Area Forecast Discussion
Issued by NWS Knoxville/Tri Cities, TN

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FXUS64 KMRX 211923
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
323 PM EDT Fri Apr 21 2017

.SHORT TERM /Tonight and Saturday/...
Scattered strong to marginally severe thunderstorms will be
possible across the region this afternoon and into the evening,
before weakening with the setting sunset and generally dissipating
by the late evening and midnight hours. An active pattern is
expected to continue overnight and into the day on Saturday as a
cold front will march from western Tennessee into Middle Tennessee
throughout the day -- and into portions of east Tennessee by the
late afternoon and evening hours. Ahead of this front, a few areas
of light showers will be possible along the weak, remnant
boundary from today. However, by midday and into the early
afternoon, the atmosphere will continue to destabilize, with
MLCAPE values approaching 1000-1500 J/kg by the afternoon,
especially south of I-40. This, combined with some increased shear
profiles will yield a threat for organized, severe thunderstorms.
Damaging winds, marginally severe hail, and locally heavy
rainfall and possible flooding is possible with this activity.
However, the main window for severe weather may be after 00z when
the front pushes into the region.

.LONG TERM /Saturday Night through Friday/...
The Southern Appalachian Region will remain in an active weather
pattern Saturday night and Sunday as a frontal boundary that has
been over the area slowly exits the region. Model consistency has
been quiet poor with the evolution of this system but current
trend is for the main band of convection to move through Saturday
night into early Sunday. With deep moisture in place...flooding is
expected to the main threat. A few showers may linger into Monday
across far northern and eastern locations as the system pulls
away from the area. High pressure builds in late Monday into
Tuesday for a return to dry and warm conditions for mid week.
Model consistency becomes poor and confidence is low by the end of
the extended but the trend is for the next system to move in
around Thursday/Friday time frame.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             62  81  59  67 /  50  40  80  60
Knoxville McGhee Tyson Airport, TN  61  77  56  65 /  70  60  80  70
Oak Ridge, TN                       61  76  55  63 /  70  70  80  70
Tri Cities Airport, TN              57  73  53  63 /  80  70  80  80

&&

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

$$

AMP/MJB



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