Area Forecast Discussion
Issued by NWS Wilmington, OH

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616
FXUS61 KILN 202038
AFDILN

Area Forecast Discussion
National Weather Service Wilmington OH
338 PM EST Fri Jan 20 2017

.SYNOPSIS...
Southerly flow will continue to bring above normal temperatures
into Saturday. Low pressure is then forecast to organize over the
southern Plains Saturday night. The low will strengthen as it
moves across the southern U.S. on Sunday. The low will eventually
move to the upper Ohio Valley and mid Atlantic region by Monday.
The chance of rain will increase Sunday into Monday as the system
approaches.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Our region will remain warm sectored overnight as southerly flow
continues. High resolution models suggest that a few showers may
develop across the Whitewater and Miami Valleys as well as west
central Ohio within the weak WAA regime. Otherwise, skies will
generally be mostly cloudy. Lows will range from the upper 40s to
the lower 50s.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
Saturday will be more of a transition day before the next major
weather system has an affect on our area Sunday into the first
part of next week. Have used a blend of the 12Z GFS and 12Z ECMWF
as they seem to be handling the track of the weather system better
through this period.

On Saturday, skies will remain mostly cloudy. Southerly flow will
continue, which will allow for another warm day in the upper 50s
to the mid 60s.

For Saturday night, there is conflict among operational and high
resolution models as to whether weak WAA along with an upper level
impulse will produce much in the way of precipitation as it moves
south to north across the region. Have kept pops in the 20 to 30
percent range. Given the late arrival of the precipitation, have
showers only as instability will be waning during evening.

For the period Sunday into Sunday night, an upper level low and
its associated surface low will strengthen as they move east
across the southern U.S., and then northeast as the system rotates
toward the upper Ohio Valley/mid Atlantic region. A deformation
zone will develop on the northwest side of the surface low. This
zones will wrap back into our area, bringing an increasing threat
for showers as it pivots back to the northwest. Temperatures on
Sunday will still be warm but just a tad cooler than Saturday
given clouds and neutral advection. Lows will drop into the 40s
Sunday night as low level northerly flow develops in response to
the surface low nearby.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
By Monday morning, almost-stacked low pressure will be centered near
southwestern Virginia, with the surface low slightly north of the
mid-level circulation. The overall progression of this system has
slowed slightly in recent model runs, with precipitation expected to
be ongoing across the ILN CWA on Monday morning, and likely
continuing for 12-24 hours after -- gradually ending from SW to NE.
With greater confidence in the precipitation pattern, PoPs were
raised slightly from the previous forecast. The switch to northerly
flow will result in a drop in temperatures from Sunday to Monday.

Cooler conditions will continue into Tuesday as clouds remain in
place, with low-level winds beginning to shift to the west, and
eventually the southwest. A narrow ridge will move east through the
area on Tuesday night into Wednesday, shifting the pattern firmly to
warm advection for a relatively short period of time. It is at this
point in the forecast that confidence in specifics becomes poorer,
with increasing spread between the timing and magnitude of features
between GEFS members and between the 12Z GFS / 12Z ECMWF. However,
there is high confidence in the general pattern, with a surface low
and upper trough moving through the Great Lakes. This will allow a
cold front to move east through the Ohio Valley at some point on
Wednesday, though limited moisture will limit the chances for
precipitation. Ahead of the front, the pressure gradient will
increase, and some slightly gusty conditions may occur -- along with
temperatures well above normal. Max temps were increased for
Wednesday, slightly above the model consensus. Behind the front,
cooler conditions through the end of the week. There is a very large
amount of spread in the timing of additional precipitation chances
on Thursday and Friday, as a general pattern of broad troughing
moves over the Great Lakes and Ohio Valley through the end of the
week. Temperatures during the low end of the diurnal cycle may be
cool enough to support some snow, depending on when precipitation
occurs.

&&

.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
Warm front is now north of the tafs and ceiling are coming up.
Cigs across the srn tafs are a mixture of VFR and MVFR, with MVFR
across the nrn TAFS. Expect this trend to continue with all the
srn tafs VFR within the next few hours. It will be close whether
the nrn tafs reach VFR, but decided to follow the majority of the
guidance and leave them MVFR.

The region will remain warm sectored throughout the period. Low
level moisture will remain high and expect cigs to gradually
lower overnight back to MVFR and for many locations IFR. Also,
MVFR fog will be possible.

Expect a recovery of cigs and vsbys again tomorrow.

OUTLOOK...MVFR/IFR ceilings possible into Saturday, and then late
Sunday into Wednesday.

&&

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

&&

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



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