Johnson City, Tennessee 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

758
FXUS64 KMRX 250723
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
323 AM EDT Fri Apr 25 2025

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

.SHORT TERM...
(Today and tonight)
Issued at 217 AM EDT Fri Apr 25 2025

Key Messages:

1. Fog is becoming an issue mainly in the Southern and Central
Tennessee Valley. A Dense Fog Advisory has been issued there until
9 AM EDT.

2. Shower activity will pick up again in the morning hours.

3. Widespread showers and thunderstorms are expected this
afternoon and evening. A few strong storms will be possible.
Localized flooding will be possible again.

Discussion:

With abundant low level moisture, fog has developed in the
Southern and Central Tennessee Valley. Several ASOS observations
are reporting 1/4 mile visibility. A Dense Fog Advisory has been
issued until 9 AM EDT for most of the Valley counties. With calm
winds and a lull in the showers, dense fog will likely persist
through daybreak.

Shower activity will increase in the morning hours but may start
out more isolated through the morning hours. Activity will become
more scattered in the afternoon hours becoming widespread in the
late afternoon and evening as a shortwave trough approaches.
Instability will be around 1000 to 1500 J/kg by late afternoon.
Wind shear will be weak around 20 knots. HRRR guidance has a
strong line of storms but the other CAMs have weaker scattered
storms. A few strong, maybe even severe storms will be possible.
Some localized flooding will be possible but widespread flooding
is not expected with storms expected to move faster today. Will
still have to watch for training.

Isolated showers are expected tonight as the shortwave moves
through the region and a cold front nears. Fog may be an issue
again tonight with cold front passage not expected until Saturday.
Mild temps today and tonight with lingering cloud cover.

&&

.LONG TERM...
(Saturday through Thursday)
Issued at 217 AM EDT Fri Apr 25 2025

Key Messages:

1. More isolated showers and thunderstorms on Saturday as cold front
sweeps the area. Very low chance for a strong thunderstorm.

2. Seasonable and dry on Sunday, warmer beginning Monday and
continuing thereafter.

3. Low chance for diurnal precipitation early next week, higher
chances Wednesday and onwards.

Discussion:

Cold front on Saturday should sweep through much of the area, with
not much in the way of cold air behind it. HRRR/NAM soundings
indicate 1000J of CAPE Saturday afternoon just ahead of the better
advection of a drier continental airmass. As a result, the two CAMs
convect small showers and thunderstorms, mainly in the northern half
of Tennessee before moving the cells into western North Carolina.
Nothing too interesting between the unsatisfactory lapse rates and
the low end shear, but a wide enough updraft may fuel a thunderstorm
with small hail and gusty winds.

Sunday, fully behind the cold front, should be a great day with dry
weather and seasonably average temperatures. As we head into next
week, the midlevel ridge axis builds right across the Appalachians,
and with southwesterly return flow with a cyclone out over the Great
Plains, we`ll rebound back to temperatures 5 to 10 degrees above
normal. Monday and Tuesday look more diurnally influenced as far as
potential for terrain driven convection, with the jet stream still
quite far to our west. As the ridge axis moves eastwards, a series
of shortwaves will eventually push a deepening trough into the area,
providing increasing forcing for a new round of daily showers and
storms, starting midweek next week and continuing through the end of
the period. As of right now there`s no significant weather concerns,
outside of a low risk for a strong thunderstorm on any day with
convection potential given enough CAPE to fuel growth. Most
locations will see a break in the rain coverage, at least for a
couple of days, before the next round of activity late next week.

&&

.AVIATION...
(06Z TAFS)
Issued at 122 AM EDT Fri Apr 25 2025

LIFR CIGs and vis will be possible mainly at TYS and CHA through
the early morning hours. Scattered showers and MVFR conditions are
likely mid to late morning. Thunderstorms are likely in the late
afternoon and evening hours.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             77  62  80  57 /  90  50  50   0
Knoxville McGhee Tyson Airport, TN  75  61  76  53 /  90  70  80  10
Oak Ridge, TN                       75  61  77  52 /  90  70  80  10
Tri Cities Airport, TN              73  59  72  45 /  90  70  90  10

&&

.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...Dense Fog Advisory until 9 AM EDT this morning for Anderson-
     Blount Smoky Mountains-Bradley-East Polk-Hamilton-Knox-
     Loudon-McMinn-Meigs-North Sevier-Northwest Blount-Northwest
     Monroe-Rhea-Roane-Sevier Smoky Mountains-Southeast Monroe-
     West Polk.

VA...NONE.
&&

$$

SHORT TERM...McD
LONG TERM....Wellington
AVIATION...McD