Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 232044

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

.SHORT TERM...(This evening through Saturday night)
Issued at 444 PM EDT FRI MAR 23 2018

Extremely complex forecast as low pressure moves out of the
central plains and into the lower OH valley by Saturday evening.
Precipitation type is an extreme challenge as model soundings in
the north show some deep near freezing isothermal profiles, which
may hold through much of the day on Saturday. If such soundings
verify that could mean a very heavy wet clinging snow where even 3
or 4 inches may result in power outage problems. However, it also
means that just a degree temperature difference can result in a
very cold rain. With the trends of recent model runs, WPC guidance
and collaboration with neighboring office have opted to go with a
winter storm warning for our northern counties. Three to 5 inches
of snow is forecast for the warning area, but a few isolated 6 or
7 inch amounts cannot be ruled out. South and east of the warning
we continued the advisory, and also added a couple of counties to
the advisory.

There will be close to a 20 degree temperature spread from north
to the southwest part of the area on Saturday. And further south
some thunderstorms will be possible, mainly in the Cumberland
basin. Latest indications are that rainfall will be spread out
over a long enough time period that small stream flooding should
not be an issue. WPC also has not placed any of the area in the
excessive rainfall outlook. With that in mind have opted to not go
with a flood watch, which we had been considering earlier today.
However, a few points on the Cumberland river could reach flood
stage sometime on Sunday.

.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 18Z TAFS through 18Z Saturday afternoon)

VFR conditions will prevail into tonight, but conditions will
deteriorate rapidly late tonight into early Saturday morning,
with IFR or LIFR conditions forecast across the entire area
Saturday morning. Low pressure will move from the central plains
this evening into the lower OH valley by Saturday evening. Clouds
will thicken and lower tonight in advance of this approaching
system, with precipitation overspreading the area early Saturday
morning. Enough cold air will remain in place over the northern
part of the forecast area that much of the precipitation will
fall as snow Saturday morning, with SYM most likely to be
affected by snow. A rain snow mix will occur in a band south of
this, likely affecting JKL and SJS, with just plain rain further
south and west. Some thunder will be possible Saturday afternoon,
mainly in the southern part of the area.


Winter Storm Warning from 2 AM Saturday to 2 AM EDT Sunday for

Winter Weather Advisory from 2 AM Saturday to 2 AM EDT Sunday
for KYZ059-107>110-119-120.



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