Information is from the NWS Wilmington, OH Office


ILN Area Forecast Discussion/SKEW-T

FXUS61 KILN 152344
AFDILN

Area Forecast Discussion
National Weather Service Wilmington OH
644 PM EST Fri Dec 15 2017

.SYNOPSIS...
Low pressure will move east through the Great Lakes tonight, as
high pressure builds into the southeastern states. This will
allow for southwesterly winds and gradually warming temperatures
through the weekend, with chances for rain on Sunday.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
A wide curved band of stratocumulus clouds is moving through
the ILN CWA, roughly along the axis of a weak surface trough.
Steep lapse rates underneath the cloud deck (about 2500-3000
feet) have promoted some slightly gusty winds (20-25 knots at
most) and a few patches of light snow moving through the area.
This is mostly flurries, with visibilities reported by surface
observation sites generally at 4SM or above. The overall lack of
moisture would point away from any chance of accumulating snow,
outside of maybe a tenth or two (at most) in central Ohio over
the next couple hours.

After the main band of low clouds moves through, a gradual
decrease in low level moisture is expected tonight, though some
700mb moisture is expected to advect in on the pivoting
NW-to-WNW flow. Persistent SSW surface flow will keep
temperatures from falling too far tonight -- likely only a few
degrees cooler than current values as of 3PM. Min temps are thus
expected to be in the middle to upper 20s.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
By Saturday morning, mid-level moisture will already be
beginning to move northeast of the ILN forecast area, as surface
high pressure becomes more established over the southeastern
states. As this occurs, mid-level ridging will be moving
gradually toward the Ohio Valley, though the ridge will be
dampening as it translates eastward. Another round of moderate
southwesterly flow will occur, though flow aloft turns quickly
to the W and WNW, with a strong/dry inversion near 900mb
limiting gust potential into the 15-25 MPH range (mainly
Saturday afternoon). Nonetheless, this warm advection will bring
a notable upward bump in temperatures on Saturday. There will be
a strong temperature gradient across the CWA thanks in part to
the departing clouds in the north, but max temps should
generally range from the lower 40s (north) to near 50 (south).
There will be some return of cirrus (and maybe some mid-level
clouds) late Saturday night into early Sunday morning, but dry
conditions are expected through the end of the short term
forecast period.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Embedded mid level shortwave to eject northeast across the area and
deamplify as it encounters the mean ridge. On Sunday Moisture
increases from the sw with this system but with it weakening only
expect 1 to 2 tenths of an inch of pcpn. In WAA pattern pcpn will be
mainly rain with only a low chance of a mix at the onset. Pcpn
diminishes Monday with this feature shifting off to the east. Expect
highs on Sunday from 40 to 45 and from the lower 40s northeast to 50
southwest Monday.

Shortwave tracking through the Great Lakes and weak front will
provide a slight chance of a shower Tuesday. Above normal
temperatures to continue Tuesday with highs ranging from the the
upper 40s north to the lower 50s south.

Model solutions diverge at mid week but will follow continuity and
keep forecast dry Wednesday with surface high pressure building into
the region. Temperatures close to normal next Wednesday with highs
from the upper 30s north to the mid/upper 40s south.

Models differ on handling next surface low which tracks through the
area at the end of the week in split flow regime. Will hold off pcpn
until late Thursday afternoon and then increase pops Thursday night
with approach of surface front. On the warm side of this system
expect Thursdays highs from the upper 40s northeast to the mid 50s
southwest.

Pcpn to diminish from nw to se late Friday into Friday night in the
wake of the front. Pcpn may mix with or change to snow prior to
ending. Highs to range from lower 40s nw to the lower 50s se
Friday.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
Ceilings starting out near the 3000 ft threshold for MVFR will begin to lift overnight as high pressure and drier air wedge in from the south. VFR will then continue through the end of the TAF period as low clouds scatter leaving cirrus as sky cover according to model soundings. Winds staying around 10 knots tonight will back to southwest as the high moves in, with gusts to 20 knots Saturday afternoon. OUTLOOK...MVFR ceilings and visibilities are possible from Sunday night through Monday night.
-- End Changed Discussion --
&& .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Hatzos NEAR TERM...Hatzos SHORT TERM...Hatzos LONG TERM...AR AVIATION...Coniglio
Skew-T

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