Johnson City, Tennessee 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

964
FXUS64 KMRX 041419
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
1019 AM EDT Fri Apr 4 2025

...New UPDATE...

.UPDATE...
Issued at 1007 AM EDT Fri Apr 4 2025

Forecast and key messages remain in good standing this morning.
Convergence along a stationary boundary draped across KY
continues to promote showers and a few rumbles of thunder to our
north. While activity may briefly encroach the very northern
border of our southwest VA counties, the bulk of the activity will
continue to be displaced to our north. CAMs suggest strong
diurnal heating could ignite isolated showers or storms across the
higher terrain in our northeast this afternoon but the general
consensus is that most will remain dry. Near to potential record
breaking daily maxTs remain the main focus this afternoon. Blended
in latest HRRR to the hourly forecast with no significant changes
to previous maxT forecast.

&&

.SHORT TERM...
(Today and tonight)
Issued at 344 AM EDT Fri Apr 4 2025

Key Messages:

1. Record high temperatures well into the 80s are expected.

2. Very limited chances for storms exist this afternoon into the
early evening. If anything develops and grows tall enough, locally
strong winds are the main concern.

Today

Currently early this morning, southwesterly flow continues across
the region with a trough and stationary frontal boundary to our
west. Very impressive, near record ridging is centered just to our
east with 500mb heights expected to reach 5,880m today. The broad
southerly flow will continue the impressive warming trend as the
overall environment is typical of June or July. There is pretty good
likelihood of temperatures reaching record values, which are shown
below:

Date    Chattanooga    Knoxville      Tri-Cities     Oak Ridge
04-04   88(1934)       87(1934)       83(2023)       84(1999)

Regarding chances for convection, the better moisture transport and
overall forcing remain well to our north and west. Still, there are
some model solutions that develop convection in northern portions of
the area by the late afternoon. The environment will consist of
largely unidirectional winds and much less shear than in previous
days. Thermodynamics indicate MLCAPE of over 1,000 J/kg with drier
air at the surface supporting decent DCAPE values. If anything does
develop and grow tall enough, strong winds would be the main
concern. However, chances are that most of the area stays dry.

Tonight

Overnight, the pattern will remain fairly similar across the region,
persisting the unseasonably warm conditions. Some low-end chances
for convection could linger into the early part of the night, but
the region will likely stay dry.

&&

.LONG TERM...
(Saturday through Thursday)
Issued at 344 AM EDT Fri Apr 4 2025

Key Messages:

1. Unseasonably warm temperatures will continue on Saturday.

2. Widespread showers and storms are expected on Sunday. Some storms
could be strong to severe with damaging winds and heavy rainfall as
the main threats.

3. Much colder temperatures are expected early to mid next week with
a widespread frost/freeze likely Tuesday and Wednesday mornings.

Saturday through Monday

At the start of the period, southwesterly flow will be in place
across the region with a fairly deep trough ejecting out of the
Rockies. At the surface, the frontal boundary that has been
stationary will be located just northwest of the Ohio River
Valley. On Saturday, strong ridging will remain across the region
but will recede slightly as the trough slowly advances eastward.
During the day, the result will be a continuation of unseasonably
warm conditions. Record high temperatures will be possible but
harder to achieve as these values are what needs to be met:

Date    Chattanooga    Knoxville      Tri-Cities     Oak Ridge
04-05   89(2023)       89(2023)       86(2023)       88(2023)

By Saturday night, the upper-level trough and surface front will
finally start to advance towards the region. This will bring
widespread chances for showers and storms. There is still
uncertainty as to when this feature will arrive, which will have a
lot of implications on the local environment. The wind profile will
be largely unidirectional, meaning the 50 to 60 kts of deep-layer
shear will be driven primarily by means of speed. Earlier solutions,
such as the GFS, will lead to more limited instability of less than
500 J/kg. Later solutions, such as the NAM, would allow for better
surface heating and destabilization beyond 500 J/kg. In any case,
this will present some threat for stronger storms. Also, pretty
decent moisture advection and persistent southwesterly flow will
allow for persistent and repeated storms. Locally heavy rainfall
could bring an isolated flooding threat, but many places are
thankfully pretty dry.

By Monday, the cold front will be moving east of the area with CAA
bringing much colder temperatures into the region. Many places will
likely stay in the upper 50s to low 60s as cloud cover will linger
in the northwesterly flow.

Tuesday through Thursday

By Tuesday and Wednesday, high pressure will be centered nearly
directly over the area with recent CAA bringing temperatures even
further below normal. Stronger subsidence will also support
overnight lows dropping to near freezing with a widespread frost
expected at a minimum. By the end of the period, there are varying
indications for a system to develop and track towards the eastern
U.S. This system looks weak enough to mainly provide a return of
rain chances.

&&

.AVIATION...
(12Z TAFS)
Issued at 707 AM EDT Fri Apr 4 2025

Over the next few hours, the main question is if MVFR ceilings
will occur at CHA. So far, it has not materialized, but some sites
to the south have reported these reductions. A SCT025 was included
for the time being. Otherwise, variable cloud cover at around 5,000
to 10,000 feet is expected, along with a persistent southwesterly
winds gusting to around 20 kts. There are some chances for storms
around TRI this afternoon, but this potential is low. Overnight,
winds will be lighter and more variable with some clouds
remaining.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             87  67  87  65 /   0   0  10  40
Knoxville McGhee Tyson Airport, TN  87  67  86  64 /  10   0  10  40
Oak Ridge, TN                       86  67  85  62 /  10   0  10  50
Tri Cities Airport, TN              84  62  85  62 /  20  10  10  30

&&

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

$$

SHORT TERM...BW
LONG TERM....BW
AVIATION...BW