551 Frontogenesis

Three main frontogenetical areas in a typical developing cyclone

• Deformation frontogenesis with cold front• Deformation (confluence)frontogenesis with

warm front• Convergence frontogenesis near low center

(generally on portion of warm front closest to the low center)

Using Garp software

Numerical Simulation of the Dec. 14-16, 1987 event

• Mass and Shultz, 1993• Shultz and Mass, 1993• Monthly Weather Review

Note fracture in frontogenesis along northern portion of CF

Important issue we will discuss

in depth:Frontogenesis

generally accompanies cyclogenesis

Surface-based fronts typically weaken with height

How do we explain this?

Classic Paper That First Applied Frontogenesis Diagnosis 3D for a

real case: Sanders 1955

Surface-basedFronts Weakening With Height

• Rising motion and adiabatic cooling on warm side.

• Sinking and adiabatic warming on on cold side.

• Vertical motions increase with height…therefore vertical motions increasingly work against frontogenesis with height.