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

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FXUS64 KMRX 230729

Area Forecast Discussion
National Weather Service Morristown TN
329 AM EDT Fri Mar 23 2018

.SHORT TERM...(Today through Saturday)...Difficult forecast for
the short term given poor model agreement. All models agree that
clouds will be increasing today, and precipitation will be moving
in tonight as an area of isentropic lift develops north of a warm
front moving in from the south. Precipitation type is difficult in
our northern counties, as models indicate there will be at least a
brief period of sleet/snow tonight before a changeover to rain
Saturday. However, how long any wintry precip lasts will be
critical for any accumulations, and this timing is still
uncertain. At this time, will generally lean toward a NAM/GFS/SREF
blend for vertical thermal profiles and keep accumulations
generally less than 2 inches for portions of SW VA and the
mountains of NE TN. Since it should not begin until late period 2,
confidence level is still low, and after coordination with
neighboring offices, no advisory at this time. Will keep mention
in HWO. By Saturday afternoon any precip is expected to be all
rain. While thunder cannot be ruled out especially south Saturday
afternoon, convective energy looks low at this point so no mention
for now. Will leave current freeze warning as is for early this

.LONG TERM...(Saturday night through Thursday)... Rain showers
will continue into the evening hours on Saturday as the system
continues to move off to the east. Late on Saturday night/Sunday
morning we could see temperatures drop low enough to see another
brief switch-over to snowfall in the higher elevations of far
Northeast Tennessee and Southwest Virginia. Snow amounts look to
be generally below an inch as the dendritic growth zone will be
pretty dry making it difficult to have accumulating snowfall.

As we move into the beginning of the work week the front looks to
stall out to our south and ridging begins to build in over the
forecast area. During this riding period temperatures will begin to
warm and by the middle of the week temperatures are expected to be
several degrees above normal. Also during this time frame the models
are forecasting for the stalled boundary to our south to attempt to
move further north and bring chances of precipitation to Southeast
TN/Southwest NC. A bigger rain maker will begin to move in during
the middle of the week as a strong cold front moves in from the
west. Lots of Gulf moisture is being brought in with winds shifting
out of the southwest ahead of this system, with forecast PWAT values
well over the 90th percentile for this time of year. With the very
high PWAT values and the strong winds out of the south/southwest
running mostly parallel to the incoming front we could see
widespread heavy rain over the forecast area. This system will be
one to keep an eye on as several inches of rainfall may be possible
as this system rolls through.


Chattanooga Airport, TN             54  46  64  54 /  10  50  70  70
Knoxville McGhee Tyson Airport, TN  55  41  55  47 /  10  90  90  80
Oak Ridge, TN                       55  42  54  46 /  10 100  90  80
Tri Cities Airport, TN              52  35  45  37 /   0  70 100  80


TN...Freeze Warning until 10 AM EDT /9 AM CDT/ this morning for
     NW Blount-North Sevier-Northwest Carter-Northwest Cocke-
     Northwest Greene-Northwest Monroe-Rhea-Roane-Scott TN-
     Sullivan-Union-Washington TN-West Polk.



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