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

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FXUS64 KMRX 181902

Area Forecast Discussion
National Weather Service Morristown TN
302 PM EDT Wed Oct 18 2017

.SHORT TERM...(Tonight and Thursday)...Surface high pressure will
remain over the region as an upper ridge builds in during the short
term period.  The atmosphere will remain quite dry.  Dewpoints/temps
running higher today than yesterday, so should be slightly warmer
tonight with less chance for any patchy frost.  Some patchy fog can
be expected late tonight especially near bodies of water.  Tomorrow
will feature plenty of sunshine and temperatures a bit higher than

.LONG TERM...(Thursday night through Wednesday)...A quiet start to the
long term, but hold on to your hats because there`s some cold air
headed back our way toward the end of the period. Riding is in place
from Thursday night through Saturday night. During this period,
expect clear to mostly clear skies along with calm conditions. Temps
on Thursday night still a few degrees below normal as the airmass
continues to modify. Temps will be in the low to mid 40s. On Friday
we see temps continuing to slowly climb with highs in the mid to
upper 70s. Friday night near normal temps in the mid to upper 40s.
Saturday temps remain in the mid to upper 70s.

On Saturday the ridge begins to amplify in response to an upper level
trough digging down across the Central Plains. The low pressure
center associated with this trough is well into Canada but the cold
front sweeps down all the way into Texas! As of now though, Saturday
looks to remain dry with pleasant conditions. Saturday night
southerly flow begins to ramp up as the front draws closer. The
actual precip doesn`t move in until later on Sunday and perhaps even
holding off until Sunday night. Will have POPs slowly increasing
through the day on Sunday from west to east. The best chance for
POPs come on Monday. By this time, a closed off low has developed
just to our west-southwest as the northern jet has separated itself
from this system. The closed-off low rotates just to our south
Monday night into Tuesday, which will therefore continue higher POP
chances. We could also hear a few rumbles of thunder as we may have
a storm or two across the area. On Tuesday we see another surge of
cold air coming down out of Canada and into the Plains. This
secondary trough will quickly catch up to the closed low and help
move it along and out of our area by Tuesday afternoon. With this
trough though comes the coldest air of the fall season. High
temperatures on Wednesday, after the secondary frontal passage, will
only be in the mid to upper 50s. These values are 10 to 15 degrees
below normal. The lows Wednesday night will range from the mid to
upper 30s with some areas dipping below the freezing mark. With the
secondary trough and front moisture looks limited for our area and
mainly stays north. However, wouldn`t be surprised to see a few
snowflakes squeezed out across the higher elevations at some point
as we see a NW flow pattern set up.


Chattanooga Airport, TN             45  75  45  77 /   0   0   0   0
Knoxville McGhee Tyson Airport, TN  44  74  44  76 /   0   0   0   0
Oak Ridge, TN                       44  74  44  77 /   0   0   0   0
Tri Cities Airport, TN              40  74  41  76 /   0   0   0   0




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