Isentropic Ascent
Friday, October 2, 2026 · 6:20 AM
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Lyrics
Medium to high rain chances develop Friday and continue into Sunday. Isolated thunderstorms are forecast, but severe weather is not expected at this time. Low to medium chance for more than one inch of rain this weekend with the heaviest rain expected Friday afternoon and Sunday. Cooler, drier conditions are expected for next week. The storm system pulls closer to the valley tonight Warmer moist air advecting in, holding tight The main moisture axis stretches out from south Texas Up into the Great Lakes, but the system loses power Shearing out to the northeast in the Polar jet stream hour! Dynamics are lifting, breaking apart in the sky! Scattered and fragmented, watching the moisture pass by! Weak nine twenty-five to eight fifty millibar confluence below! Lingering southwesterly flow overhead! Catching the light rain where the clouds have spread! We are rising up on the wire, caught in the bent! Floating on air with isentropic ascent! Friday afternoon brings the cold frontal slide The surface front pushes down to the southern side Light to moderate showers scattered over the ground Cloudy grey skies keeping us safe and sound! Lingering southwesterly flow overhead! Catching the light rain where the clouds have spread! We are rising up on the wire, caught in the bent! Floating on air with isentropic ascent! Isentropic ascent! Rising up! Isentropic ascent! Fragmented rain falls down! Isentropic ascent!
The forecast discussion
KEY MESSAGES
Updated at 615 AM CDT Fri Oct 2 2026
- Medium to high rain chances develop Friday and continue into Sunday.
Isolated thunderstorms are forecast, but severe weather is not expected at this time.
- Low to medium chance for more than 1 inch of rain this weekend with the heaviest rain expected Friday afternoon and Sunday.
- Cooler, drier conditions are expected for next week.
SHORT TERM
(Tonight through Saturday Night) Issued at 1130 PM CDT Thu Oct 1 2026
The storm system off to our west continues to draw closer to the Tennessee and Ohio Valleys.
Warmer, more moist air is being advected into the area this evening and you can tell outside that humidity levels are up compared to just a couple days ago.
The main moisture axis now stretches from southern Texas into the Great Lakes.
Though we are seeing an increase in moisture approaching the area, the overall strength of the low pressure system is decreasing with the upper-level dynamics now shearing out and lifting northeastward into the Polar jet stream.
Most areas of rain and storms to the west are losing intensity.
This will continue to be the case with rain shower activity moving into Middle Tennessee tomorrow.
It doesn't appear we'll experience a solid line of rain/storms, but rather scattered/fragmented activity, though some potential for heating to get a couple storms going.
Overall this does not appear to bring a drought busting rain event, but a welcome cool down with rain and cloud cover then an initial cold frontal passage Friday afternoon/evening.
Though the surface front will be to our south on Saturday, weak 925-850 mb confluence will remain across Middle Tennessee with lingering southwesterly flow aloft supporting isentropic ascent.
Light to moderate rain showers are possible throughout the day with mostly cloudy to cloudy skies.
LONG TERM
(Sunday through next Friday) Issued at 1130 PM CDT Thu Oct 1 2026
Southwesterly flow aloft and lingering low- to mid-level deformation are progged to be in place near our region on Sunday.
We could also see favorable alignment of the right entrance region of the upper-level jet, at least briefly, but these features have varying placement depending on individual model solutions.
These forcing considerations will help bring additional rain showers to the area, best chances are across the southeast half of Middle Tennessee.
Finally, a prominent northern stream disturbance and associated reinforcing cold front is expected to arrive Monday morning.
This will bring a notably cooler, drier airmass that is forecast to stick around for much of next week.
Lows into the low 40s to low 50s are expected, though the dry airmass will allow for efficient afternoon warming as well; into the 80s west of the Plateau by mid week.