Storm in western Mediterranean
Cover image: Sea near Marseille when Mistral blows
Next Sunday, May 5, all models predict a storm at sea, or at least a strong gale weather, with average winds of 9 Bf (40kt, 75 km/h) and gusts of more than 75kt (130km/h). This type of storm is quite common in this region and it is linked to the typical conditions that cause these violent winds.
The French coast of the Mediterranean Sea is surrounded by mountains that change the speed and direction of the winds when high pressure is established on the near Atlantic. The northwesterly flow at ground level is deflected by 3 mountains, the Alps, the Massif Central and the Pyrenees.
The Mistral blows in the narrow valley of the Rhone to the coast, in Provence and in Languedoc. It is a strong and gusty wind, usually cold, which is feared in the summer for the risk of forest fires.
Northwestern Tramontane causes sudden storms in the Gulf of Lion. Both are accelerated by the upper flow crossing the mountains with a foehn effect providing gusting conditions and a typical blue sky.
In addition to the pressure gradient, a dynamic low in the Gulf of Genoa results from the divergent upper flow after the passage over the Alps. This depression in the Ligurian Sea can move and it is its position that actually controls the direction of the winds at sea, between Corsica, Sardinia and the Balearic Islands.
At sea, sailors generally fear deep depressions, but in this region, the high pressures that settle in the west or the north of France resulting in mistral or tramontane storms, mariners rather watch the anticyclones!
@idefix37 Great article!
Same layout is predicted next Sunday May 12. You may check it on Windy.
@idefix37 Veriy Good Article. Thank You
PJB2020 last edited by
Fantastic write up, Thanks