Zonda

• Cloud Structure In Satellite Images
• Meteorological Physical Background
• Key Parameters
• Typical Appearance In Vertical Cross Sections
• Weather Events
• References

Key Parameters

The following NWP variables are the most used in practice for the identification of Zonda wind events. However, it's important to keep in mind that a better spatial resolution could represent the small scale features of the phenomena in a much more accurate way. An accurate representation of smaller-scale features requires a model resolution of 4 km or less.

• Height contours at 1000 and 500 hPa:
  Zonda events: well-developed mid-level trough west of the mountain range. Surface low southeast of the barrier, near the extreme south of the continent.
• Height contours and wind velocity at 500 hPa:
  A well-developed mid-level trough and a strong upper-level jet west of the mountain range. Zonal wind velocity at 500 hPa (near the mountaintops of the Andes) generally greater than 15 m/s.
• Equivalent potential temperature at 850 hPa:
  Frontal cloud band related to a strong gradient of equivalent potential temperature south of the Zonda occurrence region. The warm edge of the gradient is near the barrier in the area affected by Zonda wind.
• Stability:
  Vertical stability, and particularly the presence of stable layers upstream near the top of the mountain barrier, favors Zonda events. An unstable low-level layer downstream brings the Zonda closer to the surface. Once the Zonda has developed, a nearly dry adiabatic lapse rate is established and the troposphere becomes unstable.

Height contours at 1000 and 500 hPa.	28 August 2010/18 UTC - Goes WV image; Magenta: Geopotential Height at 1000hPa (mgp), cyan: Geopotential Height at 500hPa (mgp).
Height contours and wind jet streak at 500 hPa	28 August 2010/18 UTC - Goes WV image; cyan: Geopotential Height at 500hPa (mgp), blue: wind magnitude > 35 m/s.
Equivalent Potential Temperature at 850hPa	28 August 2010/18 UTC - Goes WV image; Magenta: Equivalent Potential Temperature at 850 hPa (K) and wind barbs.
Stability: Typical vertical profiles of Temperature and Humidity during a Zonda event	14 August 2009/12 UTC - Radio soundings at Santo Domingo (west side of Andes) and Mendoza (East side).