Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 072055
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
355 PM EST Thu Dec 7 2017

.SHORT TERM...(This evening through Friday night)
Issued at 243 PM EST THU DEC 7 2017

A cold front is pushing across southeast Kentucky this afternoon
with cooler and drier air working in from the northwest behind
this front. We had a touch of flurries earlier today, but they
have exited off to the east and north with dry conditions being
observed this afternoon. Dry air will continue to advect into the
region tonight and will keep the weather precipitation free
through Friday. The present frontal boundary will stall well to
our southeast tonight with an area of low pressure tracking
northward along this boundary tomorrow. All of the deeper moisture
should stay to our southeast, but an increase in mid/high level
clouds will be seen, especially over southeast Kentucky. The
clouds may hold our high temperatures down a bit lower on Friday
with temperatures in the mid 30s. Shortwave ridging will cross the
area Friday night. With dewpoints running in the low to middle
teens, combined with expected clearing, we should see temperatures
tank Friday night. Lows in the valleys could easily reach the mid
to upper teens with ridges holding in the lower 20s. The next
clipper system will approach from the northwest towards daybreak
Saturday, but the effects of this system won`t be felt until well
after daybreak Saturday.

.LONG TERM...(Saturday through Thursday)
Issued at 355 PM EST THU DEC 7 2017

A western Conus ridge and eastern Conus/North American trough
pattern is expected to persist through the period. Periodic
shortwaves/clipper type systems will bring chances for light
precipitation and reinforcing shots of colder air. The sfc low
associated with the first of these will have moved into the Great
Lakes before the start of the period with the trailing sfc cold
front trailing south into the MS Valley region. The best synoptic
forcing and moisture with this system appears to remain north of
the area while a stronger sfc low organizes and moves up the
eastern seaboard well east of the area. However, cold air
advection and solar insolation on Saturday should bring steepening
lapse rates leading to scattered to possibly numerous snow
showers on Saturday afternoon/evening along and in western flow
behind the cold front. The snow showers should be favored across
portions of the escarpment in the Daniel Boone NF and in the
higher terrain of southeastern KY. Even at that, QPF will be
minimal and during the day air and ground temperature should be
marginal at best for accumulations. Accumulations should be a half
of an inch or less in all locations. Low level moisture should
linger well into Saturday night and flurries may not end in the
far southeast part of the area until near dawn on Sunday.

Height rises and surface high pressure building into the area
should work in for late Saturday night into Sunday behind the
departing shortwave trough. The surface high should remain
dominant into the day on Monday as it shifts south and east
although upper level disturbances passing by to the north may
bring rounds of mid and high clouds. The airmass should moderate,
briefly for Monday to near normal temperatures with southwesterly
flow between the high and the next approaching clipper system.

Models vary from run to run and model to model in handling the
next more significant clipper system to affect the region Monday
night through Tuesday and thus timing is uncertain. However,
isolated to scattered coverage of snow showers appears probable at
some point between late Monday night and Tuesday evening as lapse
rates should again steepen up again as another cold airmass
arrives. Late in the period for Wed night into Thursday, the model
consensus is for another clipper system to approach the region
leading to renewed chances for snow showers. At this time, both of
these events appear they will be on the light side with the best
forcing north of the region and sfc reflection if any with the
first passing north of the area and limited moisture with both.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
ISSUED AT 222 PM EST THU DEC 7 2017

VFR conditions will continue over the next 24 hours. Some mid/high
clouds will spread over the area tonight into tomorrow. Winds will
remain light and variable through the period.

&&

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

$$

SHORT TERM...KAS
LONG TERM...JP
AVIATION...KAS



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