5/27/97 TX chase by Craig Green


				Williamson County Tornadoes

	The 27th of May was to be my last day to work before my scheduled
vacation which will complete the week. I had to supervise one of my
stations to be installed in Austin and was halfway expecting some chance
of severe weather after the Red River storms of Monday the 26th. I was
surprised to find that the Storm Prediction Center had issued a moderate
risk for severe weather for central Texas and as Pamela and I packed 
for the Austin trip, we included our chase gear.

	The surface dewpoints were in the 70s with lifted indices in the
-9 to -12 range for central Texas. With backing 30 to 40 knot mid-level
winds from the west, sufficient shear was present for supercell
development. The forcing mechanism would most likely be the weak cold
front which was moving south toward the region. Additionally, the 
presence of weak upper troughs moving over the area would add upper air
support to an already very dangerous situation! 

	Pamela and I drove to Austin early in the morning and kept the
weather on the back burner. After lunch, the SPC issued a watch box for
central Texas which included  Williamson county at the extreme western
end. At about 1400, I logged in for some weather data on the Intermet and
found that some storms were beginning to fire north and NE of Austin. 

	Having completed my mission, we started N, thinking that we could
monitor  NOAA radio and amateur frequencies for guidance. A quick stop at
my usual place in Austin, and a quick peek at The Weather Channel yielded
two storms. One was due north of us in Bell county and the other one was
in east Texas. There seemed to be  no particular concern for the Bell
county storm at about 1500 when we watched TWC, so I decided to head
north and decide later, which is often the case.

	As we drove North on I 35, we began to hear reports of a tornado
in Bell county on the 145.15 machine and decided on the north storm. As
we passed the Georgetown  exits, Many Texas Department of Safety marked
units (Black and Whites) passed us at over 90 MPH. We could see a dark
lowering to the north over I 35 about five or six miles away and as we
reached the 269 mile marker at 1535, traffic stopped on the interstate due 
to DPS roadblocks. Pamela began videotaping the Jerrall tornado which was
now visible about five miles up the road. Not wanting to get trapped on I
35 with what was apparently a large wedge tornado headed south towards
us, I drove through the grass on the right side of the roadway to get on
the northbound access road. We had escape routes to the east and south,
so we drove up to a DPS roadblock at a crossover near the 270 mile 
marker.

	I was just about to explain our spotting/chasing posture to the
officer when, directly across the highway, in a plowed field next to the
southbound service road, large dust whirls began lifting and swirling off
the ground at 1540. About 200 yards away a tornado was spinning up on the
west side of  I 35!  The DPS officer glanced at he weak tornado, uttered
an expletive as he entered his vehicle, and sped away southbound from his
post. This of course eliminated the problem of explaining our actions,  
but presented  another more immediate issue requiring resolution. 

	We continued up the northbound access road taping the dust tube
tornado with a second eye on the big wedge bearing down on us. About 100
yards up the access road a county road slanted off to the ENE and we
drove down about 1/4 of a mile out of harms way. We jumped out of the
chasetruck at 1542 and began our documentation of events. The dust tube
was still grinding away to our WSW and I nervously glanced north. No 
sign of the wedge because a rain area was in the way. Back to our NE was
the big raincore with what was most likely gorilla hail. We continued
taping and clicking away until Pamela said Its Time To Move CRAIG!.
	
	We jumped back into the truck and sped to a 90 degree turn to the
SSE and after about 1/2 a mile we stopped. Above us, back to the west was
the parent cloud of the dust tube which had now narrowed to a skinny rope
with a condensation funnel curving away 45 degree from the cloud base,
extending halfway to the ground. Debris could still be seen moving on the
ground below the tip of the funnel. Looking back to the SW, a new 
mesocyclone was forming with a growing, rotating lowering. Looking toward
the NW, an immense RFD notch was visible which now extended almost to the
new lowering. 

	As we continued taping, with the rain and hail bearing down on
us, a large cylindrical tornado became visible from behind the rain area
at the right edge of the RFD notch. The radial motion of the dying Jerral
wedge was astounding; somewhat like a white barberpole sped up ten times.
The cylinder bent into an elephant trunk and as we continued our
observations, a speeding utility vehicle with flashing grille lights was 
approaching from the NW. The emerging public servant advised us that golf
ball size hail was approaching. Pamela perceived his arrival as a portent
to move, so we headed down the road to a right turn back to the
northbound access road of I 35. 

	We tried to hide under a bridge crossing at mile marker 269 but
the DPS officer  offered to lodge me at the county callaboose if I entered
the onramp. We settled for the crowded underpass at the 268 marker and
found fortune with a spot on the wrong side of  the road. After a ten
minute stay of heavy golf balls, we were evicted by a deputy into 1/2 
inch soft hail.

	Not wanting to join the circus in Austin with the Cedar Park
tornado which we heard on the 146.94 Travis County ARES net, we departed
North at about 1615.

	Another tornadic storm in Limestone county was announced by the
Waco NWS transmitter and we zigzagged to it until it gusted out about
1800. We once thought we saw a rainwrapped cone, but not enough to report
it.

	I believe that the new mesocyclone we saw forming became the Cedar Park 
tornado. While I have no direct evidence other then the direction of
travel of the new wall cloud it seems likely. Perhaps the analysis of
surface tracks and radar data will tell.

			
			Craig A. Green   N5WEH	
*********************************************************************
"It's too close Craig!!!!!" <><><><> "God does not play at dice with
 Spousal and chase partner  <><><><>  the universe!" Albert Einstein
 27MAY97   Supercell        <><><><> "But sometimes HE throws them 
 Williamson County Texas    <><><><>  where nobody can see them."
                                        Stephen Hawking
                     My opinions are my own!!!!
*********************************************************************

Return to Reports Page