Happy Wednesday, East Tennessee!
The good news is we avoided the widespread severe weather that was possible Tuesday night.
The focus today shifts away from damaging winds and toward heavy rainfall, flooding, and flash flooding as a slow-moving frontal boundary stalls across the region.
Not everyone will see heavy rain today, but wherever this boundary sets up, repeated rounds of showers and thunderstorms could quickly lead to flooding issues.
Flooding Is Today’s Main Concern
The Weather Prediction Center continues to highlight East Tennessee with a Level 1 and Level 2 risk for excessive rainfall, while the National Weather Service has issued a Flood Watch through 8:00 PM for much of the region.
The biggest concern today is training thunderstorms.
Training storms occur when multiple showers and thunderstorms repeatedly move over the same location, much like train cars traveling down the same track. When that happens, rainfall totals can add up quickly, increasing the risk for flash flooding.
The challenge today isn’t whether it will rain—it’s exactly where the frontal boundary stalls.
That boundary will determine who picks up the heaviest rainfall.
A Hit-or-Miss Forecast
This will not be a widespread soaking rain across all of East Tennessee.
Instead, expect highly localized rainfall totals.
Some communities may receive several inches of rain while others just a few miles away stay mostly dry.
That’s why today’s forecast is one of the more challenging ones.
Several forecast models agree that the corridor from Lenoir City through Knoxville and northeast along Interstate 81 toward the Tri-Cities has one of the better opportunities for repeated heavy rainfall, but even within that zone, totals will vary significantly.
Rain Arrives in Waves
Showers are already ongoing this morning, and periods of rain will continue throughout the day.
Instead of scattered pop-up storms, today’s activity will organize into bands moving generally from west to east.
As those rain bands repeatedly move across the same locations, localized flooding becomes increasingly likely.
If you live in an area that’s already received several inches of rain over the past week, it won’t take much additional rainfall to create flooding concerns.
Flood Watch Areas
The Flood Watch includes much of East Tennessee, including portions of:
- Scott County
- Morgan County
- Roane County
- Loudon County
- Blount County
- Knox County
- Communities along the Interstate 40 and Interstate 81 corridors
- Much of the northern and northeastern Tennessee Valley
Travelers along these major highways should be prepared for periods of heavy rain and reduced visibility throughout the day.
Warm, Muggy, and Tropical
The atmosphere remains extremely humid this morning.
Temperatures started the day in the middle to upper 70s, and dew points remain well into the 70s, creating another tropical-feeling start across East Tennessee.
Yesterday brought one of the warmest overnight temperatures on record, and this morning wasn’t far behind.
Clouds and rainfall will keep afternoon highs a little cooler today, generally reaching the middle 80s, although Chattanooga may still approach 90 degrees.
Heat index values remain in the lower to middle 90s, but widespread cloud cover will prevent the dangerous heat we experienced earlier this week.
A Better Thursday Is Still On Track
As today’s cold front slowly pushes southward, slightly drier air begins filtering into northern sections of East Tennessee later tonight and Thursday.
The flood threat also shifts south.
On Thursday:
- Flooding concerns become focused mainly south of Interstate 40
- Northern sections begin drying out
- Humidity temporarily decreases
- Sunshine returns for many communities
Thursday continues to look like the pick of the week, especially across the northern Plateau and much of the Tennessee Valley.
Rain Chances Return by the Weekend
Unfortunately, the break won’t last long.
By Friday and Saturday, deeper tropical moisture returns, increasing the coverage of afternoon showers and thunderstorms once again.
Saturday currently looks like the wetter day of the weekend.
Sunday appears to offer the better opportunity for outdoor activities, with fewer storms expected and more dry hours overall.
Heat Builds Back Next Week
While temperatures remain fairly comfortable through Saturday, humidity quickly increases again late in the weekend.
By Sunday through Tuesday:
- Heat index values climb back toward 100 degrees
- Humidity returns to tropical levels
- Afternoon storm chances gradually increase again
It will once again begin feeling like a typical East Tennessee summer.
Regional Forecast
Central Valley (Knoxville)
Expect periods of showers and thunderstorms today before improving conditions arrive Thursday. Rain chances increase again Friday and Saturday, with Sunday looking noticeably drier.
Southern Valley (Chattanooga)
You’ll likely hold onto showers longer than areas farther north on Thursday as the frontal boundary slowly shifts south. Storm coverage increases again heading into the weekend.
Northern Cumberland Plateau
Thursday is shaping up to be one of the nicest days of the week, with highs near 82 degrees, lower humidity, and plenty of dry weather before rain chances increase Friday and Saturday.
Northern Valley & Tri-Cities
Today’s highest flooding concern remains across Upper East Tennessee before the heavier rain gradually shifts south Thursday. Another round of scattered storms arrives Friday and Saturday.
The Bottom Line
Today’s weather is all about where the rain sets up.
A stalled frontal boundary will produce repeated bands of showers and thunderstorms capable of generating localized flooding and flash flooding. Some communities may receive several inches of rain, while others only a few miles away stay mostly dry.
Thursday still looks like the best day of the week with lower humidity and fewer storms before tropical moisture returns Friday and Saturday.
If you’re traveling today, keep the free eastTNweather app nearby. Interactive radar, lightning alerts, and push notifications will help you stay ahead of changing weather conditions and any Flash Flood Warnings that may be issued.
Have a great Wednesday, stay weather aware, and thanks for making eastTNweather your trusted source for weather across East Tennessee.