124
FXUS64 KMRX 060221
AFDMRX

Area Forecast Discussion
National Weather Service Morristown TN
1021 PM EDT Sat Oct 5 2024

...New UPDATE...

.UPDATE...
Issued at 1009 PM EDT Sat Oct 5 2024

No major changes to note to the immediate forecast from now until
Sunday morning. Fog that has been observed the past couple
mornings, will likely repeat overnight. Patchy to areas of dense fog
possible, so exercise caution if you will be traveling Sunday
morning. Surface high pressure over Virginia is expected to
strengthen overnight, which verifies with the short term
discussion below mentioning the better chances of development
over the northeastern part of our CWA.

KS

&&

.SHORT TERM...
(This evening through Sunday)
Issued at 335 PM EDT Sat Oct 5 2024

Key Messages:

1. Patchy dense fog is likely again tonight into the morning,
especially in the northeast.

2. Similarly warm and dry conditions are expected again on Sunday.

This Evening/Tonight

Currently this afternoon, weak quasi-zonal flow is noted aloft with
a strong system centered just north of the Northern Plains in
Canada. A weak frontal boundary extends into our area with high
pressure to our northeast. With above normal heights and subsidence,
mild temperatures and dry conditions will continue this evening into
tonight. Barring any mid/high clouds, patchy dense fog can be
expected again late tonight into the early morning hours. Just like
this morning, this will be most notable around river valleys and
further north where better subsidence will exist. This is also being
promoted by continued ground moisture and dew points still remaining
in the 60s this afternoon.

Sunday

Heading into Sunday, the aforementioned northern system will
continue progressing eastward with its associated cold front
advancing towards the Ohio River Valley. High pressure will still
remain in control during the day with a more southerly shift in
winds by the afternoon. Temperatures will continue to be well above
normal, likely rising well into the 80s across most of the area.

&&

.LONG TERM...
(Sunday night through next Saturday)
Issued at 335 PM EDT Sat Oct 5 2024

Key Message:

1. Other than low-end rain chances in northeast Tennessee and
southwest Virginia Sunday night, the area is expected to stay dry.

2. Temperatures will be cooler than recent days with overnight lows
in the 40s each night, possibly lower in some mountain locations.

Sunday Night through Wednesday

At the start of the extended period, the frontal boundary mentioned
above will be moving in from the northwest associated with the
northern system. Much of the better height falls and upper-level
support will remain well to our north. However, lift and moisture
will be sufficient to support at least low-end rain chances in
northeast Tennessee to southwest Virginia and along the mountains.
Coverage is still expected to be limited with most places likely
remaining dry. By Monday afternoon, model guidance indicates that
this front will move through the area with high pressure expanding
from the northwest. This will mark a shift to northwesterly winds
and a drier and cooler pattern. Heading towards mid-week, upper-
level flow will still remain northwesterly with the surface high
gradually setting near to just north of our area. This will bring
daily high temperatures close to normal with potential for a more
notable drop off into the 40s overnight due to radiational
cooling.

Thursday through Saturday

Late in the week, troughing will remain to our northeast with
reinforcement of stronger high pressure to our north. During this
time, subsidence will be even more notable, which will allow for
temperatures overnight to drop off even more. This is especially
true further to the north and east closer to previous CAA.
Development of patchy frost in some isolated areas near the
mountains is not out of the question. By Saturday, the surface high
is likely to set up overhead with northeastern troughing expected to
lift. The height rises will allow for some increase in overall
temperatures, but the area will remain completely dry during this
time.

&&

.AVIATION...
(00Z TAFS)
Issued at 742 PM EDT Sat Oct 5 2024

Persistence forecast and won`t deviate much away from what was
sent in previous TAF packages. The past couple of nights/mornings
have exceeded what CAMs have shown with extent of very low VSBY.
Calm conditions, mostly clear skies, and high pressure
strengthening over Virginia will most likely set the stage for fog
development overnight.

&&

.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN             64  86  62  81 /   0   0  10   0
Knoxville McGhee Tyson Airport, TN  60  84  60  77 /   0   0  10   0
Oak Ridge, TN                       60  84  58  76 /   0   0  10   0
Tri Cities Airport, TN              54  79  57  72 /   0   0  20   0

&&

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

$$

SHORT TERM...BW
LONG TERM....BW
AVIATION...KS