324
FXUS64 KMRX 190510
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
110 AM EDT Sat Jul 19 2025

...New AVIATION...

.SHORT TERM...
(This evening through Saturday)
Issued at 118 PM EDT Fri Jul 18 2025

Key Messages:

1. Scattered to numerous showers and storms are expected each
afternoon and evening, with the greatest coverage north of I-40.

2. Heavy rain leading to isolated flash flooding will be the primary
concern with storms this evening through Saturday evening.

Discussion:

The large high pressure ridge in the mid and upper levels, centered
off the east coast of FL today, will drift westward and be located
just off the FL Gulf Coast by Saturday evening. With this slow-
evolving pattern, and a nearly zonal flow across the TN/OH Valley
regions, not much change is expected from what we have been seeing
the past few days. PW values will remain high, in the 1.8 to 2.1
inch range. Efficient warm cloud processes will be in place to
produce heavy rainfall rates with any thunderstorms that form. Weak
midlevel vort maxes crossing eastern KY, SW VA, and southern WV will
enhance lift in that area, so the greatest coverage of storms is
expected to be in our northern sections - the same area that has
seen excessive rainfall the past few days. Localized heavy rain
rates and low FFG from recent rainfall will likely lead to flooding
issues this afternoon and evening in SW VA and NE TN, with a repeat
on Saturday.  The current Flood Watch will be maintained with no
changes, but a new Flood Watch will probably be needed for tomorrow.
As was the case yesterday, will handle these Flood Watches one day
at a time. There will be a low-end risk of damaging winds with a few
thunderstorms today and tomorrow, with MLCAPE values around 1500
J/kg.

&&

.LONG TERM...
(Saturday night through next Friday)
Issued at 118 PM EDT Fri Jul 18 2025

Key Messages:

1. Scattered storms will continue through much of the extended
period with a low chance of strong wind gusts and localized flooding
with the storms.

2. Hot and humid conditions persist through the period with heat
index values of 100-105 degrees across the Valley next week.

The pattern aloft will get a little more amplified on Sunday as the
high pressure ridge will continue to drift westward across the Gulf,
and a trough deepens off the East Coast and western Atlantic. The
slight change in pattern will bring a more NW flow through the mid
and upper levels, and will push a surface front toward our area on
Monday. With the NW flow, we will see a slight drop of PW values
into the 1.7-1.9 range due to some midlevel drying. However, low
levels remain quite moist, and afternoon instability will continue
to support numerous showers and storms with some low-end potential
for damaging wind gusts. Another thing to watch will be the
development of upstream MCSs that could track into our northern
sections in the NW flow pattern along the stalled boundary to our
north, mainly in the Sunday through Tuesday periods. Given the
saturated soil conditions in SW VA and NE TN, the flooding concerns
may continue if the MCS development pans out.

The large ridge over the Gulf begins to build northward on Tuesday,
and becomes centered around West TN on Wednesday. This will reduce
our rain chances and increase our temperatures. Heat Index values
will likely exceed 100 degrees next week, with 105+ possible by
midweek.

&&

.AVIATION...
(06Z TAFS)
Issued at 108 AM EDT Sat Jul 19 2025

Showers and storms have largely exited the area with TRI having
seen rain in the past 1 to 2 hours. As such, TRI is most likely to
see periods of fog and low clouds with MVFR or less. CHA and TYS
are expected to stay VFR for the remainder of the night. During
the day, storms are expected to develop again with better coverage
at all of the airports. The most likely timing is from mid
afternoon through early evening, but some storms are possible
earlier at CHA. Within storms, reduction to MVFR or less can be
expected.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             89  74  93  75 /  70  30  60  10
Knoxville McGhee Tyson Airport, TN  88  74  91  74 /  70  50  60  30
Oak Ridge, TN                       86  72  91  73 /  70  40  70  30
Tri Cities Airport, TN              85  70  86  70 /  70  60  70  50

&&

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

$$

SHORT TERM...DGS
LONG TERM....DGS
AVIATION...BW