Dangerous thunderstorms likely tomorrow
Here are excerpts from this afternoon’s advisory issued from Columbia by the state’s severe weather official, Frank Strait:
“Signs continue to point toward an active weather day tomorrow with the risk of dangerous thunderstorms. A storm now centered over West Texas will be the culprit.
If you pick a hazard, this storm is causing it somewhere today. Areas from the Texas South Plains to Ohio will get a winter storm through tonight, then snow and ice will hit most of the Midwest and Northeast tomorrow. Meanwhile, severe thunderstorms with tornadoes will affect the Gulf Coast from Texas to the Florida Panhandle today and tonight. There are also flooding concerns in Southeast Texas and much of Louisiana today and tonight. Expect delays if you have travel plans to any of these areas.
The storm’s center will track from Texas to Lake Erie through tomorrow, which keeps South Carolina on the warm side of this storm. Cold air damming will keep the I-85 Corridor chilly tomorrow, while warm and humid air surges into the rest of the state. The warmth and humidity will fuel a line of thunderstorms crossing the state in advance of an approaching cold front. Storms will reach the Upstate early in the day and press eastward through the Midlands around midday, then toward the coast in the afternoon.
There are two primary hazards tomorrow. The first is gusty wind, which will be a problem even outside thunderstorms. Wind will increase to the 15-30 mph range late tonight over the areas not shielded by cold air damming, then remain strong through tomorrow as it veers to the south, then southwest. Gusts tomorrow can reach 40 mph with no thunderstorms present. That’s enough to affect motorists with strong crosswinds and maybe bring down a weaker tree branch here and there.
Thanks to the strong southerly flow tomorrow, thunderstorms will be capable of causing damaging straight-line winds. You will only have to go up about 2,000 feet tomorrow to find winds over 50 mph and only another 2,000 feet for 60-70 mph wind. Thunderstorms will pull those strong winds to the surface in some areas, so gusts over 60 mph will be possible with more intense thunderstorms.
The other hazard will be isolated tornadoes. The thunderstorms will occur in an environment with a lot of vertical shear (winds veering with height, in this case going from southerly to southwesterly as you go up). This is conducive to thunderstorm updrafts gaining rotation, which can result in isolated tornadoes.”