Flood risk to escalate across Gulf Coast states into next week

AccuWeather meteorologists are monitoring a new setup for heavy rain and possible flooding in parts of Texas and much of the Gulf Coast region from later this weekend to early next week.

The downpours of greatest concern will occur after severe thunderstorms visit parts of the region this week, and a break of dry weather will follow.

After spotty severe thunderstorms moved through into Wednesday night, more concentrated showers and thunderstorms will drench northeastern Texas on Thursday.

While Thursday's downpours will not repeat the deluge that occurred last week when 7-14 inches of rain poured down in a few days, a general 1-2 inches of rain is in store with local amounts of 2-4 inches. That can be enough to slow the recession on some rivers in the region and bring small streams quickly out of their banks again.

The Trinity, San Jacinto and Neches rivers all surged to major flood levels following rainfall up to 30 inches in the last 30 days in part of their basins.

Friday to Saturday will be mainly dry over much of central and northeastern Texas. That dry stretch will expand to much of the Mississippi Delta region and the Southeast states into the weekend.

The break in the rain will help with cleanup operations in the wake of the recent severe weather events over the region.

One or more storm systems will travel from South Texas to the northern Gulf of Mexico and tap into the moisture influx.

"A southeast wind will develop and bring a fresh surge of rich Gulf moisture back into the southern Plains, setting the stage for another potential period of wet weather which will last into early next week," AccuWeather Meteorologist Joseph Bauer said.

Severe weather cannot be ruled out, but the main concern is torrential downpours that can potentially renew flooding or trigger flooding in some areas that have been spared so far this spring, Bauer said.

Downpours will occur from central Texas, eastward to Houston from Sunday to Monday, then along the Interstate 10 corridor in Louisiana, including New Orleans, and on to Tallahassee and Jacksonville, Florida from Monday to Tuesday. How far inland the heaviest rain extends beyond I-10 or where the most intense band sets up will depend on the track of the storm moving along from west to east.

Should the downpour pattern develop to its full potential, a general 2-4 inches of rain may occur, with double those amounts possible locally. Where the heaviest rain falls, streams and secondary rivers will surge and flooding will commence or resume. The flood-ravaged area of northeastern Texas will be watched closely for potential impacts from the wet setup Sunday to Monday. Additional rounds of rain may occur on Tuesday and Wednesday in part of the same area.

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Heavy rain across the Mississippi Delta region will not trigger flooding on the lower part of the Mississippi River. Rising water levels on this part of the Mississippi River are the result of heavy rainfall on portions of the Missouri, Illinois, Ohio and upper Mississippi basins in recent weeks.

However, should downpours focus on the region, urban flooding can occur in the metro areas, including New Orleans. The Big Easy has dried out a bit as of late with rainfall of about 25% of the historical average since April 15, but during the prior six weeks or so, nearly 15 inches of rain fell, which was about two times that of the historical average.

It is a similar story in Tallahassee, Florida, where rainfall since April 15 has been less than 5% of the historical average. During the period from March 1 to April 14, 15 inches of rain fell, which was 210% of the historical average.

Downpours may reach some locations that really need the rain. Soil conditions range from abnormally dry to extreme drought in parts of southern and central Texas, according to the United States Drought Monitor.

"While it's early to get too specific on where the heaviest rain will fall, this event does look to include central to southeastern Texas, which could bring much-needed rain to the San Antonio to Corpus Christi corridor," Bauer said.

Another patch where rain is needed is across central portions of the Florida Peninsula, where pockets of moderate drought exist.

The bulk of the downpours from Monday to Tuesday may stay north of the zone from Tampa to Orlando, AccuWeather Senior Meteorologist Dave Houk said. Enough rain may fall on parts of the Florida Panhandle and the northern part of the peninsula to trigger localized flooding early next week.

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