Area Forecast Discussion
Issued by NWS Wilmington, OH

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000
FXUS61 KILN 211744
AFDILN

Area Forecast Discussion
National Weather Service Wilmington OH
144 PM EDT Tue Mar 21 2017

.SYNOPSIS...
Temperatures will be near seasonal normals today in the wake of
a cold front which will push south away from the region. High
pressure will build southward into the Great Lakes and Ohio
Valley tonight, settling across the area on Wednesday. Much
colder temperatures can be expected with this high. The high
will move east Wednesday night into Thursday. After a cold start
Thursday morning, temperatures will moderate through the end of
the week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Still some low clouds hanging in from Dayton to north of
Columbus and also across northern Kentucky and south central
Ohio. These should continue to dissipate through the afternoon.
High and mid clouds associated with a disturbance moving out of
the Mississippi Valley will spread into the region from the west
later today. Made a few minor adjustments to highs based on
observational trends.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
For tonight into Wednesday, a large scale mid level trough will
dig southeast into southeast Canada/New England. A surface cold
front associated with this trough will push south through the
region overnight. This front is expected to be dry, and will
mark the beginning of colder and drier air. Mid and high level
clouds will decrease gradually overnight as north winds
increase and become locally gusty in the 20 mph to 30 mph
range. Low-level CAA will drop overnight lows from the lower 20s
north to near 30 along and south of the Ohio River. On
Wednesday, high pressure will build south into the Great Lakes
and Ohio Valley. We should see a good deal of sunshine, with
some mid and high level clouds increasing from the west late in
the day. Despite the sunshine, a cold start and continued CAA
will keep temperatures chilly for late March. Highs will range
from the upper 30s north to the lower 40s south.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
A fairly strong area of surface high pressure will be in place
across the Great Lakes on Wednesday evening, providing a generally
dry and cold air mass, extending southward across the upper
half of the Ohio Valley. This will likely lead to Wednesday
night being the coldest night of the forecast period, though
there is some concern with some mid-level clouds potentially
moving in from the southwest, at least across the southwestern
half of the ILN CWA. However, as long as these clouds are not
especially thick, the CWA should drop completely into the 20s --
with the potential for upper teens in outlying / rural areas in
central Ohio.

An amplifying 500mb pattern will be occurring even as relatively
tranquil conditions are expected through 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
late Thursday into Friday, a warm advection pattern is expected to
begin. This required a non-diurnal temperature trace for Thursday
night into Friday morning, with min temps early in the overnight
hours, and slowly rising temperatures by morning. As this occurs,
some isentropically-driven precipitation is expected, mainly Friday
morning. The feed of moisture transport, however, is weak -- and not
strongly connected to the Gulf of Mexico. With marginal deep-layer
moisture and most of the warm frontal forcing focused further to the
north, there are no signs of heavy precipitation as of now, and PoPs
have been kept on the low end of the scale. After this activity
shifts north and east of the region, dry conditions are expected
going into Saturday, with the ILN CWA expected to be in the warm
sector of the developing system to the west.

By Saturday afternoon and evening, attention will turn to a
developing stacked low pressure center moving through Missouri.
Confidence has increased in the overall timing and placement with
this system, and it is now expected that there will be several
rounds of showers (and potentially thunderstorms) along with this
system -- running from Saturday evening through Sunday afternoon. As
such, PoPs have been increased to the 50-70 percent range, with
thunder kept in the forecast for Saturday afternoon, and a slight
chance of thunder added for part of the area on Sunday afternoon.
This system will have a respectable feed of theta-e and a
tight/compact 850mb-700mb low, so forcing and moisture should be
sufficient for widespread precipitation. The possibility for heavier
rainfall or strong storms is less certain, owing to differences in
model specifics and a pattern that is not necessarily a classic
setup for either threat. Nonetheless, there is at least a low-end
potential to watch and refine the forecast for in the next few days.

A narrow ridge behind the stacked low will provide a reasonable
chance for dry conditions for Monday, before unsettled conditions
become more likely going into the rest of the week.

The warming trend on Friday and Saturday is likely to bring
temperatures into the 60s, possibly near 70 in the southern half of
the CWA on Saturday, depending on when precipitation moves in. Near
and behind the low on Sunday and Monday, temperatures will cool
slightly, but should still remain above normal.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
Remaining MVFR ceilings will dissipate early in the TAF period.
High and mid clouds will move across the area between 21Z and
06Z. Could be a brief period of time when ceilings drop to
around 5000 ft along with some sprinkles that will have no
impact on visibility. These clouds will move off to the east
leaving little to no clouds for the latter part of the TAF
period. A cold front will move through the region tonight which
will result in a subtle shift from northwest to north. An
increase in wind speeds will be somewhat more noticeable with
some gusts around 20kt not out of the question for a few hours
immediately after frontal passage. Winds will veer around to
northeast after 12Z.

OUTLOOK...MVFR ceilings and visibilities likely Saturday
afternoon into Sunday along with a chance of thunderstorms.

&&

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

&&

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


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