Area Forecast Discussion
Issued by NWS Chicago, IL

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FXUS63 KLOT 260756

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
256 AM CDT TUE JUL 26 2016

201 PM CDT

Through Tuesday...

High pressure will continue to provide tranquil weather through
Tuesday. Calm to light/variable winds will be in place tonight
allowing for radiational cooling. Expect lows in the lower 60s
northwest to the mid 60s south, with around 70 in the immediate
Chicago metro. Southern areas will likely see a slower cool down
as dewpoints have hung on in the lower 70s, but should fall into
the mid 60s tonight. With the light flow, patchy fog may develop
but forecast soundings suggest that moisture will be very shallow.
Areas that received the most rainfall outside of the immediate
metro area are probably most favored and it may be that any fog
that develops is rather shallow.

The center of the high shifts east tomorrow but winds will
continue to be light. This will support a lake influence setting
up once again which will keep lakeshore areas around 80 for highs
while the rest of the area sees highs in the mid/upper 80s once



305 PM CDT

Tuesday night through Monday...

High pressure over the area Tuesday night will very gradually
weaken on Wednesday and Wednesday Night with any forcing for
precipitation in the Midwest being to our north and south. The
latter forcing is a shearing/weakening upper low presently located
in the northern Gulf of Mexico. There is uncertainty in model
solutions as to what degree this interacts with the northern
stream trough forcing. Just how far north the channel of higher
theta-e air returns will depend on this. So while a chance for
showers and thunderstorms over a 48 hour window or so at this
time, overall there still is not a signal for high impact weather.
Obviously with the moist air mass to our south, that could

Despite the difference in model solutions for Thursday-Friday,
there appears to be a quieter and drier weekend setting up than
last with northwest flow aloft and north-northeast flow in the
low-levels. Depending on the strength of this low-level flow,
that could bring a rip current threat to area beaches later
Friday/early Saturday.



For the 06Z TAFs...

High pressure remains overhead leading to VFR conditions and light
winds. Winds will be variable at RFD and DPA through the period,
while winds will become east at 5 kt or less along the lake. Winds
continue to veer and become variable overnight.



252 AM CDT

High pressure currently over Iowa shifts east today. Onshore flow is
expected across the southern end of the lake while winds will be
southwest at 10-20 kt over the northern end.  Winds veer and
diminish into Wednesday morning. A cold front pushes down the
lake Wednesday, and winds become north and northeast behind it.
Guidance suggests winds may increase to 10-20 kt along the front
Wednesday night. The pressure gradient tightens over the lake
Thursday afternoon as low pressure shifts northeast over IL.
Northeast winds will increase to 10-20 kt Thursday afternoon and
night. The low passes south of the lake Thursday night through
Friday morning. Winds remain northeast through Saturday and then
become south or southeast as another high pressure system spreads
over the lake over the weekend.






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