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000
FXUS64 KMRX 221906
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
306 PM EDT Sat Jul 22 2017

.SHORT TERM (Tonight and Sunday)...
Scattered to isolated storms around the area will dissipate with
sunset as forcing to maintain convection overnight will be lacking.
The models disagree sharply on what will happen later tonight, as
the HRRR brings a few showers to our north into SW VA, which develop
rapidly in NE TN around 06Z. The GFS shows a lot of QPF in this area
too. Meanwhile, the NAM is completely dry. The HRRR seems too eager
to enhance overnight convection of late, and forcing aloft is
lacking, so will lean toward the NAM and only have a slight chance
PoP overnight in SW VA.

Tomorrow, the front across IN/OH that has been the focus for
convection the past few afternoons will sink south into northern KY
as a shortwave midlevel trough moves across the Upper MS
Valley/western Great Lakes region. With this forcing for better lift
approaching and low level moisture remaining high in a SW flow, we
should see numerous showers and thunderstorms in northern sections
tomorrow. Model CAPE depictions are likely too high as their surface
dewpoints have been too high lately, but we should still see
adequate instability for a low threat of pulse severe storms in the
afternoon. Southern sections appear a little more capped tomorrow,
so storms should be more scattered there and with less of a severe
threat.

.LONG TERM (Sunday night through Saturday)...
A frontal boundary will continue to move to the south and east as
an upper level trough moves through the Ohio Valley. Scattered
showers and thunderstorms are expected to remain across the area
through most of Sunday night...as enough instability and list is
present...though these storms are expected to weaken in intensity
as the night progresses with no severe storms expected through the
overnight hours. Monday...winds will shift to out of the west and
northwest...with moisture less than previous days...around
average for this time of year. High pressure to the southwest and
low pressure to the northeast will create a boundary that will
allow diurnal showers and thunderstorms each day Monday through
Thursday. Models are inconsistent of coverage and intensity each
day...though Thursday looks like showers and thunderstorms will
remain in the highest elevations through most of the day. Strong
storms are possible each day with isolated severe storms possible.
Damaging downburst winds and large hail will be the main threat.
Friday and Saturday...a frontal boundary is expected to move
through the area with scattered widespread showers and
thunderstorms each day.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             76  93  74  88 /  10  30  50  50
Knoxville McGhee Tyson Airport, TN  74  92  72  87 /  10  50  60  30
Oak Ridge, TN                       75  93  73  88 /  10  50  60  40
Tri Cities Airport, TN              70  90  70  87 /  20  60  60  30

&&

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

$$

DGS/JW