301
FXUS64 KMRX 020206
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
1006 PM EDT Sat Jun 1 2024

...New UPDATE...

.UPDATE...
Issued at 948 PM EDT Sat Jun 1 2024

Minor tweaks to the forecast; mainly PoPs with filling in Schc
with Chc`s and adding more lkly`s to the southern plateau in the
morning. On and off showers will continue overnight as activity
moves to the NE. Have not seen any lightning strikes.

CAPE creeps in and increases early Sunday into the afternoon from
the west and southwest. If the 00Z HRRR materializes, may see
some pre-dawn showers and a couple thunderstorms for the southern
plateau and valley. Otherwise, short term forecast outlined below
is still our thinking for the nearest term.

KS

&&

.SHORT TERM...
(This evening through Sunday)
Issued at 304 PM EDT Sat Jun 1 2024

Key Messages:

1. Scattered showers and a very low chance of thunder tonight and
Sunday.

2. Temperatures near or slightly below normal with troughing and
cloud cover.

Discussion:

We`ll continue to be in a weak longwave troughing pattern across
the Ohio and Tennessee Valleys with subtle shortwaves moving
across the region bringing periods of light rain showers and a low
chance of thunder. Instability is limited with poor mid-level
lapse rates, but MLCAPE of 1000 to 1500 J/Kg on Sunday afternoon,
along with effective bulk shear of around 20 kt will be sufficient
for some organized non-severe convection. The highest precip
coverage is expected to be east of I-75 on Sunday afternoon.

&&

.LONG TERM...
(Sunday night through next Saturday)
Issued at 304 PM EDT Sat Jun 1 2024

Key Messages:

1. Daily showers and thunderstorms are expected with the best
coverage on Wednesday and Thursday and less coverage Friday to
Saturday.

2. Temperatures will rise above normal by mid-week with a reduction
to below normal by Friday.

Sunday Night through Wednesday

At the start of the period, fairly weak flow will be in place with
mid/upper ridging just to our west and a shortwave having pushed to
our east. Surface high pressure will be gradually receding to our
north and east. Embedded shortwaves and lingering moisture will be
sufficient for lingering showers and storms from Sunday, but this
activity will likely diminish with the loss of daytime heating.
Additional development is possible on Monday, but this coverage is
expected to be more limited due to increased ridging aloft and less
moisture evidenced by PWAT values closer to 1 inch. Activity will
likely be more focused along the terrain. Otherwise, this trend will
promote warmer conditions compared to recent days.

By Tuesday, the environment will become more conducive for
convection. Ridging will remain in place for much of the day, but
increasing troughing will be noted to the north and west, in
addition to more southerly flow and increasing moisture. The overall
wind profile and shear will still be fairly weak, meaning convection
will be driven by mostly thermodynamic means. Models expectedly
differ on the extent of instability, but MLCAPE values in excess of
1,000 J/kg are likely. Overall, the threat for strong/severe
convection remains low but can`t be completely ruled out if a storm
becomes tall enough.

By Wednesday, the exact flow pattern is more uncertain but will
consist of height falls and a cold front approaching from the
northwest. The flow pattern will still remain weak throughout the
layer with most indications suggesting deep-layer shear of only
around 20 kts. The thermodynamics, however, will be more notable
with MLCAPE likely exceeding 1,500 J/kg, especially in western
portions of the area. Current data suggests the afternoon to evening
being the most likely time of storms. Based on these indications,
potential for strong to severe storms is certainly higher than on
Tuesday but still somewhat uncertain. It should also be noted that
PWAT values will be approaching the 1.7 to 1.8 inch range, meaning
that efficient rainfall rates are possible, which could raise
concern for flooding. This will still be dependent on how much rain
is seen earlier in the period. Based on these indications, low
probability HWO wording will be maintained with consideration for
inclusion as we get closer.

Thursday through Saturday

By Thursday, the pattern becomes less clear with models suggesting
either a secondary frontal boundary developing to our north or
strengthening of the aforementioned one. Regardless, the front is
expected move towards the area, which will keep rain chances
elevated. The overall trend is for lessened instability and
moisture, so the threat for strong/severe storms and flooding will
be lower. By Friday, it is likely that the frontal boundary will be
near or south of the area with northwesterly flow aloft. This will
promote a drop in temperatures to slightly below normal with limited
rain chances. By Saturday, the flow becomes more zonal with
increasing moisture from the south and west. This will be sufficient
for additional low-end rain chances.

&&

.AVIATION...
(00Z TAFS)
Issued at 731 PM EDT Sat Jun 1 2024

VCSH will generally persist tonight and into tomorrow with
increased chances of a thunderstorm or two for CHA and TYS
tomorrow. This is reflected with a PROB30. Showers haven`t quite
reached TRI yet, but will in the next couple of hours. TRI also
expected to stay VFR through the period and may not see a
thunderstorm. However, CHA and TYS CIGS may drop to MVFR overnight
and in the morning. CIGS forecast to improve to VFR by mid-
afternoon.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             64  82  66  87 /  60  40  10  10
Knoxville McGhee Tyson Airport, TN  62  79  64  84 /  50  40  20  20
Oak Ridge, TN                       61  79  64  85 /  50  40  20  10
Tri Cities Airport, TN              58  77  61  82 /  40  60  30  30

&&

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

$$

SHORT TERM...JB
LONG TERM....BW
AVIATION...KS