How Flash Flooding Could Impact Louisiana This Weekend

(KMDL-FM) The National Weather Service has issued Flood Watches for portions of Louisiana and Texas for the early morning hours of Friday. And, it looks as if those watches could be extended to cover even more of the state as a series of disturbances is forecast ot enhance the threat of heavy rain and the potential for flooding across all of Louisiana and the Gulf South today.

The Weather Prediction Center has placed almost all of Louisiana at some risk for an excessive rain event today. What that means is that forecasters believe some of the showers and thunderstorms forecast to move over the area could create rainfall rates that will temporarily overwhelm municipal drainage systems.

Staff Photo

How Much Rain Can Lafayette Drains Handle Per Hour?

In many cases, drainage rates for cities in Louisiana are capable of handling a rainfall rate of two inches per hour, but only for about an hour. The city of Lafayette says its system can handle a rate of 3.5 inches per hour. If the rainfall rate is heavier, the storm lasts longer, or the drainage system has been compromised with trash or debris, then street flooding could begin even sooner.

Forecasters are not anticipating a major rainfall event, as in copious amounts of rain over the next 24 hours; the greater concern is a large amount of rain in a short period of time. That is where Louisiana residents would likely see any issues with flooding, if they see any at all.

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When Will the Heaviest Rain Fall in Acadiana, South Louisiana Today?

Based on the forecast models, the timing of today's heavier rainfall appears to be shaping up this way, this is according to the HRRR Model. You can see an animated run of that model on the KATC Television website. It does appear as though Acadiana will be under the gun around 10 this morning, again shortly after the lunch hour, and then again in the early evening between 6 and 9.

Breyanna Lewis via KATC.com

These sudden increases in shower and thunderstorm activity are connected to impulses of energy in the atmosphere that are sliding along a frontal boundary that has stalled over South Louisiana. The good news is that this system is expected to move out of the area late Friday night and early Saturday morning.

The Storm Prediction Center is not forecasting a severe weather outbreak for South Louisiana in association with this storm threat. The greater concern does appear to be heavy rainfall and the potential for flash flooding and street flooding in heavy downpours.

For those planning to attend the Breaux Bridge Crawfish Festival, you'll want to monitor the festival's social media pages for event postponements and cancellations should those be necessary later today or this evening. The outlook for the rest of the Festival Weekend is good, although it will be considerably cooler when compared to temperatures of the past few days.