278
FXUS64 KMRX 152350
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
750 PM EDT Tue Jul 15 2025

...New AVIATION...

.SHORT TERM...
(This evening through Wednesday)
Issued at 142 PM EDT Tue Jul 15 2025

Key Messages:

1. Isolated to scattered storms rest of this afternoon into the
evening with localized flooding and a few stronger storms
possible. Strong and gusty winds are the main concern.

2. Hot and muggy conditions rest today and Wednesday with heat
indices ranging from the upper 90s to near 104 degrees in the
valley.

Discussion:

Heat indices are climbing into the upper 90s to lower 100s across
much of the Tennessee valley.

A fairly stagnant upper pattern with ridging into the southeast
Tennessee valley and southern Appalachians. Given the proximity of
the ridge axis near the southern Tennessee state-line the greatest
coverage of convection will be along and north of interstate 40.

SPC meso-analysis shows MLCAPEs of 1500-2000 with DCAPES of 800+.
Shear is negligible. Typical summer pulse storms are expected.
Main concern is strong and gusty winds up to 45 mph and localized
runoff problems.

Rainfall dependent, patchy areas of dense fog is possible.

For Wednesday, essentially a repeat of today with heat indices
ranging from the upper 90s to up to 104 degrees. Mainly afternoon
and evening convection is once again expected with localized
strong/gusty winds and localized flash flooding.

&&

.LONG TERM...
(Wednesday night through next Tuesday)
Issued at 142 PM EDT Tue Jul 15 2025

1. Daily storms are expected through the period with better coverage
expected this weekend and early next week.

2. Hot and humid conditions will persist through Friday with heat
index values ranging from the upper 90s to lower 100s. Due to the
expected greater coverage of convection and clouds this weekend
and early next week, heat indices will decrease into mainly the
90s.

Thursday and Friday

For Thursday and Friday, ensemble cluster analysis shows a persistent
upper ridge will remain across the Tennessee valley and southern
Appalachian. This will continue the summer pattern with weak flow
aloft and similar thermodynamics as in the short term period. Hot
and humid conditions and diurnal convection can be expected.

Saturday through Tuesday

A frontal boundary will slowly approach the Tennessee valley and
southern Appalachians with ridge axis slowly retrograding
westward. This will allow an increased coverage of convection as
through early next week. The threat for localized flooding and
isolated strong storms will remain each day. PWs increase as well
so the threat of flooding will increase.  The overall flooding
threat will be specific to which places see repeated convection,
but efficient rainfall rates will be realized, given the
environment.

&&

.AVIATION...
(00Z TAFS)
Issued at 737 PM EDT Tue Jul 15 2025

A couple of storms producing some lighting outside the vicinity of
TYS and TRI, but the thinking is is that they won`t enter within
range of the terminals. Conditions turn calm or variable tonight
with the possibility of IFR CIG at TRI; did not change what was
placed into the 18z forecast package. Fog also a possibility, but
has been left out due to lower confidence. For Wednesday, light
winds out of the SW with the possibility of afternoon storms once
again.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             75  95  75  95 /  10  40  20  50
Knoxville McGhee Tyson Airport, TN  73  94  75  93 /  20  50  30  50
Oak Ridge, TN                       72  93  74  92 /  20  50  30  60
Tri Cities Airport, TN              69  91  70  89 /  50  60  50  70

&&

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

$$

SHORT TERM...DH
LONG TERM....DH
AVIATION...KS