Pressure Lugano − Zürich Lugano−Zürich
-2.0hPa
Neutral
Foehn possible Northerly flow Altdorf (km/h) - - - forecast
Above 4 hPa there is foehn at Visp 4 times out of 10.
Pressure Domodossola − Sion Domodossola−Sion
-1.0hPa
Neutral
Foehn possible Northerly flow - - - forecast
Above 4 hPa across the Simplon: foehn at Visp half the time.
Pressure Visp − Evionnaz Visp−Evionnaz
+2.1hPa
Down-valley Up-valley Visp (km/h) - - - forecast
Valley wind regime. Not to be read as a foehn.
700 hPa wind over the southern crest 700 hPa · ~3000 m
-0.6km/h
Neutral
Southerly flow Northerly flow - - - forecast
Above +20 km/h from the south, what drives the foehn is in place.
Visp no foehn 2/5
as of 10:00
Direction at Gütsch (90-240°) 156° Direction on site 120° Wind or gust 1.1 km/h Humidity below the limit 66.7 % Potential temperature -11.5 K Sion no foehn 2/5
as of 10:00
Direction at Gütsch (90-240°) 156° Direction on site 78° Wind or gust 7.2 km/h Humidity below the limit 66.6 % Potential temperature -12.2 K Aigle no foehn 2/5
as of 10:00
Direction at Gütsch (90-240°) 156° Direction on site 142° Wind or gust 9.4 km/h Humidity below the limit 61.9 % Potential temperature -11.2 K The other foehn valleys
Five criteria must hold together. Four out of five is not a foehn.
The wind in the Rhone valley Viège → Evionnaz
down-valley wind light drainage valley breeze
No established down-valley wind on the valley floor right now.
Binn and Jeizinen: why they are not in the strip
Foehn works down the valley: the chain says more than one station.
Neutral
Southerly flow Northerly flow
It often picks up there without ever coming down into the Rhone valley.
Cold air on the floor foehn can stay above you - - - Valley mixed - - - Cold air on the floor
Above 0.75 the foehn can reach the ground; below 0.38 it stays above you.
Rain in Ticino Locarno / Sion
0.0mm
Neutral
Locarno (south) Sion (north)
Rain in the south and dry here: the air comes back down dry and warm.
Foehn signature at Sion Sion
gust Temperature Humidity - - - forecast
All three must move together. One on its own is not enough.
Forecasts: Open-Meteo. On Lugano − Zürich and Visp − Evionnaz the solid part comes from MeteoSwiss measurements. On the other graphs it comes from the model: no source covers Domodossola, and a 700 hPa wind cannot be measured from the ground.