Hazardous Weather Outlook
Issued by NWS Chicago, IL

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FLUS43 KLOT 200839
HWOLOT

Hazardous Weather Outlook
National Weather Service Chicago/Romeoville IL
339 AM CDT Thu Jul 20 2017

ILZ003>006-008-010>014-019>023-032-033-039-INZ001-002-010-011-019-
210845-
Winnebago-Boone-McHenry-Lake Illinois-Ogle-Lee-De Kalb-Kane-
DuPage-Cook-La Salle-Kendall-Grundy-Will-Kankakee-Livingston-
Iroquois-Ford-Lake Indiana-Porter-Newton-Jasper-Benton-
339 AM CDT Thu Jul 20 2017 /439 AM EDT Thu Jul 20 2017/

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH CENTRAL ILLINOIS...
NORTHEAST ILLINOIS AND NORTHWEST INDIANA.

.DAY ONE...Today and Tonight.

WEATHER HAZARDS EXPECTED:
  Significant Thunderstorm Risk...with an associated:
      Elevated Flooding Risk.
      Limited Hail Risk...up to half dollar size.
      Limited Thunderstorm Wind Damage Risk...up to 60 MPH.
  Elevated Excessive Heat Risk.

DISCUSSION:

Thunderstorms will move slowly southeast over northern Illinois
and possibly northwest Indiana through mid-morning. These will
produce periods of very heavy rainfall which could cause flooding.
Also, they will bring isolated winds in excess of 40 mph.

Isolated storms are possible this afternoon into tonight along
the outflow boundary from the morning storms. While coverage of
storms is likely to be limited, if they can develop they will have
heavy rain and a possible flooding threat, as well as some chance
to be severe.

If rain cooled air and clouds have a limited effect, locations
south of Interstate 80 will have heat index readings approach 105
degrees this afternoon.

Flooding will continue along portions of the Fox and Des Plaines
Rivers.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Friday...
  Significant Flooding Risk.
  Elevated Severe Thunderstorm Risk.
  Elevated Excessive Heat Risk.
Saturday...
  Limited Flooding Risk.
  Elevated Severe Thunderstorm Risk.
  Elevated Excessive Heat Risk.
Sunday...
  Limited Thunderstorm Risk.
Wednesday...
  Limited Thunderstorm Risk.

DISCUSSION:

An active and humid weather pattern will continue through Saturday.
Thunderstorms are likely at times Friday and more so Friday night,
especially north of Interstate 80. The potential for heavy rain in
the region is significant which could cause worsened flooding.
However, the exact location of the heaviest rainfall is uncertain.
In addition there is a severe thunderstorm threat, mainly north of
Interstate 80, on Friday and Friday night as well.

Thunderstorm chances continue on Saturday, shifting mainly along and
south of Interstate 80 by Saturday night.

Heat index readings will approach 105 degrees both Friday and
Saturday, mainly along and south of Interstate 80.

In addition, flooding will continue along portions of the Fox and
Des Plaines Rivers and may develop along other rivers of far
northern Illinois.

.SPOTTER INFORMATION STATEMENT...

Spotters may be needed this afternoon and evening.

GENERAL STORM MOTION OF THE DAY:

Moving to the southeast at 25 mph.

&&

$$

LMZ740>745-210845-
Winthrop Harbor to Wilmette Harbor-
Wilmette Harbor to Northerly Island-
Northerly Island to Calumet Harbor-Calumet Harbor to Gary-
Gary to Burns Harbor-Burns Harbor to Michigan City-
339 AM CDT Thu Jul 20 2017

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE ILLINOIS NEARSHORE
WATERS OF LAKE MICHIGAN AND THE INDIANA NEARSHORE WATERS OF LAKE
MICHIGAN.

.DAY ONE...Today and Tonight.

Significant Thunderstorm Risk especially in the morning.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Friday...
  Significant Thunderstorm Risk.
Saturday...
  Limited Thunderstorm Risk.
Sunday...
  Limited Thunderstorm Risk.
  Hazardous Conditions for Small Craft are likely.
Monday...
  Hazardous Conditions for Small Craft are likely.
Wednesday...
  Limited Thunderstorm Risk.

&&

$$

LMZ080-261-362-364-366-563-565-567-669-671-673-675-777-779-868-
870-872-874-876-878-210845-
Lake Michigan from Michigan City IN to St. Joseph MI 5 NM
offshore to Mid Lake-
Lake Michigan from Seul Choix Point to Rock Island Passage 5 NM
offshore to Mid Lake-
Lake Michigan South of a line from Seul Choix Point to the
Mackinac Bridge and north of a line from Charlevoix MI to South
Fox Island 5 NM offshore-
Lake Michigan from Charlevoix to Point Betsie MI 5 NM offshore to
Mid Lake-
Lake Michigan from Point Betsie to Manistee MI 5 NM offshore to
Mid Lake-
Lake Michigan from Rock Island Passage to Sturgeon Bay WI-
Lake Michigan from Sturgeon Bay to Two Rivers WI 5 NM offshore to
Mid Lake-
Lake Michigan from Two Rivers to Sheboygan WI 5 NM offshore to
Mid Lake-
Lake Michigan from Sheboygan to Port Washington WI 5 NM offshore
to Mid Lake-
Lake Michigan from Port Washington to North Point Light WI 5 NM
offshore to Mid Lake-
Lake Michigan from North Point Light to Wind Point WI 5 NM
offshore to Mid Lake-
Lake Michigan from Wind Point WI to Winthrop Harbor IL 5 NM
offshore to Mid Lake-
Lake Michigan from Winthrop Harbor to Wilmette Harbor IL 5 NM
offshore to Mid Lake-
Lake Michigan from Wilmette Harbor IL to Michigan City IN 5 NM
offshore to Mid Lake-
Lake Michigan from Pentwater to Manistee MI 5 NM offshore to Mid
Lake-
Lake Michigan from Whitehall to Pentwater MI 5 NM offshore to Mid
Lake-
Lake Michigan from Grand Haven to Whitehall MI 5 NM offshore to
Mid Lake-
Lake Michigan from Holland to Grand Haven MI 5 NM offshore to Mid
Lake-
Lake Michigan from South Haven to Holland MI 5 NM offshore to Mid
Lake-
Lake Michigan from St. Joseph to South Haven MI 5 NM offshore to
Mid Lake-
339 AM CDT Thu Jul 20 2017

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE OPEN WATERS OF LAKE
MICHIGAN.

.DAY ONE...Today and Tonight.

Thunderstorms are likely this morning across the south with a
chance across the south this afternoon and tonight.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Periods of thunderstorms are expected through Saturday and
again possible on Wednesday.

&&

$$

MTF

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