Harvey’s impacts are now being felt in the Carolinas in the form of heavy rain and possible severe weather.
With landfalling tropical systems such as Harvey, wind shear and tropical moisture often spread hundreds of miles away from the center of circulation.
Within that expanding wind shear envelope, just enough instability overlapping with copious tropical moisture can create an environment favorable for spin-up tornadoes.
These tornadoes typically are weak and short-lived due to the usually-minimal instability available to developing storms; however, they can develop very quickly and move in excess of average highway speeds.
Some of this type of weather could become possible this afternoon in the Upstate, and across the entire region Friday as wind shear increases further.
The overall risk appears to be slightly higher Friday in parts of western and central North Carolina into the northeast part of the Upstate – this is where a slight risk (2/5) is in place from the Storm Prediction Center.
This is due to the aforementioned wind shear being enhanced by an incoming back-door cold front feature from the northeast. This will reinforce a temperature gradient (baroclinicity) and maximize wind shear.
The translation will be any storms encountering this boundary will have heightened tornado potential. This would from 11 AM - 5 PM Friday.
Overall, this will not be an expansive, intense tornado risk. Tropical tornadoes are not known for being significant, but you’ll want to remain weather aware in case warnings are issued for your area.
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