Flood-Fatigued Texas, Louisiana Await More Rain and Severe Thunderstorms

Jon Erdman
Published: May 15,2016
Once again, a threat of flash flooding and severe thunderstorms loom over the next several days in parts of Texas, Louisiana, and other parts of the Southern Plains and Gulf Coast, weary from what has been a 12-month siege of flood events.
Heavy thunderstorms have already caused some flooding in central and southeast Texas this weekend. On Saturday, water rescues from vehicles were reported on the southwest side of Houston in Bellaire, Meyerland, and Westbury. Locally 4-5 inches of rain fell in the area during a short period of time.
(MORE: Is Houston America's Flood Capital?)
Below is a look ahead at the flooding and severe weather threats into the new week ahead.

Setup

A series of disturbances will track through the Southern Plains in the week ahead as the southern branch of the jet stream becomes more active.
By mid-late week, a more pronounced upper-level southward dip in the jet stream will swing out of the Desert Southwest into the Plains, triggering what should be the most significant round of thunderstorms in the Southern Plains, Lower Mississippi Valley, Deep South and Gulf Coast mid-late week.
A persistent south to southeast wind off the Gulf of Mexico will provide a plethora of moisture to fuel thunderstorm development. Therefore, any storms that form will have the potential to dump very heavy rainfall.

The setup for repeated rounds of thunderstorms with locally heavy rain in parts of the Southern Plains and Gulf Coast over the next several days.

Parts of Texas and Louisiana are already flood-fatigued after April's flood and several other floods over the past year, and they do not need anymore significant rain.

Flood Threat

The threat for locally heavy rainfall from thunderstorm clusters has already begun from parts of the Rio Grande Valley of central Texas into southeast Texas.
Then, as another cold front drops south and stalls out Tuesday, more rounds of thunderstorms with heavy rain are expected to occur each day and evening through Thursday or Friday from the Southern Plains into the Deep South and Gulf Coast.
(MAPS: 7-Day Rainfall Forecast)
Through late week, the greatest heavy rain threat appears to be in central, north and east Texas into parts of Louisiana, though some heavy rain may also fall as far north as the Ozarks and east into the Deep South.
(FORECAST: Houston | Austin | San Antonio | Dallas)

Forecast Rainfall Into Late Week

Severe Threat

Severe weather is also a possibility across the region. The atmosphere will be very unstable with plenty of moisture to work with, so the strongest thunderstorms could produce damaging winds (58+ mph), large hail (1 inch diamater or larger), and tornadoes.
A major outbreak of severe weather with dozens of tornadoes is not expected, however.

Latest Radar, Watches and Warnings

(MORE: View National Interactive Radar Map | Difference Between a Watch and a Warning)
Here's and overview of where severe storms could develop the next couple of days.
Sunday:

• A few severe storms are possible in eastern New Mexico and southwest/south Texas.
• Large hail and locally damaging winds are the main threats.

Monday:

• Scattered severe storms are expected from extreme southeast Colorado into parts of Oklahoma and Texas.
• Large hail and damaging winds are the biggest threats, though a tornado or two cannot be ruled out.

Monday's Thunderstorm Forecast

Tuesday: 

• The greatest chance of severe storms will be in central and eastern Texas. This could include a large thunderstorm complex that may sweep through parts of the state.
• Once again, damaging wind gusts and large hail are the main concerns, though there is the possibility of a few tornadoes.

Tuesday's Thunderstorm Forecast

How Wet has it Been?

Houston has received over 74 inches of rain in the past 12 months, placing it as the wettest 12-month period ending on May 12 of any year.
This shatters the previous record for this period of 68.25 inches by about 6 inches. Houston currently sits at 24.8 inches of precipitation above average for this 12-month period, with Abilene, Dallas, and Austin also 20 to 25 inches above average over the past 12 months.
Some rivers in east Texas, Louisiana and Arkansas are still above flood stage, and soil moisture remains much higher than average in these areas, meaning even relatively brief heavy rainfall may quickly run off and trigger flash flooding.

MORE: Texas Flooding April 2016