-- Discussion containing changed information from previous version are highlighted. --
375
FXUS64 KMRX 131118
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
718 AM EDT Sun Jul 13 2025

...New AVIATION...

.SHORT TERM...
(Today and tonight)
Issued at 135 AM EDT Sun Jul 13 2025

Key Messages:

1. Additional showers and storms expected this afternoon. Overall,
lesser coverage and chances for an isolated severe storm relative to
yesterday. Strong gusty winds up to 40mph and isolated flash
flooding will be the main concerns with any stronger storm.

Discussion:

A pattern of persistence for the overnight hours. River valley fog
is beginning to show on satellite imagery while river valleys and
locations that observed moderate to heavy rainfall this afteroon
will have the highest chances to see some patchy dense fog. With
some weak 500mb vorticity in place it is not out of the question to
see an isolated shower or rumble of thunder in the AM hours.
However, with no heating to counteract poor synoptic forcing, no sig
weather is expected.

For this afternoon, upper trough will remain in place over the
western Great Lakes with an 80-85kt H3 jet extending from northern
Illinois into eastern Canada. There is no notable impulse rounding
the base of the trough this afternoon, and RAP soundings show
effective bulk shear less than 10kts as a result. Additional
isolated to scattered showers and storms are expected in the
afternoon and evening but organization and any severe chances seem
unlikely due to the lack of shear. 1.7-1.8" PWs and DCAPE between
600-900J/kg could still lead to the occasional precip loaded
downburst with winds to 40mph and isolated flash flooding in the
event activity occurs over vulnerable soils.

&&

.LONG TERM...
(Monday through Saturday)
Issued at 135 AM EDT Sun Jul 13 2025

Key Messages:

1. Daily summer-time convection continues. Coverage will be more
isolated to scattered to begin the period, with potential for
increased coverage as troughing influence increases the latter half
of next week.

2. Hot conditions return as an upper ridge builds back into the
region for the middle part of the work week. Heat indices in the mid
90s to low 100s will become more common across valley locations.

Discussion:

Upper trough pivots eastward Monday with continued chances for
diurnal convection. Latest  NAMBufr soundings suggest that effective
shear remains 10kts or less, with typical summer-time diurnal
convection expected. A few stronger storms could lead to wind gusts
up to 40mph and isolated flash flooding. For now, this is ultimately
the threats expected with convection each day through the extended.
Monday will be hot and muggy with with heat indices near 100F for
much of the southern and central valley. Low to mid 90s are more
likely for northern valley into southwest Virginia.

By mid-week the ridge will continue to build across the eastern
CONUS. While chances for diurnal convection persists, the main focus
will be on heat indices near the low 100s becoming more common,
especially central valley and further south. Tuesday and Wednesday
are currently looking to be the warmest days.

By Thursday a shortwave trough will be digging into the northern
CONUS. With weakening subsidence aloft there is potential to see
increased coverage of afternoon shower and storm activity but
temperatures will trend closer to seasonal normal. A humid air mass
will keep indices in the 90s to near 100. Upper ridge looks to
become dominant once again next weekend, but with no substantial
area of sfc high pressure building into to suppress convection,
daily shower and storm chances remain relentless.

&&

.AVIATION...
-- Changed Discussion --
(06Z TAFS)
Issued at 441 AM EDT Sun Jul 13 2025

After any early fog/low clouds dissipate, will see predominantly
VFR conditions all sites. There will be scattered showers and
storms around mainly this afternoon/early evening, and will
include prob30 groups for thunder all sites. Fog/low cigs will be
possible again late in the period, but this will most likely
occur if rain ends up occurring at any given site which is still
unknown, so will not include this in the TAFs for now.
-- End Changed Discussion --

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             93  73  95  74 /  40  10  30  10
Knoxville McGhee Tyson Airport, TN  92  72  94  73 /  40  20  40  20
Oak Ridge, TN                       91  71  93  72 /  40  20  40  10
Tri Cities Airport, TN              87  68  89  69 /  40  30  50  30

&&

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

$$

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