288
FXUS64 KMRX 121451
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
1051 AM EDT Mon Aug 12 2024

...New UPDATE...

.UPDATE...
Issued at 1046 AM EDT Mon Aug 12 2024

Forecast mostly on track this morning with only minor changes.
Satellite imagery showing more sky cover across the central and
southern TN Valley compared to previously forecast. Bumped up sky
grids to account for this. Otherwise, no changes.

&&

.SHORT TERM...
(Today and tonight)
Issued at 300 AM EDT Mon Aug 12 2024

Key Messages:

1. Dry conditions are expected to persist for the short term with
near normal high temperatures again today.

Discussion:

The overall pattern will continue to be the same during the period
with broad upper level troughing over the northeast and surface high
pressure extending into our area from the northwest and north. Some
weak short wave energy will move through the northwest flow aloft
but with little moisture to work with it will just bring an uptick
in high/mid clouds overnight. We will continue to see dry weather
through the short term period with high temperatures again near
seasonal normals today along with plenty of sunshine and low
afternoon humidity. Lows tonight will again be slightly below
normal.

&&

.LONG TERM...
(Tuesday through Sunday)
Issued at 300 AM EDT Mon Aug 12 2024

Key Messages:

1. Near normal temperatures to continue.

2. Mostly dry conditions through mid-week before increasing rain
chances late week into the weekend.

Discussion:

Long term period continues forward. Tuesday and Wednesday look to be
dry for the area, outside of an errant shower in the mountains,
although even this seems to be unlikely. Low atmospheric moisture
available thanks to continued unfavorable winds aloft are allowing
for dry summer weather in the Mid South. However, a pattern change
is approaching. The upper trough over the northeast will eventually
exit, an upper ridge will move quickly through before the next
trough enters the area by the weekend. Concurrently, better moisture
return occurs Thursday, increasing PWAT values from 1.1" to 1.6" or
better. Thus, rain chances will return, though still quite low
Thursday afternoon.

The better rain chances are consistently hanging Friday into
Saturday as the next upper trough swings into the Eastern US and
provides for cyclogenesis and, by some point in the weekend, a cold
front. By this time we`ll have had consistent and sustained moisture
flowing northwards into the Tennessee Valley, with increasing PWAT
and GEFS showing CAPE increasing to 1000J along the Plateau. This
should allow for showers and thunderstorms, providing beneficial
rainfall after this prolonged dry spell in August. GFS depicts
effective shear of 30 knots, which is an increase from the prior
shift. This would be enough to support stronger thunderstorms, which
will bear watching.

There may be some lingering showers on Sunday, especially in the
mountains. GFS kicks the cold front through a whole day quicker than
the Euro, which will play with how much shower coverage we`ll see
the later into the weekend we are. Otherwise heat indices look to
increase a tad by Friday with the better moisture, but temperatures
look to remain normal for mid-August.

&&

.AVIATION...
(12Z TAFS)
Issued at 517 AM EDT Mon Aug 12 2024

VFR conditions are expected for the period all sites. Winds will
generally be light.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             90  67  92  68 /   0   0   0   0
Knoxville McGhee Tyson Airport, TN  86  64  87  65 /   0   0   0   0
Oak Ridge, TN                       86  64  87  64 /   0   0   0   0
Tri Cities Airport, TN              86  58  84  61 /   0  10  10   0

&&

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

$$

SHORT TERM...
LONG TERM....Wellington
AVIATION...