July 21 – Go Away!

Today’s factismal: It once rained for 45 days straight in Texas.

One of life’s little ironies is that sometimes you get more than you asked for. That was the situation in Texas in 2007. For three years, the state had been in a steadily worsening drought. Lakes and reservoirs were empty. Water rationing was in effect across the state. Wildfires had turned two million acres of land into the world’s largest impromptu barbeque. By August of 2006, more than 90% of Texas had slipped into drought; for three-quarters of the state, the drought was exceptional or severe. All told, the dry weather caused more than $4 billion in damages. Texans were desperate and praying for rain.

And in late March 2007, Texans thought that their prayers had been answered. Texas and Oklahoma were nestled between two parallel high pressure belts in the atmosphere that kept a low pressure zone centered on them.  A continual stream of moist air from the Gulf of Mexico made its way up to the low pressure zone and fed rain clouds. And so the rains came in and stayed. Every day, for 45 days, it rained. Some days only saw a light drizzle. But others had rainfalls of an inch or more. Lakes and reservoirs refilled. The ground was soaked and saturated with water. Flood damage took the place of drought. And still the rain fell.

A radar image of the storm that ended the 2007 Texas floods (Image courtesy USWS)

A radar image of the storm that ended the 2007 Texas floods
(Image courtesy USWS)

The rainfall continued for 45 days and nights. And when it finally stopped, it did so with a bang. On June 27, 2007, a massive rainstorm hit central Texas. Over just six hours, more than 18 inches of rain fell at Marble Falls – nearly as much as had fallen in the month previous! That sudden “rain bomb” caused flash floods that took the lives of thirteen people and did millions of dollars in damage. Streams and rivers had record flow levels. Flash flooding was everywhere. By the time it was over, Texas had suffered it’s ninth worst flood.

An view from above teh floodwaters (Image courtesy Tony Gutierrez/Associated Press)

An view from above teh floodwaters
(Image courtesy Tony Gutierrez/Associated Press)

But the most amazing thing about the flood was that it was predicted and people were warned. Thanks to data collected by the National Weather Service and by hundreds of citizen scientists in Texas, forecasters had known that a major storm was coming since the day before and had warned the public about the danger. Thanks to that warning, what could have been a major disaster was just a huge one. If you’d like to help the National Weather Service prevent the next big disaster, why not join CoCoRAHS? This group hosts automatic rain gauges in their backyards and reports the data to the NWS, where it gets added into models predicting unusual rain events like the Marble Falls rain bomb. To take part, flow on over to:
http://www.cocorahs.org/

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