Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 192035
AFDJKL

AREA FORECAST DISCUSSION
National Weather Service Jackson KY
335 PM EST Sun Feb 19 2017

.SHORT TERM...(This evening through Monday night)
Issued at 335 PM EST SUN FEB 19 2017

19z sfc analysis shows high pressure moving over Kentucky. While
rather weak it has mustered enough strength to start the clearing
process through the southern two thirds of the CWA. With the
returning sunshine temperatures have rebounded into the lower 60s
in the south but still are in the low 50s under the clouds for
locations north of Interstate 64. Dewpoints, meanwhile, have held
rather steady in the mid and upper 40s along with light and
variable winds. Look for the ceilings continue to erode into the
early evening with most places seeing clear skies through sunset.

The models are in good agreement aloft through the short term
portion of the forecast. They all depict a strong ridge passing
over Kentucky and the Deep South tonight through Monday in advance
of a full latitude trough crossing thr Rockies. This trough starts
to split apart later Monday night with the southern portion
closing off as it exits into the western Gulf. Meanwhile, the
northern portion pushes quickly into the Great Lakes stretching
the energy with this trough. Some of that energy will look to ride
over eastern Kentucky early Tuesday ahead of the main trough axis.
Given the decent agreement among the models have favored a
general blend with a significant lean toward the higher
resolution HRRR and NAM12 in the near term.

Sensible weather will feature mostly clear skies to start the
night leading to good radiational cooling. With the fairly high
low level moisture in place we will likely see fog develop rather
early in the night in the valleys and spread through much of the
CWA - becoming dense late - particularly in the valleys. Have hit
this in the grids (and TAFs) and will highlight it in the
forthcoming HWO. Later shifts will need to monitor cloud cover and
vsby changes tonight for a possible SPS or Dense Fog NPW. The fog
will burn off quickly Monday morning with a very warm day on tap
ahead of the slowly approaching cold front. For Monday night, the
front starts to move into the state, but likely remain too far
west through dawn for any significant rain chances. Will also
apply some patchy fog to the valleys early Tuesday under
increasing and thickening high clouds.

Used the CONSShort and ShortBlend as the starting point for the
grids through the short term portion of the forecast. Did make
some adjustments to temperatures each night to account for a small
ridge to valley difference tonight and a bit larger one tomorrow
night. As for PoPs, kept them as initialized with no impact
expected before 12z Tuesday.

.LONG TERM...(Tuesday through Sunday)
Issued at 330 PM EST SUN FEB 19 2017

The extended portion of the forecast will begin on Tuesday with an
active and progressive pattern setting up. At this time, the main
features of concern will be a wave tracking across the northern
CONUS as well as another low tracking over the lower MS Valley
undercutting the upper level ridge along the Front Range. During this
time, eastern Kentucky falls in between the bulk of the forcing of
these two features leading to a bit less QPF over the area,
especially as it seems this boundary passing through the area begins
to shear out by Wednesday morning. The super blend seems to hint at
some lingering moisture behind this feature but with the new 12z
Euro showing no indication, will leave pops out on Wednesday.

By Thursday, a vigorous low ejects from the Front Range and into the
central Plains as strong southerly flow develops just east of the MS
River. Model profile indicate some good instability developing with
the formation of the warm front on Thursday and into Thursday night.
Therefore have introduced some thunder into the forecast during this
period. By Friday morning, the warm front has lifted north of the
area putting eastern Kentucky firmly in the warm sector. In fact,
expect highs to reach into the lower 70s across the area. For this
period, some of the best baroclinicity develops that has not been
seen for a few weeks. Model profiles indicate a renewal of some good
instability with the developed cold front. Have indicated some
thunder for late Friday and into Friday night as well. While severe
convection is still a low chance for eastern Kentucky, it is worth
noting that SPC has highlighted a slight severe chance in central
Kentucky for the Friday period.

After passage of the most significant cold front not seen in a few
weeks, temps on Saturday morning and into the day on Saturday will
either be slowly rising or steady through the day. At this point,
the bulk of the CAA is slow to enter the area with much of the
moisture exited by the time the colder air filters into the area.
While now apparent at this time, a post front would chance this
chance but it seems the profile dries and clears out after passage,
which also means for some of the coldest low temps of the
extended.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
ISSUED AT 120 PM EST SUN FEB 19 2017

IFR/MVFR ceilings are breaking up from southwest to northeast this
afternoon. VFR conditions should return to all sites within a few
hours. Winds will remain light out of the west/southwest at near
or below 5 knots throughout the period. Fog development late this
evening and tonight currently looks widespread enough to impact
all area terminals at some point prior to 12Z Monday. More
sheltered valleys will likely see areas of dense fog while higher
ridgetops should only see light visibility reductions. Some tempo
groups have been added to the TAFs for this. The fog will burn
off quickly on Monday morning with VFR conditions prevailing into
the afternoon.

&&

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

$$

SHORT TERM...GREIF
LONG TERM...SHALLENBERGER
AVIATION...GREIF



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