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Information is from the NWS Wilmington, OH Office


ILN Area Forecast Discussion/SKEW-T

FXUS61 KILN 121749
AFDILN

Area Forecast Discussion
National Weather Service Wilmington OH
1249 PM EST Mon Nov 12 2018

.SYNOPSIS...
Low pressure will move from the Gulf Coast into the Central
Appalachians today as a cold front moves in from the west. These
systems will bring initially rain this afternoon, mixing with
and changing to snow tonight. Some light snow accumulation will
be possible through early Tuesday. High pressure will build into
the area Tuesday into Wednesday, offering dry weather
conditions. The next chance of precipitation arrives Wednesday
night into Thursday with the arrival of a low pressure system.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Rain with embedded sleet is moving out of the southeast
counties. Cannot rule out some additional patchy light rain
across this same area, but for the most part it appears that
conditions will be dry through the remainder of the daylight
hours. Bumped highs down just a bit in the southeast. Otherwise
only very minor adjustments to temperatures based on latest
trends.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
Favorable isentropic lift associated with srn stream system
to result in an increase in pcpn coverage this evening as
northern stream trof digs southeast into the Great Lakes and
sfc cold front pushes into ILN/s Fa. As a result pcpn to
overspread the entire area early. As the boundary layer cools,
pcpn will change from rain to snow from northwest to southeast.
Thermal profile will likely remain warm enough in the far
southeast to keep most of the pcpn rain until very late tonight
when pcpn is diminishing.

Forecast soundings show a period later this evening into the
overnight hours where the moist lower layer is warmer than -10
deg C...suggesting all liquid supercooled water. To complicate
the matter - there is a layer aloft which may enable a seeder
feeder scenario resulting in snow. Eventually, the separation
between these layers increases to more than 1500M, pointing to
the potential for drizzle/freezing drizzle. As better lift exits
have a period of this freezing drizzle/drizzle but do not expect
much in the way of ice accumulation.

Regarding snow accumulation - have up to an inch in the far
northwest to very little in the far southeast. Pavement temperatures
look to start out warm but some slick spots will remain possible
for the Tuesday morning commute. Lows tonight to range from the
upper 20s northwest to the lower 30s southeast.

Region of 5H confluent flow to work into the Ohio Valley with
surface high pressure nosing in Tuesday. Any lingering pcpn
will come to an end early. High temperatures to range from the
lower 30s northwest to the upper 30s southeast.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Complex low pressure arriving from the southwest will be the
main weather maker for the long term.

Surface high pressure developing under a westerly flow aloft will
provide dry weather Tuesday night and Wednesday. A closed upper low
will track across Arkansas Wednesday night, before reaching Western
Kentucky by Thursday evening. The strengthening upper low will
trigger a surface trough that will lift through Kentucky to Ohio by
Thursday night. Though deeper moisture and more potent forcing will
be near a stronger surface low along the East Coast, there will be
enough lift generated in a zone of divergence aloft ahead of the
upper low to develop widespread precip over the ILN FA. Current
model temperature profiles indicate snow to start on Wednesday night
into Thursday morning, with precip changing to rain by Thursday
afternoon as the boundary layer warms above freezing. Light snow
accumulations will be possible before the transition to rain. As the
upper low tracks across Kentucky Thursday night, and the majority of
precip moves east, precip may change back to snow as colder air
filters in behind the system. While the upper flow flattens to
zonal, surface high pressure is forecast to bring dry weather on
Friday. For Saturday, a disturbance traveling across the Great Lakes
may bring a few rain and snow showers. High pressure and dry
conditions are expected Sunday following the disturbance.

Temperatures staying below normal through the period will vary
slightly with respect to weather systems. Wednesday may be the
coldest day of the period, when highs are forecast to reach the 30s.
Highs for the remainder of the long term will be in the mid 30s to
low 40s.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
Expect rain to develop into the TAF sites towards 00Z with the
exception of KDAY. VFR will continue to prevail even after
precipitation begins. But eventually lower levels moisten which
will bring a period of MVFR ceilings. In addition, precipitation
may mix with or even change over to some light snow which will
also reduce visibilities. Expect precipitation to move past the
terminals by 09Z although cannot completely rule out a few
flurries or some drizzle through 12Z. While ceilings may rise
back to VFR once precipitation stops, this will be temporary as
ceilings below 2000 ft are forecast to move back into the area.
MVFR will then prevail through the rest of the TAF period
although clouds will lift above 2000 ft towards 18Z. Winds will
back around to around the time precipitation begins. Further
backing to northwest will occur with an increase to 10 to 15 kt
on Tuesday.

OUTLOOK...MVFR ceilings will linger into Tuesday afternoon.
MVFR ceilings and visibilities possible late Wednesday night
into Thursday night.

&&

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

&&

$$
SYNOPSIS...AR
NEAR TERM...
SHORT TERM...AR
LONG TERM...Coniglio
AVIATION...



Skew-T

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