Area Forecast Discussion Issued by NWS Knoxville/Tri Cities, TN
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FXUS64 KMRX 161105 AAA
AFDMRX
Area Forecast Discussion...UPDATED
National Weather Service Morristown TN
705 AM EDT Sat Mar 16 2024
...New AVIATION...
.SHORT TERM...
(Today and tonight)
Issued at 258 AM EDT Sat Mar 16 2024
A cold front has cleared the area, leaving a N-NW flow pattern.
The upslope flow has kept some lingering showers going in the
mountains, but these should end in the next few hours as dry air
continues to build in at 850 mb. Low level moisture has collected
against the mountains, which should gradually erode this morning
with daytime boundary layer mixing. By the afternoon, most of the
area will have mostly sunny skies. A 850 mb thermal boundary will
be moving into the area today, with weak cold advection slightly
offsetting the solar heating. Highs will be mainly in the mid to
upper 60s. A high pressure ridge will be over the area tonight,
with another cold front approaching from the north. Increasing
clouds with a midlevel shortwave trough can be expected tonight,
with lows mainly in the 40s.
&&
.LONG TERM...
(Sunday through Friday)
Issued at 258 AM EDT Sat Mar 16 2024
Key Messages:
1. Much cooler airmass arriving Monday. Frost early Monday. Tuesday
morning a more Widespread frost and hard freeze expected.
2. High pressure and drier air Monday until Thursday, with rain
chances increasing Thursday night and Friday with next approaching
system.
Discussion:
Sunday morning will be mostly dry behind a fast moving cold front
that crossed the state overnight. This will reinforce the longwave
trough over the Ohio Valley and Southern Appalachians Sunday and
Sunday night. The front will pick up a little moisture as it exits
the area Sunday. Just a few showers expected over the southern
plateau, southern valley and into the southeast Tennessee and
southwest North Carolina mountains. High pressure builds in across
the area Monday and Tuesday behind this front but the front will
usher in a much colder airmass. The air will be very dry and
temperatures will be much below normal, mostly 40s. Widespread frost
is possible Monday morning. Then much colder with widespread frost
and a hard freeze early Tuesday morning could affect early growing
plants and flowers. Another factor with this front will be strong
Northwest winds 15 to 25 mph with gusts in the 30s to over 40 mph in
some areas which may require a wind advisory late Monday into Monday
night. Wind Chill temperatures will drop into the teens to single
digits higher elevations. The cold spell will be short lived as the
surface high modifies as it shifts east. Tuesday temperatures will
be at least 5 degrees warmer than Monday as southwest winds develop.
Wednesday flow turns more westerly but still warming another 10
degrees with highs in the 60s.
Thursday into Friday A weak front approaches from the north. A more
southerly flow will keep temperatures mild Thursday and with
increasing moisture Friday some light showers become more numerous
Friday. Lower pressure will approach from the west Friday with a
southern system moving across the gulf coastal states Friday. Winds
will increase from the southeast and temperatures will be several
degrees lower with the clouds and showers. The track and timing of
the front to the north and southern system is still uncertain so
rain chances may change as time gets closer.
&&
.AVIATION...
-- Changed Discussion --
(12Z TAFS)
Issued at 704 AM EDT Sat Mar 16 2024
MVFR cigs across the TN Valley will be trending upward through the
morning hours. Exactly how quickly that happens is uncertain, but
all sites are expected to be VFR in the 15-18Z time frame. The
rest of the day will have scattered to few clouds, then clouds
increase again at VFR levels tonight as a front approaches the
area.-- End Changed Discussion --
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 70 50 64 37 / 0 10 20 0
Knoxville McGhee Tyson Airport, TN 68 47 63 34 / 0 0 10 0
Oak Ridge, TN 68 47 64 34 / 0 0 10 0
Tri Cities Airport, TN 67 44 61 32 / 0 0 10 0
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
SHORT TERM...DGS
LONG TERM....TD
AVIATION...DGS