Area Forecast Discussion
Issued by NWS Wilmington, OH

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882
FXUS61 KILN 190219
AFDILN

Area Forecast Discussion
National Weather Service Wilmington OH
919 PM EST Wed Jan 18 2017

.SYNOPSIS...
High pressure will move east across the Ohio Valley tonight. As
the high moves toward the Atlantic seaboard on Thursday, low
pressure will travel from the lower Mississippi valley to the
lower Ohio Valley. The low will then move north through the region
Thursday night into Friday. Warmer temperatures will follow for
the weekend.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Have slowed any improving cloud cover tonight in favor of overcast
skies. Even if the lower levels clear out from southwest to
northeast, they will be quickly covered over by a significant
cirrus deck. Overnight temperatures were raised in the southeast
where slower than expected falls were seen this evening. Previous
discussion still valid ->

Surface high pressure will traverse east across the Ohio Valley
overnight while a mid level ridge lags behind aloft. Satellite and
surface observations still show considerable low level clouds from
our region westward across most of Indiana. The scouring and/or
moving out of low clouds this time of year is always tough to
forecast, especially when the moisture becomes trapped underneath
an inversion. Will allow a slow process for this to occur from
west to east overnight. Even so, high level clouds begin to push
northeast aloft, so any period of partly cloudy late tonight into
the first part of Thursday will likely be short lived. Lows will
range from the lower to mid 30s.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
Surface and mid level ridge will move off to the east on Thursday.
This will allow the next weather system to eject northeast into
the southern Plains/lower Mississippi River Valley. Clouds will be
on the increase through the day. Mid level circulation over the
southern Plains will open up as its mid level trof axis pivots
northeast through the Ohio Valley and the Great Lakes Thursday
night into Friday. At the lower levels, warm, moist ascent
associated with a broad/modest low level jet, along with
convergent directional flow, will bring widespread showers to the
region late Thursday into Thursday night. Precipitation will taper
off from the southwest to the northeast during Friday morning as
the deeper moisture and low level forcing shift to the north.

For Friday night, broad warm air advection will remain across the
region. Clouds will linger. There is an isolated threat for a
shower, but most locations will remain dry.

Have used a non-diurnal trend for temperatures Thursday night
into Friday night. Readings continue to be warm considering the
time of the year.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
A warm and moist southwesterly flow pattern will be in place across
the Ohio Valley on Saturday, which is expected to be the warmest day
of the forecast period. Low pressure moving into the upper midwest
will be too far from the region to provide strong forcing, but
continued moist flow will support the development of some
precipitation by evening and going into early Sunday morning. With
as warm as it may get, some very limited instability could develop,
but thunder will be kept out of the forecast until (and if)
confidence increases in this scenario. However, confidence continues
to increase in warm conditions for Saturday, and this forecast will
increase values by another degree or so. Record highs are in the 70s
for all three climate sites, and these records appear safe.

A fast-moving upper level low pressure system is expected to move
across the southern tier of states on Sunday, with widespread
precipitation (and some heavy rainfall) expected to develop in the
Tennessee Valley region. On the northern periphery of this low,
precipitation is eventually expected to spread northward into the
Ohio Valley on Sunday, with another wave arriving on Monday as
precipitable water values continue remain high for January (near or
just under an inch). Overall, model differences are not large,
though the ECMWF is slightly faster with the progression of this
stacked low pressure system. Once the low has moved from south of
the region to southeast of the region, a switch to northerly flow
will allow for a gradual drop in temperatures through Monday and
Tuesday. Timing out the end of precipitation is uncertain, however,
as there is significant model spread (within GEFS members) regarding
how the mid-level low / trough progress northeastward on Monday
night into Tuesday.

Beyond the passage of the low and the arrival of a narrow ridge,
model solutions diverge significantly with regards to the next
system moving through the quick westerly flow. Thus, confidence in
specific temperature and precipitation details beyond Tuesday is
fairly low. However, a general warmer-than-normal trend is almost
certain to continue going into the rest of the week.

&&

.AVIATION /02Z THURSDAY THROUGH MONDAY/...
Overcast cloud deck on the cusp of IFR/MVFR range will lift
slightly to be above 1kft over the next 2-3 hours. Patchy drizzle
will impact central Ohio through about 2z and could reduce vsbys
to 5sm briefly.

Warm advection kicks in overnight and spreads from southwest to
northeast, reaching central Ohio TAFs after daybreak. This will
also be the noted feature that will push a definitive back edge to
the low stratus out of the region.

Cloud cover will still be topped by bkn if not ovc ci in advance
of the next system coming in from the southwest. KCVG will be
raining by the end of the valid 30 hour TAF period, while KLUK
may see a small possibility of rain at the end of their 24 hour
TAF. Ceilings will drop the MVFR range in rain as a strong surface
low in the midwest helps push a warm front to the northeast
through the TAF sites. Rain will overspread the region in the 0-6z
time frame tomorrow night, possibly later than this at KCMH/KLCK.

OUTLOOK...MVFR/IFR ceilings possible through Friday, and then
late Sunday into Monday.

&&

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

&&

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



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