Area Forecast Discussion
Issued by NWS Wilmington, OH

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FXUS61 KILN 201500
AFDILN

Area Forecast Discussion
National Weather Service Wilmington OH
1100 AM EDT Mon Mar 20 2017

.SYNOPSIS...
Low pressure and its associated cold front will track southeast
across the southern Great Lakes and Ohio Valley today into
tonight. The front will continue to move south of the area on
Tuesday as cooler air begins to filter into the region from the
north. An embedded upper level disturbance may bring the threat
of showers to parts of the area late Tuesday into Tuesday night.
High pressure and much colder air will then arrive by
Wednesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
A decaying MCS is still tracking through SE IN and S OH as it
passes through the area. A few embedded thunderstorms still
remain but are still weakening. Have updated the forecast to
adjust the pops for this system passing through. Still expecting
redevelopment later this evening into tonight as the NAM and
other near term models have hinted at this. As well, adjusted
QPF values for this updated as this area of showers and storms
has lasted a bit longer than anticipated. A new ZFP has been
sent out with this update.

&&

.SHORT TERM / TUESDAY THROUGH 6 AM TUESDAY/...
Showers and embedded thunderstorms will be making their way
southeast this evening. Main coverage is still poised for our
east/northeast where better low level forcing will be located.
There maybe a trailing tail of likely PoPs extending into at
least the Cincinnati metro area out ahead of the front. Precipitation
will wane from northwest to southeast overnight as the cold
front slips southeast through the region. Lows will range from
the upper 30s north to the upper 40s south.

On Tuesday, the front will continue to push south from the
region. Considerable cloudiness will remain due to low clouds in
the morning, and then mid level cloudiness spilling into the
region from an approaching embedded s/wv in the northwest flow
aloft. This feature may bring a few showers to southern
locations late in the day. Highs will range from the lower 50s
north to the upper 50s south.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
A deep upper trough will be moving through eastern Canada on Tuesday
evening, with its influence pulling away from the Ohio Valley. As
this occurs, the ILN CWA will be in between two surface boundaries.
One will be well south of the area and gradually moving away, while
another will be moving south from Michigan. Attention will turn
upstream to precipitation development over the middle Mississippi
Valley -- focused on the south side of a 300mb jet, and focusing
along a sharp 850mb theta-e gradient south of the ILN CWA. There has
been a southward trend across all models with regards to the
precipitation with this system, so PoPs have been lowered slightly,
now generally in the 20-40 percent range for only the southern half
of the ILN CWA. The second surface boundary is expected to move
south through the region between 03Z-12Z, and while it is not
expected to produce additional precipitation, model soundings
suggest it will mix the boundary layer and lead to some 20-25 knot
wind gusts behind its passage.

Behind this boundary, a much colder air mass will briefly move into
place across the upper Ohio Valley and southern Great Lakes. With
continued northeasterly flow on Wednesday, as the high centers over
Michigan, cool temperatures are expected even with clouds mostly
anticipated to clear out. An amplifying 500mb pattern will be
occurring even as relatively tranquil conditions are expected
Wednesday and Thursday, with heights rising as ridging builds over
the Mississippi Valley. This will eventually lead to unsettled
conditions through the Ohio Valley on Friday and Saturday. With
upper/mid ridging moving into the region Friday, a warm advection
pattern is expected to begin, with isentropically-driven
precipitation, mainly early Friday morning. No signs of heavy
precipitation as of now, and PoPs have been kept on the low end,
with most of the warm frontal forcing remaining further to the
north. Overall, this activity will shift north of the region during
the first half of Friday, with dry conditions expected going into
Saturday. From there, attention will turn to a developing cold front
and surface low pressure center further to the west, potentially
affecting the area on Saturday. Still seeing way too wide an array
of possible solutions to try to pin down exactly how the front/low
will play out over the Ohio Valley and Great Lakes, and if any
chance for stronger storms may exist during the end of the forecast
period. It does look like the Saturday evening time frame may have
the greatest precipitation chances, based on a compromise of 18Z/00Z
GFS and 12Z/00Z ECMWF solutions. However, the timing differences are
still great enough to keep PoPs for any specific time frame limited
to 50 percent.

After cooler temperatures in the cold advection on Wednesday, a
warming trend (mainly diurnally driven) is expected going into
Thursday, strengthening further as warm advection kicks in for
Friday and Saturday -- with both days expected to see highs in the
60s.

&&

.AVIATION /15Z MONDAY THROUGH FRIDAY/...
Showers and a few embedded thunderstorms will affect the western
terminals through 16Z. Given elevated nature of the storm, only
pockets of MVFR conditions are expected.

By late this morning, convection will continue south and
eventually dissipate as it moves into retreating dry air. For
the remainder of the afternoon, focus turns toward our
northwest. An area of low pressure and a cold front will be
moving east/southeast to our region. Again, most models concur
that showers and embedded thunderstorms will get going across
northern Indiana and northwest Ohio. This precipitation will be
fed by another developing low level jet and low level convergent
flow. For now, the best chance for rain showers/embedded
thunder is poised for the northern terminals. KCVG/KLUK will be
on the edge of the likelihood of precipitation. MVFR conditions
will develop in the precipitation. As the front slips by to the
south, cooler air and an increasing subsidence inversion will
lower ceilings into the IFR category. Most precipitation should
end after 06Z across our south as the front continues to move
away. Some MVFR mist may develop behind the front as well.

OUTLOOK...MVFR/IFR ceilings and MVFR visibilities expected Tuesday
morning. MVFR ceilings and visibility`s possible Friday.

&&

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

&&

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


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