Area Forecast Discussion
Issued by NWS Knoxville/Tri Cities, TN
FXUS64 KMRX 010723
Area Forecast Discussion
National Weather Service Morristown TN
323 AM EDT SAT OCT 1 2016
.SHORT TERM (Today and Tonight)...
The main weather feature continues to be the closed upper level low.
The center of the low has tracked about 50-100 miles north over the
last 24 hours. Current water vapor imagery indicates dry air
wrapping around the south and east of the system. At the surface, a
stationary boundary is located along the Atlantic Seaboard with a
surface low under the upper low in Southern IN/IL. Closer to home,
patchy fog is developing across the area with mostly clear skies and
low dewpoint depressions. The most likely locations for patchy fog
will be across NE TN and SW VA. Any fog will quickly dissipate
shortly after daybreak.
The upper level closed low will continue to drift slowly to the
north today. The atmosphere remains dry across the Southern
Appalachians with PW values in the 0.6-0.9 inch range. The highest
values will be across the Plateau but even these higher numbers are
slightly below normal for early October. Higher heights aloft will
move into the region as the closed low drifts to the north. These
higher heights aloft and mostly sunny skies will lead to
temperatures around 3-8 degrees warmer than yesterday. Mostly clear
skies and light winds will lead to patchy fog developing once again
late tonight into early tomorrow morning.
.LONG TERM (Sunday through Friday)...
High pressure will continue to build into the region early in the
extended as an upper low slowly pulls away from the area. This high
will be the main influence of area weather through much of the
period...providing rather quiet weather with dry conditions and
warming temperatures. By mid week...temperatures across the
Tennessee Valley will climb into the upper 70s and 80s. The main
system of concern for the end of the period will be the approach of
a weakening frontal boundary. Models continue to show significant
differences in the amount of moisture and energy attached to the
system. The ECMWF brings the front through around Thursday/early
Friday and has sufficient low level moisture and lift to produce
scattered convection. On the other hand...the GFS is slower with
the frontal passage...generally into Friday...the front is
weakening with little moisture attached for minimal precip chances.
Additionally...there remains the potential for a tropical system to
track along the east coast during this time frame. Confidence
remains quite low on track of this system...so for now...will
continue with the current model trends that show it to have little
effect on weather across the Southern Appalachian Region.
So...overall...will keep the forecast as a compromise between the
two models with isolated convection Thursday and Friday.
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 79 57 81 58 / 10 0 10 0
Knoxville McGhee Tyson Airport, TN 78 55 79 56 / 10 0 10 10
Oak Ridge, TN 76 55 79 56 / 10 0 10 10
Tri Cities Airport, TN 73 52 76 53 / 10 0 10 10