Saturated ground is a concern leading into Memorial Day weekend

Austin roads coated in rain as drivers commute into the city (KXAN Photo/ Julie Karam)

AUSTIN (KXAN) — Memorial Day 2016 could have another wet forecast. Central Texas has a 50 percent chance of seeing above-average rainfall from May 27 to June 3.

In fact, Texas has the greatest chance to see more rain than usual compared to any other state in the U.S. over this period. The news is unwelcome for many, as the deadly Memorial Day floods from 2015 are still a very raw memory. 12 people perished in the floods last year.

This April was the wettest April in 40 years.

Friday is the first day in a week and a half that no rain is expected to fall in Austin. This week alone has had two flash flooding events, where more than three inches of rain fell in spots across Central Texas. We’re already more than two inches ahead of schedule for the month of May, which is traditionally one of our wettest months each year. Unsettled weather patterns are more common in May, as waves of energy sweep through the state from low pressure that drops south of the Rockies.

All of this recent rain means our soil is saturated. With so much water in the soil, runoff happens quickly. It doesn’t take more than another one to two inches on any given day to trigger a Flash Flood Warning.

This year doesn’t have quite the same conditions as 2015, but in some ways, 2016 has been worse. This April was the wettest April in 40 years, topping gauges at 7.12″. That’s more than three times the rainfall we got during last April. However, even with near-constant rain chances, this May so far has seen only about half of last May’s rain, 4.69″ compared to 9.30″.

When you put the numbers side-by-side, last April and May through this day and this April and May so far, 2016 actually ranks higher: 11.81″ compared to 11.61,” though the difference is slight. Conditions are essentially equal with 2015 as we edge closer to the holiday weekend.

Though low, there are rain chances starting tomorrow and extending all the way through the seven-day forecast. Rain totals appear to be only 0.50-1″ in the next week, but it doesn’t appear that consistent dry time will take place between now and the holiday weekend.

Nick Hampshire with the National Weather Service says that sunny days with winds 10-15 mph will be most efficient at drying out our soil. The Hill Country tends to dry out faster, as bedrock is only a few inches below the soil. That means the soil can’t hold much water, though, which is one reason flash flooding occurs so quickly. East of I-35, the soil is more clay, and it’s deeper. That means that eastern counties can take more water initially, but it also means it takes longer for them to dry out, even with sunny days on tap. Therefore flash flooding is just as likely east as it is west in the coming days.

Hampshire says the NWS isn’t currently predicting the same magnitude of storms over last year: “We don’t see anything that’s going to be widespread, heavy rain like we saw last year on Memorial Day. But all it takes is one thunderstorm over an already-saturated area to produce localized flooding, and that’s one thing we’ll have to definitely watch for over the next couple of weeks.”

Last year wasn’t the first that deadly floods hit Central Texas over Memorial Day weekend. The flash floods of 1981 killed 13 people and created more than 35 million dollars in damage in Austin.

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