959 
FXUS64 KMRX 211902
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
302 PM EDT Thu May 21 2026

...New DISCUSSION...

.KEY MESSAGES...
Updated at 238 PM EDT Thu May 21 2026

- Multiple rounds of showers with some scattered thunderstorms
  today through Saturday. The primary threats with storms each 
  day will be lightning, locally heavy rainfall, and some gusty 
  winds.

- A wet weather pattern persists through next week.

&&

.DISCUSSION...
Issued at 238 PM EDT Thu May 21 2026

Showers through the rest of the afternoon and evening will
generally be scattered, with a decreasing trend expected after
sunset as a shortwave trough exits the area. We will still have a
surface boundary lingering nearby, so some low rain chances will
continue through the night. Very little lightning has been
observed so far this afternoon, likely due to the overcast cloud
cover and weak lapse rates aloft. 

Models are showing a shortwave trough lifting NE from LA/MS/AL
tomorrow morning, which increases lift across our area starting
around 12Z. A 850 mb jet near 40 kt develops during the day, and
MLCAPE values reach near 800 J/kg in our southern sections in the
afternoon. This may allow for some storms to produce gusty winds
with stronger downbursts, potentially near severe levels. SPC has
included our western half in a Marginal Risk the latest Day 2
Severe Outlook, with winds being the main hazard. Locally heavy
rain may also be a threat given the high moisture content through
the column. Saturday looks pretty similar to Friday, with a 
second shortwave trough coming over the region in the afternoon, 
leading to occasional showers and scattered thunderstorms through
the day. 

Another potential weather impact on Friday and Saturday is gusty
mountain wave winds. A surface CAD ridge east of the mountains 
will develop, enhancing the pressure gradient in the NC/TN border
mountains as a couple low pressure areas track from West TN to the
OH Valley. Winds may approach Advisory levels in wind-prone
locations of the mountains and foothills Friday through Saturday.

For Sunday through Thursday, a wet pattern will continue as we
will maintain a deep S to SW flow. Timing of showers and storms
will depend on disturbances in the flow and surface boundaries in
the area, which are difficult to resolve at this time. High PoPs
with low chances of thunderstorms appear to be warranted in this
pattern.

&&

.AVIATION...
(18Z TAFS)
Issued at 128 PM EDT Thu May 21 2026

A complex weather pattern this period will mean a low confidence
forecast. Rounds of showers will pass over the terminals through
this evening, bringing MVFR to IFR conditions at times. Showers
should generally decrease through the night, with MVFR cigs
developing late in the night. Additional rounds of showers are
possible tomorrow morning, although details of timing are highly
uncertain at this time.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             64  78  64  80 /  80  90  90  90 
Knoxville McGhee Tyson Airport, TN  64  79  64  80 /  60  90  90 100 
Oak Ridge, TN                       62  78  62  79 /  70  90  90  90 
Tri Cities Airport, TN              61  77  60  78 /  60  80  90 100 

&&

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

$$

DISCUSSION...DGS
AVIATION...DGS


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