It’s still raining in Houston. Here’s what areas still flooded can expect

Although flooding concerns persist in Southeast Texas along the rain-swollen Trinity and Brazos rivers, the latest forecast from the National Weather Service calls for more rounds of heavy rain and the potential for severe storms this week , starting Sunday.

The combination of a warm front moving north through Houston and an influx of moisture-laden air from the Gulf of Mexico will cause an increase in precipitable water, or the amount of rain that can be extracted from water vapor in a vertical column of air. Forecast models show the precipitable water level easily exceeds 2 inches.

Between high altitude atmospheric disturbances and a warm front, numerous showers and thunderstorms are expected between now and Sunday midday.

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The effect of Sunday’s rains on southeast Texas’ swollen rivers obviously depends on where the heaviest precipitation occurs. But forecasters give the highest rain chances in Texas counties near and north of Houston, ranging from 80 to 90 percent in Brazos Valley/Piney Woods counties, 70 to 80 percent for counties near Houston. Interstate 10 and 50 to 60%. for areas near the Gulf Coast.

“There is some uncertainty about the exact locations of these storms,” weather service meteorologist Cameron Self said in a forecast statement Saturday. “But generally speaking, the best chance for heavy rain will be north of I-10.”

This Mother’s Day, Houston has an 80 percent chance of thunderstorms that could produce between half an inch and nearly an inch of rain in the city, according to the weather service. If you’re heading out to celebrate with mom on Sunday, prepare for easterly winds of 10 to 15 mph, including gusts up to 20 mph. Rain should help limit afternoon temperatures to around 82 degrees.

Meanwhile, in the suburbs, the weather service issued flood warnings Saturday for areas along river banks in southeast Texas:

• Trinity River near Crockett: As of 8:45 a.m. Saturday, the river was 43.9 feet above mean sea level. The river was expected to fall below flood stage, 41 feet, early Wednesday. The river banks are seen as a complete scene at 35 feet.
• Trinity River at Liberty: At 8:15 a.m. Saturday, the river level was 30.7 feet, or 3.3 feet above flood stage. The river was expected to drop to 30 feet Thursday morning. The banks are considered full at 21 feet.
• Trinity River near Moss Bluff: At 8:30 a.m. Saturday, the stage measured 17 feet. The river was expected to fall to 14.9 feet, or 2.7 feet above flood stage, Thursday morning. The full bank stage measures 9.2 feet.
• Trinity River at Riverside: As of 8:30 a.m. Saturday, the step measured 137.8 feet. The river was expected to drop to 137 feet Thursday morning. The flood stage is 133.5 feet, just half a foot above the full-rim level.
• Trinity River near Goodrich: At 7:45 a.m. Saturday, the stage measured 38 feet. The river was expected to fall below flood stage, 36 feet, Sunday evening and continue to fall to 33.9 feet Thursday morning.
• Brazos River at US 59, Sugar Land: As of 8 a.m. Saturday, the river reached 67.3 feet. The river was expected to peak at 67.5
  feet before falling below flood stage, 65.5 feet, early Tuesday. Its banks are considered full at 40 feet.
• Brazos River near Rosharon: At 8 a.m. Saturday, the river level was 46.1 feet. The river was expected to crest at 46.8 feet Sunday afternoon before falling below flood stage, 43 feet, Wednesday afternoon. The full bank stage measures 42 feet.

Forecasters said they are looking at two windows this week for potentially heavy rainfall that could exacerbate flooding problems in Southeast Texas: Sunday through Monday and Wednesday through Thursday.

“(The Weather Prediction Center) highlights at least part of the area at slight risk of excessive precipitation (threat level 2 of 4) for Sunday and Monday,” Self of the weather service said. “These same windows will also need to be monitored for some storms becoming strong to severe.”

Although “the main concern on Sunday will be heavy rain,” he said, “given the instability and (wind) shear parameters, we cannot rule out locally strong to severe thunderstorms” that could cause large hail and destructive winds.

Sunday’s severe weather forecast calls for a Level 1 of 5 risk in Southeast Texas for scattered severe thunderstorms, increasing to Level 2 of 5 for scattered severe storms on Monday.

Houston’s current forecast for Monday calls for a 70% chance of thunderstorms, primarily after 1 p.m., with mild southerly winds bringing moisture-rich air and helping to push daytime temperatures into the upper 80s.

Tuesday’s forecast for Houston includes the return of sunny skies and unseasonably warm temperatures that flirt with the 90-degree mark.

But after a mostly sunny and dry start to Wednesday, Houston’s rain chance increases overnight by up to 50%. Some of the thunderstorms that develop could produce heavy precipitation.

“At this point, we are too far out and the models are too scattered to be overconfident in the details,” weather service meteorologist Sean Luchs said in his long-range forecast. “But surely the increase in humidity indicates the emergence of another threat of heavy rain locally, even if it appears to be the least significant of the week?

Luchs conceded, “It’s starting to get a little speculative, though.”

“Similarly, speculation would pose a serious threat…so we will have to watch and see how things unfold in the days to come,” he said.