40 Knots
Saturday, August 22, 2026 · 6:50 PM
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A severe thunderstorm watch is in effect for portions of the Cumberland Plateau until ten P.M. Slightly below normal temperatures, particularly overnight, this weekend into early next week. Low to medium rain and storm chances most days next week with Broad upper level troff across the eastern continent! Disturbance driving southeast through the Ohio Valley! A cold front charging down to Middle Tennessee! Moisture blooming in the peak afternoon heat! Surface based convective available potential energy! Two thousand to three thousand joules per kilogram! FORTY KNOTS! FORTY KNOTS! FORTY KNOTS! The front is advancing and the wind shear aligns! Quarter size hail and the damage combined! From three P.M. to nine P.M. the atmosphere tears! We are caught in the corridor of 40 knots! NORTHWEST FLOW ALOFT! DRIED OUT BEHIND THE BOUNDARY! THE INVERSION CLEARS! TEMPERATURES CRASH! UPPER FIFTIES! UPPER FIFTIES! UPPER FIFTIES! High terrain cooling in the morning fog! The watch expires at ten P.M.! Stable air takes over! 40 knots!
The forecast discussion
KEY MESSAGES
Updated at 636 PM CDT Sat Aug 22 2026
- A severe thunderstorm watch is in effect for portions of the Cumberland Plateau until 10 PM.
- Slightly below-normal temperatures, particularly overnight, this weekend into early next week.
- Low to medium rain and storm chances most days next week with
SHORT TERM
(Rest of today through Sunday) Issued at 1150 AM CDT Sat Aug 22 2026
A broad upper-level trough remains in place across the eastern CONUS today.
An embedded disturbance is now advancing southeast through the Ohio Valley with an associated front now along the Ohio River making its way toward Middle Tennessee.
Though it is relatively dry currently, slight moistening is expected ahead of the front as it approaches Middle Tennessee during peak afternoon heating.
This will support increasing surface-based instability (2,000-3,000 J/kg) this afternoon within a nice corridor of mid- level flow (~40 kts).
As a result, any storms that form and maintain this afternoon and evening will pose a threat for damaging wind gusts and perhaps hail up to quarter size.
This band of convection should mainly be limited to 3 PM to 9 PM across Middle Tennessee and greatest overall chances are for areas east of I-65.
The rest of the short-term looks dry and stable as we remain in northwest flow aloft and amidst an area of drier air behind the front moving through tonight.
LONG TERM
(Sunday Night through next Saturday) Issued at 1150 AM CDT Sat Aug 22 2026
Cooler overnights and mornings will persist through early next week thanks to drier air in place.
Higher terrain across the Plateau are forecast to have lows in the upper 50s Monday and Tuesday mornings.
Troughing will make a slow progression to the east mid to late next week.
This should open the door for an increase in moisture from the west.
Continued mid- to upper-level flow will persist from the northwest providing a corridor for shortwaves to move through the area.
These passing disturbances support the low to medium rain and storm chances most days next week.
Temperatures are generally near seasonal norms.