912
FXUS64 KMRX 071901
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
301 PM EDT Sun Jul 7 2024

...New SHORT TERM, LONG TERM...

.SHORT TERM...
(This evening through Monday)
Issued at 253 PM EDT Sun Jul 7 2024

Key Messages:

1. SLow-moving showers and thunderstorms in the mountains through
the rest of the afternoon.

2. Rain chance expands to the Plateau tomorrow as low level moisture
increases along a weak inverted trough.

3. Heat Index in the 100-105 range in the southern Valley tomorrow
afternoon.

Discussion:

Terrain-based convection will continue through the afternoon, and
dissipate around sunset. We could see some locally heavy rainfall
rates and minor flooding as storm motion will be slow. Through
tonight and tomorrow, there will be little change in the general
weather pattern across the region. In the mid and upper levels, high
pressure will remain centered over the GA coast area. At the
surface, high pressure will be over New England with a weak inverted
trough located across the TN Valley region. With this trough will
come slightly higher surface dewpoints tomorrow, with some spots
into the lower 70s. Forecast soundings still show a weak stable
layer around 800 mb tomorrow afternoon, but weaker than today. This
may allow for convective development outside the mountains, and the
CAMS show showers in the Plateau. This seems reasonable, so will
have chance PoPs in the TN mountains and Plateau, with slight
chances in the Valley. With the higher dewpoints and temperatures in
the lower to mid 90s, the heat index tomorrow afternoon will reach
100 to 105 in the southern Valley areas. Will let the mid shift
consider the need for a Heat Advisory, but it does not look
necessary at this time.

&&

.LONG TERM...
(Monday night through next Sunday)
Issued at 253 PM EDT Sun Jul 7 2024

Key Messages:

1. Heat indices of 100-105 degrees Tuesday as low-level moisture
increases over the Tennessee Valley region.

2. Convectively active this week. Highest rain chances across the
mountains and southern Tennessee Valley early, then shifting to the
northeast and eastern mountains Thursday.

3. The remnants of Beryl will remain to the west and northwest of
our forecast area Tuesday and Wednesday.

4. Upper level ridging building back over the Tennessee Valley
Friday into next weekend. Highs back into the mid 90s. Heat indexes
again going over 100.

Discussion:

Monday night the forecast area is still on the edge of the high
pressure ridging along the southeast coast of the carolinas.
Tropical system Beryl is now expected to track north northeast just
west of the Middle Mississippi Valley Monday night through Wednesday
and reach Michigan by Thursday. Coolest days will be Wednesday in
the west and all areas Thursday with more cloud cover and convection.

The majority of tropical rainfall will be west of the forecast area
Tuesday through Thursday. However a persistent southwest flow aloft
will keep abundant moisture overhead with a good chance for
afternoon and evening showers and thunderstorms late Tuesday and
Wednesday and shifting to the northeast half Thursday as the system
tracks north northeast. A moist flow from the central Gulf Coast
into the eastern TN Valley will also help to enhance rainfall
amounts those same days. With the higher low level moisture, and hot
temperatures, heat index values will be high Tuesday with apparent
temperatures warming into the 100-105 degree range, possibly higher.
A heat advisory may need to be issued in future forecasts for
Tuesday central and southern valley.

Then for Friday through Sunday the upper ridge strengthens from
south to north. Most of the precipitation with showers and storms
will be in the higher elevations along the eastern border, parts of
the Cumberland Plateau and into southwest Virginia. With the upper
ridge strengthening again Friday into the weekend Temperatures warm
back into the lower to mid 90s and even upper 90s in the southern
valley Sunday. Heat advisories may be needed again by the end of
next weekend. It does look like dew points will be slightly lower
than early this week.

&&

.AVIATION...
(18Z TAFS)
Issued at 113 PM EDT Sun Jul 7 2024

Generally followed a persistence forecast for this TAF period as
there will be little change in the weather pattern across the
region over the next 24 hours. A possible exception may be TRI,
where increasing dewpoints tonight may result in some MVFR vis
toward sunrise.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             74  95  76  96 /  10  20  20  50
Knoxville McGhee Tyson Airport, TN  72  94  75  95 /   0  20  10  50
Oak Ridge, TN                       71  93  74  94 /   0  20  10  50
Tri Cities Airport, TN              69  93  70  94 /  10  20  10  40

&&

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

$$

SHORT TERM...DGS
LONG TERM....TD
AVIATION...DGS