308
FXUS64 KMRX 091853
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
253 PM EDT Thu May 9 2024

...New SHORT TERM, LONG TERM...

.SHORT TERM...
(This evening through Friday)
Issued at 229 PM EDT Thu May 9 2024

Key Messages:

1. A few isolated showers possible tonight across extreme northeast
TN and southwest VA. An isolated thunderstorm is also possible.
No severe threats expected.

2. Patchy fog across the southern TN valley overnight.

3. Slight chance to chance POPs Friday, with breezy winds.


Discussion...

Tonight, a few isolated showers and possibly a thunderstorm across
extreme northeast TN and southwest VA, out ahead of a longwave
trough approaching from the northwest. Winds stay up enough
overnight to prevent fog across most areas. However, calmer winds
are expected across the southern TN valley and patchy fog is
anticipated.

Tomorrow will be cooler with northwest flow, clouds, and isolated
showers. High temps will be around 5 to 8 degrees below
normal. NBM also wants to put a slight chance thunder in the
forecast but NAM soundings show a pretty significant midlevel
cap. Will leave NBM slight chance thunder in forecast but very low
confidence. If we do see a storm, it will be isolated with no
severe threats. POP chances are due to the aforementioned upper
level trough and associated shortwave rotating through the area.
The exception is the southern TN valley, where conditions should
remain dry. Breezy west to northwest winds expected tomorrow
afternoon due to a tight pressure gradient across the area. Winds
will gusts up to 25 mph in valley locations and up to 30 mph
across the east TN mountains.


&&

.LONG TERM...
(Friday night through next Thursday)
Issued at 229 PM EDT Thu May 9 2024

Key Messages:

1. Cool temperatures through the weekend, with a chance of showers
in northern sections Saturday.

2. An active pattern sets up by midweek, with rain chances Tuesday
through Thursday.


Discussion...

On Saturday, a trough will be dropping SE from the Great Lakes to
the central Appalachians and Mid Atlantic region. Mid and upper
level forcing with the channeled vort max on the southern end of
this trough will cross our SW VA counties, and bring a chance of
showers in the afternoon. Forecast soundings show some low level
instability below 700 mb with stable conditions above, so it will
mainly be scattered showers and little to no thunderstorms. The
NBM PoPs in the chance range down to Knoxville appear overdone
for this system and will be scaled back a bit.

High pressure will build over the area and provide dry weather for
Sunday into part of Monday. Sunday`s temperatures will be a little
below normal in a N-NW flow pattern on the east side of the ridge,
with highs in the lower to mid 70s. The ridge axis move east of the
area on Monday, which should bring highs back into the mid and upper
70s, with increasing moisture and cloud cover. Showers may begin to
spread into southern sections Monday afternoon and evening as a low
pressure system tracks east across the MO Valley and Ozarks. Rain
chances will ramp up to categorical and likely for Tuesday as this
low tracks along the OH River. Instability and dynamic forcing look
limited at this time, so no severe threat is expected.

A weak ridge may bring a brief dry period from Wednesday into
Wednesday night, but an amplifying trough over the Plains will
result in PoPs increasing again on Thursday. Models differ on the
amplification of this trough and the dynamic forcing associated with
it, but if the GFS pattern is correct, it may be a system to watch
for potentially strong to severe storms.

&&

.AVIATION...
(18Z TAFS)
Issued at 123 PM EDT Thu May 9 2024

We begin the period with VFR at all sites. Mostly VFR conditions
continue thereafter but a few periods of MVFR. CHA will likely
see MVFR develop overnight due to fog/visibility. TEMPO MVFR for
CIGs this afternoon at TYS. TRI should remain VFR through the
period. Also, breezy west-southwest winds expected at all sites at
around 10kts, with gusts to around 20kts at TYS and TRI this
afternoon.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             86  62  78  52 /  70  10  10   0
Knoxville McGhee Tyson Airport, TN  81  60  73  48 /  90  10  30   0
Oak Ridge, TN                       82  59  73  48 /  80   0  30   0
Tri Cities Airport, TN              77  57  70  45 /  90  10  40  10

&&

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

$$

SHORT TERM...
LONG TERM....DGS
AVIATION...