126
FXUS64 KMRX 161709
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
109 PM EDT Wed Jul 16 2025

...New AVIATION...

.UPDATE...
Issued at 1147 AM EDT Wed Jul 16 2025

Quick update to discuss current thoughts of storm potential this
afternoon into the evening. SPC meso-analysis shows instability
has increased from yesterday`s values with MLCAPE increasing to
2500+. Also DCAPE values are greater as well with values of 1000+
and Theta-E Difference of 30+, as well as, PWs up to 1.7 to 1.9
inches.

Given the above there is a better chance of seeing strong and
gusty winds up to 50 mph or so along with isolated flash flooding.
Do not expect a big outbreak by any means but environment more
conducive to isolated strong storms.

Besides the convection, heat indices this afternoon in the upper
90s to lower 100s across much of the valley.

&&

.SHORT TERM...
(Today and tonight)
Issued at 137 AM EDT Wed Jul 16 2025

Key Messages:

1. Scattered storms are expected this afternoon into the evening
with strong winds and localized flooding possible in some storms.

2. Hot and humid conditions will continue with highs rising into the
90s and heat index values around 100 degrees.

Discussion:

Currently early this morning, weak flow is in place aloft with broad
ridging and embedded shortwaves across much of the eastern U.S. A
shortwave is noted in the Great Plains with convection ongoing. A
weak tropical disturbance is also expected to move along the
northern Gulf. Overall, the pattern will remain fairly similar to
yesterday with weak flow aloft and hot and humid conditions. MLCAPE
of 1,500 to 2,000 J/kg can be expected again with nearly 0 shear.
This will continue the low-end threat for strong winds and localized
flooding. At the time of this discussion, convection is ongoing
across the mountains, and its coverage could enhance the flooding
threat for those areas today. However, many of the CAMs are limited
with coverage this afternoon and evening. Some activity may continue
overnight as we have seen this past night.

&&

.LONG TERM...
(Thursday through Tuesday)
Issued at 137 AM EDT Wed Jul 16 2025

Key Messages:

1. Daily chances for showers and storms will continue through the
whole period. Strong winds and localized flooding will remain
possible within some storms.

2. Hot and humid conditions will also continue through the period
with highs reaching into the 90s across the Valley and heat index
values around 100 degrees.

Thursday through Saturday

At the start of the period, quasi-zonal flow will be in place with
500mb heights in excess of 5,920m. The weak tropical system
referenced in the short term period is expected to be moving into
southern Louisiana and Mississippi. A frontal boundary will also be
advancing towards the Ohio River Valley. 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 to continue. Better moisture (PWATs near
2 inches) will move into our area late in the week as the tropical
system dissipates and progresses northward. The front is likely to
weaken as it settles near the Ohio River Valley on Friday, which,
combined with increased moisture, will make the case for better
convective coverage. The frontal boundary will weaken on Saturday,
but elevated convective coverage can be expected due to remaining
impressive moisture. As in recent days, localized flooding and
isolated strong storms will remain possible.

Sunday through Tuesday

Sunday into early next week, general ridging is expected to prevail
across the eastern U.S. with some variations in the exact pattern
seen locally. Some sources are more aggressive with ridging
expanding from the south while others suggest increasing shortwaves.
Regardless, 500mb heights will remain above 5,900m, along with
abundant moisture in the area to support continued convection. Hot
and humid conditions will also persist, but the current data
suggests the region to remain below advisory criteria and in line
with typical July heat.

&&

.AVIATION...
(18Z TAFS)
Issued at 104 PM EDT Wed Jul 16 2025

Scattered convection is expected across the TAF sites from 19-02Z.
TRI and TYS have the greatest chance. Depending if rain occurs at
the airport then fog/low-cloud development is possible.

Otherwise, VFR conditions. Breezy south to southwest winds with
gusts up to 10-12 knots possible at CHA and TYS this afternoon due
to up-valley winds.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             75  95  76  93 /  10  40  20  60
Knoxville McGhee Tyson Airport, TN  75  93  74  92 /  30  40  30  60
Oak Ridge, TN                       74  93  74  91 /  20  50  30  70
Tri Cities Airport, TN              70  89  70  87 /  50  70  40  70

&&

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

$$

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