Discrete Frontal Propagation in a Nonconvective Environment

Abstract Surface discrete frontal propagation in a wintertime, nonconvective environment is documented using conventional surface and upper-air data and simulated using the PSU–NCAR mesoscale model. Synoptic and mesoscale surface analyses show a cold front associated with a synoptic-scale low-pressure system propagating from northwest to southeast across the central United States. Apparently discrete frontal propagation occurs when the surface front dissipates and a new front forms approximately 500 km ahead of the original front, with no compelling evidence of frontal passage in the intervening space. Upper-air analyses indicate the infusion of three different airstreams into the frontal region, resulting in the formation of a ribbon of low static stability air parallel to and several hundred kilometers in advance of the original front. This static stability structure appears to be involved in the observed evolution of the front. The development of precipitation over the intervening zone between the old ...