Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 162043

National Weather Service Jackson KY
443 PM EDT Sun Jul 16 2017

.SHORT TERM...(This evening through Monday night)
Issued at 321 PM EDT SUN JUL 16 2017

Early afternoon surface analysis shows skinny high pressure
stretching across the state, sandwiched between a weak front
slowly sinking south across northern Ohio, Indiana and Illinois
and a stationary front draped across the Tennessee Valley.

The weak area of high pressure will remain in place overnight. As
a result, the fair weather cumulus dotting the skies this
afternoon will quickly diminish leaving mostly clear skies and
calm winds...a perfect recipe for fog. While fog will no doubt
form along our rivers and lakes, do not expect it to be as
pervasive as last night after the good day of drying that took
place today. Overnight lows will fall to between 60 and 65.

The front to our north will slowly work south and reach near the
Ohio River by tomorrow afternoon. Despite another warm day with
highs reaching the mid to upper 80s, model soundings indicate a
strong cap remains in place for most of the area and will continue
to keep the majority of the forecast area dry. The exception is
north of I-64 where an isolated shower or storm cannot be ruled
out with a weaker cap noted in soundings closer to the front. Any
shower or storm should diminish by Monday evening with a dry night
expected, along with our normal river valley fog.

.LONG TERM...(Tuesday through Sunday)
Issued at 425 PM EDT SUN JUL 16 2017

The period is expected to begin with an upper level ridge centered
over the eastern OK/western AR vicinity and another upper level
ridge centered over the Four Corners region. Meanwhile, an upper
level trough is expected to extend from Quebec south along the
East Coast. At the surface, high pressure is expected to be
centered over the Appalachians.

The upper level ridge is expected to build east into the Lower OH
Valley on Tuesday and reorganize in the Plains as a shortwave
passed north of the area through the Great Lakes. The axis of the
upper level trough should move east on Tuesday with mid level
height rises ensuing. With the ridge center to the west,
additional weak disturbances may pass through the region as they
move around the ridge on Wednesday. Heights should rise further on
Thursday though the region should remain in west to northwest flow
around the ridge with any MCS activity likely passing north and
east of the area. The GFS runs have convection further to the
south compared to the ECMWF as the ECMWF has higher heights
across the region.

From Thursday night into next weekend, a shortwave trough should
move from the northern Plains/Canadian Plains across the Great
Lakes and into the Northeast US. Model disagreement in timing and
placement of features then increases at the end of the period.
The general consensus is for the ridge to become centered over
the Southeast and extend across much of the Southern Conus while
becoming flatter as the shortwave moves into the Northeast and
eastern Canada. This should allow a cold front to drop south of
the Great Lakes by the start of the weekend, but it should stall
out from east to west north of the OH River on Saturday. This
boundary could return north by the end of the period with a
potential shortwave moving across the Northern Plains and Great
Lakes leading to surface low pressure developing over the Great
Lakes and the boundary lifting north as a warm front.

Overall, the period should be mainly dry with the region dominated
by high pressure although the center may be far enough west for
stray convection near the VA border on Tue and perhaps Wed. This
period should also consist of temperatures rising to above normal
by Wednesday with Thursday likely being the warmest day with
heights generally highest. As Friday and the weekend approach,
the potential for MCS activity to affect at least the north
increases. If convection does not affect the area on Friday, then
it could be equally as warm as Thursday if not a degree warmer.
For now have ridges in the upper 80s to around 90 for the Wed to
Friday period with the valleys topping out in the lower 90s. As
the ridge flattens a bit by the start of the weekend chances
should be areawide on Saturday. Uncertainty in timing and
placement of features increase by next Sunday, however, at least a
diurnal uptick in chances for convection should exist in the warm


.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)

Flight conditions will be VFR for most of the period. The only
exception will be in valley fog that will likely develop again
tonight. The fog is not expected to be as pervasive as it was in
our valleys this morning, but it still may affect SYM and SME to
some extent due to their proximity to larger lakes. Will leave it
out of the other TAF sites. No other forecast concerns with just
some fair weather cu and very light winds.




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