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

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FXUS64 KMRX 181855
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
255 PM EDT Mon Sep 18 2017

.SHORT TERM (Today into tomorrow)...
-- Changed Discussion --Once again we can expect to see similar conditions today to what
we saw yesterday with mostly sunny skies and slight above normal
temperatures. Light winds and mostly clear skies will allow for
some more fog to develop overnight in the sheltered locations.
Fog should not be too widespread, partially, because we will
begin to see increasing cloud coverage moving into tomorrow. A
trough moving to our north will help bring in more clouds and keep
temperatures a few degrees cooler. With the trough moving in we
could see a few isolated showers/thunderstorms tomorrow, but am
currently not expecting widespread precipitation with this weak
system for tomorrow.

.Long Term (Tuesday night through Monday)...High pressure over the
coastal states will be present through the beginning of the work
week...keeping moisture available...especially in areas south of
I40. A weak boundary will move through the area on Wednesday...with
scattered showers and thunderstorms possible in the afternoon. Lift
will be weak...but enough instability will be present that can`t
count out convection developing. PW values are around the 90th
percentile in far southern plateau...southern valley...and southwest
NC...so would expect the greatest chance for development in these
areas.

Behind the front...low level high pressure sets up over the Gulf
Coast states...while an upper level trough and associated low
pressure develop. Wednesday night...winds behind the frontal
boundary will allow for northerly flow to briefly set up over the
area through Thursday night with PW values decreasing to between the
median average and 75th percentile. With instability also
lowered...would expect only scattered showers and isolated
thunderstorms to develop.

By Friday morning...low level flow will transition to out of the
east due to the flow around the low level high pressure. This will
allow for greater warm air and moisture advection to areas south of
I40 through Saturday. Upper level forcing will be weak Friday and
Saturday...but enough moisture and instability will be present for
weak diurnal showers and isolated thunderstorms to develop each
afternoon. The greatest chance for this convection will be in areas
south of I40 where the greatest advection is located.

Sunday and Monday...the upper level trough will be east of the
Appalachians...and moving towards Hurricane Maria which is expected
to be off the FL coast. High pressure behind this trough will allow
for mostly clear skies and dry weather to remain through the
weekend.-- End Changed Discussion --

.PRELIMINARY POINT TEMPS/POPS...
-- Changed Discussion --Chattanooga Airport, TN 67 87 67 85 / 0 10 10 20
Knoxville McGhee Tyson Airport, TN 63 85 64 84 / 10 10 10 10
Oak Ridge, TN 64 84 65 84 / 10 20 10 20
Tri Cities Airport, TN 59 81 60 83 / 0 10 10 10-- End Changed Discussion --

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

ABM/JW

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