795 
FXUS64 KMRX 271749
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
149 PM EDT Thu Aug 27 2026

...New DISCUSSION, AVIATION...

.KEY MESSAGES...
Updated at 142 PM EDT Thu Aug 27 2026
 
- Scattered storms expected this afternoon and evening, with the 
  possibility of a severe storm or two. Isolated to scattered 
  storms expected on Friday too, with less coverage overall and 
  little to no threat of severe storms.

- Most locations will be dry for the weekend with return of hot
  and humid conditions early next week.

&&

.DISCUSSION...
Issued at 142 PM EDT Thu Aug 27 2026

Synoptic scale troughing from the Hudson Bay area southward through 
the eastern CONUS, along with upper ridging from the Four Corners 
region through the northern Rockies, will continue through Friday. A 
pattern change to a warmer and drier regime begins over the weekend, 
but before that happens we'll have some scattered storms to deal 
with this afternoon. More on that below. By Saturday morning the 
upper trough begins to pull away to the northeast and the western 
ridge starts its eastward trek towards the southern Appalachian 
region. The ridge should be centered over Tennessee by Monday 
afternoon, where it will remain through the end of the period, and 
lead to increasingly warm conditions across the NWS Morristown 
forecast area.

Going into a bit more detail, this afternoon we still have cyclonic 
flow aloft, with a shortwave slated to move through this afternoon 
and into the evening hours. This will push a weak front our 
direction, which, when coupled with slight height falls aloft and 
sufficient moisture and instability in place, should lead to the 
development of scattered thunderstorms later today. Expect 
initiation over the Appalachians and the higher terrain of the 
plateau areas, but convection will eventually spread into the valley 
as time progresses, especially later on as the front draws near and 
forces things eastward. The SPC Day 1 convective outlook has been 
adjusted today to expand the Marginal risk area southward to 
encompass much of our CWA. This seems reasonable to me. The normally 
bullish NAM (with regard to moisture and instability) is actually 
handling current surface conditions well I think, and it shows 
MLCAPE values ranging from near 2,000 J/kg in the south to around 
3,000 J/kg in the central and northern valley late this afternoon 
and early evening, with over 7 C/km lapse rates aloft as well. DCAPE 
values are in the 1,000 - 1,200 J/kg range. In this environment, I 
wouldn't be surprised to see some strong to severe storms capable of 
some +60 mph winds develop. Coverage will be the limiting factor in 
our severe chances. No guidance source is overly enthusiastic with 
regards to storm coverage this afternoon, so the threat of severe 
storms should be isolated in nature. For Friday, expect less 
afternoon shower and thunderstorm coverage than today. Instability 
will also be less, so the threat of any strong to severe storms seem 
very low.

Looking ahead to next week, the upper ridge centered over Middle and 
East Tennessee will mean dry conditions and a notable warming trend. 
It doesn't appear that we will approach any record highs, but it 
will be warm, and heat index values could climb to around or even 
slightly over 100 degrees at times. For those who care about such 
things, August 24th was the day that average highs start their 
decline for the year, and October 9th is the last day where record 
highs in Knoxville reach the 90 degree mark. Don't lose hope, fall 
is on the way. I mean, for those who care about such things.

&&

.AVIATION...
(18Z TAFS)
Issued at 142 PM EDT Thu Aug 27 2026

Scattered SHRA/TSRA are expected this afternoon and evening 
across the TN valley, but confidence in whether they affect any
terminals is not high enough to go beyond a PROB30 group. Development
will be driven largely by terrain and/or outflow boundary 
interactions. That said, would expect that KTYS and KTRI will have
the best chances relatively speaking. Convection should die down 
by 02-03z or so, with dry conditions overnight. Guidance is fairly
insistent on fog development in the TN valley tonight. Introduced
some 5SM at KTRI, but I didn't have confidence to go with lower
VSBY just yet, nor to include it elsewhere.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             70  92  69  93 /  30  20  10  10 
Knoxville McGhee Tyson Airport, TN  69  89  67  91 /  50  20  10  10 
Oak Ridge, TN                       68  88  67  90 /  40  30  10   0 
Tri Cities Airport, TN              65  86  64  87 /  30  20  10  10 

&&

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

$$

DISCUSSION...CD
AVIATION...CD


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