758
FXUS64 KMRX 241733
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
1233 PM EST Fri Jan 24 2025

...New AVIATION...

.UPDATE...
Issued at 947 AM EST Fri Jan 24 2025

A short-wave will move across the area this afternoon. Associated
850mb jet of 25-30 knots is producing isentropic lift over the
Plateau/middle Tennessee. This lift is producing light
snow/flurries with a dusting of snow being reported across the
Plateau.

This wave will move across the region producing occasional
flurries over much of the area with greatest potential of
measurable snowfall from the northern Plateau, southwest Virginia,
and far east Tennessee mountains.

For this afternoon/evening, cold air advection as thermal trough
approaches will squeeze out available moisture. Some scattered
snow showers will heavier snow accumulations possible.

Some orographic lift this evening/early tonight will keep chances
of snowfall over southwest Virginia and far east Tennessee
mountains.

Have lowered high temperatures for today across much of the area
by a degree or two given the evaporation cooling, cold air
advection, and cloud cover.

&&

.SHORT TERM...
(Today and tonight)
Issued at 253 AM EST Fri Jan 24 2025

Key Messages:

1. A few flurries and light snow showers possible today, mainly
across the higher terrain.

2. Continued cold for the period.

Discussion:

A mid/upper level short wave will swing across the region today, but
moisture looks very limited.  We will see a brief period of cold
advection later today as the short wave exits. A few flurries and
possibly isolated light snow showers can be expected today mainly
over the north and higher elevation areas. However, given the
limited moisture and since even during the weak cold advection
behind the wave the 850mb will flow be mainly from the west which is
not ideal for orographic lift, little if any snow accumulation is
expected with higher end amounts being perhaps a few tenths of an
inch over some of the higher mountain peaks.

Surface high pressure will settle over the area tonight. It will
remain cold today and tonight, with temperatures generally running
around 6 to 13 degrees below seasonal normals.

&&

.LONG TERM...
(Saturday through Thursday)
Issued at 253 AM EST Fri Jan 24 2025

Key Messages:

1. Seasonally normal temperatures through next Thursday.

2. A low (20%) chance a weather system Sunday night into Monday will
affect the area, with a light wintry mix the main concern.

Discussion:

Not too many changes this forecast cycle, still looking dry on
Saturday heading into Sunday with seasonal temperatures that
wouldn`t be of note if it wasn`t for the last three weeks. Sunday
night into Monday still carries a 20% to 40% chance of
precipitation...the GFS and Euro ensembles have both gradually
trended their probabilities down, LREF odds of measurable
precipitation have gone from 60-80% down to 25-55% north to south.
Curiously the EC-AIFS and Graphcast have been persistent in showing
QPF over the area, and also above freezing temperatures, which line
up with the last GFS run. The GFS sounding indicates the potential
for a light snow to make it to the ground, if the near-surface layer
is cold enough. Still, with the ensembles trending towards a drier
and colder solution, its uncertain what, if any, precipitation we
see from this system.

Beyond Monday`s potential shenanigans, we will move through Tuesday
unimpeded by any precipitation, and likely Wednesday as well, unless
the GFS` solution for rain showers comes to fruition. Uncertainty
picks up considerably at this range and thereafter, with a low
expected to eject from the southern Rockies late next week.
Solutions diverge on the speed of that ejection, but that`s likely
where the next round of rain comes from.

&&

.AVIATION...
(18Z TAFS)
Issued at 1214 PM EST Fri Jan 24 2025

A short-wave moving across east Tennessee will produce scattered
snow showers or flurries at TRI and TYS through 20-22Z. Marginal
MVFR conditions possible at TRI and TYS through 00Z, otherwise,
VFR conditions. Westerly winds this afternoon with gusts up to 15
knots.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             22  49  29  45 /   0   0   0  10
Knoxville McGhee Tyson Airport, TN  20  46  28  45 /   0   0   0  10
Oak Ridge, TN                       20  45  28  46 /   0   0   0  10
Tri Cities Airport, TN              17  42  25  44 /   0   0   0  10

&&

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

$$

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