6-hour ARI for Rainfall that Produced Flash Flooding in Austin, TX and Surrounding Communities, May 23-25, 2015

The previous week has been incredibly active for the state of Texas, including widespread flooding in Austin, TX and the surrounding area over Memorial Day Weekend.

The surface analysis at 00Z on May 24th (7 pm CDT on May, 23) shows very cold (high) cloud tops across nearly the entire state, with several squall lines embedded within, ahead of an advancing cold front on the Texas-New Mexico border.

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As seen by the mass curve for the storm center, located to the west between Austin and San Antonio, TX, a majority of the precipitation fell in a very short period of time starting during the evening on Saturday, May 23rd. Nearly 10.5 inches of rain fell over a 6-hour period from 2200 UTC on 5/23 to 03 UTC on 5/24 (5pm to 10 pm CDT)

mass_curve_30.0953086504425-98.3480932539683_201513_Zone1

These high rainfall rates at the storm center are associated with a Maximum Average Recurrence Interval (ARI) of over 1000 years! This is to say that, statistically, an event of this magnitude has less than a 0.1% chance of occurring in any given year.  While total rainfall was not nearly as high over the metro areas of Austin and San Antonio, the city of Austin still has Max. ARI values nearing 50-years, which relates to a 2% chance of an event taking place any given year. It is important to note, however, that these ARI values are of the rainfall only and are not indicative of the recurrence interval with the associated flooding.

 

ARI_metstorm201513_6hr_max_ppt

Please note that the data presented here is preliminary and will be updated with final information as all data is available.  If you are interested in this product, or any other product from our MetStorm™ Precipitation Analysis tool, please contact us at info@metstat.com or through our contacts page at http://metstat.com/contact-us/.

Thanks for visiting our blog today! Come back soon for updates to these latest MetStorm™ analyses and for more posts to come!

-MetStat Team

(edited: 6/3/2015 )