Evolution and dynamical processes of solitary precipitation bands within the comma-head of northeast United States cyclones

Intense solitary precipitation bands are frequently observed in the comma-head sector of extratropical cyclones. Limited observations and coarse resolution analyses have prohibited investigation of the mesoscale forcing and stability evolution during band life cycle in the past. This thesis uses unique Dual-Doppler observations, high-resolution analyses, model simulations, and Potential Vorticity (PV) inversions to explore the evolution and dynamical processes of solitary precipitation bands.;Analysis of 36 banded events through case study and composite approaches reveals a common cyclone evolution and associated band life cycle. A majority of banded events develop in the left-exit region of an upper jet, in an area of concentrated upper-PV advection along the poleward edge of an upper PV hook. Band formation occurs as midlevel frontogenesis rapidly increases along a mesoscale trough that extends poleward of the 700-hPa low. This trough is the vertical extension of the surface warm-occlusion. At the same time, conditional stability near 500 hPa is reduced due to differential horizontal temperature advection in moist southwest flow ahead of the approaching upper trough. The high-resolution analyses show that although conditional, conditional symmetric, and inertial instabilities may be present, shallow layers of conditional instability are present more often during band formation than layers of conditional symmetric instability, contrary to previous research using coarser analyses. Band maturity is marked by increasing conditional stability, which is offset by an increase in frontogenetical forcing. Model simulations with varying degrees of latent heating reveal that latent heating associated with the band itself is critical to the development and maintenance of the frontogenetical forcing for the band. Band dissipation occurs as the frontogenesis weakens and the conditional stability is restored. PV inversions show that the band is susceptible to changes in the meso-alpha scale flow associated with the formation of diabatic PV anomalies east of the band, which contribute to frontolysis and band dissipation.;A set of 22 null events where single band formation was absent in the comma-head were examined. Although exhibiting similar synoptic patterns, null events were characterized by weaker frontogenesis, larger conditional and symmetric stability, and less coupling with upper-level forcing for ascent.