Area Forecast Discussion
Issued by NWS Chicago, IL

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FXUS63 KLOT 190721

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
121 AM CST Sun Nov 19 2017

121 AM CST

Through tonight...

After the soggy, windy, and cool autumn weather of the past few
days, we enter a fairly quiet and dry pattern as we head into the
Thanksgiving week. Sunday will begin on the cold side of the
temperature roller coaster in wake of yesterday`s system, one that
will continue to deepen across the northeast and bring this same
messy system to that region. Nighttime satellite across the
midwest depicts a still an area of stratus across much of
Wisconsin, northeast IL and northwest IN. Despite some breaking up
of the clouds, which Will gradually continue , the upper level
flow is still cyclonic, and thus the low clouds remain trapped
below a frontal inversion. As the morning continues, expect one
last upper wave to clear the area and the associated subsidence
will allow for better lower cloud clearing this afternoon. The
heart of the cold air behind this first front will shift through
the western Great lakes this morning, and with increasing higher
clouds today, highs will hold in the low to mid 30s.

Passing high clouds tonight but low level warm advection as winds
shift back to southwesterly as surface high pressure, overhead
this afternoon, will shift to the Ohio valley tonight. Therefore
temps will fallow back to the mid 20s in our colder areas. Highs
bounce back nicely Monday, with near 50 degree readings and
plentiful sun other than some cirrus.



121 AM CST

Monday through Saturday...

The general idea is high pressure will shift across
the Great Lakes, then shift off to the Ohio valley and mid
Atlantic regions with some regularity throughout the extended. A
series of clipper like systems will bring occasional wind, clouds
and cold spells, followed by warm ups as each high pressure
departs east. This will result in several up and down swings of
temperature. No one system is expected to bring any real
precipitation, even though occasionally Tuesday night, Wednesday
night, and toward Saturday a model will try to throw out some very
light QPF, so most of the week appears dry at this point. The
first front will lead to a little cooler day Tuesday, then a
repeat of today on Wednesday with highs only in the 30s, before
readings head back closer to normal Thanksgiving day and toward
week`s end before another colder shot next weekend, and maybe some
light precipitation mainly of the liquid form to accompany this



For the 06Z TAFs...

Concerns with the TAFs through Sunday are just upper end MVFR
clouds at times through early-mid Sunday morning.

Northwest winds continue to show regular gusts and expect that to
continue, though a little less frequency overnight. Gusts into the
lower 20 kt range are likely, while sporadic mid 20 kt gusts are
possible. Winds will back to more west-northwest on Sunday
morning. Some gusts into the upper teens are likely through the
day Sunday before diminishing near sunset.

Satellite trends have shown an expansion of 2500-3500 ft clouds
across northern Illinois since 03Z. While there may be some brief
breaks, the clouds should generally be broken through daybreak.
Clearing by mid-morning is with medium-high confidence. Only some
cirrus is expected after that time.



209 PM CST

North winds have been steadily strengthening through the day today
as low pressure lifts from northeastern Indiana this afternoon to
Lake Ontario this evening. Expect strong gales to peak around 45
kt late this afternoon and evening then very gradually diminish
overnight dropping back below gale force early to mid Sunday
morning. Winds remain moderately strong to around 30 kt through
the rest of the day Sunday and will back to the southwest Sunday
night into Monday as another low moves east across the Canadian
Prairies. Winds will strengthen back to gale force Monday
afternoon and continue through much of the day Tuesday as the low
tracks just north of Lake Superior and then lifts to James Bay.
The pattern will remain active late in the week into the weekend
and cannot rule out additional periods of gales late in the



IN...Lakeshore Flood Advisory...INZ001-INZ002 until 3 AM Sunday.

LM...Small Craft Advisory...IL nearshore waters until noon Sunday.

     Gale Warning...LMZ743-LMZ744-LMZ745-LMZ777-LMZ779 until 6 AM




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