We continue to keep an eye to the sky early this afternoon. The atmosphere across Central Texas has become extremely unstable and supportive of explosive thunderstorm development. However the cap is still putting a lid on things for now. I do expect that we’ll likely start seeing a few discrete storms developing by 5 PM in the eastern Hill Country and into parts of Central Texas. Determining exactly where the first storms will fire is difficult until we start seeing signs of agitated cumulus on visible satellite. An outflow boundary from storms earlier today has set up shop south of the D/FW Metroplex and can easily be seen on visible satellite as a line of clouds from Stephenville east to Hillsboro and Corsicana. This outflow boundary could play a role in storm behavior later today as it may locally enhance the severe weather parameters with any storms that approach it.
The strongest storms today will be capable of producing destructive hail up to the size of baseballs along with damaging wind gusts over up to 70 MPH. One or two tornadoes are possible with the most intense supercells. Later this evening at least one cluster of storms may impact portions of Central Texas into the Brazos Valley and Southeast Texas. The cluster of storms would have less of a hail threat but an enhanced damaging wind threat should it develop. Today is a nowcast type of day where we have to wait until storms actually begin to develop to see how things will play out today. For the moment the clouds across the D/FW Metroplex and North Texas are keeping the severe weather threat lower compared to further south where temperatures are approaching 90 degrees in spots. Should the outflow boundary south of D/FW start to move north (retreat) there could be rapid airmass modification and an associated increase in the severe weather threat in areas where it’s cool and cloudy at the moment. We’ll keep an eye on that possibility.
Once the first thunderstorms develop this afternoon they will likely do so explosively. Extreme instability and adequate wind shear will promote rapid development and organization of storms. Storms will slowly move east/southeast with the most intense storms producing destructive hail, damaging wind gusts, and perhaps even a tornado or two. With such extreme instability in place we have to keep an eye out for storm rotation even with the weaker low level wind shear. In some cases the extreme instability values can compensate some for weaker wind shear when it comes to low level rotation. We’ll see how trends play out over the next 90-120 minutes. I expect the Storm Prediction Center will issue a discussion sometime in the next hour or two describing when they plan on issuing the first watches of the day. I’ll plan on posting another update in the 3 to 4 PM timeframe or sooner if necessary. For the severe weather outlook graphics I posted a bit earlier before the server had a hiccup head to my noon update here.