533
FXUS64 KMRX 230208
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
908 PM EST Sat Feb 22 2025

...New UPDATE...

.UPDATE...
Issued at 904 PM EST Sat Feb 22 2025

Satellite shows clouds are a bit slower to exit than earlier
forecast but are still clearing out from west to east, so will
make some adjustments to sky to better show the slower trend with
this update. Otherwise, just some tweaks mainly to hourly temps
and dew points.

&&

.SHORT TERM...
(This evening through Sunday)
Issued at 223 PM EST Sat Feb 22 2025

Mid-level water vapor imagery from GOES-16 depicts a shortwave
trough axis swinging through the Tennessee valley this afternoon.
Increasing mid-level clouds have been the only impact thus far,
though a few light returns can be noted on radar. Don`t expect any
precipitation to make it to the surface as dewpoint depressions
around 20-25f. We clear out overnight as the shortwave departs
eastward. Clear skies and light winds will lead to favorable
radiational cooling with another cold overnight, albeit, warmer
than previous nights.

A southern stream vort max will propagate eastward Sunday with
surface high pressure in control locally. Mostly clear skies owing
to strong subsidence along with a 2 to 4dam H5 height increase
will promote a very minor warming trend of just a few degrees.

&&

.LONG TERM...
(Sunday night through next Saturday)
Issued at 223 PM EST Sat Feb 22 2025

Key Messages:

1. Warming trend through first half of the week.

2. Cold front with widespread rain possible Wed night into Thu.

Discussion:

The upper levels will feature quasi-zonal flow across the CONUS to
start the period as the polar and subtropical jets remain separated
by quite some distance through the middle of next week. The lack of
highly amplified flow, and persistent southwesterly low level winds
will result in a gradual warming trend through Wednesday, which will
result in highs reaching the 60s by Tuesday and mid to upper 60s by
Wednesday.

There is some phasing of the northern and southern stream jets that
occurs late Wednesday into Thursday however, as a PacNW trough dives
into the plains and a ridge builds over the west. The jet
enhancement that ensues places our forecast area beneath strongly
diffluent flow aloft Wednesday night, just ahead of a cold front
that will sweep through the southern Appalachian region. NBM output
actually limited PoPs to chance levels for Wed afternoon through Thu
morning, which seems too low given the agreement in deterministic
model runs today. Bumped those back up to give some likely PoPs in
places Wed evening and Wed night. After warmer than normal temps
early next week, this front will knock us back down to seasonal
norms. On the back side of the front, expect to see some light snow
in the mountains. Temperatures aloft aren`t cold though for there
to be anything in the lower elevations though.

&&

.AVIATION...
(00Z TAFS)
Issued at 615 PM EST Sat Feb 22 2025

The clouds currently over the area will exit early in the period.
VFR conditions are expected to continue for the period all sites.
Winds will generally be light.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             26  52  30  61 /   0   0   0   0
Knoxville McGhee Tyson Airport, TN  23  49  26  57 /   0   0   0   0
Oak Ridge, TN                       23  49  26  56 /   0   0   0   0
Tri Cities Airport, TN              21  46  25  55 /   0   0   0   0

&&

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

$$

SHORT TERM...
LONG TERM....CD
AVIATION...