Area Forecast Discussion Issued by NWS Knoxville/Tri Cities, TN
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000
FXUS64 KMRX 180024
AFDMRX
Area Forecast Discussion
National Weather Service Morristown TN
824 PM EDT Sun Mar 17 2024
...New AVIATION...
.SHORT TERM...
(This evening through Monday)
Issued at 241 PM EDT Sun Mar 17 2024
Key Messages:
1. Cold weather arrives tonight, Monday to be 10 to 15 degrees below
normal.
Discussion:
With the stronger cold air advection lagging behind, the front has
been slow to cross the area today, which hasn`t had too much impact
on the forecast since there`s no moisture to greet the front. Once
the cold airmass moves in tonight, temperatures will begin their
trek downwards. Some locations will hit freezing tonight, but frost
formation might be a little limited, with dewpoint depressions of
around ten degrees valley wide indicating available surface
moisture is low.
Tomorrow temperatures will struggle to rebound under the cold
airmass, 850 mb temperatures during the day will be -5C to -7C over
East Tennessee, and Nashville sounding climatology suggests 10th
percentile cold for this time of year. Northwest flow looks to
strengthen Monday afternoon, bringing breezier winds to Tennessee
and southwest Virginia, as the upper trough responsible swings fully
into the region. Also notable is the precipitable water tomorrow
will be below the 10th percentile for this time of year, close to
the daily record minimum, with GFS and Euro showing values of 0.20"
across all of East Tennessee and southwest Virginia. In response,
afternoon relative humidities will dip to the low 30s area wide.
Some of the high resolution CAM guidance has suggested
flurries/brief drizzle out of the clouds tomorrow afternoon. Not
confident enough moisture will be present to see anything in even
our Virginia counties or the east TN mountains, so left PoPs as is.
&&
.LONG TERM...
(Monday night through next Sunday)
Issued at 241 PM EDT Sun Mar 17 2024
Key Messages:
1. Cold night is in store for Monday night with area-wide hard
freeze Tuesday morning. Very cold wind chills in the higher
elevations with values in the single digits to near zero.
2. Very dry conditions Tuesday through Thursday with low
afternoon relative humidity in the 20s and lower 30s.
3. Rain chances return Friday with only light precipitation totals
expected.
Discussion:
For Monday night/Tuesday morning, cold air builds into the Tennessee
valley and southern Appalachians with a hard freeze across much of
the area. Frost development will be limited due to continued breeze
and relatively low relative humidity.
For Tuesday through Thursday, a gradual moderation of temperatures
and dry conditions are expected with upper flow remaining
northwesterly and surface ridging. Main concern will be the low
afternoon relative humidity with values dropping into the 20s to
lower 30s.
For Friday and Friday night, deterministic and ensembles shows a
short-wave moving across the Gulf Coast states. Moisture and
deformation zone on the northern/northwest side of the associated
cyclo-genesis will produce an area of light rain. NBM probabilities
of measurable rainfall is only around 50 percent with probabilities
of one-quarter inch only around 20 percent.
For Saturday, drier conditions return as the system moves off the
southeast coast.
&&
.AVIATION...
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(00Z TAFS)
Issued at 814 PM EDT Sun Mar 17 2024
VFR flight conditions expected for the next 24 hours. Winds are
beginning to veer behind the departing cold front this evening.
Some occasional gusts up to 20 knots are possible at TYS and TRI
through the next 3 hours. Winds will be from the northwest Monday
between 5 and 10 knots. Winds gusts between 20 to 25 knots seem
possible during the afternoon hours Monday.-- End Changed Discussion --
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 39 51 28 58 / 0 0 0 0
Knoxville McGhee Tyson Airport, TN 35 48 27 54 / 0 0 0 0
Oak Ridge, TN 35 49 26 56 / 0 0 0 0
Tri Cities Airport, TN 32 46 25 50 / 0 10 0 0
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
SHORT TERM...Wellington
LONG TERM....DH
AVIATION...Diegan