Area Forecast Discussion
Issued by NWS Wilmington, OH

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FXUS61 KILN 221019

Area Forecast Discussion
National Weather Service Wilmington OH
619 AM EDT Thu Mar 22 2018

High pressure and a dry, but seasonably cool airmass will build
across the region today through Friday. A low pressure system
will move into the area this weekend, bringing a chance for rain
and snow late Friday night into Saturday night. High pressure
and dry conditions will return for early next week.


Clearing is continuing to work slowly east across the area
early this morning with about the western two thirds of our fa
now clear. Given the fresh snowfall, temperatures have not
fallen off as much as might be expected under clear skies and
relatively light winds. That being said, will still allow for
temperatures to fall into the upper teens to lower 20s across at
least our west since we still have several hours before

Surface high pressure will build in from the west through this
afternoon. With some lingering lower level moisture and still
some weak low level CAA, think we could see a few fair weather
cumulus develop, especially across our eastern areas. Highs
today will generally be in the low to mid 40s.


The surface high will shift slowly east across our area tonight
through Friday. This will lead to dry and continued cool
conditions. Lows tonight will drop into the low to mid 20s with
highs on Friday ranging from the low 40s in the north to the mid
40s in the south.


Friday night a potent mid level disturbance will push east out of
the Mountain West with surface cyclogenesis occurring over western
Kansas. Through Friday night the surface low will pull east with
strong isentropic upglide commencing. The latest GFS, NAM, and ECMWF
all show a LLJ approaching 40 kts forcing warm moist ascent across
Kentucky, Indiana, and Ohio. Looking at the 300 kelvin surface
reveals very strong ascent with condensation pressure deficits at
zero starting Saturday morning and continuing into the late
afternoon. Across our northeastern zones there will likely be a cut
off in the precipitation as low level moisture fields indicate dry
air remaining entrenched towards Columbus and Kenton. The main area
of concern will across our central and southern zones (towards
Wilmington, Cincinnati, Connersville, and Batesville). Along this
northwest to southeast axis the mid level wave will pass overhead
allowing thermal profiles to mostly remain below freezing through
the column. Strong overrunning and omega (from the PVA and WAA) near
the DGZ will produce a band of moderate snow. On the latest GFS,
ECMWF, GEFS, and EPS there are consistent signals for an
accumulating snow event, and perhaps even significant. Many factors
will come into play here though that will affect snow amounts. These
will include surface temperatures, low level thermal profiles, track
of the surface low, and road temperatures (to name a few).

Current forecast soundings on the GFS show a slightly colder thermal
profile than the NAM with the ECMWF being similar. As of now the
area of highest confidence for remaining all snow will be just north
of the Ohio river. Areas south of the Ohio river will likely mix
with pellets and go to rain possibly. Still though, this type of
strong vertical motion near the DGZ (with the support of an FGEN
band out ahead of the low level low pressure) snowfall totals can
quickly add up. It should also be noted that with the strong upper
level wave moving across at this time mid level lapse rates quickly
steepen with elevated instability forming.

Given the latest exceedance probabilities on the GEFS and EPS have
gone ahead and issued a Winter Storm Watch starting late Friday
night through Saturday night across portions of east central and
southeast Indiana, northern Kentucky and western Ohio.

Late Saturday night into Sunday morning the mid level wave will
begin to wash out and head southeast. For the most part Sunday into
Monday will remain dry as mid level ridging moves overhead. Any snow
that did fall on Tuesday will quickly melt as high temperatures
warm close to 50 degrees on Monday.

By Tuesday an upper level low will remain quasi-stationary over the
southwestern United States. This will allow for much warmer weather
with highs approaching 60 degrees by Wednesday. Also, the pattern
looks to be wet with multiple rounds of upper level disturbances
crossing the region.


Some patchy MVFR fog may affect KLUK for the first hour or so of
the TAF period. Meanwhile, the back edge of the mid level
clouds is continuing to make a slow eastward push and should
clear KCMH/KLCK in the next couple of hours. High pressure and a
dry airmass will move into the region through tonight. This will
lead to VFR conditions through the remainder of the TAF period.

OUTLOOK...MVFR/IFR ceilings and visibilities are possible
Friday night through Saturday night. MVFR ceilings are possible
again on Monday.


OH...Winter Storm Watch from late Friday night through late
     Saturday night for OHZ042-060-061-070>072-077>081.
KY...Winter Storm Watch from late Friday night through late
     Saturday night for KYZ090>093-095>099.
IN...Winter Storm Watch from late Friday night through late
     Saturday night for INZ050-058-059-066-073>075-080.


LONG TERM...Haines
AVIATION...JGL is the U.S. government's official web portal to all federal, state and local government web resources and services.