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

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FXUS64 KMRX 261952
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
252 PM EST Sun Feb 26 2017

.SHORT TERM (Tonight and Tomorrow)...
Surface high pressure centered over the area this afternoon will
begin to shift NE off the Middle Atlantic coast by Monday morning.
Meanwhile, latest water vapor and RAP upper air analysis
indicates a shortwave trough embedded within the larger scale
zonal flow over central Kansas this afternoon, will move rapidly
east across the area by Monday evening.

Although current visible imagery indicated perfectly clear skies
across much of the area this afternoon, a broad area of middle and
upper level cloudiness will move in ahead of the disturbance
overnight tonight. This will cut off radiational cooling after
midnight and will keep temperatures above freezing for a large
portion of the area tonight. This is in slight contrast to the
latest GFS and NAM MOS guidance that continue to suggest
subfreezing temperatures throughout the area, exception being CHA
and points south and west.

With passage of this disturbance late tomorrow, areas in the SW
corner of the CWA will have likely chance of pcpn by the end of
the day while the remainder of the area will see only a slight
chance of pcpn into the afternoon hours. With the current low
level air mass being so dry (dewpoints below 40 degree for much of
the day on Monday) any appreciable pcpn will have to wait until
beyond the fcst period.

.LONG TERM (Tomorrow Night through Sunday)... An upper level
trough will make it`s way slowly east from the Western U.S.
through the Mississippi Valley through mid week. As it does so,
warm and moist air will override a cooler air mass in place across
the Southern Appalachians. Scattered showers and even a few
thunderstorms will occur in this warm frontal push into the
Southern Appalachian region. But the big event will be on
Wednesday into Wednesday evening as another strong cold front
sweeps through the Eastern U.S. Sufficient instability and shear
will be available for storm strengthening with this feature, and
the thunderstorms that accompany this frontal passage could become
severe. The front should move across the Appalachian spine later
Wednesday night with drier and cooler air streaming back into the
region on northwesterly winds. The remainder of the forecast will
be dry with a gradual warming trend into the weekend as the low
level ridge shifts east to the Southeast Atlantic Coast.

$$


&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             36  55  50  69 /   0  60  60  70
Knoxville McGhee Tyson Airport, TN  33  59  48  69 /   0  30  40  70
Oak Ridge, TN                       33  58  47  67 /  10  30  50  70
Tri Cities Airport, TN              29  59  42  68 /   0  20  40  50

&&

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

$$





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