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

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FXUS64 KMRX 181909
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
309 PM EDT Fri Aug 18 2017

.SHORT TERM (Today and Saturday)...A few areas in NE TN and SW VA
will continue to experience scattered showers with isolated
thunderstorms until the late afternoon as the frontal boundary
continues to move through the region. With mid and upper level
drier and cooler air filtering in to the area from the NW...clouds
will slowly clear through the evening. Enough low level moisture
will be left through the night...especially in areas still
receiving rainfall this afternoon...for patchy dense fog
development through the early morning.

.LONG TERM (Saturday night through Friday)...
The main theme for Saturday night through Monday is developing
ridging into the southeast United States and southern Appalachians.
This ridging will tend to suppress any convection development with a
fairly dry airmass across the region. PWs will be between 1 and 1.2
inches. Some upslope flow into the mountains, especially Monday,
that isolated showers/thunderstorm possible by confidence is low.

The eclipse forecast overall looks favorable for mid/late August
with only scattered cloud cover between 18-20Z.

For Tuesday, ridging begins to break down with moisture and
instability returning to the Tennessee Valley as an upper trough
moves across the western Great Lakes. Will include low chance PoPs.

For late Tuesday night and Wednesday, a fairly strong upper trough
establishes itself across the Great Lakes/northeast United States
with associated cold front swing across the Tennessee Valley.
Model soundings show airmass will be moist and unstable with CAPES
of 1000- 1500. Main concern will be isolated strong/gusty winds,
lightning and heavy rains. WBZ are fairly high (above 12kft), so
hail threat is minimal.

Fair strong surface ridging will build into the Ohio Valley with
drier weather anticipated. Only caveat is an inverted trough near
the spine of the Appalachians. The convergence along this trough may
produce isolated convection for the latter half of next week.


&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             69  91  70  92 /   0   0   0  10
Knoxville McGhee Tyson Airport, TN  67  89  67  91 /   0   0   0  10
Oak Ridge, TN                       67  89  67  90 /   0   0   0  10
Tri Cities Airport, TN              64  88  61  89 /  10   0   0  10

&&

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

$$

JW/DH



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