Again, more of the same: Heat, sun and southwind.
Synopsis: The Atlantic low moves slowly towards the Celtic Sea, the heat dome over the Pyrenees remains quasi-stationary. Over Spain and the Pyrenees, a moderate to strong flow from sector south-southwest remains active.
Details: Sunny weather prevails. Temperatures remain extraordinary high with maximas around 32 to 36°C in the flats, in some French valleys even 38°C are possible. It’s the first day where there the models show a significant movement in the 0°C-isotherme: It’s climbing from 4300 to 4800 MASL during the day.
Thermals: With the persisting south wind, the thermic stratification of the atmosphere quite complex. Multiple isothermic layers and inversions are to be expected until noon. Especially in France, a strong inversion is forecasted around 1700 MASL, most likely surviving the whole day. In Spain, the inversions are less pronounced. In the Central Pyrenees and higher mountains (Around Añeto, and towards Andorra), a stubborn and rather stable layer remains below 1600-1900 MASL. In the foothills and the Catalan Pyrenees, a quite good gradient is establishing towards noon which seems much better at lower levels than in the higher mountains.
Summarized, in general good thermals can be expected in altitudes above 2000 MASL from noon onwards, potentially reaching again a cloudbase of 4000 MASL. Below, 2000 MASL, rather good thermals can establish during the afternoon in the Catalan mountains with a cloudbase of around 3700-4000 MASL around Andorra and Puigmal and around 2800 in the foothills. Some thermals are also possible between 1000-17000 MASL in the French Valleys, but they are most likely not able to break through the inversion above.
However, thermals are most likely strongly affected by the wind and often disorganised or ruptured.
Overdevelopments don’t seem to be significant tomorrow, with most models showing little to none precipitation signals. The highest risk for Overdevelopments remains along the convergence of the foehny south wind with northerly valley winds in France, probably affecting the area around TP 4, Pic du Midi Bigorre and the direct line towards TP 5.
Wind:
The southerly wind remains active but it’s strength is modelled a bit lower than today. Nonetheless, there is a rather clear foehn-signal on the French side of the Pyrenees, especially at layers above 2000 MASL. Below, the aforementioned inversion can block the south wind and allowing a thermic valley wind up to approx. 1600 MASL.
In Spain, the south wind is present at altitudes above approx. 18000 MASL in the morning with lower altitudes remaining rather calm- During the day, the wind gets mixed down and combined with the thermic wind systems, widespread moderate to strong south wind will establish in most altitudes.
In areas with venturi effects, gap flow or downslope wind effects, windspeed can reach up to 40, locally up to 50 km/h, otherwise reaching about 25-35 km/h at 2000-3000 MASL.
In the flats of Figueres, the Tramuntaña remains blocked by the south wind, in this area windspeed around 40 km/h at 1000 MASL are possible.
Outlook:
Saturday is still dominated by south wind, quite likely stronger than tomorrow. Still hot.
