Extended Abstract (424K)JP2.6
Analysis of mesoscale banded features in the 5–6 February 2001 New England snowstorm
David Novak, SUNY, Albany, NY; and R. S. W. Horwood
On 5-6 February 2001 a major winter storm produced widespread snow accumulations greater than 30 cm through most of New England, with over 75 cm locally in New Hampshire. The storm featured a quasistationary intense snowband associated with snowfall rates of 8-13 cm h -1, with a number of finescale bands and convective elements merging into the primary band through the storm’s evolution. The synoptic and mesoscale environment supporting this structure is analyzed.
Investigation shows the synoptic flow configuration became favorable for mesoscale banding during cyclogenesis. Namely, the formation of a mid-level closed circulation maximized deformation northwest of the surface cyclone. This mid-level deformation acting on the ambient temperature gradients contributed to intense mid-level frontogenesis, which served as forcing for the banded structure.
Assessment of the atmospheric stability southeast of the primary band showed an environment characterized by elevated convective instability and conditional symmetric instability. The precipitation in this region was marked by finescale bands and convective elements, which yielded intense snowfall maximums in orographically unfavored areas. Further northwest, the primary band was found in an environment characterized by weak symmetric stability. The vertical motion forced by the frontogenesis was likely enhanced by the weak symmetric stability, contributing to the intensity of the primary band.
As the cyclone became removed from the main baroclinic zone during occlusion, the frontogenesis gradually diminished while the symmetric stability increased. Consequently, the banded structure slowly dissipated during this time.
Joint Poster Session 2, Severe Local Storms Forecasting (Joint with 21SLS and 19WAF/15NWP) new
Tuesday, 13 August 2002, 3:00 PM-4:30 PM
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