Published: July 26, 2007 11:02 am      

Rain & Risk

Be alert, weather expert advises

San Marcos — Water, it’s everywhere. Falling from the sky as if buckets had been upended, creeping across lawns and roadways and gushing through ditches as streams and rivers near flood levels.

Oh, and it’s bubbling up from the ground too, as long-dry springs have come back to life.

The wet period Central Texas has been experiencing might yet break records. Regardless, residents need to keep a close eye on changing conditions, says a meteorologist with the National Weather Service’s New Braunfels office.

“It looks like the upper low (pressure) will continue for the next several days, and we also have a tropical system in the Bay of Campeche moving this way that may add to rainfall amounts,” said Joe Arellano. “The wet pattern will continue through at least the weekend.”

Arellano said the tropical system now drifting north along the Mexican shore isn’t expected to develop into a tropical storm or hurricane — but that hardly matters.

“Even if it stays a tropical wave and moves ashore it will bring that much more moisture to the area, it will only add to what we’re getting right now.”

This January through July has been the second-wettest the area has seen, with only 2002 ahead, Arellano said.

“Some sites have already exceeded their annual rainfall. San Antonio has, and Austin has gotten more than a year’s rain in the first half (of this year),” he said. “Add an active tropical season, and we could be looking at some pretty close calls coming up over the next couple of months.”

Noting that the low-pressure system has been a “very efficient” rainfall producer, Arellano said residents along streams and rivers should be particularly watchful.

“If you live in an area that’s flooded before or if you live close to a river, you need to keep very close tabs on what’s happening. Soils are so saturated and rivers, streams and lakes at capacity that it doesn’t take very much to create flooding. So keep very close tabs and be prepared to move to higher ground.”

Residents along the Blanco River and lower San Marcos rivers know that lesson very well, with many turning to the Internet for the latest on how much the water has risen or gone down.

On Monday and Tuesday, for example, the Blanco at Wimberley saw three peaks. On Monday at 8 p.m. the U.S. Geological Service gauge measured a flow of 4,630 cubic feet per second (cfs) with a gauge height of 8.92 feet.

Tuesday at 3:30 a.m., the Blanco at Wimberley was flowing at a rate of 5,690 cfs at a gauge height of 9.65 feet; at 6:15 p.m. that day it was 5,590 cfs and 9.58 feet.

As a point of reference, that gauge was flowing at 88,500 cfs with a gauge height of 28.05 feet on Oct. 17, 1998 and at 108,000 cfs with a gauge height of 29,89 feet on Nov. 15, 2001.

The watershed measured at that gauge encompasses 355 square miles.

“We’re seeing one of the wettest years we’ve seen in a long time,” Arellano said.

“We were in probably one of our worse droughts before this rain started. They say all droughts in Texas are ended by a flood. That’s what we’ve been through this year.”



amiller@sanmarcosrecord.com