Georgetown, Tennessee Weather Forecast Discussion

693
FXUS64 KMRX 231059
AFDMRX
Area Forecast Discussion
National Weather Service Morristown TN
659 AM EDT Tue Sep 23 2025
...New UPDATE, AVIATION...
.KEY MESSAGES...
Updated at 653 AM EDT Tue Sep 23 2025
-  Periods of rain and thunderstorms through this week,
    culminating on Thursday. Flash flood risk will increase by
    Wednesday and Thursday as multiple days of rain steadily lead
    to higher accumulations.
-  Wednesday and Thursday more widespread storms will be likely.
    A few strong to severe storms will be possible on Wednesday,
    primarily in a damaging wind threat.
-  The weekend into Monday will trend drier, with slightly below
normal temperatures trending toward normal by Monday.
&&
.UPDATE...
Issued at 653 AM EDT Tue Sep 23 2025
Rain coverage has been more than expected early this morning, so
PoPs were raised across most of the area to incorporate this
trend.
&&
.DISCUSSION...
Issued at 133 AM EDT Tue Sep 23 2025
Quasi-zonal flow with a couple weak embedded shortwaves is the mode
for the next couple of days until the larger upper level trough digs
into the Eastern US on Thursday. Regardless of the size of the
disturbance, periods of rain and thunderstorms will occur through
the course of this week, bringing a couple more inches of rain to
the area. Today is the least saturated in the moist atmospheric
profiles, and vorticity fields depict slight height rises whilst
being between two of the shortwaves, so the 00z HRRR`s solution of
only isolated showers during the daylight checks out. Arrival of
the next shortwave will likely spark off a new round of showers
and storms overnight tonight.
Wednesday storm activity should flourish once more with higher
PWATs yielding a greater risk for heavier rain rates, that risk
will persist into Thursday as well as the larger trough arrives.
Effective shear on Wednesday will be around 30 knots per the HRRR
- more supportive of organized convection, so a strong to severe
storm is a low potential. A limiting factor will be our position
under the suppressive side of the upper jet streak, with a weak
subsidence layer high aloft on CAM soundings. GFS/NAM don`t seem
as enthused, but again, this is a low risk. Thursday also has
available shear, but exact timing of the trough, and how saturated
the whole atmospheric profile is by then may limit storms to a
heavy rain risk.
The overall message for this week still seems consistent and
persistent. Periods of rain, both during the day and the night,
will eventually bring higher rainfall totals to much of the area.
Vulnerable low lying locations in places that receive multiple
rounds of rainfall this week. Current forecast keeps the heaviest
rainfall west of I-81 over western portions of VA and northwestern
portions of East Tennessee including the northern portions of the
Cumberland Plateau. Any strong thunderstorms will be able to
efficiently put down heavier rainfall amounts.
Beyond Friday and some lingering rain chances, the forecast is more
likely to be dry and quiet, despite still large uncertainties in
the forecast fields of various model suites. Not seeing any
significant weather signals at this time, and we`ll have a chance
to soak in the rain from this week. Temperatures will remain near
seasonal averages as we close the weekend and head into next week.
&&
.AVIATION...
(12Z TAFS)
Issued at 653 AM EDT Tue Sep 23 2025
Showers and a few storms are located north of CHA and west of TYS,
moving generally towards the east. TYS and TRI can expect
expansion of rain and periods of MVFR through the rest of the
morning. This was also added in for CHA with activity from the
west expected to move in a few hours after sunrise. By early
afternoon, this activity is expected to diminish with improvements
back to VFR and persistent southwesterly winds of around 10 kts.
Additional rain chances return late tonight but were left out of
the TAFs due to more limited confidence on timing and coverage.
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             87  68  88  70 /  30  20  40  80
Knoxville McGhee Tyson Airport, TN  85  67  86  69 /  60  30  40  80
Oak Ridge, TN                       83  66  83  67 /  60  40  50  80
Tri Cities Airport, TN              80  64  82  66 /  60  30  50  60
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
DISCUSSION...Wellington
AVIATION...BW

NWS MRX Office Area Forecast Discussion