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

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FXUS64 KMRX 140515
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
115 AM EDT Thu Mar 14 2024

...New AVIATION...

.UPDATE...
Issued at 1031 PM EDT Wed Mar 13 2024

No drastic changes needed to the immediate forecast period.
Blended forecast with most recent observations and overnight
lows with recent model data. Still expecting a mostly clear night,
although temperatures will be a bit mild compared to last night,
with moisture on the incline.

KS

&&

.SHORT TERM...
(This evening through Thursday)
Issued at 315 PM EDT Wed Mar 13 2024

Key Message:

Afternoon relative humidities low this afternoon with above normal
temperatures today and tomorrow.

Discussion:

Currently mostly clear skies with high pressure over the
region and a few passing mid to high level clouds traversing across
the region. Temperatures this afternoon are once again warming up
very quickly with the dry air in place, about 5 degrees warmer than
what we experienced yesterday and about 10 degrees warmer than
seasonal normals. Quiet weather will continue overnight and into
tomorrow, with the main difference being an even warmer day ahead of
the upcoming system. Temperatures tomorrow are expected to climb to
near 80 degrees across parts of the eastern Tennessee Valley... And
temperatures look like they will be within about 5 degrees of the
record highs for March 14th.

Daily Record High Maximum Temperatures

Date    Chattanooga    Knoxville      Tri-Cities     Oak Ridge
03-13   83(1967)       81(1967)       78(1990)       83(1967)
03-14   83(2012)       85(1990)       82(1990)       84(1990)

&&

.LONG TERM...
(Thursday night through next Wednesday)
Issued at 315 PM EDT Wed Mar 13 2024

Key Messages:

1. Chances for thunderstorms increasing Friday. Isolated flooding
may become a concern if an area sees repeated moderate to heavy
convectively enhanced rainfall. A strong thunderstorm is possible
south of Interstate 40.

2. Hard freeze growing increasingly likely (60-70%) for much of the
area Tuesday morning.

Discussion:

Synoptic pattern over the continental US still appears to be the
same this afternoon for the next week`s weather. An upper trough
over the Rockies will cut off into a Rex block set up, with the
upper low underneath the upper ridge. This eventually allows for an
upper trough to dig in over the eastern US, bringing a harsh but
brief end to our warm weather.

The start of the period (Friday morning) is growing increasingly
interesting. CAMs this morning came in aggressive, depicting a
mesoscale convective system (MCS) moving across western and middle
Tennessee Thursday night arriving sometime Friday morning. The 12z
GFS has moved closer to be in agreement, depicting a likely band of
thunderstorms entering east Tennessee Friday morning. Time of day is
definitely a drawback for severe potential. With all early spring
events, especially early morning, the biggest question is how much
CAPE will be available for storms, with some guidance (like the
HRRR) depicting potentially up to 1000 J of MUCAPE available,
allowing for storms to persist closer (or into) East Tennessee.
Though SPC did not place us under any risk for Day 2, this does not
preclude the possibility of strong to severe thunderstorms for the
southern valley Friday morning. The other main risk to watch is for
any potential flooding on Friday, and with CAMs being aggressive
with thunderstorm development and maintenance, heavy convective
downpours given the moist atmosphere could produce isolated
flooding. One hour flash flood guidance across the southern valley
is roughly two inches, which provides a decent buffer, even against
convection. Lesser so up across northeastern Tennessee, which is
where the orientation of showers and thunderstorms will also play a
role.

Rain will be moving out Friday evening and Friday night, followed by
a weak cold front. Weekend still looks to be mostly dry, maybe a
light shower possible Sunday afternoon as a shortwave moves by and
weak isentropic lifting may encourage shower development, though
odds overall are low. Heading into next week, a deep upper trough
will dig into the Eastern US, sending sharp cold southwards behind a
strong cold front. Subfreezing temperatures look likely Tuesday
morning, with 60-70% of a hard freeze for good swaths of the region.
With the recent warmth thus far in March, this will hurt. The good
news is the trough is progressive and the cold short lived. For the
most part, the first half of next week looks to be dry, with not
much moisture at present for any snow showers in the mountains early
Tuesday.

&&

.AVIATION...
(06Z TAFS)
Issued at 1259 AM EDT Thu Mar 14 2024

VFR conditions at TRI, TYS, and CHA through the forecast period.
Winds will increase by late morning and afternoon as the pressure
gradient begins to tighten. Southerly winds of 10 to 12 knots with
gusts up to 18 knots possible.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             79  60  70  54 /   0  60 100  50
Knoxville McGhee Tyson Airport, TN  79  58  68  52 /   0  30 100  60
Oak Ridge, TN                       78  58  68  50 /   0  50 100  50
Tri Cities Airport, TN              75  52  67  49 /   0  20  90  70

&&

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

$$

SHORT TERM...
LONG TERM....Wellington
AVIATION...DH


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