As you can see by examining the composite radar image above (click image to enlarge), two primary bands of thunderstorm activity exist at this hour across Texas. One is located from the Dallas area on Northeast into southeastern Oklahoma. The other arcs from near San Antonio through Hays County into eastern parts of Austin, then Eastward through the Bryan/College Station area.
There is some threat of hail with the storms along the Red River at the moment, but heavy rainfall is quickly becoming the main concern.
This is particularly the case with the cluster of persistent heavy rain and thunderstorm activity bounded by a line from Cameron to Franklin to Madisonville to Bryan/College Station to Caldwell and back to Cameron (within the white circle on the radar image below):
Radar estimates indicate that 5-6 inches of rain have fallen across this region in the last 2-3 hours, and rain continues to fall at a rate of 1.5-3.0 inches per hour, particularly between Franklin and Caldwell.
Folks living in this area should move to higher ground if you live in a flood prone or low-lying area. If you must travel across this region over the next several hours, remember to never drive across a water covered road - no matter how shallow the water appears to be.
Meanwhile, further West, a cold front and dryline are advancing East / Southeastward toward the I-35 corridor at this hour:
Additional thunderstorm development is likely to take place along this boundary as it approaches the I-35 corridor from Austin through San Antonio toward Midnight.
Very heavy rainfall and dangerous lightning will be the primary severe weather threats with this activity. A few of the stronger storms may be able to briefly produce hail and/or wind gusts to near severe limits, especially in the early and middle stages of development from near Midnight through 2am CST.
Widespread rainfall of 1-2 inches can be expected, with localized amounts near 5 inches in heavy, persistent thunderstorm activity:
Once developed, this activity will likely continue Eastward into the areas already experiencing flash flooding across east-central and southeast Texas overnight, further aggravating that situation.
A Flash Flood Watch is in effect overnight for much of southcentral and portions of southeast Texas, including the Austin-San Antonio metro areas.
If you enjoy reading 'The Original Weather Blog', please be sure to "like" our facebook page.