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Creeks rise as rain soaks in

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By Christopher Brooke, Reporter

A National Weather Service hydrologist got an eyeful of Chestnut Creek in Galax and Carroll County after more than three inches of rain dropped from the skies on May 27.

Peter Corrigan drove a dark blue Ford F150 down from the weather service office in Blacksburg to check out a U.S. Geological Service gauge in Chestnut Creek in the city limits. He made the visit to verify reports and improve future forecasts.

After several days of rain throughout Memorial Day weekend, information from the Galax Water Plant shows there was at least a trace of rain 20 days this month, through May 27.

NWS Meteorologist Robert Stonefield said the region is no longer in the drought that has plagued it for many months.

Of the total of 7.62 inches of rain through Wednesday, about 3.25 inches had fallen on that last day alone.

The National Weather Service gauge collects information about the levels of Chestnut Creek once every 15 minutes and sends it to Blacksburg once an hour.

Corrigan wanted to verify for himself what was happening on the ground in Galax, after the creek swelled and water topped both Chestnut Drive and Coal Creek Road in spots.

Both roads were closed for a time Wednesday, but water receded by the time Corrigan arrived to study the situation. "It takes me all day to get to one gauge, basically."

Wednesday, the gauge in Chestnut Creek read 6.63 feet.

That's 11 feet lower than the historic high from flooding along the same creek in 1940, which receded after reaching 17 feet.

Chestnut Creek is one of the few small streams that the weather service gets regular updates from in the 40-county area that Corrigan covers.

He plugs that data into calculations in order to make forecasts about what's happening in the unmonitored bodies of water.

The calculations are intended to show the amount of rain that runs off the mountains into the creeks and how fast a small stream here may fill to overflowing.

It helps to observe the creek and other factors that contribute to the water rising, Corrigan explained.

Many items need to be taken into consideration, such as rainfall rate and duration, but also topography, land use, time of year, existing vegetation and more.

Had this happened in November, when there's less vegetation to slow down the water, there would have been a much more serious flood, for example.

Corrigan had been on duty watching the radar as rain fell around midnight Tuesday. He wondered if he should have issued warnings based on what he was seeing on the instrument.

On Coal Creek Road, Corrigan noticed the wood debris and trash collecting at the bridge at Wards Branch, just before it goes into Chestnut Creek.

He commented on how fast the water ripped along in Chestnut Creek, which rose to take in one resident's clothesline, about 10 or 12 feet from their mobile home, nearby.

A neighbor here said the rain gauge at their home read four inches.

It was here that the Galax Fire Department received a report of a vehicle stuck in water Wednesday morning.

Corrigan could also see exactly how high the water got by the crushed-down grass on the creek embankments.

"So, yeah, this is a pretty good little washover," Corrigan said, looking at the mud still caked on the road where the little branch met the brown, rushing creek. "I think this would be called a missed event."

But the rain looked light on the radar, he said. However, radar tends to underestimate the rain from tropical air mass like the one responsible on this occasion.

What he saw in Galax made Corrigan believe a warning should have been issued, as minor as the flooding here may have been.

The National Weather Service issues warnings when waters overtop roads. As part of the agency's "turn around, don't drown" campaign, they tell drivers to find another route whenever they encounter water on the roadways.

"You don't need that much to wash a car away," he said. "You only need a couple feet."

Flooding is the number one cause of weather-related deaths, Corrigan noted.

It's called a "flash flood" if it occurs in less than six hours. It's just called "flooding" if it occurs in more than six hours.

Looking at the creek and taking photos will help him understand what happened and how they can use the information to help make a better forecast next time, he said.

Corrigan will combine what he witnessed with more collected information to try and improve the process.

The Twin Counties — and all of Southwest Virginia — have had a lot of precipitation in the last month. Corrigan feels certain that it's already one of the six wettest months of May since record-keeping began in 1952.