Yet another threat for strong to severe storms looms for Friday.
A deepening trough of low pressure, eventually becoming a closed low in the mid to upper levels, will bring a threat for heavy rain and severe storms to the Carolinas Friday.
In particular, this trough will actually be in the strengthening phase as it approaches from the west, taking on at least a slight negative tilt by the time it reaches our area Friday morning. This will translate to heightened flood potential as well as the threat for severe weather.
Wind shear will continue to increase as the trough strengthens, with 500mb wind speeds approaching 95-100 knots out of the southwest in some areas atop a low-level jet of 50-60 knots out of the south. At the surface, winds will be southerly to south-southeasterly, helping to usher in moisture to the tune of dew point temperatures once again exceeding 60-63 deg F by Friday morning.
In the upper levels, the Carolinas will be perfectly placed in diffluent and increasingly divergent flow; this will translate to excellent lift over a big area for rain and storms. However, increasingly backed flow at this level (becoming more southerly) will tend to incite a more widespread shield of precipitation with a linear feature embedded within.
Thermodynamically, we’ll likely not be as unstable as Sunday, but with better shear, it could compensate for what otherwise is a lack of excessive energy for storms. Mid-level lapse rates, while not moist adiabatic (5.5 deg C/km), they’re close to it at around 6 deg C/km. However, a good measure of low-level partial acceleration is 0-3km CAPE, and that number is ranging from 75-150 J/kg which is quite favorable.
All things considered, a line of showers and embedded storms is expected to sweep across the area Friday morning. As the aforementioned trough deepens and shear further increases, a general increase in storms’ ferocity is expected in the southern and eastern areas of the Upstate. Damaging wind and torrential rain will be the primary concerns, though a secondary risk of a few tornadoes will also exist, especially in areas where the 0-3km shear vector crosses any segments of the line at least a 30-45 degree angle.
One potential wild card in the forecast is the morning rain moves quickly out of the area, allowing for the air to recover across a greater portion of the area toward midday – if this occurs, severe weather threats could ramp up for some.
One way or another, all severe storm potential should exit the region by 5 PM Friday.