Though there is cloud dissipation in the area of Front Decay, vertical cross sections from the numerical model still show a downward inclined compact zone of moist isentropes (equivalent potential temperature). However, derived parameters of TA, vertical motion, humidity and divergence all indicate cloud dissipation.

• Temperature advection:
  The decaying part of the frontal cloud band is completely positioned in CA at all levels, or at least only at upper or lower levels.
• Relative humidity:
  The relative humidity has a minimum at high and middle levels, which can be interpreted as dry (cold) descending air within the frontal zone
• Divergence:
  There is a pronounced zone of divergence below and within the frontal surface and convergence above, which is in contrast to the classical CF.
• Vertical motion (Omega):
  The field of vertical motion is characterised by positive values within the gradient zone indicating distinct descent. This is in contrast to the classical CF. Cases with remaining low level cloudiness show rising at low and middle levels in front of the gradient zone.

Temperature advection: vertical cross sections from numerical model

Relative humidity: vertical cross sections from numerical model

Divergence

Vertical motion (Omega): vertical cross sections from numerical model