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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KILN 181742
AFDILN

Area Forecast Discussion
National Weather Service Wilmington OH
142 PM EDT Wed Oct 18 2017

.SYNOPSIS...
High pressure will keep dry air and mainly clear skies over the
region through the week. Temperatures will gradually warm as
the high moves slowly east.

&&

.NEAR TERM /THROUGH TONIGHT/...
Quiet weather as sprawling 1028mb surface high pressure just
southeast of the forecast area continues to drift toward the
Atlantic Coast. 18.12Z KILN sounding was anomalously dry with
tropospheric PWAT at about a third of an inch...which is about
45% of normal. Very little, if any, clouds are expected today,
with abundant sunshine allowing for some locations to push
toward a 30-35F diurnal rise, which is typical for a very dry
mid-October day. Some southerly breeze on the backside of the
high will bring some modest winds to the open areas of eastern
IN/western OH, with lightest winds in the Scioto Valley and
northeast Kentucky closer to the departing high.

Tonight, added some valley fog in the far east/southeast parts
of the forecast area /Scioto Valley and associated tribs/ and
this may need to be expanded in further updates. Approaching
very weak/dry cold front may bring enough pressure gradient to
keep things stirred up but fcst soundings still showing a very
stable boundary layer after sunset. Expect min temps tonight to
be a little warmer thanks to said gradient, though some upper
30s will still be possible in the far east/southeast portions of
the area, and much warmer west where winds and perhaps a few
clouds will keep temps in the 40s.

&&

.SHORT TERM /THURSDAY/...
The surface ridge axis will shift a little east into Thursday
as a dry cold front pushes east/southeast into the Great Lakes.
Again, only a few cirrus is expected, with perhaps a FEW-SCT
cumulus clouds developing along ahead of the frontal boundary in
our far northwest late in the day Thursday.

Southwest to west winds ahead of the front along with sunshine
will boost highs into the lower 70s.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Under an amplifying mid-level ridge over the eastern half of the
CONUS, a sprawling area of very dry surface high pressure will be
moving slowly east on Thursday night, still maintaining control of
the weather situation over the Ohio Valley for another couple days.
Aside from a very weak cold front stalling out (and then returning
north) in the northern Ohio valley on Thursday night into Friday,
there will be little change in the overall pattern through Friday
night. Low-level warm advection, with gradually increasing 925mb
temps, will allow for Friday to be slightly warmer than Thursday.

As confidence has increased in a more amplified pattern on Saturday,
with deep-layer flow becoming more southerly over the Ohio Valley,
there is greater confidence as well in temperatures being warm for
the first day of the weekend. If the forecast for max temps in the
middle to upper 70s verifies, it will be about ten degrees above
normal. This looks to be the warmest day of the entire forecast
period.

On Sunday, a sharp but narrow trough will begin its progression
eastward across the Mississippi Valley, eventually reaching the Ohio
Valley at some point between then and Monday. Model timing agreement
remains somewhat sub-par with this system, and the differences are
primarily focused around the interaction between the southern end of
the trough (which may form a cut-off low) and the strong jet stream
pushing east across the northern tier of states. Unfortunately, this
time frame remains in an unstable part of the forecast cycle, with
GFS/ECMWF run-to-run consistency performing poorly.

With the above in mind, PoPs will be kept in the chance range until
this really gets locked in a little better. As of now, the greatest
precipitation chances appear to be during the Sunday night forecast
period, possibly continuing into Monday. Once the trough and its
associated cold front pass through the area, there appears to be
potential for a larger upper trough to move into the Great Lakes
late on Monday and into Tuesday, which should provide two things --
much cooler temperatures and continued chances for rain.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
-- Changed Discussion --
VFR conditions expected through the period, although some valley
fog is likely to plague KLUK as it has in recent mornings. Clear
skies this afternoon into tonight as flow begins to drop off
with boundary layer cooling. Don`t expect winds to go calm
however as increasing gradient will offset radiational component
to a degree, so expect light SSWLY flow to maintain in the 3-6kt
range at most sites through the night. Given how dry the
boundary layer is, this should keep most fog at bay. However
sheltered valleys may drop off enough to form a shallow fog
layer after 07Z, so included this at KLUK.

Expect winds to be a little stronger out of the southwest on
Thursday but expect very few clouds aside from a little cirrus.

OUTLOOK...No significant weather expected.
-- End Changed Discussion --

&&

.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.

&&

$$
SYNOPSIS...Hickman
NEAR TERM...Binau
SHORT TERM...Hickman
LONG TERM...Hatzos
AVIATION...Binau