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

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FXUS64 KMRX 290655
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
255 AM EDT Sat Apr 29 2017

.SHORT TERM(Today and Tonight)...

Current IR satellite imagery indicates an elongated E-W area of
showers and storms stretching along a stalled frontal boundary from
Oklahoma to Maryland. Fortunately this activity is forecast to
remain to the north of the area. IR imagery does indicate the cirrus
shield is expanding southward from the showers/storms and expect
some high clouds to start the day. Current water vapor imagery also
notes strong moisture convergence near the Ozarks stretching to the
Ohio River Valley. Closer to home, an upper level ridge sits just to
the east of the Florida peninsula. This upper level feature will be
the main focus throughout the short-term forecast for the Southern
Appalachians.

This morning should not start out as foggy as yesterday. High clouds
and slightly higher winds will hinder fog formation. The main
challenge once again will be PoPs. The cap will remain in place
around 700-800 mb but is forecast to be a bit weaker today. There is
not much to speak of in the way of lift with the ridge being the
main weather influence. In addition, the surface front will remain
to the north of the forecast area as well. The weaker cap should
allow for a few isolated to scattered summer-like afternoon
shower/storms with the better chances in the higher elevations. The
main story will be the record breaking high temperatures forecast
today. The higher heights aloft and insolation will push
temperatures up into the upper 80a and low 90s for most valley
locations. The record for Knoxville is 88 degrees set back in
1872 during the Grant Administration. The records for CHA and TRI
are a bit more recent. See the data below for more information.

Knoxville    88 set in 1872     Forecast High 90
Chattanooga  88 set in 1942     Forecast High 90
Tri-Cities   86 set in 1996     Forecast High 90

.LONG TERM (Sunday through Friday)...

An upper ridge of high pressure will shift eastward on
Sunday...allowing for slightly cooler but still well above normal
temperatures. Limited diurnal convection is possible late in the
afternoon but this activity should remain confined to higher
elevations. Will see a pattern change Sunday night into Monday as
a cold front approaches from the west. A line of showers and
thunderstorms is expected to develop and move through the region
ahead of the front. A strong 60 to 70 KT jet will accompany the
front and will provide widespread breezy and gusty
conditions...and also may allow for a stray thunderstorms to
generate significant winds. By Tuesday...the frontal boundary will
be well to our east for a dry day with near normal temperatures.
Model consistency becomes poor and confidence is low Wednesday
through the end of the extended. Overall...the pattern looks
unsettled with an area of low pressure moving through and the
approach of an upper trough. The best chance for precip through
this period currently looks like Thursday and will keep likely
pops in place with decreasing chances into Friday.


&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             90  68  87  65 /  20  20  10  70
Knoxville McGhee Tyson Airport, TN  90  68  85  64 /  20  10  10  50
Oak Ridge, TN                       91  68  85  63 /  20  10  10  60
Tri Cities Airport, TN              90  64  81  61 /  20  10  10  30

&&

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

$$

MA/MJB



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