Information is from the NWS Wilmington, OH Office


ILN Area Forecast Discussion/SKEW-T

FXUS61 KILN 161739
AFDILN

Area Forecast Discussion
National Weather Service Wilmington OH
139 PM EDT Mon Jul 16 2018

.SYNOPSIS...
Thunderstorms will develop today ahead of a cold front which
will push through the area tonight. A drier and cooler airmass
will build in for the middle of the week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Broad mid level weakness/trof in the mid levels over the Ohio
Valley today. A couple of weak perturbations to pass through
the trof today, with models showing a weak surface reflected
n-s oriented trof developing across ILN/s area this aftn.
Moderate instby develops in the warm sector with ML CAPE values
of 1200-1600 J/KG anticipated. Expect scattered storms to
develop in this airmass with the best coverage over the southern
and eastern counties. Bulk shear is weak so do not expect much
in the way of organization. DCAPE values approach 1000 j/kg, so
stronger updrafts could produce gusty winds. Model precipitable
water values are forecast to increase above 2 inches. These
values are typically fcst too high but expect values to approach
2 inches by late aftn. With very light flow(slow storm movement)
and in a moisture rich environment, locally heavy rain will be
possible.

Temperatures at or a little above normal today with highs in
the mid to upper 80s.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
Tonight, precipitation chances will be highest at the beginning
of the period and will decrease with the loss of daytime
heating. Meanwhile as the cold front pushes through the region,
convection will end from northwest to southeast.

By 12Z Tuesday, the front will be lingering in the southeast
counties. An isolated shower will be possible early Tuesday
morning. High pressure will gradually build in on Tuesday.
Dewpoints will gradually lower throughout the day. Highs on
Tuesday will range from the lower 80s in the north to the mid
80s in nrn KY.

Dewpoints will continue to dry out Tuesday night as the high
pressure settles into the region. Lows Tuesday night will drop
to 60-65.

On Wednesday, the surface high will be centered over the Great
Lakes. Skies will be mostly sunny and highs will be in the
upper 70s to lower 80s.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
High pressure will remain in place for several days. This air
mass will be a little cooler and drier than the last one,
characterized by dewpoints in the lower 60s (Wednesday and
Thursday) and max temps in the lower to mid 80s. In an air mass
that will be generally dry (with precipitable water values under
an inch) and capped, no precipitation is expected during this
period.

A return to southerly flow is expected on Thursday night into
Friday, as the surface high moves east of the region, and a
deepening shortwave moves into the area from the northern plains.
There is high confidence in this overall amplification to the
pattern, which has been shown through several model cycles. There is
less confidence in the strength of the mid-level wave, and the
closed mid-level low that both GFS/ECMWF projections suggest will
develop out of it. There has definitely been a trend toward a slower
and deeper solution, which will keep the ILN CWA in a regime of
cyclonic flow and occasional precipitation chances through next
weekend. The forecast has been trended in this direction, with PoPs
increased for Saturday and Sunday. The temperature forecast for
Friday/Saturday/Sunday will be kept conservatively in the lower to
mid 80s, with expectations of increased moisture and precipitation
in the area. These values are slightly below climatological
normals.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
Scattered thunderstorms developing across the region in the
moderately unstable airmass ahead of an approaching cold front.
Prevailing VFR cigs will drop to MVFR conditions during storms,
with brief IFR conditions also possible. Gusty winds will be
possible in some of the stronger storms.

With the loss of daytime heating, convective activity should
diminish in coverage this evening but there will still remain
a low chance of showers/thunderstorms until the cold front
passes through between 07Z and 09Z.

As drier air advects in on northwest winds clouds will scatter
out late tonight. Some patchy MVFR fog is possible toward
sunrise where clearing occurs but some low level moisture lags.

Expect VFR conditions Tuesday with scattered to bkn cumulus
clouds at 4000 to 5000 feet. Northwest to north winds at 10-12kt
will gust up to 18kts at times Tuesday afternoon.

OUTLOOK...MVFR CIGS/VSBYS possible in TSRA on Friday.

&&

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

&&

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



Skew-T

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