Area Forecast Discussion
Issued by NWS Wilmington, OH

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992
FXUS61 KILN 190722
AFDILN

Area Forecast Discussion
National Weather Service Wilmington OH
322 AM EDT Thu Oct 19 2017

.SYNOPSIS...
High pressure will remain from the mid Atlantic to the
Tennessee Valley today while a weak, dry cold front pushes
southeast into the Great Lakes. The front will wash out tonight,
while high pressure strengthens over the Ohio Valley into
Friday. High pressure will then extend across the region into
Saturday. The next weather system to affect the area will
arrive late Sunday into Monday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
High pressure will remain from the mid Atlantic to the
Tennessee Valley today while a weak, dry cold front pushes
southeast into the Great Lakes. FEW-SCT cirrus is expected with
southwest winds and sunshine boosting temperatures into the
lower 70s.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
The weak, dry front will wash out over northern Ohio this
evening, allowing high pressure to begin reestablishing itself
over the Ohio Valley. Under mostly clear skies and decreasing
wind, lows tonight will range from the lower 40s in the
east/southeast to the upper 40s northwest. Conditions look
favorable for river fog formation across our southern/eastern
river valleys, so have included this in the forecast.

Mid level ridging will build northward into the Ohio Valley on
Friday while high pressure also remains at the surface. Under
mostly sunny skies, temperatures will warm slightly from
Thursdays readings, ranging from the lower to mid 70s.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Under an amplified mid-level ridge over the eastern half of the
CONUS, a sprawling area of very dry surface high pressure will be
centered somewhere in the mid-Atlantic region, slowly moving east as
the weekend begins. This scenario will still maintain control of the
weather situation over the Ohio Valley for at least another day or
so, as deep-layer southerly flow sets up over the region on both
Saturday and Sunday. There is high confidence in a dry day Saturday,
which means that confidence remains high in this being a notably
warm day -- with max temps in the middle to upper 70s, it will be
about 10 degrees above normal. As the progression of the next
weather system appears to be slower than previously expected -- to
be discussed further below -- the change is that Sunday may well set
up to be dry for the majority of the day, which forces an increase
in the max temp forecast for the second day of the weekend as well.
Though there could be more of a gradient in temperatures, as clouds
increase from the W and NW, values in the upper 70s will again be
possible in the southeastern ILN CWA.

On Sunday, a sharp mid-level trough will begin its progression
eastward across the Mississippi Valley, eventually reaching the Ohio
Valley at some point between then and Monday. With the southerly
flow helping to provide a northward flow of moisture from the gulf,
there is high confidence that this trough (and its associated cold
front) will result in precipitation developing across the region.
However, with regards to timing and specifics, model agreement
remains sub-par with this system, and the differences are primarily
focused around the interaction between the southern end of the
trough (which is likely to 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. Depending on how the cut-off low develops, there is the
potential for the surface front to stall or develop waves somewhere
in the vicinity of the Ohio Valley, which could significantly affect
the timing of the most likely chances for precipitation.

With the above in mind, PoPs will yet again be limited to the chance
range until this really gets locked in a little better. Seeing an
overall trend toward a slightly slower progression, as of now, the
greatest precipitation chances appear to be during the Sunday night
into Monday time frame. Secondary wave development could keep
precipitation possible through Monday night. Once this moves out of
the area, there appears to be potential for a larger upper trough to
move into the Great Lakes on Tuesday into Wednesday, which should
provide two things -- much cooler temperatures and continued chances
for rain.

Not seeing enough potential for instability to include chances for
thunder at this point in the forecast cycle.

After warm temperatures on Sunday, a relatively sharp cooling trend
will commence, as the front moves into the area and precipitation
becomes more likely. Though Tuesday may be close to normal, under
the deeper trough going into the middle of the week, temperatures
will likely fall to values below normal.

&&

.AVIATION /07Z THURSDAY THROUGH MONDAY/...
Some MVFR/IFR visibilities may be possible at KLUK until 13Z.

Otherwise, for today, surface high pressure will extend from off
the mid Atlantic coast southwest to the Tennessee Valley.
Meanwhile, a weak, dry cold front will push east/southeast into
the western Great Lakes. Only FEW to perhaps SCT cirrus is
expected with southwest winds around 10 knots, local gusts
around 16 knots.

For tonight, the western end of the weak, dry front will sag
into northern Ohio will it will wash out by Friday morning.
Winds will decrease overnight with some areas seeing calm
conditions. Skies will be mostly clear.

OUTLOOK...MVFR ceilings and visibilities possible Sunday night
into Monday.

&&

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

&&

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



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