731
FXUS64 KMRX 232322
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
622 PM EST Sat Nov 23 2024

...New AVIATION...

.SHORT TERM...
(This evening through Sunday)
Issued at 253 PM EST Sat Nov 23 2024

Key Message:

1. Potential for areas of fog mainly along and north of I-40 late
tonight into early Sunday morning.

Stubborn cloud cover will persist over northeast Tennessee and
southwest Virginia through the overnight hours. Expect some lesser
cloud cover farther south where clear skies and light winds should
produce some areas of fog to develop. Confidence is low for fog to
develop farther south near Chattanooga. By mid morning, most of the
low clouds and fog should start mixing out.

Northwest flow aloft will gradually shift to more zonal by late
afternoon. Winds will remain light and become southerly. Daytime
temperatures will be 5 to 10 degrees warmer than Saturday.

&&

.LONG TERM...
(Sunday night through next Saturday)
Issued at 253 PM EST Sat Nov 23 2024

Key Messages:

1. Above normal temperatures Monday before a frontal passage headed
into Tuesday. Near normal temperatures return mid-week.

2. A more significant system moves in late Wednesday and through
Thanksgiving into Friday. A general 1 to 2 inches of rain with this
system and over 2 inches possible across parts of the higher terrain.

3. Much colder Friday and Saturday.

Discussion:

We start the period with a more zonal flow pattern aloft ahead of a
cold frontal system that will impact the area late Monday into
Tuesday. Before that, however, high temperatures Monday will be very
warm for end of November standards. Mid to upper 60s are likely to
encompass the middle and southern valley; nearly 10 to 15 degrees
above normal. Under a half inch of rain area-wide is forecast with
this "appetizer" of the week. Winds will increase coinciding with
the front, but the parameters don`t line up for any sort of mountain
wave event.

Precipitation with the aforementioned system will taper off into the
day Tuesday, turning dry for the next 24 to 36 hours or so into
Wednesday. Temperatures will be around normal with general highs in
the 50s.

The entree of the week or the highlight of the long term, will be a
much stronger system late Wednesday and persisting into Friday. A
more southern moving shortwave trough will send a low pressure
system that develops off of the Rockies into Texas to our region by
late Wednesday. There will be a whole lot more moisture with this
system as flow originates from the Gulf beginning around early
Wednesday. QPF amounts have been consistent the past couple forecast
packages of rainfall amounts of more than 1 inch everywhere. 2, 3,
or even up to 4 inch totals could be possible between Wednesday
night and Friday night, especially over higher terrain. This should
and will be monitored for the potential of flooding for our area.
Unfortunately, those that travel to their destinations on
Thanksgiving Day, may be dealt with moderate to heavy rainfall as
the low center passes just to our north Thursday with numerous to
widespread rain. The cold front itself will pass overhead sending
temperatures downward sometime during the night hours on
Thanksgiving.

Beyond Thanksgiving, precipitation odds become less defined if there
will be northwest flow on the backside of the system, but the one
sure thing we can expect to round out the week will be much colder
temperatures. Black Friday weekend shopping to kick off the
Christmas season will be welcomed with highs remaining in the 30s to
40s and overnight lows Saturday morning plummeting to the 20s.

&&

.AVIATION...
(00Z TAFS)
Issued at 555 PM EST Sat Nov 23 2024

Main concerns is how fast MVFR clouds moving out of TRI and how
much fog development occurs at TRI and TYS early Sunday morning.

Timing of MVFR ceiling movin out of TRI is around 01Z. Given the
good radiational cooling expect MVFR fog development at TRI and
TYS early Sunday morning. Otherwise, VFR conditions.

Due to surface ridging across the Tennessee valley, winds will
remain light at all TAF sites through the forecast period.
Generally less than 10kts.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             36  64  43  69 /   0   0   0  10
Knoxville McGhee Tyson Airport, TN  33  61  40  67 /   0   0   0  10
Oak Ridge, TN                       32  60  39  65 /   0   0   0  10
Tri Cities Airport, TN              31  57  34  62 /   0   0   0   0

&&

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

$$

SHORT TERM...DH
AVIATION...DH