FXUS64 KMRX 192305
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
705 PM EDT Tue May 19 2026

...New AVIATION...

.KEY MESSAGES...
Updated at 131 PM EDT Tue May 19 2026

- Very warm temperatures continue for Wednesday with highs 
  roughly 10 degrees above normal.

- Scattered to numerous showers and storms return for Wednesday,
  with continued high rain chances through the weekend.

&&

.DISCUSSION...
Issued at 131 PM EDT Tue May 19 2026

Scattered to isolated showers have popped up this afternoon across 
Middle TN, but so far the cap has suppressed convective development 
in our area. Some of the activity to our west could reach our 
Plateau counties in the next few hours, but coverage should remain 
isolated. Can't rule out a few short-lived pop-up showers in our 
mountain zones along the TN/NC border. 

Convective activity will be greater on Wednesday as the Gulf opens 
up a bit more and provides some moisture around 850 mb. We will 
still have a dry layer above that, which will limit coverage and 
development through dry air entrainment. Shear appear quite weak 
too, so convection should be short-lived, and the severe threat 
looks low. Areas along and west of I-75 should have the greatest 
chance of showers/storms tomorrow, as convection is likely to 
develop in the Cumberland Plateau with a slow NE movement. 

PW values jump into the 1.6 to 1.8 inch range on Thursday as a 850 
mb low moves into northern MS/AL, opening the Gulf for deep and 
persistent moisture advection. A boundary will extend from the low 
across the Plateau into SW VA, acting as a focus for convergence and 
convective development. PoPs will be categorical across the entire 
area, with a chance of thunderstorms. Instability and shear will be 
lacking for any organized severe threat, although some gusty 
downbursts winds and locally heavy rainfall will be possible. 

A warm, moist southerly flow will continue on Friday as another low 
pressure system crosses AR and lifts the aforementioned boundary 
farther north into KY. High PW values in an uncapped environment 
will again lead to categorical PoPs across the area in the 
afternoon. CAPE and shear appear a bit higher on Friday, mainly in 
our southern sections where clouds may scatter enough to enhance 
afternoon heating, so we will need to keep an eye on the potential 
for some severe storms as we get closer to Friday. 

A deep SW flow persists through the weekend and early next week, 
with broad troughing over the central US. Disturbances ejecting from 
this broad trough will bring several rounds of enhanced rain chances 
through early next week, but the timing of these disturbances 
remains highly uncertain. Overall, the pattern favors continued 
high rain chances each day. The primary impacts will be lightning 
and locally heavy rainfall.

&&

.AVIATION...
(00Z TAFS)
Issued at 626 PM EDT Tue May 19 2026

There will be scattered showers and thunderstorms around late in
the period, and will have prob30 thunder groups all sites during
the time when the probability looks highest. Otherwise, VFR 
conditions are expected for the period all sites. 

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             68  89  66  86 /   0  60  40  80 
Knoxville McGhee Tyson Airport, TN  68  89  66  84 /   0  40  20  90 
Oak Ridge, TN                       66  88  64  84 /   0  50  30  90 
Tri Cities Airport, TN              64  88  63  82 /   0  30  60 100 

&&

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

$$

DISCUSSION...DGS
AVIATION...99