980530 - The forecast models and data all suggested that there would be
supercells in northwest Iowa and that initiation would occur early in the
day.  A departure time of 8 a.m. was set and the caravan headed east into
Iowa.  By 1245 pm, the first tornado warning was issued for a fast moving
cell that we hoped we could intercept in a few hours.  We continued north
and east toward Ames, Iowa.  Continuous tornado warnings were issued for
this storm for many hours as it travelled southeast at close to 40 mph.  As
we moved in for the intercept southeast of Ames, the storm went from 70 dBz
to 55 dBz to 35 dBz in three successive scans and quickly dissipated.  Post
analysis showed the storm had moved south of the jet core into a region of
warm temperatures aloft and the loss of CAPE and increase of CIN
contributed to its quick demise.  VORTEX turned back west but was unable to
make an intercept in South Dakota.