Area Forecast Discussion
Issued by NWS Knoxville/Tri Cities, TN
FXUS64 KMRX 291929
Area Forecast Discussion
National Weather Service Morristown TN
329 PM EDT Wed Mar 29 2017
.Short term (tonight and tomorrow)...
Mostly clear skies will remain
this evening and tonight...with low temperatures tonight several
degrees above normal. A low pressure system and associated frontal
boundary will approach the area tomorrow late afternoon. Ahead of
this boundary...low level flow will be consistent out of the S and
SW...bringing an increase in moisture and warm air advection to the
area. Clouds will increase through the late morning Thursday...with
high temperatures settling about 10 degrees above normal for this
time of year.
Models show minimal instability...only a couple of hundred J/kg
through the afternoon...with dry mid levels. As moisture increases
with the low level flow...could see a few isolated...non severe
thunderstorms form...mainly along the plateau...extreme southern
valley...and higher elevations in the east TN mountains. Would
expect light rainfall with these storms.
Gusty winds will be a concern through the afternoon Thursday...with
a mid level jet moving through the area. Higher elevations could see
the worst of the wind...with gusts up to 60 mph possible. With this
possibilty...with keep a High Wind Watch going from Thursday
evening through Friday morning.
.LONG TERM (Tomorrow night through Tuesday)...
Main line of storms will be pushing through Middle Tennessee
tomorrow evening and heading towards us. Right now the models are
depicting the main line to move into our western counties sometime
around midnight (or maybe a bit before). Best chance for severe
storms will be ones that form to our west and maintain strength as
they move into our western counties. The decent amount of shear in
the mid to low levels could help maintain storm intensity, with
strong straight-line winds being the main threat. Can`t rule out
large hail and a possible tornado in our area, but the chances are
much lower for them. Storms will quickly lose strength as they move
through our area as the instability and shear quickly decreases the
further east you move.
The low level jet that is aiding the strength and shear of these
storms will eventually have a southeasterly component across the
Southern Appalachian Mountains leading to a possible mountain wave
event tomorrow night. Direction of the winds isn`t exactly like a
traditional mountain wave event, but we have strong enough winds in
the low levels so some locations should experience the strong winds.
We`ll take a break from precipitation and warm up through the
weekend ahead of our next system. Models are in a bit of
disagreement on the strength and timing of this next system, but it
looks like another round of showers and thunderstorms will accompany
it the first half of the next work week.
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 60 79 59 72 / 0 20 80 40
Knoxville McGhee Tyson Airport, TN 55 78 57 69 / 0 10 80 60
Oak Ridge, TN 55 77 58 70 / 0 10 80 60
Tri Cities Airport, TN 51 71 54 66 / 0 10 70 80
TN...High Wind Watch from Thursday evening through Friday morning for
Blount Smoky Mountains-Cocke Smoky Mountains-Johnson-Sevier
Smoky Mountains-Southeast Carter-Southeast Greene-Southeast