A Tornado Watch has been issued for eastern North Texas, Northeast Texas, and portions of East Texas until 11 PM. This watch runs along and east of a Corsicana to Terrell to Greenville to Bonham line to the Arkansas/Lousiana state line. This tornado watch includes Tyler, Longview, Mount Pleasant, Paris, Texarkana, Jefferson, and Marshall. A tornado watch means conditions are favorable for the development of severe weather – including hail up to the size of quarters, straight-line wind gusts up to 70 MPH, and the potential for a couple of tornadoes. It is worth noting these same locations were under a Winter Storm Warning less than a week ago.
Showers and thunderstorms have been developing ahead of a dryline in North Texas for the past two hours. So far this activity has behaved itself, but that could change over the next hour or two. Upper-level lift across West Texas will spread east into the warm sector. Once that lift arrives I do anticipate an uptick in thunderstorm intensity across Northeast Texas and East Texas this evening. I don’t think we’re going to see numerous severe thunderstorms, but the potential is certainly there for a few semi-discrete supercells. Instability values are marginal, but wind shear values are quite supportive of rotating thunderstorms. We’ll have to watch any discrete storms for signs of organized low-level rotation. A couple tornadoes cannot be ruled out, but hopefully, we can keep the tornado threat limited. Once storms grow upscale into a squall line this evening and march east we’ll see the threat of straight-line winds of 45 to 70 MPH increase. Brief tornadoes will be possible within enhanced circulations in the squall line.
Here is the full watch information statement from the Storm Prediction Center. These fine folks are still working even though the government is shut-down.
Tornado Watch Number 1 NWS Storm Prediction Center Norman OK 305 PM CST Sun Jan 21 2018 The NWS Storm Prediction Center has issued a * Tornado Watch for portions of Western Arkansas Eastern Oklahoma Northeastern Texas * Effective this Sunday afternoon and evening from 305 PM until 1100 PM CST. * Primary threats include... A few tornadoes possible Scattered damaging wind gusts to 70 mph possible SUMMARY...Thunderstorms will continue to slowly increase in coverage and intensity this afternoon into this evening from north and northeastern Texas into southeastern Oklahoma and western Arkansas in advance of a strong storm system progressing eastward over the Great Plains. The storm environment will support some threat for semi-discrete supercells for the next few hours, and then convection should gradually grow upscale into more of a squall line tonight. A few tornadoes with the supercells and/or embedded circulations, as well as damaging winds with bowing segments, will be possible.