textproduct: Memphis

KEY MESSAGES

Issued at 1152 PM CDT Mon Jul 20 2026

- Dangerous heat reaches its peak Tuesday, with heat indices up to 116F. An Extreme Heat Warning and Heat Advisory remain in effect through late Tuesday evening.

- An incoming cold front will trigger organized severe storms late Tuesday afternoon through midnight. Damaging wind is the primary threat with a secondary threat of heavy rainfall.

- The front exits Wednesday, providing a reprieve from heat and humidity for both Thursday and Friday. Uncertainty persists regarding the return of hot and humid weather next weekend.

DISCUSSION

(Tonight through next Monday) Issued at 1152 PM CDT Mon Jul 20 2026

It's currently a muggy night across the Mid-South, with temperatures ranging from the upper 70s to mid-80s and heat indices holding steady near 90 degrees.

Attention is focused on newly-formed Tropical Storm Bertha in the Gulf. This system helped relax heights across the region on Monday, allowing for enough convective coverage to provide some heat relief. We're tracking Bertha on a nearly westerly path near the Gulf Coast over the next 24 hours, which may impact storm development across North Mississippi on Tuesday afternoon.

Meanwhile, prepare for our most dangerous and oppressive heat of this event on Tuesday. NBM 50th percentile guidance indicates widespread, dangerous heat indices reaching up to 116F. The Extreme Heat Warning has been expanded eastward to include the majority of west Tennessee and portions of northwest Mississippi. The peak and cumulative effect of this current heatwave will create dangerous health risks for our most vulnerable-check on your neighbors, stay hydrated, and avoid being outdoors between 11 AM and 7 PM.

A cold front will begin tracking south into the area late Tuesday afternoon. With an unstable airmass-MLCAPE values exceeding 3000 J/kg-and bulk shear around 30 knots, organized severe storms are highly likely. While HREF guidance suggests we'll be in the right exit region of the mid-level jet (typically inhibiting large-scale lift), the combination of extreme instability and the incoming boundary should trigger strong to severe convection. Storm mode will favor multi-cells that could grow upscale into line clusters capable of producing severe wind gusts.

The current Slight Risk covers northeastern counties near the Tennessee River, with a Marginal Risk across much of West Tennessee, the Missouri Bootheel, and parts of Northeast Arkansas. Based on the latest data, I anticipate the Slight Risk expanding across West Tennessee and likely further west into Northeast Arkansas. Expect the primary threat to be damaging wind, supported by DCAPE values over 1000 J/kg, with the main window from late afternoon through midnight.

The front will lose momentum overnight as the parent trough lifts northeast, then slowly traverse the region on Wednesday. Our southernmost counties may still see heat indices of 100-104F, but heat products seem unlikely at this point. Significant relief arrives Thursday; temperatures will feel "downright cool" by comparison, with highs in the 80s and dewpoints dropping below 70.

The late-week outlook hinges on the dissipation rate of TS Bertha as it tracks west. Current LREF and deterministic guidance suggests dissipation by late Wednesday, which would allow the subtropical ridge to nudge east, bringing back heat and humidity. However, if the system persists longer near the Gulf Coast, we'll likely see a broad northwest flow, leading to near-normal highs in the low 90s and continued convective activity. Long-range guidance consistently shows the ridge amplifying across the Plains while troughing persists over the Ohio Valley, likely positioning us on the edge of the ridge under the main storm track.

AC3

AVIATION

(06Z TAFS) Issued at 1152 PM CDT Mon Jul 20 2026

VFR conditions will prevail across the airspace this issuance. Overnight, fog may begin to develop mainly north of the Tennessee/Mississippi stateline, however, confidence was not high enough to prevail at the terminals. Tomorrow, overall thunderstorm coverage, placement and mode is tough to pinpoint as 1) storms could be driven by daytime heating at MKL/TUP with lower chances at MEM and 2) with a cold front dropping south after 00z. For now, confidence in the coverage and timing of any TS only allows for PROB30s, but upgrades to a TEMPO are not out of the question, beginning as early as 21z. South/southwest winds will remain sub 10 kts over the next 30 hours.

AEH

FIRE WEATHER

Issued at 1152 PM CDT Mon Jul 20 2026

Light 20-ft winds and minimum RH values remaining above 40% will keep fire weather concerns minimal through the period.

MEG WATCHES/WARNINGS/ADVISORIES

AR...Extreme Heat Warning until 9 PM CDT Tuesday for ARZ009-018- 026>028-035-036-048-049-058.

MO...Extreme Heat Warning until 9 PM CDT Tuesday for MOZ113-115.

MS...Extreme Heat Warning until 9 PM CDT Tuesday for MSZ001>003-007- 008-010>012-020.

Heat Advisory until 9 PM CDT Tuesday for MSZ004>006-009-013>017- 021>024.

TN...Extreme Heat Warning until 9 PM CDT Tuesday for TNZ001>004- 019>021-048>052-088>090.

Heat Advisory until 9 PM CDT Tuesday for TNZ022-053>055-091-092.