-- Discussion containing changed information from previous version are highlighted. --
869
FXUS64 KMRX 261122
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
722 AM EDT Thu Jun 26 2025

...New AVIATION...

.SHORT TERM...
-- Changed Discussion --
(Today and tonight)
Issued at 134 AM EDT Thu Jun 26 2025

Key Messages:

1. Heat Advisory continues today for Heat Index around 105 in the
southern and central TN Valley.

2. Isolated strong to severe storms are possible late this afternoon
and evening.

Discussion:

The large high pressure ridge that has been over the region will
continue to be the dominant weather feature for one more day. Under
this ridge, we will have another day of hot and humid conditions,
with the Heat Index reaching near or just over 105 for much of the
Tennessee Valley and Cumberland Plateau. Temperatures are expected
to be a degree to two lower compared to what we saw yesterday, but
dewpoints will be slightly higher. Current obs are showing some
locations with dewpoints in the mid to upper 70s, higher than
what we have seen at this time the last few nights. Afternoon
mixing will lower those values to lower and mid 70s, which will
lead to a Heat Index around 105 for the southern and central TN
Valley.

CAPE will continue to be plentiful in this hot and humid air mass.
Convection should have no problem breaking through a weak cap in the
early to mid afternoon, mainly in the higher terrain of the
mountains and Cumberland Plateau. Outflow boundaries from this
activity will likely initiate convection into the Valley through the
late afternoon and evening. DCAPE values in the 1100-1300 J/kg range
and steep low level lapse rates will mean storms will be capable of
producing damaging wind gusts. Very weak flow through the column
with PW values in the range of 1.5-1.7 inches will result in slow-
moving storms that dump heavy rainfall, potentially causing
localized flooding.
-- End Changed Discussion --

&&

.LONG TERM...
-- Changed Discussion --
(Friday through Wednesday)
Issued at 134 AM EDT Thu Jun 26 2025

Key Messages:

1. Increasing moisture brings higher rain chances and slightly
cooler temperatures through the weekend. Isolated severe storms and
localized flash flooding are possible each day.

2. A cold front approaches the area Tuesday/Wednesday.

Discussion:

A weak tropical wave that is currently over the eastern coastline of
Florida will make its way northwestward, and the large ridge will
loosen its grip on the Southeast. This will bring greater moisture
into the TN Valley through the weekend. This weak low lingers over
the Southeast through Sunday, until it starts to get picked up by a
shortwave trough to the north on Monday. The high CAPE/low shear
environment will result in numerous afternoon showers and
thunderstorms each day, driven mainly by orographic lift and outflow
boundaries. These pulse storms will be capable of producing damaging
wind gusts. With PW values rising into the range of 1.7-2 inches,
any storms will be capable of producing heavy rainfall that causes
localized flooding.

On Tuesday and Wednesday, a broad mid/upper trough develops over the
eastern Conus, and a cold front will approach the region. It remains
to be seen whether this front stalls over the area, or if it pushes
through. The latest models runs seem to be pointing more toward
pushing the front to our south and east on Wednesday, which would
-- End Changed Discussion --

&&

.AVIATION...
-- Changed Discussion --
(12Z TAFS)
Issued at 717 AM EDT Thu Jun 26 2025

Early morning thunderstorms behind an outflow boundary are
generally progressing to the northwest except for a cluster near
Athens and Sweetwater. TS should dissipate over the next 1-2
hours. VFR conditions to continue through today, scattered TS
expected again this afternoon into early evening, low confidence
on direct terminal impacts. Gusty winds with TS. Late in the
period patchy fog has a medium chance of formation, more likely to
see impacts for airports who see rain today.
-- End Changed Discussion --

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             95  72  92  72 /  30  30  50  30
Knoxville McGhee Tyson Airport, TN  94  71  90  71 /  30  20  50  30
Oak Ridge, TN                       95  71  90  71 /  30  20  50  30
Tri Cities Airport, TN              92  68  89  68 /  50  30  50  40

&&

.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...Heat Advisory until 8 PM EDT /7 PM CDT/ this evening for
     Anderson-Bledsoe-Bradley-Hamilton-Knox-Loudon-Marion-McMinn-
     Meigs-North Sevier-Northwest Blount-Northwest Monroe-Rhea-
     Roane-Sequatchie-West Polk.

VA...NONE.
&&

$$

SHORT TERM...DGS
LONG TERM....DGS
AVIATION...Wellington