-- Discussion containing changed information from previous version are highlighted. --
276
FXUS64 KMRX 171919
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
319 PM EDT Fri May 17 2024

...New SHORT TERM, LONG TERM...

.SHORT TERM...
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(This evening through Saturday)
Issued at 315 PM EDT Fri May 17 2024

Key Messages:

1. Mostly light and isolated to scattered rain showers this
afternoon and evening, with a relative lull in activity overnight.

2. Some fog development possible tonight but extent of
coverage/density is a bit uncertain.

3. Additional showers and a few storms possible tomorrow. Isolated
stronger storms could result in gusty winds and small hail.

Discussion:

Developing low pressure and a surface warm front remain in place
along the Gulf states. A resulting precip shield has notably choked
off moisture advection into the region, with light precipitation
becoming more isolated to scattered within our forecast area. Light
rain showers will continue to remain possible through the evening
with a relative lull in activity expected overnight, though we may
not stay totally dry. At this point, believe thunder chances are
quite low. Additionally, given the low level moisture expect there
to be some amount of fog/mist development over night. However,
uncertainty exists as to how widespread or how dense this may
become as low stratus clouds will promote poor radiational cooling
and any light rain showers could result in brief mixing at times.

Additional activity is expected to develop tomorrow afternoon,
especially in terrain influenced locations such as southwest
Virgina, the Cumberland Plateau, and the East Tennessee mountains.
Recent model derived soundings suggest some some instability will
build back into the region - generally 750-1250J/kg as the
aforementioned warm front lifts into central Georgia. Lapse rates
look to be meager, in the low 6C/km range. Believe thunder chances
will be better tomorrow, though activity will generally remain
scattered. It is possible that a few general thunderstorms develop
and become on the stronger side with gusty winds of 40mph and small
hail but think the severe threat is quite low. Considerations to
take into account will be additional precip to our south potentially
cutting off moisture once again and how long we remain socked in
with low stratus/fog. Temperatures will remain mild trough the near
term.
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&&

.LONG TERM...
-- Changed Discussion --
(Saturday night through next Friday)
Issued at 315 PM EDT Fri May 17 2024

Key Messages:

1. Our wet weekend doesn`t end until mid to late Sunday afternoon.

2. Drier on Monday and Tuesday.

3. Cold front to bring additional showers, and a few storms, into
the area mid to late week.

Discussion:

We begin the period with a weak upper level trough and shortwave
traversing across the area. Light and scattered showers will
continue until mid to late Sunday afternoon. Then, precip comes to
an end as upper riding builds in from the southwest and pushes the
trough to the leeward side of the Appalachians.

Ridging further builds into the area and remains in place Monday
through Tuesday. Conditions should be mostly dry with warmer
temperatures. NBM wants to put in a few isolated showers and storms
each afternoon. However, low confidence this actually occurs as
there will be very little moisture to work with in the atmosphere
under the northerly flow regime that will be in place.

As of now, our midweek system doesn`t look very impressive. An area
of strong high pressure to our south will really slow down the cold
front as it approaches from the west. Also, the best dynamics still
remain well north with the low all the way up into the Great
Lakes/Canada. Models generally show precip moving into our area
Wednesday afternoon into Thursday, along with a few storms but with
no concerning severe threat as of now. Model solutions diverge past
Thursday with varying solutions. NBM keeps POPs in on Friday behind
the cold front but can`t find a reason to remove them due to model
uncertainty.
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&&

.AVIATION...
(18Z TAFS)
Issued at 139 PM EDT Fri May 17 2024

Unsettled weather continues with rain showers across the area for
the afternoon and evening, with low BKN/OVC clouds persisting.
Pretty good model agreement that MVFR/IFR cigs become prevailing
at all locations by the overnight. Next question this poses is if
this will inhibit fog development or if low level moisture will
be strong enough to get reduced visibility as well. More
uncertainty with this but have opted to included in TAFs at this
time. Winds will remain light through the period.

&&

.PRELIMINARY POINT TEMPS/POPS...
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Chattanooga Airport, TN             66  80  63  83 /  30  70  40  30
Knoxville McGhee Tyson Airport, TN  63  76  62  78 /  60  50  60  40
Oak Ridge, TN                       62  77  62  81 /  60  60  50  30
Tri Cities Airport, TN              60  75  60  76 /  50  50  60  50
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&&

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

$$

SHORT TERM...KRS
AVIATION...KRS