Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 191814 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
214 PM EDT Thu Apr 19 2018

.UPDATE...
Issued at 214 PM EDT THU APR 19 2018

Lowered the highs a bit this afternoon, as clouds have held
readings down through early this afternoon. The best chance of
seeing 50 degrees will be in the valleys near the Tennessee
border, where clouds have scattered out better. Updates have been
sent.

UPDATE Issued at 1114 AM EDT THU APR 19 2018

Sprinkles have dried up across the area, as the main trough axis
shifts off to our east. A secondary short wave trough will swing
southeast across Ohio and West Virginia through the rest of this
afternoon. This should help anchor the clouds a bit longer, which
the current forecast has captured well. Mainly just tweaked some
of the temperature curves based on the latest trends in
observations. Highs in the upper 40s to near 50 look on target.

UPDATE Issued at 712 AM EDT THU APR 19 2018

Low stratus will continue to hold strong this morning with a few
brief periods of sprinkles across northeastern Kentucky. Expect
gusty northwest winds to continue into this afternoon, making for
a raw day across eastern Kentucky.

Have gone ahead and issued a Freeze Warning for Harlan, Letcher,
and Bell Counties as clearing/decoupling tonight will allow for
rural valleys to fall below freezing.

&&

.SHORT TERM...(Today through Friday)
Issued at 411 AM EDT THU APR 19 2018

Light rain showers across the far eastern reaches of Kentucky will
taper off into the Virginias early this morning in a post-frontal
airmass. Cyclonic flow underneath a weakening upper low, located
across the Ohio Valley and being absorbed into an upper low across
Quebec, may promote another batch of light showers/sprinkles nearer
to daybreak through this morning across northeastern Kentucky. Gusty
west/northwest winds will remain in place this morning and likely
into this afternoon prior to the pressure gradient relaxing later
this afternoon. Upslope flow and shallow low level moisture will
combine to keep low stratus in place through a good chunk of the
day, keeping high temperatures confined to the upper 40s to low 50s.

Surface ridging building through the Midwest this evening and
tonight will allow for clearing skies and diminishing
north/northwest winds, thus leading to good radiational cooling and
temperatures revisiting the freezing mark. Valley locales will
likely cool into the upper 20s to near 30 degrees, with ridges
mainly residing in the low 30s. Near saturation in the boundary
layer will promote widespread frost across all of eastern Kentucky.
Have elected to issue a Freeze Warning for all but southeastern
Kentucky tonight given these expected favorable conditions for
abrupt cooling. A Frost Advisory has been hoisted for southeastern
Kentucky at this time, but will have to monitor later trends
regarding adjustments to both products.

Rising heights ahead of shortwave ridging will allow for warming
temperatures Friday. Surface ridging sliding across the lower Great
Lakes and upper Ohio Valley will keep the amount of warming in
check, but readings look to generally warm into the mid 50s to low
60s during the afternoon underneath sunny skies.

.LONG TERM...(Friday night through Wednesday)
Issued at 445 AM EDT THU APR 19 2018

Models continue in decent agreement to begin the period. An area
of surface high pressure is expected to be centered across the
Great Lakes on Friday evening while associated upper level ridge
axis should initially be near the MS Valley with both progressing
into the eastern Conus through Saturday evening. This will lead
to a period of mostly clear skies and dry conditions through the
first portion of the long term period. The temperatures will
modify through the weekend, but does remain cold enough for Friday
night into Saturday morning to lead to frost and possibly a freeze
in eastern valleys. Patchy frost in some of the eastern or
northeastern valley cold spot is not out of the question on
Saturday night into early on Sunday either as the trend is for
high pressure to generally dominate through Saturday night as well.

Then a southern stream upper level low initially over the Four
Corners at the start of the period will have moved into the
Southern Plains on Saturday. This upper low should then move into
the Lower Mississippi River Valley on end the weekend. The model
guidance appears to be coming into better agreement with the
position and track of the upper low through Monday. The GFS
continues to be wetter and also has qpf further north through
Monday night while the ECWMF points toward qpf only in the south.
However, current trends are for dry weather for all but perhaps
the southwest through sunset on Sunday. Models diverge after
Monday and with run to run variability in timing and track of the
upper system and with potential phasing of this system as is
slowly meander toward the Appalachians with northern stream
system near the end of the period. All the solutions generally
point toward unsettled weather with shower potential with either
some more broad troughing/open wave or more of a closed system
working through followed by the approaching of the northern
system. Trended slightly drier than the blended pops through
Sunday evening and then did not stray far from blended model pops
from Sunday night through the end of the period. This led to
several periods of slight chance to chance pops.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
ISSUED AT 214 PM EDT THU APR 19 2018

Ceilings will raise to VFR at all locations through 19 or 20z,
with clouds scattering out this evening, as high pressure builds
in from the northwest. Northwest winds around 10 kts, with
occasional gusts of 15 to 20 kts will diminish by dusk, with
winds averaging 5 kts or less through the rest of the period.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
Freeze Warning from 1 AM to 10 AM EDT Friday for KYZ044-050>052-
058>060-068-069-080-086>088-104-106>120.

Frost Advisory from 1 AM to 10 AM EDT Friday for KYZ079-083>085.

&&

$$

UPDATE...GEOGERIAN
SHORT TERM...GUSEMAN
LONG TERM...JP
AVIATION...GEOGERIAN



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