Roanoke Times
                 Copyright (c) 1995, Landmark Communications, Inc.

DATE: FRIDAY, August 19, 1994                   TAG: 9408190092
SECTION: VIRGINIA                    PAGE: A1   EDITION: METRO 
SOURCE: MEGAN SCHNABEL STAFF WRITER
DATELINE:                                 LENGTH: Medium

MOUNTAINS REDUCE ODDS OF TWISTERS, BUT VALLEYS NOT IMMUNE, EXPERTS SAY

They make fairly effective tornado busters, too.

Consider this: From 1953 to 1990, 240 tornadoes hit Virginia. Only four of those were in the mountain-ringed Roanoke Valley and only one was in the New River Valley.

Coincidence?

No: meteorology and geography, say local weather experts.

Seems the same peaks that provide such breathtaking views also break up the circular weather patterns that spawn tornadoes, according to Chip Knappenberger, a climatologist at the state Climatology Office in Charlottesville.

Would-be twisters that might wreak havoc on smoother terrain tend to spin out and dissipate over uneven landscapes, he said.

The mountains don't necessarily stop tornadoes from developing - the funnels form up in the clouds and, as Knappenberger said, "The cloud doesn't really know there's a mountain down there" - but they do reduce touchdowns.

Knappenberger added, though, that the numbers may be a bit skewed because recording tornadoes in sparsely populated, mountainous terrain is a bit more difficult than in the flat Midwest.

"If a tornado happens in Kansas, someone's going to see it," Knappenberger said. "It's hard to see very far in the mountains."

Because a tornado has to be verified by the National Weather Service to be counted, the actual numbers of hill-terrain twisters may be somewhat higher than the published figures, Knappenberger said.

Verification by the National Weather Service doesn't require funnel-cloud sightings but is based on damage surveys conducted after the storm passes, said Rich Kane, a meteorologist at the recently opened National Weather Service station in Blacksburg.

Kane said the Martinsville twister presented a classic example of tornado damage: a clear-cut path, evidence of counterclockwise winds, twisted trees, rocks hurled through windows.

Although a tornado watch issued Tuesday night by the Severe Storms Forecasting Center in Kansas City covered the Henry County area and gave Martinsville residents some warning, predicting tornadoes with conventional radar systems is difficult, if not impossible, Kane said.

A new Doppler radar system scheduled to be operating in Blacksburg by February will improve dramatically the ability to predict twisters, he said. Unlike conventional radars, Doppler systems show the rotation as well as the intensity of storms, making it much easier for meteorologists to pinpoint funnel clouds.

Right now, the nearest Doppler systems are in Sterling and Wakefield, both just out of range of Martinsville. If the Blacksburg radar had been up and running early Wednesday, the Weather Service easily could have predicted the Martinsville tornado, Kane said.

As it was, the storm that spawned the twister appeared no more ominous than any other storm cell on the conventional radar screen, he said.

Although Southwest Virginia has been fairly protected from tornadoes in the past, Kane emphasized that the area is not immune to the destructive storms - as shown by the Henry County tornado.

Bearing that in mind, here are some tornado season tips from Charles Edwards at the National Weather Service station in Roanoke:

When a tornado warning is issued, go to a basement if you can. Stay there until the warning officially is called off.

If you can't reach a basement, get underneath a heavy, sturdy piece of furniture.

Tornadoes usually travel from southwest to northeast, so try to stay in the north or northeast portion of your house.

If you're outside and see a tornado coming, do not try to outrun it. Lie down in a low spot, but not one that will be flooded easily.