Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 01/05/21

AREA FORECAST DISCUSSION

National Weather Service Jackson KY

 632 PM EST Mon Jan 4 2021

.SHORT TERM...(This evening through Tuesday night)
Issued at 356 PM EST MON JAN 4 2021

Surface features over the region were relatively weak and
amorphous at mid afternoon. Stratiform clouds which were
prevalent early in the day over the northeast part of the forecast
area very gradually shrunk in coverage and became more convective
in nature as a minimal amount of heating/mixing occurred during
the day.

The break in clouds will be short-lived, as clouds with the next
system will be on the way in tonight. A potent jet streak dropping
down the back side of an eastern CONUS trough will be translating
through the base of the trough to our south as it goes by late
tonight into Tuesday. Although there`s no good inflow of moisture,
models suggest it will use what`s there to wring out some light
precip, especially in our southeast counties. The real problem
which could come into play is the temperatures at higher
elevations, where it looks like it will be around freezing above
about 3K or 3.5K feet. Forecast soundings show that during the
height of the precip, the colder locations will see snow. However,
on either side of this time window, the moisture looks too
low/shallow to assure ice formation. As a result, there could be
some very light freezing rain or drizzle. Confidence in problems
from winter wx is not high enough for an advisory at this point,
but an SPS may be issued to highlight the potential for the
highest elevations.

Once the upper level system departs, ridging will build in from
the west late Tuesday and Tuesday night, first at the surface and
then aloft. Upslope cold air advection persisting as the surface
ridge approaches will hinder low level clouds from clearing out,
with the area most likely to see clouds break up being our
southwestern counties, and the least likely in the east.

.LONG TERM...(Wednesday through Monday)
Issued at 431 PM EST MON JAN 4 2021

We start the period Wednesday morning with rising heights as a
modest ridge moves over the Ohio Valley. Meanwhile, a trough sits
not far behind over the Plains. Moving forward in time, this trough
continues to dig before eventually forming into a closed low that
travels across the Deep South Thursday and Friday. After the passage
of this low, the flow becomes less amplified with a few weaker waves
possibly riding through late Saturday into Sunday, however there`s
still some disagreement and a fair amount of spread in the ensembles
surrounding this detail of the forecast. Though there is agreement
surrounding the existence of a more significant trough to impact our
weather near the end of the period on Monday, the details are not
well nailed down yet.

Down at the surface Wednesday, high pressure, and the ridging aloft,
allows for at least some partial clearing during the day. On
Thursday the high pressure is pushed out and the cloudiness returns
ahead of an approaching system from the south. The northern extent
of this low`s associated precip grazes our southern counties
Thursday night through Friday morning. The chance exists for some
snow during the overnight hours and early Friday morning, if
temperatures are able to cool down enough, but confidence at this
point is not exceedingly high. As this system exits off the coast of
the Carolinas, higher pressure attempts to move in over the weekend,
bringing the return of drier weather and another brief period of
clearing in the clouds on Saturday. The forecast for the end of the
period Sunday and Monday is more uncertain. Overall, another surface
low moving across the south looks to bring increasing clouds and the
next chance for precipitation. However, there is a decent lack of
confidence over the timing and placement of this system, so, have
stuck closer to the blended guidance for now.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
ISSUED AT 632 PM EST MON JAN 4 2021

The forecast period started off with generally VFR conditions
across eastern Kentucky, with SYM reporting BKN CIGs at 3K at
issuance time. The rest of the TAF sites reported VFR conditions
with mainly FEW to SCT highs clouds in place overhead. These
conditions will gradually deteriorate overnight and through the
day on Tuesday, as an area of low pressure moves across the
region. Most areas will experience scattered light rain showers
tonight and Tuesday. Locations along the just to the west of the
Virginia and West Virginia borders may see more widespread rain.
For elevations above about 3000 ft in our far southeast, folks may
see a bit of light snow or freezing rain at times. Very minor
accumulations may occur along the tallest ridges and could lead to
isolated instances of aircraft icing. MVFR CIGs are expected to
begin occurring around 7Z, and will likely fall to IFR by around
13Z on Tuesday. The precipitation should begin winding down
Tuesday morning, and be out of the area by the end of the TAF
period for all but far eastern Pike county. Winds should generally
be from the northwest at around 5KTs after 13Z on Tuesday.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...HAL
LONG TERM...HAS
AVIATION...AR