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000
FXUS64 KMRX 221904
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
304 PM EDT Thu Jun 22 2017

.SHORT TERM (This Afternoon through Saturday)...

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The short-term forecast will focus on the expected impacts across
the Southern Appalachians from Tropical Depression Cindy. Widespread
showers currently across the area along the eastern periphery of
the tropical system. Low level southerly flow has advected the
tropical airmass into the Southern Appalachians with PW values in
excess of 2 inches. So far, rainfall rates have not been overly impressive
generally around a tenth to a quarter of an inch an hour with
radar estimates of around a quarter of an inch to three quarters
of an inch today across most locations. Current water vapor
imagery and RAP upper air analysis indicates Cindy spinning
northward near the TX/LA line. An area of dry air can be spotted
just to the east of the center of circulation and will also have a
great deal of impact on the short-term forecast.

For the remainder of the day, the widespread showers have acted to
stabilize most of the area and have not seen any lightning. There may
be a chance for a stronger storm or two with gusty winds being the
main threat if there is some brief clearing but expect this is a low
probability. Rain rates with the area of precipitation lifting
northward are too low to expect any widespread flooding issues but
there could be a few areas of localized flooding for areas of poor
drainage. The latest hi-res models forecast drier conditions
overnight into the early part of the day Friday as the drier air to
the east of the system advects into the region. Therefore, lowered
PoPs during the overnight period and into the day on Friday.

A fast moving system will interact with the remnants of Cindy on
Friday as a cold front races across the central CONUS. The remnants
of Cindy will progress quickly to the east ahead of this boundary
across the Lower Mississippi River Valley and into the Ohio River
Valley. The airmass late Friday will feature high low level shear
with weak instability as the remnants of the tropical system
approaches. Low level SRH values will increase into the 300-500
m2/s2 late in the day with SBCAPE values around 250-500 J/Kg.
Therefore, will have the potential for a few possible weak short-
lived tornadoes across the area with any stronger updrafts. The
system will be moving rather quickly late Friday night and into
early Saturday and do not expect any widespread flooding issues
and will forgo a Flood Watch at this time. Forecast rainfall
amounts throughout the event will range from 2 to 3 inches which
are similar to the 3-hr FFG values. Again, not expecting anything
widespread but expect some problems in areas of poor drainage
again late Friday into early Saturday due to localized flooding.
Rain chances will come to an end from northwest to southeast
throughout the day on Saturday as the front progresses across the
region.

.LONG TERM (Saturday night through Wednesday)...

By Saturday night the front will have pushed through and the
atmosphere will dry out with winds out of the northwest. We will
then begin a decent period of dry and quiet weather as the region
is dominated by high pressure at the surface. Really no major
precipitation chances are forecasted through the weekend and
through much of the upcoming work week. In the upper levels we
will see generally zonal flow to a weak trough in our vicinity.
This will help lead to temperatures that are slightly average.
Highs will top out int he upper 70`s to lower 80`s for most of the
region, along with light winds and mostly sunny skies. Weather
during the upcoming work week is best described as "pleasant, but
boring."
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&&

.PRELIMINARY POINT TEMPS/POPS...
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Chattanooga Airport, TN             72  85  72  84 /  60  60  80  50
Knoxville McGhee Tyson Airport, TN  70  85  70  82 /  70  40  80  40
Oak Ridge, TN                       70  84  70  83 /  70  60  80  40
Tri Cities Airport, TN              67  82  68  81 /  70  40  90  30
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&&

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

$$

MA/ABM