980715 - A large and diffuse Denver Convergence Vorticity Zone (DCVZ) began
to contract during the day and over the course of a few hours became a very
tight convergence line that pushed to the west.  There was plenty of
vorticity present along the line with southeast winds of 10-20 knots on the
east side and northwest winds of 5-10 knots on the west side.  As the DCVZ
contracted, the wind shift line and associated band of large vertical
vorticity exhibited an abundunce of dust whirls, some of which reached a
considerable height.  CAPE was marginal so that stretching of the ambient
vorticity into landspouts was generally unsuccessful.

Despite the low CAPE, some storms were able to form on the boundary and
ultimately produced their own outflow that was added to the existing
boundary.  

The DCVZ also had a distinct circulation center located north of DIA in
Adams County during the early part of the day.  This circulation also
underwent a scale contraction from ~15-20 km to about 5-10 km in diameter
and moved north into western Weld County.

Mobile Mesonets made numerous east-west transects along I-70 during the
early stages as we attempted to locate the boundaries.  As it became clear
that the boundary was strengthening and moving westward, we completed some
box patterns that extended well east and west of the boundary.