Area Forecast Discussion Issued by NWS Knoxville/Tri Cities, TN
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000
FXUS64 KMRX 170521 AAA
AFDMRX
Area Forecast Discussion...UPDATED
National Weather Service Morristown TN
121 AM EDT Sun Mar 17 2024
...New AVIATION...
.UPDATE...
Issued at 1029 PM EDT Sat Mar 16 2024
No updates needed tonight. Temperatures have been a degree or two
warmer than the forecast but still think overnight lows are in
good shape.
&&
.SHORT TERM...
(This evening through Sunday)
Issued at 318 PM EDT Sat Mar 16 2024
Key Messages:
1. Dry and pleasant for most tomorrow as moisture starved cold front
crosses the region Sunday morning.
Discussion:
Clouds are finally breaking up this afternoon for remaining portions
of the Tennessee foothills, and full brilliant March sunshine has
led to a great day. Decent weather will hang on through tomorrow.
Despite the cold front passing through overnight, the main cold air
advection will hold on for one more day, with 850 mb temperatures
not falling below 0C until after midnight Sunday night. Clouds will
be on the increase overnight as a midlevel shortwave approaches the
area.
Daytime Sunday will therefore be decent, with mild and dry weather.
Low chance for a sprinkle around daybreak south of Knoxville, but
the drier atmosphere aloft might prevent that from reaching the
ground. Otherwise maintained a low PoP across the counties bordering
Georgia tomorrow afternoon, but CAMs are united on keeping
precipitation south of us in Georgia.
&&
.LONG TERM...
(Sunday night through next Saturday)
Issued at 318 PM EDT Sat Mar 16 2024
Key Messages:
1. Much colder temperatures will start the period with an area-wide
hard freeze on Tuesday morning and very cold wind chills in the
higher elevations. A warming trend will follow.
2. Very dry conditions are also expected Monday and Tuesday.
3. Rain chances will return Thursday into Friday with fairly light
totals expected overall.
Sunday Night through Wednesday
At the start of the period, anomalous troughing will be building
into the area from the north with a cold front having pushed to the
south. During this time, high pressure originating in Canada will be
expanding from the north with strong CAA taking place. By the day on
Monday, 850mb temperatures will fall below the 10th percentile for
this time of year, i.e. below -7 Celsius. Persistent northwesterly
flow, the MSLP gradient, and very anomalous 850mb temperatures will
make for breezy conditions and temperatures near or below January
normals on Monday. As the high pressure arrives to our west,
stronger subsidence will promote dry conditions during the day,
followed by an area-wide hard freeze. The coverage of frost may be
less widespread if winds continue, but even light winds will make
for even colder wind chills in the higher elevations, possibly
single digits in some areas.
By Tuesday, the region will begin to see height rises and increasing
southerly flow as troughing shifts further east and high pressure
becomes centered further south. As the subsidence continues and
temperatures increase, afternoon RH`s will likely drop lower than on
Monday, possibly approaching 20 percent. For Wednesday, there are
indications of increasing low-level moisture, which would likely
limit dryness at the surface. However, recent southerly flow and
continued height rises will still allow for many places to reach
seasonal temperature norms in the 60s.
Thursday through Saturday
By Thursday, focus will turn towards a shortwave that will likely
become cut off from the main flow over western Texas and Oklahoma
before progressing towards the southeastern U.S. Based on the latest
model guidance, this system is expected to reach the area towards
Friday, which will also be the time of increasing rain chances. With
the surface low pressure center expected to track south of our area,
the better moisture and any instability are expected to remain well
to our south. This will keep overall rain totals and impacts with
this system very limited. Ultimately, this will provide widespread,
overall light rain, which may continue into Saturday.
&&
.AVIATION...
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(06Z TAFS)
Issued at 119 AM EDT Sun Mar 17 2024
VFR conditions are forecast through this period. Clouds will
increase through the morning but will remain at VFR levels, mainly
around 10 kft today. Winds will increase in the mid/late morning
hours, between 8-12 kt, and a few gusts near 20 kt are possible
at TRI this afternoon.-- End Changed Discussion --
&&
.PRELIMINARY POINT TEMPS/POPS...
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Chattanooga Airport, TN 65 37 51 29 / 20 0 0 0
Knoxville McGhee Tyson Airport, TN 63 35 49 27 / 10 0 0 0
Oak Ridge, TN 64 34 49 25 / 10 0 0 0
Tri Cities Airport, TN 60 32 46 25 / 10 0 10 10-- End Changed Discussion --
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
SHORT TERM...Wellington
LONG TERM....BW
AVIATION...DGS