Rainy Mother’s Day in Houston. Here’s how the flooding could get worse

If you’re hoping for a dry and slightly less muggy start to the weekend, Saturday offers a good forecast. But this kind of weather won’t last much longer. Rounds of heavy rain return Sunday and could exacerbate flooding along swollen rivers in southeast Texas.

With a high atmospheric pressure system over Texas on Saturday, we will benefit from its downward airflow and dry weather. Of course, a few storms this time of year are still possible along coastal sea breezes during high pressure, but that won’t be the case Saturday.

Partly cloudy skies are expected throughout the day, with afternoon temperatures generally peaking in the low to mid 80s. You’ll still notice some humidity in the air, but nothing like this to what we experienced earlier this week.

On Saturday, the wind direction changes as high pressure gradually slides eastward. Eventually, winds will shift from east to southeast as high pressure moves away. This increasingly humid air introduced due to the change in wind direction will trigger chances of isolated showers Saturday evening, particularly west of Interstate 45.

Earlier this week, a cold front moved through Houston on Thursday. It was really more of a “a little cooler” facade than “cold”, but we’re not going to split hairs. This same front will reverse course and move north through Houston – this time as a warm front – through Sunday. This will cause the scorching air to return in time for Mother’s Day.

Between the upper altitude atmospheric disturbances and the warm front pushing north of Houston, numerous showers and thunderstorms are expected by Sunday noon.

Sunday’s precipitable water readings — or PWAT, which measure the amount of rain that can be extracted from water vapor in a vertical column of air — are expected to easily exceed 2 inches, according to the National Weather Service.

“Taking into account the water and synoptic parameters, areas of heavy rainfall will unfortunately lead to a new risk of flooding.” the weather service said in a forecast statement Friday, adding that widespread precipitation totals are expected to be in the range of 1 to 4 inches, with the highest flood risk being for those north of Interstate 10.

For those leaving the house to celebrate Mother’s Day, you will still need to plan accordingly and have rain gear with you while you travel.

Given the amount of rain that has fallen recently, another 1 to 4 inches will only serve to worsen flooding along local rivers still swollen from last week’s heavy rains.

The East Fork of the San Jacinto River near New Caney, the Trinity River from Riverside to Moss Bluff, and sections of the Brazos River in Brazos County are still higher than normal.

Much of Southeast Texas along and north of I-10 is under a Level 2 of 4 flash flood risk through Monday morning. This risk area shifts slightly eastward through Monday afternoon as heavier rains move toward Louisiana and off the Texas Gulf Coast.