An upper-level low-pressure system will begin to influence our weather tonight and it may not go anywhere for some time. Severe weather will be possible Monday before the atmosphere stabilizes in response to showers and cold air damming Tuesday into Wednesday.
With cloud cover increasing as we speak, don’t expect temperatures to fall too much from where they are now at 11:00pm. Fog may develop in some river valleys toward daybreak but it doesn’t look like it will be widespread.
Monday, our area will be on the southeast side of the low pressure system, that will drop into the Tennessee Valley. The morning will start off relatively dry but showers and storms will quickly develop around Noon. The position of the low to our northwest will put us in the southwesterly flow and an unstable atmosphere. With winds backing into the mountains by afternoon, wind shear increases and this should allow for widespread thunderstorms to organize. Bands of heavy rain producing thunderstorms will move from southwest to northeast. Individual storms will move west within the bands of storms. There will be a damaging wind risk and I wouldn’t be surprised if we saw a tornado or two spin up between 1pm and 7pm, especially along Highway 16. Something we will watch through the day.
Thunderstorms and heavy rain continue into Monday Night before moving northeast of the area by daybreak Tuesday. The pre mentioned banding and organized clusters may train over the same areas repeatedly before moving northeast though. This could create some localized flash flooding along the southern and eastern slopes of the Blue Ridge. The main areas of concern for flash flooding would be the eastern slopes of Polk, Rutherford, McDowell, Burke, and Caldwell. Creek levels in these areas are already running near normal but antecedent conditions have been dry over the last few days so this should limit the risk of the flooding to only isolated areas, atleast through Monday Night.
By Tuesday high pressure will settle over the Northeast and our upper low is now modeled to be southwest of our area. This setup would be good for us as it puts our area in be more stable airmass. With cool moist conditions pushing down the eastern slopes of The Appalachians, expect low clouds, light / moderate rain, and drizzle much of the day Tuesday. The steadier rain will be across the western foothills while more drizzle will likely be the stronghold across eastern and southern foothills (Alexander, Catawba, Cleveland, Lincoln).
Details Wednesday through Friday still vary greatly depending on which model you look at. Some models retreat the upper low west, while it weakens. That would high pressure to move in for the weekend and dry things out. Most models though retreat the low pressure back to our northwest though, which puts us in the unstable sector of the system. That would mean more of a washout scenario right up through the weekend. Below are current forecast rainfall totals over the next 7 days from NOAA. Stay tuned for updates.