# Foehn Simulator - Boss Calling

## Task List: Your Boss Calls

### 19:30 local time

### Synoptic situation

"Here your boss speaks to you.
I wanted to make sure that things are all going okay in the office. What did you find out about the large-scale weather situation?"

a) A low pressure system is moving over southern France and a cold front is passing over the Alps during the night from SW to NE.
b) North of the Alps a low pressure system is travelling from West to East and intensifying the N-S pressure gradient over the Alps.
c) A low pressure system over Greece is bringing strong southerly winds to the Alps.

The correct answer is: a) A low pressure system moves over southern France and a cold front passes the Alps during the night from SW to NE.

### The Foehn Wind

"Ok, thank you for the information. We have already higher wind speeds at some stations. Can this be an indication for foehn winds?"

a) No, foehn wind can only occur during day. In the night it is too cold and today the cold front prohibits foehny conditions even more.
b) No, until now the winds are associated to the cold front only.
c) Yes indeed. Measurements north of the Alps show rising temperatures, increasing wind and decreasing humidity.

The correct answer is: c) Yes indeed. Measurements north of the Alps show rising temperatures, increasing wind and decreasing humidity.

### The Wind Forecast

"Can you give me a rough forecast on the wind development?"

a) Due to the cold front and the increasing pressure gradient, strong foehn winds south of the Alps are expected. This will cause wavy lee cloud structures over Italy (satellite images + webcams).
b) The cold front does not reach the Alps and passes by in the south. The N-S pressure gradient however induces stronger foehn winds north of the Alps.
c) According to the regional model (AROME, T2m) and the satellite images the cold front will pass the Alps quite soon! The cold air outflow from the mountains might cause an increase in wind in a wider area north of the Alps.

The correct answer is: c) According to the regional model (AROME, T2m) and the satellite images the cold front will pass the Alps quite soon! The cold air outflow from the mountains might cause an increase in wind in a wider area north of the Alps.

### The Intensity

"I see. What wind speeds do you expect due to the front?"

a) The combination of front and foehn wind is devastating; I expect maximum gusts north of the Alps of 40 to 50 m/s (144 to 180 km/h)
b) At 21 o'clock I expect maximum gust speeds north of the mountains of 20 to 40 m/s (72 to 144 km/h).
c) The cold front has a weakening effect on the foehn wind. Therefore I expect no more than 5 to 10 m/s (18 to 36 km/h).

The correct answer is: b) At 21 o'clock I expect maximum gust speeds north of the mountains of 20 to 40 m/s (72 to 144 km/h).

### "Please be prepared when media wants you to give a forecast. They usually call at 2 am.
Have a look at the pressure gradients N/S of the Alps, that' s always a good indicator for south foehn! Accurately observe the development of temperature and humidity.
Important: When you think the gusts will exceed 15 m/s in populated areas, issue a warning!! You can do this at the button on the left hand side in your simulator environment.
Good bye."

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