Temperature advection
The zero line of temperature advection is in advance of the front which can be detected through
the position of the inclined zone of isentropes (black). There is cold
advection behind and within the front and it is extending from the ground up to 400 hPa.
Relative humidity
Relative humidity shows high values in most of the VCS region. The reason for that is the position of the VCS. There is high humidity within and
ahead of the frontal zone. In the upper left corner of the cross section lower
values of relative humidity indicate dry air penetrating from the stratosphere.
Potential Vorticity
The
PV anomaly can be observed in the upper rear part of the frontal zone, matching with the low humidity region in
the previous image. Weak PV anomaly can also be seen in the
region of the frontal zone close to the ground.
Omega
Negative values of Omega (upward motion) can be found within and above the frontal zone,
a situation typical for
the Cold front. Some positive values (sinking) can be observed behind the frontal
zone in the lower levels.
Vorticity Advection
There is no important feature in the field of vorticity advection and the reason for that is the position of the VCS.
A weak positive vorticity advection is found in the levels above 500 hPa with a
maximum above the cloud band of the front.
