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

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FXUS64 KMRX 251047
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
647 AM EDT Mon Mar 25 2024

...New AVIATION...

.SHORT TERM...
(Today through Tuesday)
Issued at 322 AM EDT Mon Mar 25 2024

Key Messages:

1. Increasing winds this afternoon as the pressure gradient
increases across the area. Upgraded to a High Wind Warning across
the mountains/foothills and added a Wind Advisory for portions of
the southern valley and plateau.

2. Low RH values expected this afternoon with dry air and
downslope flow. This will increase fire danger when combined with
high winds.

3. Rain arrives late tonight into Tuesday morning with mountain
wave wind gusts across the higher elevations and foothills of 80+
mph.

4. Along the line of rain showers, and a slight chance of embedded
thunderstorms, winds will be strong ahead of the cold front.

Discussion:

A 150 kt upper-level jet streak across the Southern Plains is
resulting in strong upper divergence and surface cyclogenesis
across eastern Kansas early this morning. This longwave trough is
setup across the Central CONUS with ridging across the Southeast
and East Coast. As the trough shifts east and the upper-level jet
streak progresses northeastward, strong divergence across the Ohio
Valley and Great Lakes will result in an increased LLJ across the
Tennessee Valley with 850mb winds around 80 kt. The tightening
surface pressure gradient and strong gradient winds will result in
breezy conditions developing across the area this afternoon and
evening, and a Wind Advisory has been issued for portions of the
southern valley and plateau where wind gusts up to around 45 to 50
mph are expected. A High Wind Warning has been issued for the
mountains and foothills where mountain wave enhanced winds will
likely gust in excess of 80 mph. Fire weather issues are discussed
in the fire weather discussion.

With the longwave ridge across the East Coast, strongest DPVA will
be across the Ohio Valley with limited height falls ahead of the
cold front. This will limit instability Monday night into Tuesday
with poor mid-level lapse rates. Even the strongest upper-level
divergence will be displaced far north of our area as the cold
front moves eastward across the forecast area on Tuesday. This
will result in a line of weakening showers with very limited (10
to 15 percent) chances of an embedded thunderstorm. Even with
limited instability, any convective showers with minimal
instability could produce strong wind gusts with any downdraft.
Rain showers begin to taper off late Tuesday evening as the cold
front shifts eastward.

&&

.LONG TERM...
(Tuesday night through Monday)
Issued at 322 AM EDT Mon Mar 25 2024

Key Messages:

1. Rain will be gradually decreasing west to east towards Wednesday
with an approaching front bringing cooler conditions by Thursday.

2. A widespread frost/freeze event is increasingly likely by Friday
morning, followed by a warming trend through the weekend.

Tuesday Night through Thursday

At the start of the period, a deep trough will be approaching from
the west with a low pressure system having pushed into the Upper
Great Lakes region. The associated frontal boundary will be in
Middle Tennessee. By this point, the better moisture will have
shifted off to the east of our area but still sufficient for PoPs in
eastern areas. Upper-level troughing and the front will be slowly
approaching the area through the day on Wednesday with moisture and
higher PoPs also slowly shifting off to the east. The front is
expected to move through the area by the evening with high pressure
slowly expanding. This will put the region in a northwesterly flow
pattern with CAA and increasing subsidence. With the lingering MSLP
gradient and low-level flow, radiational cooling will be fairly
limited, but notably cooler temperatures can be expected
nonetheless.

During the day on Thursday, upper troughing will be overhead with
surface high pressure centered near the Mississippi River Valley.
Continued northerly flow, CAA, and recent height falls will make for
a notably cooler day with many places remaining in the 50s. By
Thursday night, conditions will be a lot more ideal for radiational
cooling as high pressure becomes centered almost directly into the
area. As such a widespread frost/freeze event is increasingly likely
late Thursday night into Friday morning.

Friday through Sunday

During the day on Friday, significant height rises are expected,
which will begin a warming trend. High pressure will remain in the
general area, promoting continued dry conditions. Height rises will
continue into Saturday with temperatures rising further above normal
across the area. Towards the end of the period, there are
indications of a frontal boundary approaching from the north, but
overall moisture will be more limited in our area. At most, this
will lead to low-end rain chances approaching from the north.

&&

.AVIATION...
(12Z TAFS)
Issued at 645 AM EDT Mon Mar 25 2024

VFR conditions prevail this morning through the afternoon with
increasing winds, especially at CHA. Lowering cigs are expected
tonight with MVFR cigs at CHA; however, downslope flow will keep
cigs VFR at TYS and TRI. Rain approaches the region from the west
late tonight into early Tuesday morning. With the stronger winds
aloft, and uncertain with how strong gusts will be at the surface,
LLWS will be possible late in the forecast period across the area.

&&

.FIRE WEATHER...
Issued at 322 AM EDT Mon Mar 25 2024

Key Messages:

1. Low RH today. Many areas, especially across northeast
Tennessee, will have minRH values in the teens.

2. Winds become gusty today, especially across the mountains and
foothills.

Discussion:

Dry air and warmer temperatures, will result in low RH values
across the area today. Localized lower RH values will be possible
across the western foothills of the mountains and for northeast
Tennessee where downslope flow further dries the air. Finer 1 and
10 hr fuels will dry out quickly with the low RH values. When
combined with strong winds, an enhanced fire danger will develop
later this afternoon. Strongest winds will be near the higher
elevations of the mountains, ridge tops, and western foothills
near the mountains. While RH values will recover overnight, winds
will continue to increase through Tuesday morning. Rain chances
begin to increase late Monday night into Tuesday morning with
highest rain chances mid-day through the afternoon on Tuesday.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             63  54  64  51 /   0  70 100  20
Knoxville McGhee Tyson Airport, TN  68  51  63  50 /   0  40 100  40
Oak Ridge, TN                       68  51  62  50 /   0  50 100  30
Tri Cities Airport, TN              64  45  60  48 /   0  10  90  60

&&

.MRX WATCHES/WARNINGS/ADVISORIES...
NC...Wind Advisory from 5 PM this afternoon to 2 PM EDT Tuesday for
     Cherokee-Clay.

TN...Wind Advisory from 5 PM EDT /4 PM CDT/ this afternoon to 2 PM
     EDT /1 PM CDT/ Tuesday for Bledsoe-Bradley-East Polk-
     Hamilton-Loudon-Marion-McMinn-Meigs-Morgan-Northwest Monroe-
     Rhea-Roane-Scott TN-Sequatchie-West Polk.

     Wind Advisory until 5 PM EDT this afternoon for Blount Smoky
     Mountains-Cocke Smoky Mountains-Johnson-Sevier Smoky
     Mountains-Southeast Carter-Southeast Greene-Southeast
     Monroe-Unicoi.

     High Wind Warning from 5 PM this afternoon to 2 PM EDT Tuesday
     for Blount Smoky Mountains-Cocke Smoky Mountains-Johnson-
     Sevier Smoky Mountains-Southeast Carter-Southeast Greene-
     Southeast Monroe-Unicoi.

VA...NONE.
&&

$$

SHORT TERM...JB
LONG TERM....BW
AVIATION...JB


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