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Storms from Previous Years

Page 2

On some of the these, I can't find the dates of these storms as most of them were photographed while actively spotting for the NWS. Where possible I have tried to include the date.

Storm north of Brownfield, 1997.
This was a persistent southeasterly moving supercell which was very photogenic and was attracting large numbers of chasers, the public, and spotters. It moved from northwest of Levelland almost directly toward the city of Brownfield in Terry County. Large amounts of dirt were being drawn into the intake areas, of which there were often several at a time, and funnel like scud clouds hung below causing many public reports of tornadoes. While several gustnadoes were confirmed by spotters in front of the main intake, no tornadoes were actually confirmed.
As with many northwest flow storms, this one featured what the South Plains Storm Spotting Team has labeled a CAC or Complex Accessory Cloud. This feature shifts between wall cloud and shelf cloud characteristics rather rapidly as the intake area first firms up with a weak rotation then gets undercut by outflow and becomes shelf cloud like in appearance. The area then shifts forward a short distance and cycles through this again.

The first three are of a tornado look alike formation. This was the wall cloud stage drawing dirt laden air in from the outflow to the north side of the intake area. While a little too far away for definite details, the 'funnel' did not seem to be rotating and the dust was tending to push on south of the feature and it soon dissipated.
These three are taken fairly close together and likely are more from "bracketing exposures" than from any real change in the structure.
Next (fourth) is a shot of the CAC showing the rotation and a new lowering underneath.
Shots five through seven are of the condensing scud material under the updraft forming a new and rather ominous lowering or possibly what could be considered a funnel. It is practically on the ground and is rotating in a broad manner. Technically this might be called a tornado, but it's not what I'd call a 'violent rotation'.
The last three show the scud and dirt tail moving up into the CAC as it moves past in the shelf cloud stage.
These structures can and have produced tornadoes, though as a rule they are weak and short lived. I personally have seen two tornadoes from such northwest flow storms. The most recent may have had a debris cloud persist for up to 40 minutes. This was an unusual case.

'Funnel' reaching back into the outflow.

Rotating CAC in early wall cloud stage.

Scud condensing and curling under the CAC. Clear slot cutting into wall cloud as lowering becomes more defined. A similar, weaker structure is seen at the left.

I might call it a funnel, but not a tornado despite the dust below. However, this type structure is what usually does tighten up and become the tornado from a northwest flow storm's CAC. Moisture and dirt lifting into the CAC.

The middle of the same structure, with inflow into the rear of the CAC. The shelf cloud front on the now outflow dominant CAC. The next cycle of wall cloud would usually be only a couple of minutes away.

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'Funnel' reaching back into the outflow.
	Rotating CAC in early wall cloud stage.
Scud condensing and curling under the CAC.	Clear slot cutting into wall cloud as lowering becomes more defined. A similar, weaker structure is seen at the left.
I might call it a funnel, but not a tornado despite the dust below. However, this type structure is what usually does tighten up and become the tornado from a northwest flow storm's CAC.	Moisture and dirt lifting into the CAC.
The middle of the same structure, with inflow into the rear of the CAC.	The shelf cloud front on the now outflow dominant CAC. The next cycle of wall cloud would usually be only a couple of minutes away.