530
FXUS64 KMRX 081407 AAB
AFDMRX

Area Forecast Discussion...UPDATED
National Weather Service Morristown TN
1007 AM EDT Sat Jun 8 2024

...New UPDATE...

.UPDATE...
Issued at 958 AM EDT Sat Jun 8 2024

Regional radar imagery shows an MCV moving through far southern
Illinois and into western Kentucky this morning. Some very light
returns/showers are seen well southeast of this feature across
middle Tennessee this morning as well, but so far no observations
support any of this precip making it to the ground. On that front,
the forecast looks to be in good shape as the night shift had no
mention of precip in the forecast until this afternoon, and even
then only has sprinkles mentioned. Otherwise, will keep an eye on
dewpoints and temperatures to see if lingering dry air and
subsequent daytime mixing require any updates for RH values or
afternoon max temps. But overall the forecast seems to be in good
shape and no changes were necessary for the update.

&&

.SHORT TERM...
(Today and tonight)
Issued at 259 AM EDT Sat Jun 8 2024

Key Messages:

1. A few light sprinkles possible in the northern Plateau and
Virginia counties during the afternoon hours.

2. Rain begins to spread in from the west late tonight.

Discussion:

Dry has has built in as high pressure is centered over the area,
with dewpoints in the 50s and pleasantly cool overnight
temperatures. The high will shift east of the mountains today,
allowing a more southerly low level flow and slightly warmer
temperatures compared to yesterday. But low levels will remain
quite dry, and model soundings show a very dry layer around
700-800 mb. Meanwhile, the MCS over MO tonight will track east
across KY. It will weaken as it approaches, and the main impact
will be slight sprinkles in northern sections this afternoon and
evening. Forecast soundings show top-down moistening above the
very dry layer, so the chance of measurable precip is low; expect
mainly virga.

Another upstream MCS is expected to develop this afternoon and
track east tonight ahead of a cold front. This MCS will have a
more southerly track than the previous one, and may arrive in our
Plateau counties in the 09-12Z time frame. Chance PoPs will be
included for that area late tonight, but most of the precip will
be after 12Z.

&&

.LONG TERM...
(Sunday through Friday)
Issued at 259 AM EDT Sat Jun 8 2024

Key Messages:

1. Showers and thunderstorms return Sunday ahead a cold front.
Continued cooler temperatures.

2. Monday isolated showers and thunderstorms, a more typical summer
pattern. Tuesday dry with Wednesday isolated rain chances again.
Cooler pattern behind Sundays cold front. Highs mid 70s to lower
80s, warming slightly Wednesday.

3. Thursday and Friday a chance of showers and storms eastern
mountains and slight chance elsewhere. Warmer temperatures in the
mid 80s to near 90.

Discussion:

High pressure exits to the east as a cold front and associated
trough moves across the Ohio and Tennessee Valleys Sunday.
The upper level high over TX and the western Gulf coast today will
shift south and east Sunday allowing the cold front to settle
southward. Rain chances will be highest for the whole extended
period Sunday ahead of the cold front. An upstream complex of storms
over MO early in the morning could move into the region later Sunday
morning or hold off to as late as evening. Best model timing shows
convection moving in late morning and through the day into the
evening. The severe threat to the west is expected to lower as the
convective activity moves into the forecast area Sunday. Marginal
severe is still possible, as CAPE values will be 1000 to 1500 in the
south and 500 to 1000 J/kg in the north, with sufficient shear, and
moisture. SPC still only has the area under general thunderstorms.
Will continue to monitor to see if conditions become more favorable.
After the cold frontal passage, humidity levels drop again.

After Sunday, cooler temperatures will be felt through Tuesday with
an upper trough settling over the eastern third of the country.
However it doesn`t look completely dry as upper level impulses move
through the NW flow pattern. With daytime heating isolated showers
and storms could form with higher chances over the eastern
mountains. Temperatures will be below normal through about
Wednesday. Thursday and Friday ridging develops to the south and
builds north. This will increase temperatures several degrees. Also
on Thursday or Friday a tropical like system may form in the Gulf
and move moisture north into the Tennessee Valley.

&&

.AVIATION...
(12Z TAFS)
Issued at 650 AM EDT Sat Jun 8 2024

VFR conditions are forecast for this period. High to mid clouds
will increase through the day. Calm winds this morning will become
SW at 4-9 kt this afternoon.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             88  67  88  65 /  10  20  50  20
Knoxville McGhee Tyson Airport, TN  84  66  81  61 /  10  10  70  30
Oak Ridge, TN                       82  65  80  60 /  10  20  70  20
Tri Cities Airport, TN              81  63  78  57 /  10  10  70  30

&&

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

$$

SHORT TERM...CD
LONG TERM....TD
AVIATION...DGS