the Atlantic and a cyclone moving from Algeria towards southern Italy.
The highest severe weather threat is forecast across western Iberia. A tongue of enhanced lower tropospheric moisture, with mixing ratios above 10 g/kg, will impinge on the coastline of Portugal and southwestern Spain by the late evening hours.
In combination with steepening lapse rates ahead of a deep approaching trough, MLCAPE between 500 and 1000 J/kg is forecast along the coastlines between Wednesday 21 and Thursday 06 UTC. Numerous waves of deep-moist convection are forecast across the area during this time.
Strong lower tropospheric bulk shear, attaining 15 m/s in 0-1 km layer, as well as SRH between 100 and 250 m2/s2 in the same layer point to enhanced tornado threat, particularly if isolated supercells manage to develop. Besides tornadoes, severe wind gusts (What's a wind gust?) and excessive precipitation will be possible as well. Level 2 highlights an area with the highest threat of severe.
Further east, vertical wind shear will be lower and forecast profiles across coastlines of Algeria or Sardegna and Corsica point to the enhanced threat of excessive precipitation given high RH through low to mid-troposphere and low LCLs.