402 
FXUS64 KMRX 180619
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
219 AM EDT Mon May 18 2026

...New DISCUSSION, AVIATION...

.KEY MESSAGES...
Updated at 128 AM EDT Mon May 18 2026

- Very warm temperatures are expected early this week with highs 10 
  to 15 degrees above normal.

- Increasing chances for showers and storms return Wednesday.
  Scattered showers and thunderstorms are expected each day from
  Thursday through the weekend especially across the higher
  elevations.

&&

.DISCUSSION...
Issued at 128 AM EDT Mon May 18 2026

Main weather feature for Monday and Tuesday will remain an upper 
ridge over the southeast United States into the southern 
Appalachians. Main impact will be mostly dry and unseasonably very 
warm temperatures. Highs will be 10 to 15 degrees above normal.

For Wednesday, ensemble cluster analysis shows a short-wave trough 
moving across the Great Lakes and upper Ohio valley. This wave will 
begin to weaken the upper ridge over the region and allow a frontal 
boundary to approach the area. Surface ridging will also weaken 
across the southeast United States allowing for slightly better 
moisture return. Lower heights and better PWs will allow for 
increasing chances of showers and thunderstorms especially over the 
Plateau counties. Instability with remain marginal with CAPES of 
1000-1500, mid-level lapse rates of 6 degrees or less with little to 
no shear. At this time severe storms are not anticipated.

For Thursday, frontal boundary remains near the region with PWs of 
1.5-1.7 inches so moisture returns over the area. Instability and 
shear remain limited with little to no severe threat, but fairly 
good coverage of showers and storms with much needed rainfall. 
QPF for Wednesday through Thursday will range from 0.10 to 0.50 inch.

For Friday, frontal boundary lifts north as an upper trough/jet 
moves northeast into the mid-west and Ohio valley producing pressure 
falls there. The increase in southerly boundary jet will pull 
frontal boundary north. Plenty of moisture and instability remains 
so scattered showers and thunderstorms developing into the afternoon 
especially across the terrain features. 

For Saturday and Sunday, the southern Appalachians will remain with 
plenty of moisture and afternoon instability with upper ridge 
building back into the region. More typical warm and muggy 
conditions are expected.

Ensemble QPF and WPC depicts from 1 to 1.5 inches across much of the 
area from Wednesday through the weekend.

&&

.AVIATION...
(06Z TAFS)
Issued at 128 AM EDT Mon May 18 2026

A brief period of LLWS to start this TAF period as strong winds
aloft are occurring. Winds are expected to weaken before daybreak.
VFR and dry weather expected today, a few southwesterly wind gusts
to 15 knots Knoxville and south.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             88  66  89  66 /  20   0  10  30 
Knoxville McGhee Tyson Airport, TN  90  66  90  67 /  10   0   0  10 
Oak Ridge, TN                       89  64  88  64 /  10   0   0  20 
Tri Cities Airport, TN              90  61  88  62 /  20   0   0  10 

&&

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

$$

DISCUSSION...DH
AVIATION...Wellington


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