• Temperature advection (TA)
  The zero line of TA is in advance of the frontal cloud band. It is not possible to find one level for the TA which is characteristic for the whole front. TA at 1000 hPa very often has its zero line close to the frontal surface. TA at all levels in the troposphere has to be taken into consideration which can best be done using vertical cross sections (see next sub-chapter).

• Thermal Front Parameter (TFP) (note: cold advection on both sides of the front does not contradict a pronounced TFP), equivalent thickness (crowding zone at the cloud band) and fields of pressure height show similar features as classical Cold Fronts. (see Cold Front - Key Parameters ).

• Humidity advection shows positive values in advance, and negative values behind the front. Since humidity is depending on temperature, the lower levels show higher values. Therefore, levels above 500 hPa are not of great importance here. The zero line of humidity advection, therefore, lies in an area where there is already cold advection.
  That means that within the frontal cloud band it becomes not only colder but also drier. If both conditions coincide a gradual dissipation of the frontal cloud band is very likely (see Typical appearance in vertical cross section).

This example shows dry advection throughout the whole area. Normally there is a change of sign at the frontal surface. If there is none, the front is likely to decay.

• Vertical motion
  Upward motion (found especially at the leading part of the front) normally dominates the cloud band. Fronts with lower clouds are characterised by a higher probability of smaller values of upward motion. At these fronts the humidity advection shows a higher frequency of being dominated by negative values than with fronts with multilayered cloudiness (see Typical appearance in vertical cross section).

Upwards motion is found in front and within the frontal cloud band. At the rear edge downward motion can be seen.
The image shows upward motion over a large area: only at the rear edge is there a small region where sinking is evident.