ORGANIZATION AND STRUCTURE OF CLOUDS AND PRECIPITATION ON THE MID-ATLANTIC COAST OF THE UNITED-STATES .6. THE SYNOPTIC EVOLUTION OF A DEEP TROPOSPHERIC FRONTAL CIRCULATION AND ATTENDANT CYCLOGENESIS

Interactions between an upper-level frontal system and an initially we ak surface cold front resulted in the production of a deep, precipitat ing frontal structure Over the south Atlantic states on 26-27 January 1986. Attendant with the intensification of the frontal circulation wa s the development of an intense marine cyclone off the Delmarva penins ula. The increase in frontal-circulation strength is attributed to a f avorable vertical superposition of the surface frontal trough and the upper-level frontogenetic horizontal deformation field that resulted i n a deep column of divergence over the surface frontal trough. The sur face cyclone developed partly, and indirectly, in response to the incr ease in warm-air advection in the lower stratosphere, which was direct ly related to an increase in the slope of the dynamic tropopause. The increase in the slope of the tropopause is hypothesized to have been t he result of the combined effect of adiabatic advection of low tropopa use height in the cold air of the upper trough and the latent heating associated with the onset of deep convection during the frontal develo pment.