Area Forecast Discussion
Issued by NWS Wilmington, OH

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000
FXUS61 KILN 271523
AFDILN

Area Forecast Discussion
National Weather Service Wilmington OH
1123 AM EDT Sat May 27 2017

.SYNOPSIS...
With warm and moist air over the Ohio Valley, there will be
occasional chances for showers and thunderstorms through the
weekend. After a cold front moves through the region Sunday
night, drier conditions are expected for Monday.

&&

.NEAR TERM /THROUGH TONIGHT/...
A fair amount of sc has developed across the area this morning,
especially along and south of a weak boundary that is laid out
across our area. These clouds should begin to mix out/lift into
more of a cu field as we progress through this afternoon and
begin to destabilize. Good instabilities are progged to develop
through this afternoon with ML Capes forecast up into the
2000-3000 J/KG range by mid to late afternoon. Forecast
soundings continue to show some capping along and north of the
boundary, but across our south it does appear that at least some
scattered thunderstorms development will be possible. This may
be aided somewhat by a very weak wave that is forecast to push
east along the boundary through mid to late afternoon. Wind
fields are not all that impressive though with both the 0-3 km
and 0-6 km shear values somewhat marginal for organized storms.
However, given the degree of instability, some strong to severe
storms will be possible with any development later this
afternoon into early evening with the main threat being large
hail and damaging winds. With mid and upper level flow parallel
to the boundary, some training storms may also be possible if
things do get going. This combined with PWs forecast to push up
into the 1.5 to possibly 2.0 inch range, would support a locally
heavy rain/flash flood threat.

&&

.SHORT TERM /SUNDAY/...
After any storms along the boundary have dissipated or moved SE
of the ILN CWA this evening, another break in the action is
expected. From here, attention will turn to the severe
(potentially very severe) convection occurring well upstream
across Missouri and southern Illinois. This activity is not even
expected to reach the lower Ohio Valley until late evening, and
thus, any impacts on the ILN CWA will be well into the overnight
hours. 00Z runs across the suite of models have been fairly
consistent in depicting this activity propagating into the
instability / greater theta-e air mass, roughly along an ESE
trajectory. The ILN CWA will be on the northern fringe of this,
still in a favorable area for convection to develop ahead of a
mid-level shortwave, but removed from the best thermodynamic
environment at a sub-optimal time of day. A severe threat will
exist -- mainly a damaging wind threat -- but should not be as
significant as areas further south and west. The main focus here
will be in the overnight / early Sunday morning hours.

Once the morning activity has passed east, another break is
expected through the first half of Sunday. Additional storms
associated with the cold front will be discussed in the Long
Term AFD section below. With less certainty in the pattern, will
not allow a completely dry forecast for this time period, as
there should still be some isentropic ascent with continued warm
advection aloft.

The temperature forecast through the first three periods of the
forecast is one that is largely dependent on convection and
clouds, so perhaps it would be better read as a mid-point of the
expectations -- get some clearing and it will be too low, get
some convection and it will be too high. There will be a general
SW-to-NE gradient in temperatures across the ILN CWA through the
period, and depending on the position of the surface boundaries,
a tighter gradient may exist than what is currently in the
forecast.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
A cold front will move east through the region Sunday night.
Scattered showers and thunderstorms are expected along and ahead of
the front. A few strong to severe storms will be possible late
Sunday afternoon into the evening hours with damaging winds and
large hail the primary severe weather threats. Precipitation should
exit east of the eastern CWFA after midnight, with clearing expected
behind the front.

The first half of the week will feature a large closed upper level
low which is forecast to rotate slowly east across Ontario. Embedded
disturbances rotating around the low, along with weak sfc trof axes,
will bring a low chance threat of a few showers from time to time,
mainly during the peak heating of the day. Otherwise, partly cloudy
conditions with seasonable temperatures in the 70s are expected.

As the upper level low finally rotates farther east by the end of
the work week, we should finally see a distinct dry period as
surface high pressure settles over the Ohio Valley. Again,
temperatures will be near seasonal normals.

&&

.AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...
Some patchy MVFR ceilings remain in place across the region, but
these should lift to VFR over the next few hours, and VFR
conditions are expected to prevail through the day today.
Chances for precipitation will be limited to passing light
showers this morning, before dry conditions are expected late
morning into the afternoon. Winds will be westerly to
northwesterly at generally around 10 knots.

During the mid to late afternoon, there will be a chance of some
showers and storms developing near Cincinnati. However,
confidence remains too low to include specifically, so a VCSH
will be used in the TAFs.

Additional chances for showers and storms will be possible late
Saturday night into Sunday morning, along with MVFR ceilings.

OUTLOOK...Intermittent chances of thunderstorms along with MVFR
ceilings will be possible from Saturday night through Monday
morning.

&&

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

&&

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



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