471 
FXUS64 KMRX 031730
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
130 PM EDT Thu Sep 3 2026

...New DISCUSSION, AVIATION...

.KEY MESSAGES...
Updated at 123 PM EDT Thu Sep 3 2026
 
- Very hot conditions are expected through the rest of the week
  with highs reaching well into the 90s and heat index values
  approaching or exceeding 100 for most places outside the higher
  elevations. Take frequent breaks and drink plenty of water when
  outdoors this week!

- Temperatures will gradually moderate some through the weekend
  with a return of isolated to scattered showers and storms. 

- A few storms Friday afternoon/evening mainly north and then
  including the remainder of the area Saturday may become strong
  to severe, with damaging wind gusts the primary threat.

&&

.DISCUSSION...
Issued at 123 PM EDT Thu Sep 3 2026

There are two main talking points for the forecast period. The first 
is the continued heat across the region, driven by a strong upper 
ridge located overhead. And the second is the chances for severe 
storms on Saturday as the ridge shifts westward...briefly.

First of all, the upper ridge responsible for our heatwave this week 
will remain situated over the southern Appalachian region today and 
Friday. Deterministic guidance shows highs in the 95-100 degree 
range throughout the valley this afternoon and again on Friday. 
Dewpoints will remain in the upper 60s to low 70s both days, 
resulting in afternoon heat index values in the 100-105 degree 
range. Model guidance shows the ridge being almost perfectly 
centered over the MRX forecast area during the day tomorrow, with 
an expansion in warmer H85 temps noted. I could see us eking out 
another degree or two above what the NBM guidance is showing, 
which is also supported by some guidance sources including the 
ECMWF. If that happens, advisory criteria would definitely be 
reached further north. Since we're going to be close to advisory
criteria today in areas outside the Heat Advisory that was issued
yesterday, and there's a decent shot we'd need it tomorrow, I went
ahead and expanded it effective this afternoon. The ridge shifts 
west on Saturday, allowing a "cold" front to move through, and 
remains centered over the Great Plains through Tuesday before 
shifting back east again. In other words, the heat returns next 
week it seems. Lastly, I've included a Climate section below to 
highlight some potential records that are in jeopardy in the 
coming days.

With regards to severe chances on Saturday, a deep trough digs over 
the west coast Friday into Saturday, allowing the ridge to shift 
west to the plains and a trough to strengthen along the eastern 
seaboard. This will send at least one impulse through the Ohio 
valley, southern Appalachians, and into the Carolinas on Saturday 
and push a cold front through the region. Forecast soundings show 
some rather extreme instability values over the forecast area on 
Saturday afternoon, characterized by mixed layer CAPE values of 
2,500 to 4,000 J/kg, coincident with mid level lapse rates of over 
6.5 C/km in some cases. Any storm that can get a sustained updraft 
going in that environment will have little to no issues become 
strong to severe. Downbursts and even large hail would be on the 
table, despite freezing levels above 13,000 ft. Thankfully, shear is 
on the low-end of the spectrum in terms of supporting organized 
convection, so coverage is expected to be somewhat sparse.

The "cold" front knocks highs down into the 80s to 90s for Sunday 
through Tuesday, but as I mentioned above the ridge shifts back east 
by mid-week next week so I suspect we'll see a return of quite warm 
temperatures. 

---- Climate section ----

I wanted to highlight the Chattanooga area in the climate section. 
Currently they're sitting at 30 straight days (valid 9/2/2026) of 
highs at/above 90 degrees, which is tied for 4th place. High 
temperatures are forecast to remain at/above 90 degrees through the 
forecast period. Unless something goes off the rails and a 
thunderstorm impacts their max temps one day, there's a very good 
chance they break the all time record of consecutive days at/above 
90 next week. Contrast this with Tri-Cities and Knoxville, which 
don't have active streaks that even rank in the top 50.

Below are some tables that highlight daily record highs for all 4 
climate sites through next week, as well as some information on the 
90 degree day streak for Chattanooga specifically.

Chattanooga 90 Degree Day Streak

Rank  Days   Ending Date
1     38     08-02-1993
2     32     08-29-2007
3     31     07-21-1954 
4     30     09-02-2026 
5     29     08-16-2010


Daily Record High Maximum Temperatures

Date    Chattanooga    Knoxville      Tri-Cities     Oak Ridge      
09-03   100(1954)      98(2011)       96(2011)       99(2011)       
09-04   102(1954)      101(1954)      99(1954)       100(1954)      
09-05   104(1925)      103(1954)      99(1954)       102(1954)      
09-06   103(1925)      101(1954)      100(1954)      102(1954)      
09-07   104(1925)      102(1925)      100(1954)      99(1954)       
09-08   100(1925)      96(1941)       92(2002)       95(1999)       
09-09   102(1925)      100(1925)      95(1954)       97(1954)

&&

.AVIATION...
(18Z TAFS)
Issued at 123 PM EDT Thu Sep 3 2026

Will go with a persistence forecast at KTRI and include at least 
a hedge towards fog development by putting in some 3SM VSBY early
tomorrow morning. Otherwise VFR conditions are expected to prevail
at all sites. ISOLD SHRA/TSRA could develop this afternoon and
again tomorrow but they're not expected to impact any terminals.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             75  99  76  98 /   0  10   0  30 
Knoxville McGhee Tyson Airport, TN  74  97  75  96 /   0  10   0  20 
Oak Ridge, TN                       74  98  74  96 /   0  10  10  30 
Tri Cities Airport, TN              70  95  70  91 /   0  10  10  50 

&&

.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...Heat Advisory until 8 PM EDT /7 PM CDT/ Friday for Anderson-
     Bledsoe-Bradley-Campbell-Claiborne-Grainger-Hamblen-
     Hamilton-Hancock-Hawkins-Jefferson-Knox-Loudon-Marion-
     McMinn-Meigs-Morgan-North Sevier-Northwest Blount-Northwest 
     Cocke-Northwest Greene-Northwest Monroe-Rhea-Roane-Scott TN-
     Sequatchie-Union-West Polk.

VA...NONE.
&&

$$

DISCUSSION...CD
AVIATION...CD


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