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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS64 KMRX 201126
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
726 AM EDT Sat Apr 20 2024

...New AVIATION...

.UPDATE...
Issued at 709 AM EDT Sat Apr 20 2024

Current showers across middle TN are over performing compared to
what previous and current HRRR runs were/are showing. This precip
is expected to continue to spread eastward into the central east
TN valley over the next few hours. Precip should generally remain
less than 0.2 inches. Have updated POPs across these areas to
account for this. Current thinking is rain will persist through 15
to 16Z then clear out. Have updated the zone forecast and resent.

&&

.SHORT TERM...
(Today and tonight)
Issued at 302 AM EDT Sat Apr 20 2024

Key Messages:

1. Slight chance to chance pops through sunrise.

2. Clouds slowly clear today, with high temps around 5 degrees below
normal.

Discussion:

A cold front is currently located on the leeward side of the
Appalachians. However, 925 to 850mb frontogenesis still resides
across our area. The lift, combined with lingering moisture, will
allow for slight chance to chance pops to remain in place for
potions of the area through sunrise. Latest HRRR runs support this
and show isolated to scattered showers developing over the next
few hours, then dissipating shortly after sunrise.

Otherwise, clouds will be slow to clear this morning but will
eventually do so for most areas by this afternoon. The southern TN
valley will likely see the most clouds today as additional
moisture pushes in from the southwest late in the afternoon. Areas
along the TN/KY/VA border will see the least amount of clouds as
drier air briefly moves in. Lastly, temperatures will be slightly
below normal behind the cold front, around 5 degrees below
normal.

&&

.LONG TERM...
(Sunday through Friday)
Issued at 302 AM EDT Sat Apr 20 2024

Key Messages:

1. Low chance of rain, mainly across our southern areas, on Saturday
night and Sunday morning associated with a surface low to our south.

2. High pressure arrives early next week with cooler temperatures;
chance of frost across the higher elevations and plateau on Monday
morning.

3. A quick system will bring low chances of precipitation towards
the middle of next week with high pressure returning behind the cold
front.

Discussion:

Generally quiet weather is expected for most of the extended period
with limited impacts. As a surface low pressure system moves across
the Southeast CONUS, widespread cloud cover and rain chances are
expected Saturday night into Sunday. This will mainly impact our
southern areas with clearer sky conditions and drier weather
arriving Sunday evening into the overnight hours.

Cooler temperatures and light winds will result in opportunities for
patchy frost across the higher terrain and plateau areas on Sunday
night into Monday morning and again on Monday night into Tuesday
morning. At this time, limited impacts are anticipated. With the
cold surface high pressure airmass and Eastern CONUS troughing,
temperatures will be 5 to 10 degrees below normal early next week.

Ridging begins to build back in on Tuesday with a low pressure
system moving quickly across the Great Lakes region. This will bring
another cold front across our region on Wednesday. However, with
high pressure and ridging across the Lower Mississippi Valley
limiting moisture advection northward across the Tennessee Valley
and Southern Appalachians, probabilities of precipitation remain low
with only light accumulation expected.

High pressure is forecast to return in the wake of the departing
cold front late next week.

&&

.AVIATION...
-- Changed Discussion --
(12Z TAFS)
Issued at 719 AM EDT Sat Apr 20 2024

MVFR conditions will persist through late morning across all
sites. Then, VFR conditions through the rest of the period. Winds
will remain northerly at CHA and TYS, and west-northwest at TRI,
generally less than 10kts. MVFR conditions move back in just
beyond the end of this TAF period.
-- End Changed Discussion --

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             71  48  62  43 /   0  50  40   0
Knoxville McGhee Tyson Airport, TN  67  47  58  40 /  20  40  30   0
Oak Ridge, TN                       68  46  60  40 /  30  20  20   0
Tri Cities Airport, TN              65  43  57  35 /  20  20  30   0

&&

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

$$

SHORT TERM...
LONG TERM....KRS
AVIATION...