The above visible satellite image was taken a short time ago. I have drawn two boundaries on the image, the first, in yellow, is a surface dryline. The second, in red, represents the leading edge of cool air that was blown out of nighttime thunderstorm activity along the Red River, and is now moving Southward.
Thunderstorms are already trying to develop along the dryline to the West of San Antonio, as shown on the radar image below:
It may take another couple of hours for this part of the dryline to become active, but plenty of sunshine to the East of the boundary over southcentral Texas is making the atmosphere very unstable. Once thunderstorms persist and break through a capping inversion that is present across the region, they will rapidly become severe. This process will be aided by the arrival of energy from an upper-level disturbance to the West by early afternoon.
Based on present trends, thunderstorms may threaten the I-35 corridor from San Antonio through Kyle and Buda to Austin anytime after 2pm. In particular, the time period of 3-5pm appears vulnerable. If the dryline were to make a move Eastward more rapidly than currently expected, this timing may be earlier.
Folks living across southcentral Texas, including the Austin-San Antonio corridor along I-35, should remain alert this afternoon. Take a few moments to review severe weather safety tips now, and have a sheltering location in mind should severe weather threaten your area later today.
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