Topographical Phenomena of Zurich, Cyclones, and Air Masses

Source: http://www.swisseduc.ch/immersion/geo/meteo/weather/docs/weather_situations.pdf

Four advective wind situations are defined for Switzerland, they are horizontal air flows, a low pressure, cold system from Iceland and a high pressure system from the Azores.

Source: http://www.swisseduc.ch/immersion/geo/meteo/weather/docs/weather_situations.pdf

During Northfoehn the precipitation in Zurich increases as air moves toward the Alps in the south.  The rise and cool as they approach the Alps creating clouds.

During Southfoehn conditions the precipitation is much greater because the air is moving in from the Mediterranean Sea.  Zurich is on the leeward side of the Alps during these condition so it will often see a foehn window where the cloud breaks up.

During a Bise situation the air is moving easterly, Zurich is on the eastern side of the country and therefore sees less wind than the west side where the mountain ranges get closer and the valley gets narrower.

West Winds blow for approximately 60% of the year, and creates more intense weather on the north side of the Alps than the south.  This is an important factor for the local weather conditions.

Source: http://www.swisseduc.ch/immersion/geo/meteo/weather/docs/weather_situations.pdf

 This is a westerly polar front connecting two low pressure cells.  The polar front is forcing it's way under the warm front from the east and causing a cold occlusion.

Two convective systems are defined for Switzerland, the anticyclone and the flat pressure distribution system.  These convective air movements create local climate conditions by vertically moving air.  Differences in local high or low pressure conditions will cause differing local winds.

Source: http://www.swisseduc.ch/immersion/geo/meteo/weather/docs/weather_situations.pdf

Anticyclonic patterns create fairly boring weather patterns.  The air is dropping slowly while losing humidity.  They do tend to create haze or stratoform clouds, especially in winter in low lying areas north of the Alps.

Flat Pressure distribution results in rising air, converse to anticyclonic patterns, they are more likely to form cumuloform clouds.

The Swiss Alps have a lot of influence on the weather and climate of the country, when precipitation is compared to different regions such as Oklahoma where the land is flat the patterns are very different.  Because systems get interrupted and don't have time to build up they tend to be more mild.  Switzerland does see hail storms but they do not see intense tornado producing thunderstorms like Oklahoma does.

The air masses that occur over Zurich are much the same as the rest of Europe.  The continent itself is relatively small, mostly falls in high latitudes and is largely surrounded by water. 

In the summer months Continental Polar (cP) and Maritime Polar (mP) air masses dominate.  The cP air masses are cooler whereas the mP masses are more stable in temperature, having crossed the Atlantic Ocean.  When these two air masses meet they develop cyclonic summer precipitation.  Summer months also see influence Continental Tropical (cT) and Maritime Tropical (mT) air masses.  These tropical air masses have some influence but because they are blocked by mountains and stabilized by ocean and sea they produce far less dramatic weather events than similar air masses in North America.

In winter months the same four air masses are influential.  The mP and cP fronts are what cause most of the precipitation in the Alps however it falls mostly to the south and affects Zurich less.  The clashing of mT and cT air masses have similar effects.

Source: http://www.publishyourarticles.org/knowledge-hub/articles/brief-notes-on-air-masses-of-europe.html



Source: http://www.wunderground.com/global/stations/06670.html

This is a satellite image of Swizterland from April 5, 2012.  The current temperature at 9:10pm CEST was 47F and raining.  The data is collected from the Zurich Airport and is accompanied by webcam photos.  Tomorrow's forecast says 0% chance of precipitation and a high of 57F with fog.

Here is a link to view, among many things, a live webcam of the Zurich airport. Live Web Cam at Zurich Airport

Source: http://www.zurich-airport.com/desktopdefault.aspx/tabid-277/473_read-113/