Knoxville, Tennessee 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

167
FXUS64 KMRX 301949
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
349 PM EDT Sun Mar 30 2025

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

.SHORT TERM...
(This evening through Monday)
Issued at 348 PM EDT Sun Mar 30 2025

Key messages:

1. Severe weather could still occur tonight, but I think the trends
are in favor of a lesser threat overall, especially in light of
cooler than temperatures so far today.

2. However, the threat is not zero and the background environment
would support damaging winds and even a possibility of a tornado if
instability develops as forecast.

Discussion:

An upper trough stretching from Iowa down through the Ozarks will
shift eastward across the mid and upper Mississippi river valley
this evening and tonight, driving a cold front eastward through
Tennessee and giving a chance for some severe storms across our CWA
after midnight tonight. Shortwave energy in the base of this trough
is already moving east through the Ozarks this afternoon, sparking
off increasingly vigorous convection over southeast Missouri. CAM
guidance indicates that additional development further south along
the cold front will continue to take place through the afternoon,
all of which will eventually congeal into a squall line and rapidly
push east across TN and into our area after midnight tonight.

Timing wise, most all guidance has come into agreement with bringing
part of the line into the CWA (namely in the north near the KY/TN/VA
state lines) around 06z-08z or so, with the line making it into
areas south of the I-40 corridor a couple of hours later. This was
likely the most uncertain aspect of the forecast and there seems to
be much more consensus on the timing now, so that is a positive.

In terms of severe threats, HREF ensemble guidance shows surface-
based instability well northward into our CWA late tonight just
ahead of the approaching squall line. This would coincide with shear
values supportive of a strong squall line capable of damaging winds
and even a QLCS tornado threat. Other models show similar things.
However, I am unsure about how serious to take these scenarios as
the HREF, along with most all guidance, have been woefully too warm
today with hourly temperatures. Persistent shower activity and
subsequent cloud cover has lead to temperatures being several
degrees behind the forecast and forecast updates today. So the
question is whether this trend continues into the evening and
overnight hours and what the implications will be with regards to
severe potential. I would tend to believe it likely does continue,
but obviously I don`t know the answer to that question.
Nevertheless, without convincing evidence one way or the other, the
forecast environment would support a damaging wind threat well into
the overnight hours as well as a non-zero risk of a QLCS tornado so
we`ll continue to message that possibility. In an attempt to narrow
down the more supportive areas of severe weather, I would imagine
areas south of I-40 and especially in the southern plateau will be
the areas most at risk for damaging winds as those areas will have
access to better moisture and warmer temperatures from the south.

For Monday, most of this overnight activity is east of the
Appalachians by daybreak or shortly thereafter it seems. The cold
front moves in from the west around midday so expect another round
of convection to sweep through at that time. Soundings suggest maybe
some small hail or something could occur, but nothing severe.

&&

.LONG TERM...
(Monday night through next Sunday)
Issued at 348 PM EDT Sun Mar 30 2025

Key Messages:

1. Unseasonably warm weather pattern for the latter half of the week
with temperatures 15 to 20 degrees above normal.

2. Record high temperatures on Thursday?

3. Gusty winds for Wednesday through Thursday especially
for the far east Tennessee Mountains and Foothills.

4. Frontal boundary may move across the Tennessee valley and
southern Appalachians next weekend but low confidence on timing.

Discussion:

By Monday night the last remnants of storm activity will be east of
the Appalachian mountains. The middle portion of the week will be
highlighted by a very rapid warming of the region as mid to low levels
of the atmosphere see a strengthening ridge. Temperatures are
expected to climb into the 80`s for much of the area by Wednesday
and even the upper 80`s on Thursday as we sit just south of an
approaching frontal boundary and strong ridging over the Atlantic
drawing up air from the south. The biggest question with regards to
temperatures is where the front to our north holds up. If it dips
down closer to our are a we could see some more cloudy skies from
move in which would limit heating... And if it stays further north
we might get slightly higher dew points creep in which could cause
additional storm development during the hottest parts of the day
throwing a wrench into how warm a climate site might get.
So while it`s not off the table to see record highs on Thursday,
there are still some big question marks in the forecast.

The more hazardous weather for this dry period during the middle of
the week is Wednesday/Wednesday night as the jet moves northeast
across the area allowing increased pressure gradients leading to
breezy conditions in the southern Appalachians. We could see another
mountain wave event Wednesday into Thursday with advisory level
winds possible in the typically windy locations.

For the end of the week this stubborn frontal boundary looks to
remain in the Kentucky/Mississippi River Valley region just to our
north. With the warm temperatures continuing for the rest of the
week we could get a glimpse of summer weather with afternoon
diurnally driven convection, sparking off in the orographically
enhanced areas common in the summer. Still lots up in the air with
the location of this frontal boundary that will act as the focus for
repeated heavy rain somewhere over the central/eastern U.S. and how
it will influence temperatures and dewpoints over the southern
Appalachians.

Front looks like it might finally see it`s way out over the weekend
as it gets a reinforcing shove from a northern states low pressure
system. This would bring a round of widespread showers and storms to
the area over yet another weekend.


Daily Record High Maximum Temperatures

Date    Chattanooga    Knoxville      Tri-Cities     Oak Ridge
04-02   88(2012)       88(1940)       88(2010)       87(2012)
04-03   89(1999)       85(1946)       82(2012)       87(1963)
04-04   88(1934)       87(1934)       83(2023)       84(1999)
04-05   89(2023)       89(2023)       86(2023)       88(2023)

&&

.AVIATION...
(18Z TAFS)
Issued at 141 PM EDT Sun Mar 30 2025

Scattered to numerous SHRA should continue through the TN valley
for a few more hours before we get into a lull in convective
activity. Said lull will then be broken by incoming squall line
tonight, with TSRA affecting all terminals. Best estimates are
suggest an arrival time roughly between 06z and 09z at all
terminals, shifting east by 12-13z tomorrow morning. Additional
showers appear likely in the wake of the squall line. Flight
categories will be a mix of VFR/MVFR this afternoon, then firmly
into the IFR/MVFR range tonight with the thunderstorms.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             62  72  44  72 /  80  90   0   0
Knoxville McGhee Tyson Airport, TN  61  70  43  70 /  90  90  10   0
Oak Ridge, TN                       60  69  42  69 /  90  90  10   0
Tri Cities Airport, TN              58  69  43  67 /  70  90  40   0

&&

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

$$

SHORT TERM...CD
AVIATION...CD