Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 231712

National Weather Service Jackson KY
112 PM EDT Fri Mar 23 2018

Issued at 1103 AM EDT FRI MAR 23 2018

NDFD has been updated for latest observational trends, but there
are no substantial changes to the forecast at this time.

A very complex forecast is shaping up for the weekend, with
concerns for heavy wet snow in the north, thunderstorms in the
south, and maybe even some flood issues. Beginning to see some of
the 12Z model data, but not enough yet to begin drawing any
conclusions. Some of the forecast soundings in the far north are
of concern, with deep nearly isothermal profiles near the freezing
mark. If such a sounding verifies that could mean a very heavy
wet clinging snow where even 3 or 4 inches could result in power
outage problems. However, it also means that just a degree
temperature difference can result in a very cold rain. It is
likely some adjustments will be made to the advisory area this
afternoon, and it is possible at least a few counties may need to
upgraded to winter storm warnings. The other concern is rainfall
in the southern part of the forecast that could eventually lead to
some high water issues. This morning`s river runs are taking
Barbourville and Williamsburg into minor flood later this weekend.
It is possible a flood watch may be needed for at least part of
the area as well.

UPDATE Issued at 755 AM EDT FRI MAR 23 2018

Mid clouds have increased across the lower Ohio Valley this
morning as mid-high clouds continue to stream toward the northeast
out of western Kentucky. Otherwise, expect frost and any lingering
fog to mix out within an hour or two as temperatures warm.


.SHORT TERM...(Today through Saturday)
Issued at 411 AM EDT FRI MAR 23 2018

High pressure will maintain dry weather across eastern Kentucky this
morning and afternoon as clouds steadily increase from the
southwest. This uptick in cloud cover will be stemming from a
shortwave trough and accompanying surface low migrating from the
Great Plains into the Midwest. This will bring precipitation across
the eastern portion of the Commonwealth this evening through
tonight, beginning in the Lake Cumberland region and moving
northeast through the night. While warm enough air should filter in
to keep precipitation of the liquid variety south and west of
roughly a McKee to Harlan line, areas northeast of this line will
see a mix with snow and perhaps some periods of sleet. Not expecting
freezing rain to be an issue given the presence of ice aloft.
However, a tight gradient will likely exist between rain and a mix
with snow/sleet as the recent cold dome holds strong across
northeast Kentucky with the approaching surface low translating
east/southeast through the Ozarks toward the northern reaches of
Tennessee. Exactly where the accompanying warm nose and remnant cold
air reside will play an integral role in where impactful snowfall
amounts occur.

Given recent trends, have opted to hoist a Winter Weather Advisory
from early tonight through early Saturday night for points north and
east of a Mount Sterling to Pikeville line. While storm total
snowfall amounts may reach or slightly exceed 4 inches across
portions of the Bluegrass and Big Sandy regions, the likelihood of
this seems fairly low over a 12 hour timespan early Saturday given
surface temperatures right around the freezing mark. The sun angle
this time of year and the wet nature of this snow should also
prove detrimental to significant accumulations, although a quick
burst early Saturday morning could allow for some rapid
accumulations. Omega profiles are rather stout above the surface
and within the dendritic growth zone, but this latter feature does
look to remain fairly high (above 13-14k feet) atop a
saturated/isothermal layer just below freezing. Would therefore
think that impacts will be more that of advisory level as road
surfaces should see decent meltoff, especially after sunrise. The
greatest of these impacts will be early Saturday morning and again
Saturday evening underneath dark skies. Storm total snow
accumulations should generally range from 1 to 4 inches through a
24 hour period from Friday night through Saturday evening, with
isolated amounts of 4-5 inches in Fleming and perhaps
Bath/Rowan/Elliott Counties. Will assess trends this morning and
afternoon in regard to expansion of the advisory or a necessary
upgrade to a warning. Additionally, may experience a few rumbles
of thunder Saturday afternoon and evening across portions of
southeast Kentucky as elevated instability increases.

.LONG TERM...(Sunday through Friday)
Issued at 111 PM EDT FRI MAR 23 2018

The long term portion of the forecast will feature a deepening
upper level trough over the western U.S. early next week, with
deep southwest flow becoming established across the OH and TN
valleys. By the end of the week the trough will shift east, but
with southwest flow across the eastern U.S. continuing. There is
good model agreement with the overall upper air pattern though
some differences are to be expected with individual short waves
ejecting from the upper low that will be over the southwestern
part of the United States through the first half of next week.

With good model agreement with the overall pattern, the concern
for the coming week will be the potential for heavy rain somewhere
in the central to eastern U.S. with deep southwest flow becoming
established. Current indications are that the heaviest rains will
likely affect areas to our west early to mid week as a slow
moving front moves into the MS Valley. The front will eventually
move across our area during the second half of the week, but it is
possible it will stall again at some point near us or just to our
east. The greatest threat for heavy rains next week appears to be
over western KY and TN. While this is outside our forecast area
it is close enough that the coming week will need to be monitored
closely. Considering the heaviest rain potential is still 5 days
away or so, it is likely the forecast axis of heaviest rains will
shift during the coming days.

The southwest flow will also result in warming temperatures, with
above normal temperatures expected from Tuesday through at least


.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)

VFR conditions will continue to rule through this afternoon and
this evening as clouds gradually thicken and lower ahead of an
approaching disturbance. Light rain will begin to impact sites
near SME and LOZ this evening, with snow and some periods of sleet
impacting sites northeast of a McKee to Harlan line. Conditions
will continue to deteriorate overnight with MVFR or worse
ceilings overspreading much of eastern Kentucky by dawn. Snow and
slippery/slushy tarmacs will be most problematic tonight into
Saturday north of a KPBX to KJKL to KLEX line. Winds will largely
remain below 10 knots as they veer from northwesterly today to
east/northeasterly this evening.


Winter Weather Advisory from 2 AM Saturday to 2 AM EDT Sunday
for KYZ044-050>052-060-104-106-107-109-110-119-120.



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