INTERPRETATION
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Regional and Mesoscale Meteorology Team Cooperative Institute for Research in the Atmosphere (CIRA) Colorado State University Fort Collins, Colorado |
May 7, 2002
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5 May 2002 Tornado Event |
Figure 1 |
Figure 2 |
| An outbreak of severe weather, including several large tornadoes, took place on 5 May 2002 as illustrated by the SPC's (Storm Prediction Center's) map of severe storm reports (Figure 1). Upper-level flow on 5 May 2002 was relatively strong in the morning and forecast to intensify by late afternoon over the Texas panhandle and most of Kansas. Note, for example, the 12-hr forecast of 250 mb heights and isotachs (Figure 2). There were two areas of particular interest at the surface. The first was a potential dryline bulge northeast of a developing low in eastern Colorado. The associated dry push was forecast to move northeast into north-central Kansas by 00:00 UTC. The second area of interest was a region of anticipated backed winds ahead of the dryline in the Texas panhandle. The SPC outlook issued at 06:00 UTC May 5 shows a moderate risk of severe weather from west Texas through eastern Nebraska (Figure 3). |
Figure 3 |
Figure 4 |
Figure 5 |
| Figure 4 shows the Dodge City,
KS sounding from 00:00 May 6. The 0-6 km shear at this location was
more than sufficient for supercells, even though the surface winds were
not backed as much as they were in the two areas noted above.
Figure 5 is a loop of surface data overlaid with the RUC analysis of MSLP and surface wind. The shaded color shows Lifted Indices. Note the increasing convergence in the two areas noted above. Figure 6 is a loop of the GOES-8 visible imagery from 14:15 UTC (5 May) through 01:01 UTC (6 May). Convection forms first in western Oklahoma, but dissipates quickly as it moves into an area of clear skies in the eastern half of the state. Convection along the dryline forms in western Kansas at about 19:30 UTC, and develops into large thunderstorms within an hour. Development in west Texas is delayed somewhat, perhaps because of the cirrus cloudiness. By 21:30 UTC large storms are found in both areas noted above. |
There are several storm-scale features of interest.
Notice the development of enhanced cumulus along the southern flank of
the large storm in Kansas beginning about 21:15 UTC. Walls of low-level
cumulus can be glimpsed beneath the edge of the anvil as the storm intensifies.
A series of tornado reports from this region begin about 21:30 UTC.
The storm in the northern Texas panhandle also develops feeder bands on
its southern flank beginning around 22:00 UTC. There are reports
of large hail and a tornado (at 22:35 UTC).
Figure 6 |
Figure 7 |
Figure 8 |
Figure 7 is a loop of the GOES-10 visible imagery from 14:15 UTC (5 May) through 01:00 UTC (6 May) which affords a different viewing angle. At 22:30 UTC there are two large supercells in the Texas panhandle. A smaller storm can be seen developing south of the southernmost supercell. Over the next 45-minutes this small storm moves northeast and overtakes the larger cell. By 23:30 UTC the two storms have merged completely, and a tornado touches down 7 miles southwest of Happy, Texas. Jim Ladue photographed this tornado as it entered the town (Figure 8). This is the storm that resulted in two deaths and 4 injuries in Happy.