Area Forecast Discussion
Issued by NWS Chicago, IL

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FXUS63 KLOT 151701

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
1201 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.



241 AM CDT

Saturday through Thursday...

The ridge dominates the pattern through Saturday leading to another
very warm and dry day.

The surface low currently over the central Plains reaches
southwestern Ontario Saturday night, and its cold front approaches
the Mississippi River.  Kept a chance of showers and storms in for
Sunday morning as decaying convection could impact areas west of I-
55.  The cold front continues across the region Sunday, and
expecting another round of storms to fire along it Sunday afternoon.
 CAPE and shear values seem marginal at best, but PWATs are forecast
to be around 1.75 inches. Steering flow looks weak, so I am a bit
concerned about slowly moving storms producing heavy downpours. This
could lead to localized flooding.

The pattern remains active with multiple shortwave troughs moving
through the region next week.  None of the shortwaves look overly
impressive so kept a slight chance to chance of showers and storms
in the forecast.

Temperatures take a tumble Monday behind the front, and temperatures
remain at or above normal the rest of the week.



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.



241 AM CDT

High pressure will remain anchored along the Appalachians and east
coast through the weekend and the early part of next week while low
pressure remains in place over the Great Plains and Canadian
Prairies through the weekend. This will result in fairly steady
state conditions with south winds 10 to 20 kt, occasionally to 25 kt
today through the weekend. Low pressure will lift from the Upper
Midwest to near Hudson Bay later Sunday while a trailing cold front
pushes across Lake Michigan turning winds north to northeast in its
wake Monday. High pressure will build over Lake Superior behind the
front Monday then low pressure will develop once more over the Great
Plains by midweek allowing winds to veer to the south to






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