Priming The Atmosphere
Wednesday, August 19, 2026 · 6:23 AM
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Wednesday will be very warm and more humid with temperatures rebounding into the low to mid nineties most areas. Heat indices will reach the low one hundreds in some areas generally west of Interstate sixty-five. Storms are expected to develop by late evening and impact Middle Tennessee during the overnight hours and into Thursday morning. All of Middle Tennessee west of the Cumberland Plateau is in at least a marginal risk of severe storms, with areas around Clarksville, Waverly and Dover potentially being the most impacted, as a slight risk extends into this region. Strong to damaging winds and heavy rain are the main risks, but there is also a very low threat of large hail and tornadoes. Near normal temperatures are expected this weekend. A decaying mesoscale convective system dies on the state line. Clear skies turn heavy as night falls over Clarksville. The heat index pushed low one hundreds this afternoon. Now cold air advection waits in the distance. Upper level troffing holds the pattern on Friday. A cold front approaches Middle Tennessee in the dark. The moisture builds as southerly winds roll in. Destabilization accelerates across the plateau. Clarksville and Dover watching the skies collide! Damaging winds hidden inside the cloud deck! The southerly flow is priming the atmosphere! Clusters of storms breaking through the midnight heat! Seven hundred millibar jet! Seven hundred millibar jet! Seven hundred millibar jet! Seven hundred millibar jet!
The forecast discussion
KEY MESSAGES
Updated at 620 AM CDT Wed Aug 19 2026
- Wednesday will be very warm and more humid with temperatures rebounding into the low to mid 90s most areas.
Heat indices will reach the low 100s in some areas generally west of I-65.
- Storms are expected to develop by late evening and impact Middle Tennessee during the overnight hours and into Thursday morning.
All of Middle Tennessee west of the Cumberland Plateau is in at least a marginal risk of severe storms, with areas around Clarksville, Waverly and Dover potentially being the most impacted, as a slight risk (level 2 out of 5) extends into this region.
Strong to damaging winds and heavy rain are the main risks, but there is also a very low threat of large hail and tornadoes.
- Near normal temperatures are expected this weekend.
SHORT TERM
(Tonight through Thursday Night) Issued at 1044 PM CDT Tue Aug 18 2026
Clear skies currently over the mid-state, with lows in the 60s expected overnight and to start Wednesday morning.
Cloud cover will increase into Wednesday morning, as a decaying MCS makes its way towards the area.
Some guidance shows the MCS making it into our northwestern counties before falling apart, whereas others show it will stay north of the TN/KY state line.
If it does make it into TN, it will likely be confined to our NW counties.
Southerly flow will make things moist in the area, priming the atmosphere for the severe threat into Thursday morning.
Highs will be in the upper 80s to mid 90s.
Wednesday evening, a cold front will approach Middle Tennessee.
A 700 mb jet will pick up around this time as well, leading to destabilization and possibly some strong to severe storms.
Because of this jet, our main hazard is damaging winds, but heavy rainfall is also a threat.
Storm mode with this threat looks to be clusters of storms, but some supercells cannot be ruled out (our tornado threat is very low).
Thursday the front should move east by mid-afternoon, leaving us with drier air and high temperatures in the mid 80s to low 90s.
LONG TERM
(Friday through next Wednesday) Issued at 1044 PM CDT Tue Aug 18 2026
Troughing in the upper levels will lead to more shower chances on Friday, but we are not expecting any severe weather at this time.
These rain chances look to be fairly isolated, thankfully, and the pattern turns dry for the weekend.
Into the beginning of the work week, we remain in NW flow aloft, which looks to bring in isolated rain chances through mid-week.
Temperatures will remain in the upper 80s to low 90s through the forecast period.