363
FXUS64 KMRX 222018
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
318 PM EST Fri Nov 22 2024

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

.SHORT TERM...
(This evening through Saturday)
Issued at 227 PM EST Fri Nov 22 2024

Key Messages:

1. Snow showers are expected to bring 1-3 inches of additional snow
to portions of southwest Virginia and the East Tennessee mountains
tonight, with isolated totals between 3-5 inches in the highest
peaks and ridgetops.

2. Breezy and at times, blustery conditions expected with wind
gusts in the 35 to 45 mph range across the highest elevations
resulting in wind chill values in the teens

Discussion:

Current radar may look rather dry and satellite currently paints
a picture of broken cloud cover, but that is expected to change
tonight. Another upper level impulse rounding the upper trough
will again send moisture to our area from the north and west. 15
to 20 KT 850 mb winds or so right now are expected to increase to
around 30 to 40 KT after 00Z Saturday. Then all of the ingredients
come into place to repeat northwest flow induced snowfall again
tonight, except it will be more confined to far north and eastern
sections of our CWA (north and northeast TN and southwest VA).
Generally can expect an additional 1 to 3 inches of snow, with the
highest terrain or mountain peaks seeing an additional 3 to 5
inches. Snowfall will begin to taper off during the very early
morning hours Saturday.

Winds out of the west will also increase tonight leading to 20 to
30 mph gusts or so for TN bordering NC and southwest VA. Wind
gusts in the 35 to 45 mph range will be possible over the highest
elevations. With this in mind and another cold night in store, but
not as cold, wind chills as low as the teens are possible.

Saturday with time, will improve with decreasing cloud cover and
high pressure moving in from the Mississippi Valley. Temperatures
will be on the upswing with 850 mb readings rapidly increasing 10
deg C or so from Saturday morning to the afternoon. This will
result in high temperatures for the middle and southern valley to
reach the low to mid 50s.

&&

.LONG TERM...
(Saturday night through next Friday)
Issued at 227 PM EST Fri Nov 22 2024

Key Messages:

1. Brief return to above normal temperatures Sunday and Monday.

2. Rain returns Monday afternoon and night to start the week.

3. More significant system moves in late Wednesday and through
Thanksgiving. One to two inches of rain possible with this system.

Discussion:

A progressively wavy zonal flow will persist in the extended period,
allowing a quick warm up Sunday and Monday ahead of the next cool
front that returns us to near normal late-fall temps. This front
will contain a quick shot of showers followed by cool and dry
weather Tuesday.

Then the next system approaches Wednesday and produces most of its
rainfall on Thursday before ending Friday. Models have been bouncy
with the main QPF location, sometimes over SW VA, sometimes south of
I-40. So the "where" is still in question. But indications are that
some flooding problems are to be expected if this system holds true
to its 2" potential rain maximum.  Some streams may escape their
banks and inundate their flood plains and whatever is in them, made
all the worse that the potential for this happens on Thanksgiving
Day.

Behind this second system will be a reinforcement of cold air
leading to a chilly post-Thanksgiving weekend.

&&

.AVIATION...
(18Z TAFS)
Issued at 1238 PM EST Fri Nov 22 2024

W-NWly winds will prevail, with gusts at times through the
afternoon at all terminals. TRI will experience the most
persistent and strongest gusts up to 25KT lasting overnight. CIGS
should remain VFR at CHA, but CIGS forecast to dip to MVFR at TYS
tonight and persist for the next several hours. VFR CIGS return
towards end of the TAF period. Though moisture is set to return,
not looking at great chances around TYS. TRI is forecast to reach
MVFR CIGS earlier than TYS and may dip into the lower end of MVFR
close to 1kft. Snow showers will return at TRI during the
overnight hours when another round of moisture swings down from
the NW. PROB30 added to reflect this due to possible non-
persistent showers. Snow showers should taper around/after 12z
leading to decreased winds and eventual return to VFR conditions
either at the very end of the TAF period or will be reflected in
the 00z issuance. For now, have kept MVFR CIGS through end of TAF
at TRI.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             36  57  35  64 /   0   0   0   0
Knoxville McGhee Tyson Airport, TN  37  53  32  61 /   0   0   0   0
Oak Ridge, TN                       37  54  32  60 /   0   0   0   0
Tri Cities Airport, TN              36  47  30  57 /  30   0   0   0

&&

.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...Winter Weather Advisory until 7 AM EST Saturday for Blount Smoky
     Mountains-Cocke Smoky Mountains-Johnson-Sevier Smoky
     Mountains-Southeast Carter-Southeast Greene-Unicoi.

VA...Winter Weather Advisory until 7 AM EST Saturday for Russell-
     Washington VA-Wise.

&&

$$

SHORT TERM...KS
LONG TERM....GC
AVIATION...KS