Area Forecast Discussion
Issued by NWS Wilmington, OH

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000
FXUS61 KILN 110559
AFDILN

Area Forecast Discussion
National Weather Service Wilmington OH
1259 AM EST Mon Dec 11 2017

.SYNOPSIS...
A weak ridge of high pressure will build into the region late
tonight. As this ridge moves east on Monday, a low pressure
system will dive southeast to the Great Lakes and Ohio Valley.
The low will strengthen as it pulls northeast Monday night,
allowing a cold front to swing southeast through the region.
Colder air will filter back into the area with the threat for
snow showers Monday night into Tuesday.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Area of stratus associated with a weak surface trof has settled
down over portions of the fa. Latest satellite loop is
indicating that it has reached its southern extent and that the
backedge should begin to slowly begin to push e over the next
couple of hours. This should leave southern sections mostly
clear, while northern sections will be cloudy though midnight,
then will experience clearing.

Adjusted lows based on current readings. Lows will range from
the lower to mid 20s.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY NIGHT/...
The surface ridge will quickly move east Monday morning as a low
pressure system (clipper) dives southeast into the Great Lakes.
The majority of models now keep isentropically driven WAA
precipitation north of the CWFA on Monday, so have a dry
forecast. There will still be considerable mid/high level
clouds. WAA will allow highs to range from the lower 30s north
to the lower 40s south.

For Monday night, the low pressure will deepen as it pivots
northeast toward western New York. As this occurs, a cold front
will move southeast through the region. Lift along the front,
and moist CAA behind the front should result in a chance of snow
showers. Precipitation may briefly mix with rain over the
southeast. Lows will range from the mid 20s northwest to the
lower 30s southeast.

On Tuesday, a large scale deep mid level trough will reside over
the eastern third of the U.S. and eastern Canada. Colder air
(perhaps as cold as -18 C at 850 mb) on a northwest/north flow
will move over the relatively warmer waters of the Great Lakes.
This will keep the threat for some snow showers going, with
perhaps a "streamer" developing off of Lake Michigan and
extending southeast into our area. Highs will be early on with
slowly falling temperatures through the day as CAA continues.

By Tuesday night, the upper level trough will begin to move
east, while a surface ridge builds toward the western Great
Lakes and lower Ohio Valley. As the flow weakens and begins to
back away from Lake Michigan, the threat for snow showers will
taper off over the north through early morning. It will be cold
with lows generally falling into the 10 to 15 degree range.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Weak ridging will occur at the surface later on Wednesday. It
will remain cold with highs ranging from the mid 20s north to
the lower 30s south.

Wednesday night has a chance for additional snowfall as models have
a progressive cold front working in. European is an outlier at this
point with a closed low tracking south of the region, but either
solution puts a higher chance of snowfall in play. Cold air on the
back side of this system will actually be relatively warmer than the
arctic air in place at the surface when the system crosses.

On Friday, the surface ridge axis crosses the region late in the day
and a warm front sets up north of the area, permitting temperatures
to return to near seasonal norms for the weekend due to a good warm
push. GFS MOS has taken the highest temperatures that the ensembles
have for the weekend, which may need to be adjusted upwards if
enough warm air is being funnelled into the region as advertised. As
the upper ridge breaks down later Saturday, models diverge in the
surface features associated with the strong low that will cross the
Great Lakes region early Sunday. GFS has a good cold front crossing
the Ohio Valley while the European never turns the flow out of the
southwest. Will opt for WPC guidance and just run with the model
blend being this is day 7 of the forecast.

After Wednesday night, the better chance for precipitation will
occur on Saturday night in the form of rain. Given a wider variance
in solutions this far out, timing and strength of these systems will
keep a high amount of uncertainty in the forecast, for both
temperatures and probability of precipitation.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
MVFR cigs will be possible across KDAY, KILN, KCMH, and KLCK
overnight. VFR conditions will return for the day on Monday with
generally mid clouds expected. Winds will pick up at the end of
the TAF period as a low pressure system approaches. In addition
some snow showers will work into the longer KCVG TAF at the end
of the TAF period.

OUTLOOK...MVFR ceilings and visibilities possible Monday night
into Tuesday and then again Wednesday night into Thursday. Gusty
winds are expected Monday night into Tuesday night.

&&

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

&&

$$
SYNOPSIS...Hickman/Sites
NEAR TERM...Sites
SHORT TERM...Hickman
LONG TERM...Franks
AVIATION...Novak



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