Knoxville, Tennessee 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

429
FXUS64 KMRX 131441 AAA
AFDMRX

Area Forecast Discussion...UPDATED
National Weather Service Morristown TN
1041 AM EDT Fri Jun 13 2025

...New UPDATE...

.UPDATE...
Issued at 1034 AM EDT Fri Jun 13 2025

The forecast reasoning in the short term discussion below still
holds true this morning. The main change to the forecast will be
to cut back PoPs over the next few hours, as the NBM is showing
PoPs this morning in dry conditions, way overdone in this very
moist air mass with little to no forcing. Once we get the morning
clouds to erode and surface heating developing in the afternoon,
showers and thunderstorms will develop, favoring the higher
terrain areas. We will probably see convection persisting
this evening and overnight as we get some better synoptic forcing
ahead of an apporaching low pressure system near the Ozarks, but
this will be counter-balanced by diminishing instabilty. The
severe threat looks low, but flooding will be a greater concern
with high rainfall rates and potential for training cells with the
deep moisture and uni- directional flow.

&&

.SHORT TERM...
(Today and tonight)
Issued at 310 AM EDT Fri Jun 13 2025

Key Messages:

1. Scattered storms are likely by late afternoon, possibly
continuing overnight. A few stronger storms can`t be ruled out with
winds and isolated flooding as the main threats.

2. Warm and humid conditions are expected with many places reaching
well into the 80s.

Discussion:

Currently early this morning, a closed low is centered west of the
Mississippi River Valley with surface high pressure well off to our
west. Throughout the day, this feature will progress slowly eastward
but also weaken in intensity. Recent WAA and moisture advection will
provide better area-wide support for convection compared to
yesterday when moisture was limited further north. PWATs will be at
or above 1.8 inches area-wide. Fairly weak uni-directional flow is
forecast but in the presence of around 1,500 J/kg of MLCAPE but with
mid-level lapse rates only 5 to 5.5 C/km. Based on the trends in the
CAMs, diurnal development is expected during the afternoon to our
west and along the terrain. There are a range of solutions for
timing and evolution through the period with the HRRR and NAM3km
suggesting a line to arrive late this evening with less activity
during the day. As the closed low to the west shifts further east,
winds will increase and veer slightly more. So, the environment
overnight would have less instability but slightly better shear to
25 kts or more. The height falls also do support better mid-level
lapse rates closer to 6 C/km. However, instability will certainly
depend on how much activity occurs during the late afternoon.
Nevertheless, some strong to maybe even marginally severe storms
can`t be ruled out. High PWATs will also support very heavy
downpours, which could result in isolated flooding. Activity will
decrease overnight with potential for fog development in places that
see rain.

&&

.LONG TERM...
(Saturday through Thursday)
Issued at 310 AM EDT Fri Jun 13 2025

Key Messages:

1. Unsettled and active weather expected through the long term.

2. A few strong storms are possible each afternoon with peak
heating. Gusty winds and heavy rainfall are the main concerns.

2. Above normal precipitable water values through the extended.
Several inches of rain expected for some locations. Isolated flash
flooding possible at some point over the next 7 days.

Discussion:

An active and unsettled long term period is expected through the end
of next week. This is due to several waves of energy rolling across
the region in a moisture rich environment. Each afternoon will
feature likely POPs at a minimum, coinciding with peak heating.
The good news is that there doesn`t appear to be much risk for
organized severe weather, as there isn`t much shear through the
profile.

Hazards and Impacts:

A few strong storms will be possible each day during the afternoon
and early evening hours. While an isolated severe is possible at
some point in the next 7 days, most storms should remain sub-severe.
Any stronger storms will be capable of producing strong and gusty
winds. The main thing to keep an eye on will be isolated flash
flooding. PW values through the long term will be above normal, with
values ranging from 1.7 to 2 inches. Based on BNA sounding climo,
this correlates to around the 90th percentile to Max values for
this time of year. Because of the elevated moisture and likely
POPs each day, some areas could receive in excess of 3 to 4 inches
of rainfall throughout the course of the extended. However, due
to the scattered and unorganized nature of the convection, this
makes pinpointing the areas of higher precip impossible.
Therefore, everyone should be aware that any area(s) that
receive(s) multiple rounds of showers and storms will have a
greater risk to see isolated flooding as the week progresses.

&&

.AVIATION...
(12Z TAFS)
Issued at 707 AM EDT Fri Jun 13 2025

A mix of VFR and MVFR at CHA until this afternoon. LIFR to IFR at
TYS through 14Z, then VFR this afternoon. Mostly VFR at TRI.
Beyond this afternoon, low confidence forecast due to timing
differences between models for showers and storms.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             86  70  86  71 /  50  40  90  70
Knoxville McGhee Tyson Airport, TN  86  70  85  70 /  60  40  90  70
Oak Ridge, TN                       85  69  84  69 /  60  40  90  70
Tri Cities Airport, TN              84  67  84  67 /  60  30  90  60

&&

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

$$

SHORT TERM...BW
AVIATION...