A powerful upper level trough, and itsassoicated surface low moved
through southern Colorado from 10-11 October 1997. This case study will
document and investigate the evolution of the severe weather events in
southern Colorado during this time frame.
A series of strong to severe thunderstorms developed in thc southwest
Colorado mountains the evening of 10 October. A tornado dipped out of a
severe thunderstorm in Mineral county and cut a path 1/4 mile wide and 3
msiles long in a forested saddle above 10,000 foot MSL, between two
mountain peaks above 12,000 feet MSL. Six million board feet of lumber
was taken down by the tornado, rated F2. WSR 88D coverage where the
tomado occurred is poor, given the 140 mile distance from the radar, and
the beam-blockage with three mountain ranges between the radar and
tornado. Regardless, the synoptic upper air pattern and satellite data is
investigated in this paper, along with eyewitness accounts of the event.
From the late afternom to late evening of 11 October 1997, the same weather system passed through southeast Colorado. The wind profile featured strong speed shear and veering winds with height, and consequent high helicity values conducive to supercell development. Dew point temperatures were in the lower to mid 50s (quite high by October standards), and an intrusion of very dry air aloft was noted. A very unstable air mass was in place over southeast Colorado. The resulting environment spawned numerous rotating severe thunderstorms, in advance of a line of strong to severe storms in southeast Colorado. The National Weather Service in Pueblo issued over 20 severe thunderstorm and tornado warnings during this worst tornado outbreak in southeast Colorado in about 30 years.
The evolution of the southeast Colorado event was captured on Pueblo's
WSR 88D radar at ranges of 10 to 80 miles from the radar site. Numerous
classic and high-precipitation (HP) supercells were documented, producing
seven tornadoes and numerous reports of hail ranging from one inch to 4
1/2 inches in diameter. In this paper the evolution of this event is
investigated, and comparisons are made between the apparent strength of
the mosocyclones indicatd by storm relative motion(SRM) data, and the FO
to F1 damage done by the tornadoes discovered from NWS surveys.
Conclusions may be drawn to help determine future real-time
relationships between actual tornado intensity and apparent intensity of
mesocyclones as viewed by the WSR 88D during high plains tornado
outbreaks.