Friday, September 23, 2005

Rita Could Stall And Flood Texas

As I have been saying for a day or two, it looks very like Hurricane Rita will stall inland somewhere West to Southwest of Dallas and loiter for two or three days. The most recent National Hurricane Center prediction says:

AFTER LANDFALL...THE GUIDANCE BECOME VERY DIVERGENT AS HIGH
PRESSURE BUILD TO THE WEST AND POSSIBLY NORTH OF RITA. GIVEN THE
SPREAD...THE FORECAST TRACK WILL CALL FOR LITTLE MOTION AFTER 72 HR
JUST AS THE PREVIOUS FORECAST DID. THIS STALLING WILL POSE A
SERIOUS RISK OF VERY HEAVY RAINFALL WELL INLAND.


And looking at the NHC maps, the 5-day cone prediction isn't a cone at all but a perfect circle.

Ed Rappaport, the Deputy Director of the NHC, yesterday called the potential for the storm to stall his No. 2 concern, after the more immediate threat of coastal devastation. He added that Rita could dump up to 25 inches of rain inland.

This is what happened in Dallas last July after just one foot of rain. However, this time the rainfall will be prolonged and spread over a very wide area - perhaps as much as 200 miles in diameter.

So far, the media and FEMA seem to be focussed on landfall, where one heck of a lot of damage is going to be done.

A study performed last year by the engineering firm Dodson & Associates found that a Category 5 storm could inundate 369 square miles of Harris County, which contains Houston and some of its suburbs. The study estimated the total cost of a worst-case storm at $80 billion, with 75 percent due to flooding and the rest from wind damage.

You're looking at the southeast quadrant of the city of Houston, from downtown to Galveston Bay, being underwater," said Chris Johnson, president of Dodson & Associates.

That area is home to about 700,000 people, 15 percent of the metro population.
...
In Galveston, Texas, where the deadliest hurricane in U.S. history killed up to 8,000 people in 1900, flooding is a virtual inevitability.

"Galveston is going to suffer," city manager Steven LeBlanc said at a news conference Thursday.

The city is protected by a 16-foot seawall specifically designed to block incoming storm surges. But some forecasters said Rita could pound the barrier with waves twice that high.


But I am more and more worried that no-one is thinking about and taking precautions to deal with catastrophic inland flooding too.

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