Cold front hits South Texas tonight, severe storms are possible

5:30 p.m. Update: A severe thunderstorm watch has been issued for much of South and Central Texas, the National Weather Service announced Sunday afternoon. The watch will stay in effect until midnight Sunday night.

The entire San Antonio metro area is included in the severe thunderstorm watch. Several cities along the I-35 corridor, including New Braunfels, San Marcos, and Austin are also included in the watch, as well as much of the Texas Hill Country.

A line of strong to severe thunderstorms is expected to move into the northern Hill Country by 7 p.m., and it will likely reach the I-35 corridor by 9 to 10 p.m. Areas in the watch area could encounter damaging wind gusts – up to 75 mph – as well as isolated large hail. An isolated tornado is also possible, but the overall tornado threat is low.

Below is the full forecast for Sunday, May 10

It’s Mother’s Day, and if you have plans with Mom, we have some good news.

While there is a high chance of thunderstorms late in the day, most of Sunday is expected to remain dry across South Texas, so any outdoor plans should be good to go. However, hot and humid conditions across the region may make it feel uncomfortable at times.

Big changes are expected Sunday night. A cold front will start moving through North Texas Sunday afternoon before quickly rushing southward. As it reaches South Texas later in the night, a line of thunderstorms is expected to develop, bringing the potential for severe weather, including large hail and damaging wind gusts. Here’s what you can expect.

It’ll be a mild and muggy start to the day as temperatures will likely hover in the low 70s through the early morning hours, rising into the upper 70s to near 80 degrees just after 10 a.m. Skies will be partly cloudy early, but will turn more sunny by the middle of the day.

The heat will become a major factor by Sunday afternoon. Temperatures are expected to reach the 90-degree mark as soon as 2 p.m., before afternoon highs top out between 91 and 93 degrees. Very humid conditions are also expected, resulting in heat index values as high as 97 degrees.

To the north, a cold front will begin to slide through the Dallas-Fort Worth metroplex and Interstate 20 corridor. As the front moves south, it will interact with the humid air and allow strong to severe storms to form alongside it. Storms are likely in the Dallas area as early as 4 p.m., moving into the northern Hill Country by 7 p.m.

The cold front, along with a potential line of storms, will move through the San Antonio metro area between 9 p.m. Sunday and 1 a.m. Monday. While some storms will be weakening, there is still a significant chance of severe weather. Damaging wind gusts, up to 75 mph, are the primary threat, but isolated large hail is also possible.

San Antonio is under a level 2 of 5 risk of severe thunderstorms, as set forth by the Storm Prediction Center. The risk of hail is even higher to the north, where a level 3 risk of severe weather has been issued for Dallas, Waco, San Angelo, and parts of the northern Hill Country. San Antonio’s overall chance of rain is about 70%.

The activity is likely to move through relatively quickly, leaving mostly dry conditions across the region by 2 a.m. early Monday. However, a quick inch of rain is possible, which may lead to isolated street flooding.

The cold front will only result in a subtle drop in temperatures on Monday. Morning lows will drop into the upper 60s before afternoon highs rise into the low to mid-80s. Partly to mostly sunny skies are also expected, along with gusty north winds at 10-20 mph.

Tuesday will bring very similar conditions, albeit with a cooler start as low temps dip into the mid-60s. Afternoon highs will once again rise into the mid-80s, and with relatively dry air in place, the humidity will not be a big factor.

As high pressure starts to develop during the second half of the week, temperatures will rise a few degrees. On Wednesday, San Antonio high temps are expected to reach 88 degrees, rising to around 90 degrees by Thursday and Friday. Hot weather will continue over the weekend, with highs continuing in the low 90s.

Throughout the week, there is no significant chance of rain. That is unusual for the middle of May, which is typically one of the more active times of the year in terms of storm chances. Long-range models suggest that the next decent rain chance will not arrive until at least the May 17-19 timeframe.