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fxus63 klot 181719 
afdlot

Area forecast discussion
National Weather Service Chicago/Romeoville, Illinois
1219 PM CDT Thu Oct 18 2018

Short term...
1217 PM CDT

Through Friday...

Mainly quiet/dry conditions continue into tonight, as high
pressure remains situated across the region. Expect upstream mid
level energy ahead of larger upper level trough to begin to usher
in mid/high clouds later tonight into Friday. The arrival of this
energy, and approaching surface trough/boundary, will support
increasing chances for scattered rain showers during the day on
Friday. Confidence on coverage is slightly lower at this time, but
do think most locations will see at least periodic sprinkles or
light rain showers.

Rodriguez

&&

Long term...
244 am CDT

Friday through Wednesday...

For the longer term forecast period, general weather trends are
expected to be persistent below normal temperatures. Very windy
conditions with scattered showers are expected for Friday and
Saturday.

A strong shortwave is expected to over-top a broad upper ridge,
decreasing the amplitude of the upper level pattern as it drops
across the upper Midwest on Friday while pushing a cold front across
the area. In advance of the approaching sfc cold front, as
strengthening swly pressure gradient and daytime mixing will help
tap into 35-40 kt winds at the top of the mixed layer. Expect that
Friday will be a rather windy day, however, increasing cloud cover
in the broad isentropic lift of the warm sector may help limit the
Max potential mixing, with gusts to arnd 30-35 mph possible through
the day. There is a chance for some scattered showers, mainly
diurnally driven, during the daytime hours. However, forecast
soundings indicate quiet a bit of dry air in the lower levels, so
any pcpn will likely be light and patchy.

Strong cold air advection will set up across the region Friday night
into Saturday following the passage of the cold front. Strong cold
advection and strong pressure rises between the exiting frontal
trough and high pressure building into the Central Plains will
result in another windy day. Forecast soundings continue to show
winds at the top of the mixed layer of around 40kt and suggest
another day with the potential for wind gusts in excess of 30 mph,
but from the northwest. Meanwhile, a second and weaker shortwave is
expected to digs across the area on Saturday and may produce another
wave of scattered diurnally-driven showers as the region sits under
cyclonic flow aloft. High pressure should build over the region
Sunday through Monday, ending the pcpn chances. Another cold front
is expected to pass over the area Monday night into Tuesday, but the
latest long range guidance suggests that this will be a dry fropa as
sfc ridging extending from the mid-Atlantic region through the lower
Mississippi Valley should keep the local area shut off from any
significant moisture influx.

&&

Aviation...
for the 18z tafs...

Dry/VFR conditions expected today into tonight, while southwest
winds persist. Expect these southwest winds to steadily increase
later tonight into Friday, becoming more west southwest late in
the period. VFR ceilings return on Friday along with the potential
for scattered light rain showers. The potential for MVFR ceilings
also return late in the period, mainly Friday afternoon.

Rodriguez

&&

Lot watches/warnings/advisories...
Illinois...none.
In...none.
Lm...none.
&&

$$

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