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

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FXUS64 KMRX 260213
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
913 PM EST Sun Feb 25 2024

...New UPDATE...

.UPDATE...
Issued at 908 PM EST Sun Feb 25 2024

Radar is showing light returns north, but given the very dry
subcloud air and lack of obs showing precipitation a decent amount
of it is still likely virga. Will keep PoPs low but will expand
and adjust the area based on latest trends and short range model
data. Otherwise, have beefed up cloud cover mainly northern half
and have made some tweaks to temps and dew points with this
update.

&&

.SHORT TERM...
(This evening through Monday)
Issued at 313 PM EST Sun Feb 25 2024

Key Messages:

1. Weak disturbance moves through overnight into early Monday
afternoon. Isolated, light, showers possible along and north of
I-40.

2. Warmer and dry tomorrow along with breezier conditions.

Discussion:

Weak disturbance moves through the zonal flow overnight. NBM giving
slight chance and low end chance POPS along I-40 and northward. This
includes northeast TN and southwest VA. POPs seem reasonable so will
make no changes. The central east TN valley should be precip free by
mid Monday morning. POPs will linger across northeast TN and
southwest VA through early Monday afternoon, until the disturbance
exits our area. QPF should generally be less than 0.1 inches but
isolated amounts up to 0.25 inches are possible.

Southerly flow increases on Monday ahead of an approaching shortwave
to our west. This will result in warmer and breezier conditions
across the area. Expect wind gusts from 15 to 20 mph areawide during
the afteroon hours, with gusts up to 30 mph across the higher
terrain of the east TN mountains. High temps will be around 10 to 15
degrees above normal.

&&

.LONG TERM...
(Monday night through next Sunday)
Issued at 313 PM EST Sun Feb 25 2024

Key Messages:

1. A dynamic system will affect the area mid-week, bringing strong
winds by Tuesday, mainly in the mountains, followed by showers and
storms on Wednesday, some of which could be strong to severe.
Confidence is still limited on the exact impacts.

2. Very warm temperatures of nearly 15 degrees above normal Tuesday
and Wednesday.

3. Cooler and dry weather for Thursday. Warming trend into the
weekend again with a possible continuous wet pattern.

Discussion:

Tuesday will begin with southerly flow well underway with warm and
moist conditions funneling in. Highs around Chattanooga may reach
the mid 70s by the afternoon. Ahead of the frontal system expected
Wednesday, scattered showers with a possible thunderstorm Tuesday
due to isentropic ascent. Accumulation will be light of a couple
hundredths to a couple tenths of an inch. Tightening MSLP across the
mountains Tuesday will prematurely increase the winds a day before
the front with approaching low pressure to the west and high
pressure over the Atlantic.

Wednesday, the strong trough with >140kt jet aloft will be just to
the west with low-level flow increasing around 50kts or more in
response. Gusty southwest winds expected area wide by Wednesday
afternoon. Highly likely that at least the higher terrain may be
within Wind Advisory criteria. Will see how this unfolds for the
valley, but nonetheless, a breezy afternoon expected. As the sub 990
mb low deepens over the Great Lakes before exiting north into
Canada, a line of showers and thunderstorms extending from it will
approach the area by Wednesday afternoon. Rainfall totals forecast
to be mostly over a half inch to over an inch for the area. Still
monitoring if strong to severe storms will be possible with this
strong and dynamic system. SPC has removed the 15% chance of severe
for everywhere come Wednesday. Current deterministic runs aren`t so
hot on instability, so will see how this evolves. Damaging winds
will be the main threat, if so.

Late Wednesday and into the early morning hours Thursday, the change
in airmass will be fast with a quick shift to northwest flow, but
possibly limited moisture in the cold sector for any substantial
snowfall on the backside with strong surface high pressure screaming
in from the west. Currently, a couple tenths of an inch snowfall
Thursday morning for Southwest Virginia and the Appalachians. The
rest of Thursday will be nice with high pressure briefly dominating,
although temperatures much cooler.

Temperatures rebound into the first weekend of March with highs in
the upper 60s by Sunday. However, disturbances in the Gulf and over
the southeast may keep chances of precip around much of the weekend.
Models of course, very uncertain this far out in where the flow in
the atmosphere will be located with respect to an approaching
shortwave trough and high pressure anchored over the east.

&&

.AVIATION...
(00Z TAFS)
Issued at 604 PM EST Sun Feb 25 2024

There will be more clouds north than south with bases mostly
around 7 to 10 kft, and will have a VFR forecast for the period
all sites. A few showers may be around mainly TRI later
tonight/early Monday, but at this time the probability at the
terminal looks too low to include rain in the TAF. Other concern
will be LLWS tonight as winds above the surface increase. Right
now it looks borderline at TYS/TRI and more likely at CHA, so will
just include the LLWS at CHA with this issuance.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             44  72  57  74 /  10   0  20  20
Knoxville McGhee Tyson Airport, TN  44  69  54  71 /  20  10  30  40
Oak Ridge, TN                       41  68  54  70 /  30  10  30  40
Tri Cities Airport, TN              40  63  46  67 /  30  30  30  40

&&

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

$$

SHORT TERM...
LONG TERM....KS
AVIATION...


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