-- Discussion containing changed information from previous version are highlighted. --
775
FXUS64 KMRX 181201
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
801 AM EDT Wed Sep 18 2024

...New AVIATION...

.SHORT TERM...
(Today and tonight)
Issued at 255 AM EDT Wed Sep 18 2024

Key Messages:

1. Isolated to scattered showers and possibly some thunderstorms,
are possible this afternoon and evening for similar areas that saw
precipitation yesterday - northeast Tennessee, southwest Virginia
& North Carolina, and in the foothills of the Southern
Appalachians.

2. High temperatures bounce back into the 80s today for much of
non-elevated areas.

Discussion:

What`s left of the tropical cyclone, is currently centered over
the Carolina`s providing some cloud cover and fog under broken
skies. Through the next 24 hours, a weak low will develop off of
the Virginia coast and try to get it`s act together as it deepens
some before reaching New England by tomorrow. Wrap around from
that system and residual energy leftover under troughing aloft,
will bring showers and maybe some thunderstorms back to the same
areas this afternoon and evening; most likely less in the form of
amounts. Chances for thunder are pretty low (< 30 percent), so
not expecting any severe weather. It doesn`t appear rain will be
as widespread as it was early yesterday either.

Again, the southern valley and plateau will not see much in the
way of any accumulating precipitation which is not what a lot want
to hear. Temperatures are expected to be several degrees warmer
this afternoon with readings back in the 80s for many. For
comparison, our climate sites ranged in the mid 70s and upper 60s
for highs Tuesday. Like some areas are seeing this morning, low
clouds and fog development may be possible again Thursday morning.

&&

.LONG TERM...
(Thursday through Tuesday)
Issued at 255 AM EDT Wed Sep 18 2024

Key Messages:

1. Other than showers and an isolated rumble of thunder in the east
on Thursday, dry and progressively warmer conditions are expected
Friday through the weekend.

2. Early next week, temperatures moderate closer to normal with some
low-end rain chances returning.

Discussion:

Not much has changed for the long term forecast. An upper low to our
east early Thursday will lift northeast to become an east coast
trough by Friday morning. Meanwhile ridging to our west, anchored
over Texas, will strengthen and expand to the east through at least
the first half of the weekend.

Still can`t rule out some isolated to scattered showers in the
northeast on Thursday, and possibly even a rumble of thunder, but in
general expect dry and increasingly warmer conditions Thursday
through Saturday. With the strengthening ridge and H85 temps warming
to 18-19C Friday and Saturday, feel pretty confident in saying some
locations in the south will likely see highs top 90 degrees. This
won`t be calendar day record territory, but it will definitely be
warm. Did undercut NBM dewpoints by a decent amount. Models suggest
deep mixing through this period, with increasingly dry air in place
so I went with a blend of CONSAll and the NBM 10th percentile to
bring dewpoints down a bit. Expect we`ll see some areas of sub-forty
percent RH on Friday and Saturday as a result. Winds should be light
though, so no notable uptick in fire weather concerns exist.

On Sunday, similarly strong ridging will remain in place, keeping
the area very warm and dry. By early next week, the main question
will be how troughing to our northwest will evolve. Some solutions
suggest a strong system to develop and progress to our north with
others showing more zonal evolution. Seems like the trends have been
towards a less dynamic system and more zonal upper pattern, but
there`s still quite a bit of uncertainty. In any case, some
moderation in temperatures and a return of low-end rain chances can
be expected.

&&

.AVIATION...
-- Changed Discussion --
(12Z TAFS)
Issued at 743 AM EDT Wed Sep 18 2024

As mostly thought and expected, TYS stayed mostly within LIFR and
IFR most of the night, but CIGS have come up some. Expect
improvement there in the next few hours. CHA`s VSBY didn`t go down
as much as forecast, but the CIGS forecast verified pretty good.
Expect them to improve this morning as well. TRI finally came down
in CIGS and VSBY and have most recently reported LIFR. Expect slow
improvement there through the morning. Chances for afternoon and
evening showers will return for TYS and TRI. Think it will be
isolated enough to keep VC at TYS. CAMs seem to lighten the
showers more, so kept PROB30 at TRI, but dropped the TS. Again,
fog possible at TYS and TRI Thursday morning, but timing and
extent not certain. Final lines in TAF though hint at this
possibility.
-- End Changed Discussion --

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             85  65  88  64 /  10   0   0   0
Knoxville McGhee Tyson Airport, TN  83  64  85  61 /  20  10  10   0
Oak Ridge, TN                       83  63  85  61 /  10   0  10   0
Tri Cities Airport, TN              79  61  80  59 /  30  10  30   0

&&

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

$$

SHORT TERM...KS
LONG TERM....CD
AVIATION...KS