Area Forecast Discussion
Issued by NWS Chicago, IL

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FXUS63 KLOT 151833

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
133 PM CDT Fri Sep 15 2017

241 AM CDT

Through tonight...

Benign weather continues under an upper level ridge.  Warm air
builds leading to high temperatures in the mid 80s away from the
lake. Southeast winds are expected this afternoon which will lead to
high temperatures around 80 along the lake front.  Low temperatures
fall into the 60s tonight.



127 PM CDT

Saturday night through Friday...

After a period of relatively quiet weather, the southern stream will
become more unsettled as the high amplitude long wave upper level
pattern trends toward more zonal flow.  By Saturday night, the upper
trough over the west will move out over the central plains.  The
parent upper low over the Canadian Rockies will also progress east,
helping to break down the upper ridge over the east. Temperatures
will trend closer to more seasonable levels of upper 70s to lower
80s by Sunday. As the upper level pattern trends to more zonal, a
more active southern stream will set up with a series of weak
shortwaves rippling through the fast wswly-wly flow aloft brings
periodic chances for showers and thunderstorms for much of next
week.  The longer range guidance is coming into decent agreement on
a stronger shortwave impacting the region Monday evening, so have
increased PoPs to likely for that time.  Otherwise, keep periodic
slight chance to chance PoPs through much of the longer term
forecast period.


For the 18Z TAFs...

Overall, very quiet weather conditions are expected through the
period. Expect a south-southeasterly wind through the period as
the region remains on the western periphery of high pressure over
the Ohio Valley. VFR conditions are expected through the period.



130 PM CDT

High pressure will remain in place over the eastern CONUS through
the weekend and the early part of next week while low pressure
deepens over the central plains. This will result in persistent,
generally southerly winds over Lake Michigan. The low will lift
through the Upper Midwest to Hudson Bay Sunday night while a
trailing cold front pushes across Lake Michigan, turning winds to
north to northeast on Monday. High pressure will then build over
the upper Great Lakes Monday. Another low will develop over the
central plains by midweek allowing winds to veer to the south to





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