The Flood of 2010

By Brian Alonzo

Warm moist air coupled with a low pressure system combined over South Central Texas Tuesday night into Wednesday morning. This flood event even turned deadly for one man.A little history first: Last Wednesday June 2, 2010 the San Antonio area was hit hard with a Mesoscale Convective System that blew through causing lots of tree and home damage. It even knocked out power to numerous residents across the city and even took CPS Energy a couple of days to get everyone back up and running with electricity. As this storm left our area it headed to the coast where it turned a bit more severe with a couple of tornadoes that did some damage in the Corpus Christi area.

We forecasted this storm to leave Texas and come back at us. It did just that. It caused flash flooding in the San Antonio, NW Wilson county and New Braunfels area. The main difference between this storm and last weeks storm was that this storm took on more tropical characteristics. It had a lot of moisture to work with from the Gulf of Mexico and this low pressure system was the trigger to cause  lift in the atmosphere to create showers, rain, lightning…the works.  This storm was essentially a cut off low. We call it that because it’s cut off from the main jetstream and goes where ever it wants.

The big concern we saw with this system was that there was the possibility of a “core rain event”. A core rain event is when a low pressure system contracts at night and if the right atmospheric conditions are present, can produce a tremendous amount of rain in a short amount of time.  Sometimes we call them “Rain Bombs”. Remember the Marble Falls flood event back in 2007? That was caused by a rain bomb but nearly 18 inches fell in that event. This one turned out to be around 11 inches.  The problem for forecasters is that you know its going to happen but you don’t know where. They are highly localized. The worry, much like Marble Falls, was that this storm was going to happen at night when people are asleep. It’s situations like these that its always a great idea to get a weather radio. I’ve said this in previous blogs because they can and have saved lives.

Here is how the storms progressed: Watch the areas under the “A” in San Antonio. That was the heavy rain that fell on the Bexar/Wilson county line. Also watch under the “N” in New Braunfels that’s where the second area of heavy rain fell.

A different perspective. Notice how they contract in the overnight hours and spread out during the day.

Here are some rainfall totals courtesy of the National Weather Service:

 NEW BRAUNFELS 5.5 WNW              11.87 INCHES
 NEW BRAUNFELS 5.9 NW               11.30
 NEW BRAUNFELS 7.2 NW               11.00
 BEAR CREEK                         10.92
 NEW BRAUNFELS 5 W                  10.90
 SHADOW HILLS                      10.24
 BRESKY ROAD ON ISAAC CREEK         8.97
 PLEASANTON 5.3 ENE                 7.81
 NEW BRAUNFELS 2.8 NNE              7.71
 NEW BRAUNFELS 2.3 NE               7.55
 NEW BRAUNFELS 1.6 NW               7.25
 NEW BRAUNFELS 2.4 SSW              6.80
 NEW BRAUNFELS 3.1 WSW              6.16
 ELMENDORF 5.6 ENE                  5.26
 CIBOLO 3.9 N                       5.25

San Antonio Area:

 KIRBY .2 WNW                       3.40
 TERRELL HILLS 1 NE                 3.05
 MEDINA RIVER @ 281                 3.01
 RANDOLPH AFB                       2.72
 LIVE OAK 3.8 NW                    2.58
 GARDEN RIDGE 1.8 WNW               2.45

Here is a picture from Vipir 24/7. The radar is underestimating some of the totals by an inch but not that far off:

Click Here for Larger Image

Remember in any flood event, if water is crossing the road….Turn Around Don’t Drown.

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One Comment on “The Flood of 2010”

  1. digg like Says:

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