Narrow cold-frontal rainband

A narrow cold-frontal rainband (NCFR) is a kilometer-wide organization of elliptically-shaped cores of heavy precipitation. NCFRs associate with areas of strong convergence on the surface, the so-called "precipitation cores" (PCs), which move along with surface cold fronts. The main NCFR and PCs formation mechanisms are shear instability, forced lifting of air and gravity currents.

Strong surface convergence, strong wind shear, and a low-level jet can be observed alongside the PCs within NCFRs. During the passage of PCs, a sequence of pressure changes, wind shift, rain rate peaks and temperature drops can occur. NCFR's impact like flash floods and debris flows after wildfire is especially prominent in Southern California.

Mesoscale numerical weather prediction models are deemed as confident models for forecasting NCFR events. The improved knowledge about synoptic scale forcing and dynamics have helped provide confidence in predicting NCFRs, however, the resolution of NCFR's fine structures and the assessment of local rain intensity still require improvement.