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

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FXUS64 KMRX 150724
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
324 AM EDT Mon Oct 15 2018

.SHORT TERM...(Today and Tonight)...

Deep southwesterly flow remains anchored over the region this
morning, with upper level high pressure over Florida and upper
troughing moving through the northern plains and upper midwest.
At the surface, a wedge setup is currently in place east of the
Appalachians, with a warm front crossing through the Smokies and
Tri Cities area before moving further north into eastern Kentucky.
Meanwhile a cold front is draped from central Kentucky southwest
through middle Tennessee and finally into southeastern Arkansas.
Another cold front, which is associated with the aforementioned
upper trough, stretches from northern Indiana back through eastern
Missouri and finally through western Arkansas. This secondary
front will overtake the weaker central KY/TN front later today and
will move through the forecast area tonight.

Partial clearing over the northern half of the forecast area
overnight has allowed some areas of fog to develop, with patches
of dense fog noted as well. This is mainly from the Knoxville
metro northward. Despite being in the warm sector, winds have been
light in the central valley and fog has developed as a result.
Dense fog appears to be fairly isolated, so held off on any dense
fog advisories. Expect the fog to dissipate shortly after
daybreak.

For today, the CWA will remain in the warm sector as surface low
pressure strengthens over the great lakes region in response to
the approaching plains/upper midwest trough. Fairly deep mixing
should allow temperatures to surge well into the 70s today, with
some southern valley locations, perhaps Chattanooga, taking a
crack at 80 for a high. Rain will make a return as well, but not
in earnest until midday as better isentropic ascent moves in from
the WSW. Did keep with previous shift`s thinking of adding in
some thunder to the forecast. Think this will be mainly south of
the I-40 corridor. Overall the best rain chances will remain in
the north today, which is closer to upper forcing and also the
peak of broad ascent. Peak in rainfall chances will be late this
afternoon and into the early evening hours, just ahead of the cold
front. Speaking of the front, it should enter the northern
plateau counties towards the end of the work day, and finally move
into the Smokies and far western NC by midnight or thereabouts.
Hold on to decent precip chances through the night, but there are
good indications that a lull in precipitation will occur after 00z
this evening as upper level support kicks off to the east.

.LONG TERM...(Tuesday through Sunday)...

For Tuesday, west to southwest flow aloft and surface ridging into
the lower Ohio Valley. Weak waves will quickly move along the
westerly flow with a chance of showers, mainly south.

For Tuesday night and Wednesday, long-wave upper trough will deepen
over the northeast United States with upper flow becoming more
northwesterly pulling drier air into the southern Appalachians.
Return of sunshine can be expected.

For Wednesday night and Thursday, surface ridging will build into
the central and southern Appalachians before more east for Thursday
night. Long-wave trough will move east allowing an upper ridge to
build into the area. Continued dry with a slight warm-up is expected.

For Friday, flat upper ridge and surface ridging east and south of
the area will keep moisture limited over the southern Appalachians.
However, increase mid and high level clouds expected as upper flow
pulls a good deal of moisture into the region.

For Friday night and Saturday, another strong northern stream wave
will deepen across the Great lakes/northeast United States pulling a
strong cold front through the area. Southern stream flow will phase
some with northern stream trough to produce widespread rain/showers.

For Saturday night and Sunday, deep upper over the northeast United
States with strong surface ridging build into the Tennessee Valley.
Freezing temperatures are possible early Sunday morning across the
higher elevations.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             80  59  69  54 /  30  30  30  60
Knoxville McGhee Tyson Airport, TN  78  56  66  49 /  40  40  30  50
Oak Ridge, TN                       77  55  66  48 /  40  40  20  50
Tri Cities Airport, TN              76  55  64  46 /  60  60  20  40

&&

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

$$

CD/DH



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