Outflows Will Merge
Thursday, September 3, 2026 · 10:31 PM
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Major to extreme heat risk through Saturday with heat index values up to one hundred nine degrees. A Heat Advisory remains in effect for all of Middle Tennessee through eight P.M. Saturday. Heat risk lessens early next week, but temperatures remain above-normal through the forecast period. Low chance for afternoon rain and thunderstorms through next week. Strongest storms will pose a threat for strong wind gusts and heavy rainfall. Another calm night in Middle Tennessee. The Omega block holds us beneath the ridge. Precipitable water at one point nine inches. Mixed layer convective energy at two thousand. Inverted-V soundings in the stagnant air. Thirteen hundred to sixteen hundred joules of downdraft cape. The ridge begins to retrograde westward! A shortwave disturbance moving out of Kentucky! Small uptick in mid-level flow! Multicell clusters forming in the dark! STORM CELLS COLLIDE IN THE MIDNIGHT HEAT! THE RIDGE BREAKS DOWN BUT IT WON'T BE ENOUGH! DESPERATE WIND GUSTS THIRTY TO FORTY MILES PER HOUR! OUTFLOWS WILL MERGE! ISOLATED SEVERE GUSTS! MULTICELL CLUSTERS FORMING! COLD POOLS MERGING IN THE NIGHT! THE OMEGA BLOCK WILL NOT LET US GO! Outflows will merge. Outflows will merge.
The forecast discussion
NEW SHORT TERM, LONG TERM
KEY MESSAGES
Updated at 1030 PM CDT Thu Sep 3 2026
- Major to extreme heat risk through Saturday with heat index values up to 109 degrees.
A Heat Advisory remains in effect for all of Middle TN through 8 PM Saturday.
- Heat risk lessens early next week, but temperatures remain above-normal through the forecast period.
- Low chance for afternoon rain and thunderstorms through next week.
Strongest storms will pose a threat for strong wind gusts and heavy rainfall.
SHORT TERM
(Tonight through Saturday Night) Issued at 1030 PM CDT Thu Sep 3 2026
We have another warm but calm night ahead with lows in the 70s amidst the persisting ridge and ongoing Omega blocking pattern.
We'll likely see high temperatures making another run for 100 degrees in some spots across Middle Tennessee Friday afternoon with dewpoints upper 60s to mid 70s causing heat index values up to 109 degrees.
The major to extreme heat risk levels unfortunately will continue through Saturday as a result.
For Friday afternoon, isolated showers and thunderstorms are forecast with PWs running ~1.9" and MLCAPE ~2,000 J/kg.
With inverted-V soundings and very high values of DCAPE (1,300-1,600 J/kg), pretty much any storm producing lightning will pose a threat for brief 30-40 mph wind gusts, with some strong gusts possible.
For Saturday we'll see a slight transition in flow aloft as the ridge mercifully begins to break down and retrograde westward.
This will open the door for more organized thunderstorm potential moving out of Kentucky Saturday afternoon and evening ahead of a shortwave disturbance.
With a small uptick in mid-level flow, multicell clusters are possible and would likely form and merge cold pools/outflows.
These storms will pose a little more wind threat with isolated severe gusts possible.
LONG TERM
(Sunday through next Friday) Issued at 1030 PM CDT Thu Sep 3 2026
Deep-layer ridging is forecast to position closer to the Southern Rockies on Sunday and we'll be more in a north-northwest flow here in Middle Tennessee.
This pattern will persist into early next week bringing some relief from major to extreme heat risk.
However, the overall Omega blocking pattern will remain in place across the CONUS and the ridge is forecast to migrate back to the east mid to late next week.
This will favor above-normal temperatures across the area for the next several days with very limited diurnal rain chances most days next week.