STORM TRACK: July 31, 1983 (Volume 6 Issue 5)

(Editor's Note: An abbreviated summary of this storm appeared in the March issue of Storm Data. The following is a more complete account.)

"On March 3, 1983, an early season storm system produced a total of five tornadoes in west Texas and Oklahoma. I had the opportunity to photograph two tornadoes near the town of Clarendon, located in the Texas Panhandle (Fig. l from Storm Data, March 1983, Vol. 25, No. 3, with chase route arrows added).

Figure 1

The day began with low overcast skies in Lubbock. Temperatures were in the low 60's and dew points in the low 50's. NSSFC forecasted a moderate risk of severe thunderstorms along the Red River Valley by late afternoon. Seeing this, I had already decided to chase that day, whatever the chances, since it was the first chase of the spring (and it had been a long, hard winter you know!)

I went to the Lubbock Weather Service and plotted hourly surface analyses. As the morning progressed, skies remained overcast in west Texas, but I remained hopeful that they would soon clear. By 11 AM, I forecasted the most favorable area for severe weather to be from Lubbock (LBB) to Fort Sill, Oklahoma (FSI) (Fig. 9). A dryline was developing in southeastern New Mexico and was moving eastward. In addition, a warm front was becoming prominent from Lubbock to near Dallas-Fort Worth (DFW). I didn't want to travel too far from Lubbock, since I was anticipating convection in close proximity to the warm front-dryline intersection. I chose the town of Matador as the "target" town, since it was also south of where previous morning convection had taken place.

Figure 2

The upper air maps favored severe weather development in west Texas. The area was on the anticyclonic side of the mid-level jet and the cyclonic side of the low-level jet (Fig. 2). With cold air advection downstream and a closed low moving into central California, the upper level dynamics were becoming more favorable for severe weather throughout the day. The morning sounding for Amarillo looked like the 'classic' bell shaped tornado sounding from Miller (1972). However, there was little or no wind shear with height.

At noon, I left Lubbock and drove to Matador. The sky gradually became broken and small cumulus dotted the sky. A tornado watch was issued along an axis from Amarillo (AMA) to Mineral Wells (MWL). Hearing those three beeping tones on the radio brought back the sweet, memories of last May. Naturally, my adrenalin surged! I reached Matador at 2 PM. The winds were light southeasterly, and the temperature was about 70 degrees. I could see towering cumulus beginning to develop along the Caprock escarpment to the west. At the same time, smaller cumulus overhead were beginning to dissipate. A small cirrus anvil could also be seen to the distant north in association with a developing Cb. I called the Lubbock Weather Service, and they informed me that the dryline was surging from Midland (MAF) toward Abilene (ABI). They said the wind direction at Lubbock had turned southwesterly and the dewpoint had dropped into the 30's. Meanwhile, the wind at Childress was backing more toward the east, and their dewpoint was increasing. Since moisture convergence was increasing in the area, I drove northward toward the developing Cb.

From a rest area north of Turkey, I watched the Cb explode upward to my northwest. The storm was over the Palo Duro Canyon and moving slowly northeastward over a sparsely populated area, with few roads. I drove north toward Clarendon, hoping to intercept the storm. I arrived at the town about 4 PM and stared almost in disbelief at what I was seeing. There was a large bowl-shaped lowering extending from the rain free base, and it was rotating rapidly. ... I said to myself that this storm must believe it's a May-type storm! (Later, I learned that it went from 38,000 to over 50,000 feet during this time).

I positioned myself just north of the approaching lowering, just west of Clarendon on FM 2363. Striations were evident along the east and north sides of the updraft. I had just set up my cameras on tripods, when the wind became calm and marble-size hail began falling. At 4:50 PM, a large cone-shaped funnel extended toward the ground to my southwest (Fig. 3).

Figure 3

The updraft had a 'step-like' appearance, and the precipitation area to the north was quite small. The blue-colored tornado moved slowly northward across rangeland (Fig. 4).

Figure 4

A clear slot could be seen wrapping around the vortex. At times, a core could be seen within the condensation sheath around the tornado (Fig. 5).

Figure 5

The tornado began to turn to the northwest and became rope-shaped, finally occluding in precipitation at 5:11 PM. In all, the tornado traveled about five miles in twenty-one minutes and was rated F2 (Also, see Fig. 11). Meanwhile, a second updraft developed just east of the first and also began to rotate. I moved eastward out of the path of the approaching updraft. A cell merger was taking place, and the precipitation area to the north was increasing. Within minutes, precipitation was wrapping around the lowering. The lowering moved northward across Rt. 287, and I could see cars and trucks driving through the rain curtains and under the impending circulation. To the northwest, I could see ominous looking cloud bands spiralling up the east side of the updraft (Fig. 6). A large inflow tail extended eastward, demarcating the boundary between the precipitation area and the moist inflow.

Figure 6

About 5:45 PM, a rain-laden gust front rapidly moved around the updraft, originating from the northwest. As the gust front passed my location, a brief period of rain fell, followed by a wind shift to light west. I continued northward along Rt. 70 and stopped at my second filming location, which was on top of the Caprock escarpment, overlooking the Greenbelt Reservoir. I could see the occluded updraft to the north, with no apparent wall cloud. By this time, the gust front had surged several miles to the east. Then, at 5:59, a narrow column-shaped tornado touched down right in the reservoir about two miles north of my location (Fig. 7).

Figure 7

A spray of water could be seen around the base of the tornado. Meanwhile, a clear slot wrapped around the updraft, such that the updraft appeared as a giant cylinder. As the tornado moved onshore, it suddenly widened into a large cone-shaped vortex. The tornado traveled northeastward across Rt. 70, just missing the community of Howardwick. One person did suffer minor injuries, when the tornado flattened a liquor store on Rt. 70. I drove northward, underneath the darkened updraft, and took a picture of the tornado when it was less than a mile away to the northeast (Fig. 8). The tornado resembled a long tube, and the core extended to the ground. At times, the tornado moved toward me, back over its damage path, reminding me not to get too close.

Figure 8

In all, the tornado traveled about five miles in 23 minutes and was rated F2. I took close to 80 slides and 250 ft of 8 mm movie footage." Tim reported no tornado sounds of which he could be certain. Noteworthy, however, was the light 3-4 MPH winds beneath and adjacent to the wall clouds; strikingly different from the 60 MPH winds which Tim experienced along the wall cloud boundary of the May 19 Pampa supercell (six large tornadoes, plus one a mile wide). (Also, see Fig. 12)

'In order to better understand how the severe weather occurred, I plotted the 4 PM surface analysis (Fig. 9). It is interesting to note how the warm front moved throughout the day. Note that most of the tornadoes developed along the intersection of the temperature and dewpoint axes. It appeared that there was enough lifting at low levels, either from isentropic upglide, upslope effects, or the dryline, to force buoyant air above the inversion and begin the convective process. I learned that the forecast areawould have been more accurate, had I advected the area along with the mean surface winds. Then, in six hours, the forecast area would have been closer to Amarillo.

Figure 9

Figure 10

Figure 11