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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KILN 250602
AFDILN

AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
102 AM EST Sat Jan 25 2020

.SYNOPSIS...
A low pressure system will bring precipitation to the area
through the weekend. Periods of rain are expected this morning,
before cooler air starts to work into the region later today
which will allow some snow to mix in. A few snow showers will
linger Sunday into Sunday night before high pressure moves into
the region.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Overall thinking regarding precipitation has not changed too
much this evening, with additional bands of showers wrapping
northeast into the ILN CWA, and a larger area of steady light
rain developing a bit further upstream. In addition, the
temperature forecast appears largely on track. This adds
confidence to the expected mix with light snow later in the
overnight (mainly in the northwestern sections of the CWA) but
also the fact that accumulations appear unlikely.

The area of partial clearing that has been gradually moving
northeast through the region has provided a post-sunset window
for some fog to develop in the eastern ILN counties, and this is
showing up very nicely on GOES Nighttime Microphysics imagery.
In addition to the clearing, winds have briefly become light/calm
within this area as well. However, these factors are not
expected to last more than another couple hours, as
stratocumulus clouds and a steadier gradient will be moving into
the area soon.

Previous discussion >
Rain is moving through the CWA this evening as a shortwave
trough and weak surface cyclone move across the region. As of
3:25 EST a heavier band of rain was being observed on radar
across central Ohio into northern Kentucky. This band of rain
will move east as the strongest gradient of differential
cyclonic vorticity advection progresses eastward. A brief period
of reduced rainfall coverage is forecast as PWATs decrease and
the trough moves into the CWA prior to another round of
precipitation moving back into the Ohio Valley from the
southwest tonight.

As the second round of precipitation moves in, temperature
profiles are expected to be warm enough to support rain. Snow
may start to mix with rain before daybreak as cooler air bleeds
in from the west across central Ohio. Little to no snow
accumulation is expected due to surface temperatures being above
freezing. Lows in the middle 30s are forecast areawide.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SUNDAY/...
Chances for precipitation remain across the CWA all day on
Saturday as a shortwave trough will be centered over the Ohio
Valley contributing to unsettled weather. Increased chances for
rain and snow will move in during the afternoon as an area of
precipitation wraps around a surface low from the northwest.
Surface temperatures are forecast to be marginal for snowfall
and snow accumulation as highs will be in the middle to upper
30s. Little to no snow accumulation is expected, although some
accumulations less than an inch are possible Saturday
afternoon/evening across central Ohio on grassy or elevated
surfaces.

Snow showers may linger across the area Saturday night as the
shortwave trough continues eastward across the region. Lows
Saturday night are expected to be near freezing.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Mid level low to pivot northeast into New England Sunday but hang
back shortwave to drop southeast through the Ohio Valley. This will
keep clouds and a low pop chance of mixed rain and snow showers in
the forecast Sunday into early Monday, mainly in the east and south.
Temperatures look to be close to normal with Sundays highs fcst
between 35 and 40.

Northwest flow with surface high pressure building into the area
offering dry weather early next week. Although dry weather is
expected, clouds look to linger Monday and Tuesday with highs from
the mid/upper 30s north to the lower 40s south.

Mid level flow backs westerly with weak shortwave passing through
the Great Lakes late Wednesday into Thursday. Model spread exists
regarding timing and strength of this s/w. QPF looks rather light.
Will limit pops to slight chance category. Expect highs Wednesday
and Thursday from the upper 30s northwest to the lower/mid 40s
southeast.

Models solutions diverge and therefore do not offer high confidence
heading into the end of the week and into next weekend.

Northern plains energy drops southeast and srn low rotates northeast
and eventually a mid level low develops over the Ohio Valley this
weekend. The details in timing and strength have yet to be resolved.
Therefore, will limit pops to low chance Friday with better threats
for pcpn likely holding off until later in the weekend.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
Upper low continues to spiral out over IL/IN. Ahead of the low,
pockets of pva will work across the tafs overnight. This will
create area of rain which will lift north across the region.
Ceilings will be mainly MVFR though 12z, but there are pockets
of VFR clouds which could affect the ern tafs, and IFR clouds
are forecast to move into DAY around 10Z.

After a lull in precipitation during the morning, another area
is expected to move back into the TAF sites during the
afternoon. This will bring ceilings down to IFR. The pcpn will
start as rain and change to a rain snow mix in the northern tafs,
before changing to all snow after 00Z. Winds may also gust into
the 20-25 knot range tomorrow afternoon.


OUTLOOK...MVFR/IFR ceilings and MVFR visibilities will continue
into Sunday. MVFR ceilings may persist at times through
Wednesday.

&&

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

&&

$$
SYNOPSIS...Campbell/Sites
NEAR TERM...Campbell/Hatzos
SHORT TERM...Campbell
LONG TERM...AR
AVIATION...Sites