276
FXUS64 KMRX 301108
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
708 AM EDT Tue Jun 30 2026

...New AVIATION...

.KEY MESSAGES...
Updated at 658 AM EDT Tue Jun 30 2026

- Isolated to scattered showers and thunderstorms this afternoon
  in the mountains and adjacent foothills, some may be strong to
  severe.

- Very hot this week with high temperatures well into the 90s
  common. Afternoon heat index values will climb to around or
  above 100 degrees in in most valley locations multiple days.

&&

.DISCUSSION...
Issued at 232 AM EDT Tue Jun 30 2026

The coverage and intensity of storms this past evening exceeded
expectations, outperforming what the CAMS showed. We had a very
unstable air mass with SBCAPE over 4000 J/kg with little to no
capping over NE TN/SW VA. Today, forecast soundings suggest a
similar environment, possibly even more unstable as the NAM shows a
700-500 mb lapse rate around 8 C/km this afternoon. CAMS pick up on
convection developing along the NC border with a southwest drift,
but outflow boundaries will likely initiate additional storms in the
Tri-Cities area and NE TN foothills. Heavy downbursts that cause
damaging wind gusts and hail up to quarter size are possible. On
Wednesday the cap strengthens as the large midlevel ridge drifts a
little to the east, becoming centered over eastern KY. Convection
will shift to GA/AL and possibly our SW NC/SE TN counties where the
cap will be weaker. Again, there will be ample instability for
strong to severe storms if the cap can be broken Wednesday
afternoon.

A Heat Advisory will be in effect from today through Thursday. High
temperatures are expected to be in the 90s across all but the higher
elevations each day this week and through the weekend, with mid to
upper 90s across portions of the TN Valley. Heat index values around
or above 100 will common in the afternoons, and heat index values
may exceed 105 across portions of the area, especially Wednesday and
Thursday. The Heat Advisory may eventually need to be extended
longer in time as it still looks very hot Friday and into at least
the beginning of the weekend.

A short wave may bring more precip and slightly lower temperatures
by Monday, but confidence in the details is low that far out.

&&

.AVIATION...
(12Z TAFS)
Issued at 658 AM EDT Tue Jun 30 2026

Later today could possibly be a repeat of yesterday with
showers and storms shifting down from the north, potentially
impacting TRI, possibly TYS and CHA as well. In addition to PROB30
already at TRI, they`ve been added at TYS and CHA to include the
possible chances there. Clear and calm tonight with fog in the
forecast at TRI again. 3SM occurred there this morning for an
hour.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             97  77  98  77 /   0   0  30  20
Knoxville McGhee Tyson Airport, TN  93  74  95  75 /  10  10  10  10
Oak Ridge, TN                       94  75  96  75 /  10   0  10   0
Tri Cities Airport, TN              92  71  95  71 /  30  10   0  10

&&

.MRX WATCHES/WARNINGS/ADVISORIES...
NC...Heat Advisory from 11 AM this morning to 9 PM EDT Thursday for
     Cherokee-Clay.

TN...Heat Advisory from 11 AM EDT /10 AM CDT/ this morning to 9 PM
     EDT /8 PM CDT/ Thursday for Anderson-Bledsoe-Blount Smoky
     Mountains-Bradley-Campbell-Claiborne-Cocke Smoky Mountains-
     East Polk-Grainger-Hamblen-Hamilton-Hancock-Hawkins-
     Jefferson-Johnson-Knox-Loudon-Marion-McMinn-Meigs-Morgan-
     North Sevier-Northwest Blount-Northwest Carter-Northwest
     Cocke-Northwest Greene-Northwest Monroe-Rhea-Roane-Scott TN-
     Sequatchie-Sevier Smoky Mountains-Southeast Carter-
     Southeast Greene-Southeast Monroe-Sullivan-Unicoi-Union-
     Washington TN-West Polk.

VA...Heat Advisory from 11 AM this morning to 9 PM EDT Thursday for
     Lee-Russell-Scott VA-Washington VA-Wise.

&&

$$

DISCUSSION...DGS
AVIATION...KS