Area Forecast Discussion
Issued by NWS Chicago, IL

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FXUS63 KLOT 291935

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
235 PM CDT SUN MAY 29 2016

232 PM CDT

Through Monday...

Hi-res models hint at light rain showers west of I-55 this afternoon
and tonight, but thinking we will continue to see dry conditions.
Scattered storms are forming over northern Iowa and southern WI.
Scattered convection has a better chance of forming north of the
vort max currently over Iowa and thus north of the CWA. If any
convection does get going, thinking locations will only see
sprinkles given dewpoint depressions around 20 degrees.

Clouds clear tonight and winds diminish.  Lows will be in the lower
60s.  A few clouds are expected tomorrow with lighter winds and
highs in the low to mid 80s. Limited highs south of I-80 where there
may be more cloud cover, but if cloud cover is less than forecast,
could see high temps above 85.  The weak surface flow allows a lake
breeze to form in the afternoon.  The lake breeze looks like it will
push onshore later than normal so thinking lake side locations have
a good chance of seeing 80. Models suggest precip will spread west
of I-39 late Monday afternoon, but thinking the precip will hold off
til Monday evening when the vort max gets closer to the CWA.  Did
include a slight chance of showers and storms east of I-39 late
Monday aftn in the off chance precip does form.



318 AM CDT

Monday Night through Saturday...

Mild the low to mid 80s...are expected to
continue on Tuesday and Wednesday. However...a potent storm system
is expected to move across the Dakotas and Upper Midwest by late
Wednesday. This storm system promises to push a rather decent cold
front across the area by Thursday morning. Cooler conditions in
the 70s are likely to follow for Thursday through Saturday.
Onshore flow on Friday and Saturday could even keep temperatures
in the 60s along the lake shores of Lake Michigan.

While the later portion of the forecast period...particularly
Thursday through Saturday...looks to be mainly dry but cool across
the area...the same cannot be said for midweek...during the
transition period to this cool and drier air mass. The chances for
showers and thunderstorms will be on the increase Tuesday as better
moisture begins to filter in over the area ahead of the storm system
taking shape over the Dakotas and Upper Midwest.
appears the best chances for thunderstorms will be Wednesday into
Wednesday night as the cold front gradually approaches the area. Due
to the fact the deeper layer steering flow looks to be somewhat
parallel to the approaching surface front...there could be the
potential for some training storms and some heavy rain threat given
increasing PWATS. Also cant rule out the potential for a few
stronger storms on Wednesday...though deep layer shear looks
marginal. The threat of storms looks to end by Thursday following
the frontal passage.



For the 18Z TAFs...

Gusty southwest to west winds dissipate this afternoon. Low end
VFR cigs will also continue to thin into this evening with clear
skies expected overnight. High pressure continues Monday with
west winds and VFR conditions. Some guidance members suggest
precip is possible south of the terminals. Have low confidence in
precip actually occurring and high confidence that precip will be
well south of the terminals if it does occur. The weak flow will
allow a lake breeze to form. Thinking the lake breeze will not
reach the eastern terminals until late in the afternoon/early
evening and will be less than 10 kt.



232 PM CDT

Will let the fog advisory expire this afternoon as fog has
dissipated over the northern end of the lake. Drier air is also
moving over the lake.  Low pressure over Ontario continues northeast
while high pressure just south of the lake spreads north.  West to
southwest winds become south Monday.  The high shifts east Tuesday
allowing winds to become southeast. A low shifts east over the
northern plains and upper Mississippi valley Wed and south winds
increase to around 20 kt.  High pressure spreads over the lake late
in the week as the low continues northeast over Quebec.  Light winds
become north by late Thursday night/early Friday morning. Another
low is forecast to impact the northern Great Lakes early next week.






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