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649
FXUS64 KMRX 280445
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
1245 AM EDT Sat Jun 28 2025

...New SHORT TERM, LONG TERM, AVIATION...

.SHORT TERM...
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(Today and tonight)
Issued at 1206 AM EDT Sat Jun 28 2025

Key Messages:

1. Scattered showers and thunderstorms again this afternoon.

2. Relatively normal summer heat with some heat index values near
100F.

Discussion:

Today is expected to be somewhat of a copy of Friday`s forecast
with warm, humid conditions across the region. Temperatures remain
hot with heat index values near 100F, but we`ll remain below Heat
Advisory criteria. The weakness in the ridge remains with
numerous scattered showers and thunderstorms expected to develop
across the region during the afternoon. Convection will first
develop across the higher elevations and plateau between Noon and
2pm with increasing chances of showers and storms across the
valley after 2pm as outflow boundaries initiate new convection.
Primary convective mode will be pulse convection once again as
EBShear remains weak around 10 kt with afternoon MLCAPE in the
2000 to 2500 J/Kg range. PW values remain primarily between 1.7
and 1.9 inches which will result in heavy rain rates, but not
extreme, tropical-like rates. Flash flooding will be possible, but
mainly where there is convective training. Convection will begin
to diminish in coverage after sunset.
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&&

.LONG TERM...
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(Sunday through Saturday)
Issued at 1206 AM EDT Sat Jun 28 2025

Key Messages:

1. Numerous diurnal convection continues through Tuesday.

2. Cold front expected to bring drier air by mid to late week.

Discussion:

Diurnal convection will continue on Sunday with a pattern very
similar to Saturday with highest probability for thunderstorms
during the afternoon and evening hours.

An upper-level trough begins to amplify across the upper
Mississippi Valley and Great Lakes as a strong shortwave moves
across the northern CONUS. This will bring a surface frontal
boundary approaching our area by Monday and Tuesday. Moisture will
increase ahead of this trough as southwesterly flow becomes more
pronounced with LREF ensemble guidance showing PW values
increasing to around 1.9 to 2.0 inches by Monday afternoon through
Tuesday. The GFS and NAM also show areas of 2.0 to 2.2 inch PW
values on Monday and Tuesday. These very high PW values will lead
to the potential of very heavy rainfall rates of 3 to 4+ inch per
hour QPE which will enhance flooding concerns. Flooding issues
will likely be isolated, but with these types of rates, any areas
with drainage issues or ample impervious surfaces could flood
quickly.

There is still higher spread in the ensembles of if we get full
frontal passage on Tuesday/Tuesday night, so there is still some
low PoPs on Wednesday, especially for southeast Tennessee and
southwest North Carolina. However, the trend is for drier
conditions on Wednesday through Independence Day across the
region with more pleasant, slightly less humid conditions for this
time of year.
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&&

.AVIATION...
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(06Z TAFS)
Issued at 1206 AM EDT Sat Jun 28 2025

Areas of fog and low clouds are expected this morning with VCFG
across the region due to rainfall earlier tonight at all sites.
MVFR and tempo IFR conditions will be possible in spots early this
morning due to the fog and low bkn clouds. VFR conditions are
forecast to prevail by 15z with additional vcsh and Prob30 TSRA
during the afternoon hours. Prevailing winds are light and
variable.
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&&

.PRELIMINARY POINT TEMPS/POPS...
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Chattanooga Airport, TN             90  71  90  72 /  50  20  50  20
Knoxville McGhee Tyson Airport, TN  90  70  90  71 /  70  30  60  20
Oak Ridge, TN                       89  70  90  71 /  60  20  60  20
Tri Cities Airport, TN              86  67  88  68 /  70  30  60  30
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&&

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

$$

SHORT TERM...JB
LONG TERM....JB
AVIATION...JB