Area Forecast Discussion
Issued by NWS Chicago, IL

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FXUS63 KLOT 220723

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
123 AM CST Wed Nov 22 2017

123 AM CST

Through Thanksgiving Day...

Quiet conditions will be in place for the busy travel day and for
Thanksgiving Day.

It will indeed be a cold start to the day in wake of yesterday`s
front, though lake effect cloudiness across northwest Indiana is
doing its work as a natural blanket to keep things warmer in lee
of the lake. High pressure across the plains will shift into the
region today which allow for winds to slacken over what has been
several windy/breezy days. The high center will pass to our south,
so we will still maintain a lighter wind that will shift to
southwest through the day. In spite of warm advection kicking in
through the day, highs will struggle to get out of the 30s. Some
passing high clouds will give way to some thicker mid and high
clouds ahead of the next disturbance, this one currently across
Canadian prairies/northern plains. The wave will pass through
Wisconsin tonight, providing us just increased cloud cover and a
warmer night. Weak high pressure will fill in behind this weaker
system for Thanksgiving day, which will result in mostly sunny
conditions and temperatures in the lower to mid 40s, just a tad
below normal.



123 AM CST

Friday through Tuesday...

The only real chance for precipitation will be Friday night. The
up and down pattern continues as low pressure will again deepen
north of Lake Superior Friday in a similar fashion to what
occurred on Monday. With a sub 980 mb low, expect south/southwest
winds to increase quickly, and highs will be on par with or maybe
a tad higher than Monday`s highs which were in the low to mid 50s.
The pendulum will shift back down on Friday night with the cold
front providing a chance for some light rain. This cold air is
only a glancing blow, thus temps Saturday will be near normal in
the low to mid 40s. Expansive high pressure across the west will
shift in Saturday night into Sunday, resulting in a cold night and
cool day Sunday, though cloud cover will be minimal.

Longer range guidance, which has been all over the place for some
time here, is indicating a system will eject out of the west
early in the week. All indications are that this system will
impact areas to our north a bit more, with our region remaining on
its warmer and generally drier side, though it could bring some
light rain.



For the 06Z TAFs...

No significant aviation forecast concerns through Wednesday night.

Strong surface high pressure continues to build southeast across
the Plains overnight in the wake of Tuesday`s cold frontal
passage. Cold, dry low level air spreading in on northwest winds
has allowed skies to clear across the region, except for some VFR
3500-4500 foot stratocu along the lake and downwind into northwest
Indiana and Michigan. This too will shift off to the east
Wednesday morning as low level winds back more westerly. Winds,
still above 10 kts at times late Tuesday evening, will continue to
diminish and back to the southwest by Wednesday afternoon. Speeds
will come up a bit again Wednesday night. Warm air advection will
spread lowering VFR cloud cover back across the terminals late in
the day and Wednesday night.



252 PM CST

The gales have ended across much of the lake this afternoon, and
have let the gale warning expire this afternoon. However, could
see a few gale force gusts continuing for a time this afternoon
and have included this mention in the forecast. Winds will remain
elevated through tonight, with winds to 30 kt expected. This will
provide continued hazardous conditions for small craft along both
the Illinois and Indiana nearshore waters tonight. However, some
diminishing trend tonight is expected along the Illinois side,
while waves remain elevated into Wednesday morning on the Indiana
side. As high pressure moves across the region Wednesday, this
diminishing trend will briefly continue for much of the lake.
Winds increase Wednesday night ahead of a trough of low pressure,
with a fairly active weather supporting another period of higher
winds Friday into the weekend when gales will once again be



LM...Small Craft Advisory...IN nearshore waters until 9 AM Wednesday.




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