145
FXUS64 KMRX 092311
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
611 PM EST Sat Nov 9 2024

...New AVIATION...

.SHORT TERM...
(This evening through Sunday)
Issued at 244 PM EST Sat Nov 9 2024

Key Messages:

1. Low chance of measurable rain in most areas tonight and
tomorrow; highest chances in the Cumberland Plateau.

2. Cooler temperatures tomorrow under cloudy skies, but still
above normal.

Discussion:

Surface high pressure remains over the Mid Atlantic region today,
extending SW across the Carolinas and Georgia. Aloft, a large
ridge remains across the southern Appalachians that has kept
precip to our west so far and skies over East TN mostly sunny,
although a few light showers in an area of weak isentropic lift
are beginning to reach our SW counties. Through the night, the
ridge will shift east and allow for increasing clouds and
isentropic lift, mainly in our western sections. Model soundings
maintain a dry layer from 850-700 mb, so any showers will be light
and shallow. Moisture depth and lift increases late tonight and
tomorrow morning. However, a strengthening southerly flow will
create downslope conditions near and downstream of the mountains.
PoPs tonight and tomorrow will be in the chance range for the
Plateau, with slight chances elsewhere. This is under what the
NBM is showing. Topside the cloud cover being broken to overcast,
the southerly low level flow with warm advection, plus some
downslope warming, will continue to provide above normal
temperatures in the upper 60s to lower 70s tomorrow.

&&

.LONG TERM...
(Sunday night through next Saturday)
Issued at 244 PM EST Sat Nov 9 2024

Key Messages:

1. Best chances for widespread rain now Sunday night into early
Monday.

2. Above normal temperatures Monday through Wednesday. Temperatures
will be cooler than last week. Chance of rain Wednesday night ahead
of a weak cold front.

2. Cooling temperatures closer to seasonal normals behind
cold front Thursday and Friday.

Discussion:

Sunday night we will have the best chance to see widespread rainfall
across the eastern Tennessee Valley and southern Appalachians as the
frontal boundary thats moving out of the Southern Plains this
afternoon finally moves into middle Tennessee overnight Sunday night
and then into the Southern Appalachians Monday morning. Low QPF
amounts Sunday should increase Sunday evening from west to east as
the front approaches. The northwest half could see 0.10 to 0.40
inches before 06Z Monday and then about the same amount between 06Z
to 12Z over the southeast half. A few locations may see up to 1 inch
of rain before the front moves away Monday. There is some limited
instability overnight ahead of the front so a few thunderstorms are
possible.

This cold front will lower temperatures about 10 degrees from todays
warm temperatures but still keep highs in the 60s to near 70 which
is at least 5 to 10 degrees above average but not near records.
Upper trough that moves through Monday will be replaced by ridging
by Tuesday and continue through Wednesday. Wednesday night into
Thursday morning another weak cold front will pass through the
region with just a chance of showers and little additional QPF.
However it will be enough to lower temperatures another 5 to
possibly 10 degrees. Low temperatures will be noticeably cooler, in
the upper 30s to mid 40s Friday and Saturday mornings. Weak ridging
begins to move up across the forecast area Friday and then the flow
becomes more zonal Saturday. Expect temperatures to only warm a
couple degrees Saturday.

&&

.AVIATION...
(00Z TAFS)
Issued at 608 PM EST Sat Nov 9 2024

Overall, CHA is the site with the most aviation concerns through
the TAF period. While rain is likely to hold off through the
period, MVFR conditions are anticipated by the morning hours.
Additionally, LLWS was added because of winds over 35 kts around
2,000 feet AGL before surface winds increase late morning. At the
other sites, stronger low-level winds are expected but just later
in the day where it may be more turbulence than anything. TYS and
TRI are likely to remain VFR through the period.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             58  65  60  73 /  20  20  70  30
Knoxville McGhee Tyson Airport, TN  58  72  60  71 /  20  30  90  40
Oak Ridge, TN                       57  67  58  72 /  30  30  90  40
Tri Cities Airport, TN              51  69  57  68 /  20  30  80  40

&&

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

$$

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