STORM TRACK: November 30, 1981 (Volume 5 Issue 1)

(The following is a highly summarized account of a dry-line severe storm intercept by Tim Marshall, sent to the Editor some weeks ago, and planned for presentation in more detail at the San Antonio conference. Some additional personal observations of his are included, which were not part of the conference article.)

In the past three years, I've headed the Texas Tech Tornado Chase Team. We have covered nearly 12,000 miles per spring and have filmed several tornadoes. ... On the morning of April 12th, 1981, the Texas Tech Chase Team forecasted southwestern Oklahoma as the region most favored for severe weather that afternoon. We based our decision mainly on hourly changes of dew point temperatures and surface pressure falls. We left Lubbock at 1:00 PM and headed eastward. Skies were clear except for a band of cirrus overhead, extending to the northeast. ... mobile temperature and dew point, measurements were taken every five miles along the chase route. In addition, wind speed and direction measurements were taken within close proximity to the storm. These data are unique in that they crossect the dryline and sample the low level environment of the storm prior to tornado formation on both meso-beta and meso-gamma scales. By 4:43 PM, we hadcrossed the dryline and were chasing an isolated storm with two flanking lines -- each with wall cloud.

The east wall cloud only produced a small funnel, and then that flanking line dissipated as the western-most flank intensified. Soon we were underneath the rainfree base and noticed that everytime the wall cloud started rotating, it would occlude with rain, which seemed to inhibit the updraft from organizing. By 6:00 PM, we were at our filming site, only five miles from the wall cloud, when all of a sudden a clearing could be seen wrapping around the updraft.

(At this point, Tim encountered one of those singular occasions which many of us have experienced when a seemingly unrelated and bizarre event registers a given moment indelibly in the memory.)

Meanwhile, I was unwrapping my film packet while this bull was looking at me very intently. Suddenly, he let out a loud 'Mooo,' and then hundreds of cows appeared from over the hill and lined up to oversee our chasing operations, all speaking in kind, in a most, improbable bovine symphony, at just the moment of developing vorticity!! As the wall cloud began to occlude, the herd became silent.

The flanking line accelerated rapidly eastward, and precipitation dissipated around the updraft. Large hail (up to 4" diameter) was reported in Roosevelt, Oklahoma, five miles to the NE. As the tornado touched down, it became more vertical and lasted for 10 minutes . . . nearly a half mile wide. The flanking line became stationary to our east, and a new wall cloud began to develop ahead of it, as the first tornado subsided with the evolving updraft. The storm propagated in this manner until after dusk, thru three more cycles, but, only produced funnels and no more tornadoes."