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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KILN 221756
AFDILN

Area Forecast Discussion
National Weather Service Wilmington OH
156 PM EDT Sun Apr 22 2018

.SYNOPSIS...
High pressure will push off to the east through this afternoon.
A low pressure system will lift out of the lower Mississippi
Valley and into the Ohio Valley Monday into Tuesday. This will
bring a chance of showers to the region through the first part
of the work week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Dense high clouds continue to affect the region this morning.
Upped the cloud cover to account for this. Models are still
indicating that this high cloudiness will try to thin by late
afternoon.

Still think that highs can make the lower 60s across the
northwest and the mid to upper 60s elsewhere.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/...
A stacked low over the lower Mississippi Valley tonight will
lift slowly northeast into the western Tennessee Valley through
the day on Monday. Moisture associated with this will push
slowly northeast toward our area tonight with deeper moisture
spreading in from the south through the day on Monday. This
will lead to thickening clouds with showers spreading into our
southern areas Monday morning and then across the remainder of
our area through Monday afternoon. Lows tonight will range from
the mid 40s in the north to the lower 50s in the south. The
warmest temperatures on Monday will be across our north,
where the thicker clouds/pcpn will arrive the latest. Will
range highs on Monday from near 60 in our southwest to mid 60s
across our far north.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
The first couple of periods in the extended will be characterized by
cool and wet conditions as an upper level low moves overhead. Monday
night the upper level low will be centered over the Tennessee/
Kentucky border with rain ongoing across the region. Through the day
Tuesday the upper level low will be overhead allowing showers to
continue. The GFS and NAM does have some weak instability (actually
GFS forecast soundings are little bit more impressive than the NAM),
but for the most part it is transient and confined towards the Ohio
River. For now have just scaled back the chance of thunder given the
forecast soundings and position of the vertically stacked low.

Tuesday night into Wednesday a potent upper level disturbance will
be pushing southeast out of Ontario with the upper level low that
was over the Ohio Valley ejecting northeast. The GFS, NAM, and CMC
all have the low (and precipitation) moving out of the area
Wednesday morning while the ECMWF holds onto precipitation through
Wednesday. Either way the GFS has precipitation filling back in as
the upper level disturbance over Ontario moves over Michigan. Due to
this have kept the chance of precipitation through Wednesday
afternoon for most of the area.

Thursday has now trended drier as the upper level disturbance that
was over Michigan exits the area. This will put Ohio on the back
side of the low and in brief subsidence/ drier air (GFS PWATs around
0.30"). Mostly clear skies and highs in the lower 60s will make for
a pleasant Thursday.

Past the Thursday period, models quickly diverge as another upper
level low dives south out of Canada. The general idea is that the
upper level low will dive southeast and push a cold front through
the area Friday into Saturday. Significant differences between
models exist here though. The ECMWF is weakest with the upper level
disturbance and slower with the front (pushing it through Friday
evening). The GFS and CMC are much stronger and wrap up the upper
level low and occlude it over the area. This allows for significant
differences in models to propogate through the remainder of the
extended. For now have kept Saturday afternoon through Sunday mostly
dry. If the GFS and CMC are to be believed precipitation might hold
on through Saturday.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
-- Changed Discussion --
High and some mid continue to dominant the tafs this afternoon.
This trend will continue through most of tonight, when the
affects of the stacked low over the Mississippi Valley finally
begin to affect the region.

Overnight, the low pressure system will cross the Mississippi
River. The models move a band of showers northeast into the
CVG/LUK tafs shortly after 12Z as convergence associated with a
low level jet increases. MVFR cigs and vsbys will accompany the
rain.

The rain band lifts northeast through the region, reaching
ILN/DAY by 15Z, but CMH/LCK should remain dry through 18Z.

Winds increases after sunrise Monday as the affects of 30-40kt
low level jet are mixed down. Gusts into the 20s will be
possible.


OUTLOOK...MVFR ceilings will be possible Monday night into
Wednesday.
-- End Changed Discussion --

&&

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

&&

$$
SYNOPSIS...JGL
NEAR TERM...Sites
SHORT TERM...JGL
LONG TERM...Haines
AVIATION...Sites