Heavy Rain Could Overwhelm Louisiana Streets Through Monday Afternoon

(KMDL-FM) Forecasters with the National Weather Service say a deep plume of deep tropical moisture is sliding up and over Louisiana this morning. This abundance of moisture and instability in the atmosphere will produce a significant risk of torrential downpours and flooding rains across almost all of Louisiana today.

Louisiana Motorists Could Face the Biggest Risk in Storms Today

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Perhaps the biggest concern with today's potential excessive rainfall risk is flash flooding on city streets. The Weather Prediction Center has placed almost all of Louisiana south of Alexandria in the slight risk category for an excessive rainfall event today.

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An excessive rainfall event is when rainfall rates exceed a municipal drainage system's ability to drain the stormwater away. In cities such as Lafayette, we have been told the drainage system was designed to handle rainfall rates of two inches per hour, but not for several hours.

When is the Heaviest Rain Most Likely to Fall Today?

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The National Weather Service Forecast Office in Lake Charles is suggesting that the greatest chances for rain along the I-10 corridor in southwestern Louisiana will come after sunrise but before 5 pm. Rain chances will taper off when the sun goes down, only to rebound again on Tuesday.

The NWS Forecast Office in Lake Charles has prepared the graphic below that explains the potential rainfall accumulation.

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The left side of the graphic is the most likely rainfall scenario. In that case, you can see rainfall amounts of 1.5 inches to 2 inches should be common. However, the right side of the graphic shows the potential for what could happen with rainfall amounts projected much higher.

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The Storm Prediction Center is not forecasting any severe storms in this current round of rainfall. So, we do have that going for us. However, we can't rule out gusty winds and frequent lightning during some of the stronger showers or storms that could move across the area during the day today and on Tuesday.