672
FXUS64 KMRX 141122
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
722 AM EDT Mon Jul 14 2025

...New AVIATION...

.SHORT TERM...
(Today and tonight)
Issued at 142 AM EDT Mon Jul 14 2025

Key Messages:

1. Additional isolated to scattered showers and thunderstorms
expected this afternoon and evening. Locally gusty winds and heavy
downpours possible with the strongest storms.

2. Hot and humid conditions. Central and southern E TN Valley will
see indices in upper 90s to near 100F. Low to mid 90s more likely
for NE TN, SW VA, and SW NC.

Discussion:

Radar has become quiet among the night sky. Some light high clouds
from the PM convection are partially concealing developing fog/low
stratus on satellite imagery. Latest HREF ensemble suggest 40-50%
probabilities of visibility less than 4mi along some of the river
valleys - the most likely location, alongside anywhere that observed
heavy rain, to see some patchy dense fog as we head through the AM
hours.

For Monday afternoon, the upper shortwave trough bringing enhanced
coverage of diurnal showers and thunderstorms the past few
afternoons is expected to lift northeast. H5 heights will increase
~2dam in response. A stationary boundary will also be draped
parallel across the Ohio River from its parent low over northeastern
Canada. Showers and thunderstorms will initiate in diurnal fashion
once again. Latest RAP soundings paint MLCAPE moreso in the range of
1250-1750J/kg with effective shear less than 15kts. Any stronger
storm could lead to gusty winds to 40mph or isolated flash flooding
with PWAT around 1.75" and DCAPE near 800J/kg, but the overall
concern for severe impacts is very low.

Additionally, the hot and humid airmass will promote heat indices
in the upper 90s for the central East Tennessee valley, with the
southern valley expected to reach near or into the low 100s.
Slightly lower values in the low to mid 90s are expected for
northeast Tennessee, southwest Virginia, as well as southwest North
Carolina. That being said, the exact timing of convective initiation
and coverage of storms could impact these values to some degree(pun
intended). If coverage of storms is more scattered and begins to
initiate closer to 16-17Z, that could knock those maximum heat
indices down a few degrees - much like what we observed happen this
past afternoon. Quiet weather will return for the overnight period
with the exception of some patchy dense fog in river valleys and
locations that see heavy rainfall.

&&

.LONG TERM...
(Tuesday through Sunday)
Issued at 142 AM EDT Mon Jul 14 2025

Key Messages:

1. Daily chances of PM showers and storms continue through the
extended period. With each day the strongest storms could produce
locally gusty winds and heavy downpours.

2. Strength of an upper ridge will peak mid-week. Heat indices in
the mid 90s to low 100s will become more common across valley
locations Tuesday onward.

Discussion:

Upper level ridging will dominate the southeast with H5 heights
between 592-594dam for the mid-week. A strong Bermuda high will
enhance moisture advection via southerly low-level flow. The hot and
humid air mass will continue to promote diurnal showers and
thunderstorms with the absence of any strong surface high pressure
center. General summer-time activity is expected, with isolated
strong gusty winds and flash flooding possible with the strongest
storms. The main concern will be the heat. Indices across the
southern and central valley in the low 100s will become more common.
Some locations may flirt with advisory level criteria. Though
similarly to the short-term section above, timing and coverage of
afternoon convection could limit peak heating and perhaps provide
some relief to those near advisory criteria indices.

By Thursday, a shortwave trough will be digging into the northern
CONUS with nearly zonal flow aloft. With weakening subsidence there
is potential to see increased coverage of afternoon convective
activity. Dewpoints in the low to mid 70s will counter balance
slightly cooler ambient temps to continue muggy conditions. Upper
ridge looks to become dominant once again by the latter half of the
weekend, but with no substantial area of sfc high pressure building
into to suppress strong thermodynamic profiles, the daily shower and
storm chances remain relentless. A slight warming trend is expected
with the increased ridge influence and the Climate Prediction Center
highlights the forecast area in a 40-50% chance to see continued
above normal temperatures for the 6-10 Day Temperature Outlook.

&&

.AVIATION...
(12Z TAFS)
Issued at 512 AM EDT Mon Jul 14 2025

Will see scattered showers and thunderstorms around again today.
Will include a prob30 thunder group at all sites during the time
of highest probability. There may be fog/low cigs again late in
the period especially if significant rain occurs at any site this
afternoon/evening. For now will include MVFR conditions in fog at
TRI late.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             94  73  95  75 /  30  10  20  20
Knoxville McGhee Tyson Airport, TN  93  72  96  73 /  30  20  30  30
Oak Ridge, TN                       90  71  94  72 /  40  10  30  30
Tri Cities Airport, TN              87  68  89  70 /  50  30  50  40

&&

.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&

$$

SHORT TERM...KRS
LONG TERM....KRS
AVIATION...