***4:45 pm Update*** - Daniel Crawley
Good Saturday afternoon to everyone, we continue to monitor for the potential of strong to severe thunderstorms late this afternoon and evening across the Western Carolinas. So far we have dealt with no storms of any kind, that was thanks in part to a thunderstorm complex that stabliized the atmosphere this morning, however that may be in the process of changing...
At 4:30 pm Doppler Radar indicated that storms have begun to develop across the eastern slopes and down along the southern escarpment of North Carolina. A Severe Thunderstorm Warning is in effect for neighboring Polk County and another, strong storm was developing in Western Rutherford County, a lightning alert has been issued for that area until 5:45 pm.
This could be the beginning of more storms to develop over the next few hours, with good jet stream energy in place along with abundant moisture, these storms could turn severe in our coverage area. As you can see on the threats image below, strong damaging winds and hail could be the bigger threats that come from any storm that develops. Heavy rainfall and frequent lightning is possible as well. The tornado threat while not at zero does remain very low at this time. A Slight Risk (2 of 5) for severe weather through tonight has been re-introduced for the southern counties in the coverage area while a Marginal Risk (1 of 5) remains elsewhere.
With the later initialization of storm development, we have adjusted our timeline for severe weather potential across the region. This does not mean all locations will receive severe storms but its a good indicator as to when any rough weather might occur.
We will have all prudent severe weather information posted on our social media outlets and here at the website as we go through the evening. If you haven't already, download our free Phone/Tablet App at your local App Store. Just type "Foothills Weather Network" in the search bar.
***11:30 am Update*** - Daniel Crawley
Good Saturday morning, we are nearing the noon hour and here is the latest on the potential for severe weather for this afternoon and evening...
Visible Satellite imagery shows what is going on at this hour. First we have an upper low across the Ohio Valley with a nice jet streak of about 50 knots along the southeast quadrant of the upper low. That jet streak helped accelerate a thunderstorm complex this morning down across the state of Georgia. It also helped push drier air at the mid levels into the Carolinas, skies that were cloudy this morning are clearing at this time.
Both the current thunderstorm complex and the drier air advecting in has changed things up slightly in regards to thunderstorm activity later today. The current storm complex across Georgia is going to help take some of the instability that would have been in place across a greater part of the Southeast US had no storms been currently active, so that is somewhat encouraging news, however by no means does that take us completely out of the threat for later today.
The Storm Prediction Center has lowered our area from a Slight Risk to a Marginal (1 of 5) Risk for the rest of today...
Even with a lower risk level, the same threats appear to be in play as storms will re-develop this afternoon...please DO NOT let your guard down just because of the change from Slight to Marginal. A few of those could produce damaging winds, large hail and frequent lightning as they move eastward this afternoon and evening.
The general timeline for storms has not changed much, as you can see on the graphic below we expect the worst to be from mid afternoon until just after sunset. (areas shaded in red)
By late evening the severe weather threat should diminish but general showers and storms could still be in progress...
Stay with the Foothills Weather Network for additional updates throughout the afternoon and evening on the severe weather potential...
2:30am - Chief Meteorologist Chris White
Good early Saturday Morning. Today is a WEATHER READY ACTION DAY across our 8 county forecast area.
An upper level low is dropping south from The Great Lakes to the Southern Appalachians tonight. Pieces of energy aloft will rotate through the area starting today and continuing the next several days. Saturday will be the day of the severe weather. Instability will build during the late morning as the sun emerges. Atmospheric instability will approach 2500 - 3000 j/kg of CAPE over a lot of the forecast area by 6pm Saturday Evening. Our start timing of 3:00pm may be just a little too early but Ill punt to the morning shift for updates on the timing. Cape values needed for severe weather are generally 1500 j/kg this time of year....not always but most of the time. We will eclipse that easy on Saturday. To get rotation for tornadoes the atmosphere needs to have sheer all the way down to the surface. Saturday's atmosphere will have 30-40 knots of sheer aloft but from the surface to 3000ft sheer is not that impressive. Sheer also is something we look for when we look to see if thunderstorms will organize. With 30-40 knots of sheer aloft there is no question that thunderstorms will organize. Storm motion will generally be from the Northwest to the Southeast. These clusters will likely organize into a couple of lines of storms just as they did today across Kentucky. Those lines of storms build up a cold pools of air behind them and that causes the wind to rush out ahead of the line and begin to bow. Once these lines bow out they can really put out the wind. That is why we are as concerned for widespread wind damage later this evening.
A couple of final notes to add in here. We obviously cannot rule out tornadoes Saturday. The threat is much lower than the straight line damaging wind threat. Wind is wind. It doesn't matter whether it is moving in a straight line or rotating. Straight line winds can do as much and in some cases more damage than weak tornadoes. That is the reason that we are telling folks to treat Saturday's severe thunderstorm warnings as seriously as you treat tornado warnings. I have attached a great guide from The National Weather Service in reporting severe weather.