Area Forecast Discussion

KEY MESSAGES

Updated at 135 PM CDT Sun Jul 26 2026

- Heat Advisory in Effect for areas along and west of I-65 through Tuesday 7 PM.

- There is a low chance for strong to severe storms early Monday morning and again Tuesday afternoon.

- A cold front (preceded by thunderstorms) will bring a slightly cooler/drier airmass to the region for the end of the work week. Rain chances will increase once again early next weekend.

NEAR TERM

(Tonight) Issued at 135 PM CDT Sun Jul 26 2026

Morning low level cloud cover has cleared out leaving just some high clouds overhead with plenty of sunshine filtering through. As of 1pm, temperatures have climbed into the upper 80s and are forecast to continue to rise into the lower 90s later this afternoon. Of greatest concern is that the dewpoints have not mixed out at all and are sitting in the upper 70s to 80F. This has resulted in dangerous heat conditions. While we have not reached heat advisory criteria as of yet, with a few more hours of warming left it is expected heat indices will climb above 105 degrees for areas along and west of I-65. Therefore, a heat advisory has been issued and will continue through 7 pm Tuesday evening. The rest of the forecast remains on track with more details about the early morning storms in the following paragraph.

Previous Discussion: Our attention tonight is on an upstream MCS forming to our north and riding southward along the instability gradient into our local forecast area. Timing and intensity of this system as it reaches southern middle TN is quite uncertain. However, several CAMs show this feature arriving in the early morning hours Monday (4-8 am) with the most likely area being locations east of I-65. Forecast soundings show between 1000-2000 J/kg of MLCAPE with deep layer shear between 20-30 kts. If storms can remain sfc based the main threats would be damaging wind gusts and heavy rainfall.

SHORT TERM

(Monday through Tuesday) Issued at 1108 AM CDT Sun Jul 26 2026

There is the potential for an ongoing MCS to be present at the start of the short term period Monday morning. As it continues to push south, it will likely be on a weakening trend before it gradually dissipates by the late morning. The impacts of the cloud cover and rain associated with this system will likely impact the potential for dangerous heat later Monday afternoon.

Through the first part of next week, the upper level pattern remains unchanged with a large ridge over the central US and a trough across the Northeast. The morning CAM suite indicates that with daytime heating, additional showers and storms may redevelop along residual outflow boundaries from the morning MCS. Coverage of these storms during the afternoon appear too low to really impact the heat potential during the peak heating hours. Afternoon highs will warm into the lower 90s east and mid 90s west with heat index values in low 100s in NE AL and between 103F-107F further west. On Tuesday, the upper ridge shifts a bit further east. This will warm afternoon temperatures up a few degrees with afternoon highs reaching the mid to upper 90s. This will bring afternoon heat index values between 105-110 degrees with a few degrees cooler in NE AL. Given these conditions, a Heat Advisory has been issued for our counties along and west of I-65 from 10 am Monday through Tuesday evening. Additional counties may be added, especially on Tuesday if forecast confidence increases.

LONG TERM

(Tuesday night through Saturday) Issued at 1100 PM CDT Sat Jul 25 2026

Extended range model data suggests that a developing surface low will track eastward across the northern Mid-Atlantic states on Tuesday night/Wednesday, in conjunction with an amplifying longwave trough across the eastern CONUS. A cold front attached to the low appears likely to drop southward through the TN Valley during this timeframe, although details regarding specific timing are unclear at this point. A warm/moist airmass is expected to be in place ahead of the front, with steep low/mid-level lapse rates and CAPE to support a couple of rounds of thunderstorms (perhaps an MCS Tuesday night followed by additional convection more directly forced by the cold front Wednesday). Furthermore, deep-layer NW flow of 20-30 knots will exist within a contracted height gradient between the trough to our east and a strong mid-level high over the southwestern CONUS, and this could support a risk for damaging winds given the favorable thermodynamic environment.

In the wake of the front, light-moderate northerly winds will advect a cooler/drier continental airmass into the region, with dewpoints briefly falling into the 60s an PWAT values falling to around or slightly below 1" from Wednesday night-Thursday night (and perhaps into Friday as well). By the end of the forecast period, deep-layer SSW flow will return to the region as an amplifying shortwave trough (traveling around the periphery of the ridge to our west) digs southeastward into the Mid-MS/Lower-OH Valley region and a surface low shifts eastward from the Red River Valley into the Arklamiss vicinity. Rich moisture will return to the region as this occurs, with an increase in the coverage of showers/thunderstorms expected beginning late Friday night and continuing through Saturday.

AVIATION

(18Z TAFS) Issued at 1126 AM CDT Sun Jul 26 2026

MVFR clouds continue to linger at HSV, but should lift early this afternoon. Then VFR conditions continue through the rest of the period. The one exception is Monday morning where an MCS is expected to bring showers and thunderstorms to the terminals. For now left thunderstorms within a prob 30 group as there is a lot of uncertainty in timing and location of this system.

HUN WATCHES / WARNINGS / ADVISORIES

AL...Heat Advisory until 7 PM CDT Tuesday for ALZ001>007-016.

TN...Heat Advisory until 7 PM CDT Tuesday for TNZ076-096.