National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FLUS43 KLOT 200908
HWOLOT

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
408 AM CDT MON MAY 20 2013

ILZ003>006-008-010>014-019>023-032-033-039-INZ001-002-010-011-019-
210915-
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-
408 AM CDT MON MAY 20 2013 /508 AM EDT MON MAY 20 2013/

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

.DAY ONE...TODAY AND TONIGHT.

  WEATHER HAZARDS EXPECTED:

  SCATTERED THUNDERSTORMS WHICH MAY PRODUCE...
   WIND GUSTS TO 65 MPH.
   ISOLATED TORNADOES.
   HAIL TO ONE INCH IN DIAMETER.
   LOCALLY HEAVY RAIN.
   CLOUD TO GROUND LIGHTNING.

  AREAS AFFECTED AND TIMING:

  THUNDERSTORMS WILL SLOWLY DEVELOP LATE THIS MORNING ACROSS
  CENTRAL ILLINOIS AND EASTERN IOWA...THEN LIFT NORTH AND EAST
  INTO NORTH CENTRAL ILLINOIS. ADDITIONAL THUNDERSTORMS ARE
  EXPECTED TO DEVELOP THIS AFTERNOON THROUGH TONIGHT ACROSS ALL OF
  NORTHERN ILLINOIS AND NORTHWEST INDIANA...WITH SOME OF THESE
  THUNDERSTORMS HAVING THE POTENTIAL TO BECOME SEVERE.

  DISCUSSION:

  AN UNSEASONABLY WARM AND TROPICAL LIKE AIRMASS HAS ARRIVED ACROSS
  THE REGION. THUNDERSTORMS FROM EARLY THIS MORNING HAVE
  DISSIPATED...HOWEVER THESE STORMS HAVE LEFT OLD BOUNDARIES ACROSS
  OVER NORTHERN ILLINOIS. THESE BOUNDARIES ARE EXPECTED TO SERVE AS
  A FOCAL POINT FOR THUNDERSTORM DEVELOPMENT LATER THIS MORNING.
  A WEAK LOW PRESSURE IS EXPECTED TO LIFT NORTH INTO CENTRAL ILLINOIS
  EARLY THIS AFTERNOON...ALLOWING SOUTHERLY WINDS TO BACK SLIGHTLY TO
  THE SOUTHEAST. THIS WILL PROVIDE ADDITIONAL FORCING AND LIFT INTO
  AN ALREADY UNSTABLE ENVIRONMENT. AS A RESULT THUNDERSTORMS ARE
  EXPECTED TO STRENGTHEN AND POSSIBLY BECOME SEVERE THIS AFTERNOON
  THROUGH TONIGHT. THE MAIN THREATS FROM SEVERE THUNDERSTORMS WILL
  BE DAMAGING WIND GUSTS AND HAIL TO ONE INCH IN DIAMETER.

  THE AIRMASS THAT WILL BE IN PLACE ACROSS THE OUTLOOK AREA HAS
  BEEN CONDUCIVE TO NOT ONLY PRODUCING WIND DAMAGE ACROSS THE
  CENTRAL PLAINS...BUT HAS PRODUCED TORNADOES. AS THE ATMOSPHERE
  BECOMES UNSTABLE THIS AFTERNOON THROUGH TONIGHT...LOW LEVEL
  CONDITIONS WILL BECOME FAVORABLE FOR A FEW ROTATING UPDRAFTS TO
  FORM IN SOME OF THE STRONGEST THUNDERSTORMS. THIS COULD LEAD TO
  THE DEVELOPMENT OF AN ISOLATED TORNADO ACROSS NORTHERN ILLINOIS
  AND NORTHWEST INDIANA.

  IN ADDITION TO THE SEVERE WEATHER CONCERNS WILL BE THE POTENTIAL
  FOR LOCALLY HEAVY RAINFALL. AS MENTIONED ABOVE...THE AIRMASS TODAY
  THROUGH TONIGHT WILL FEATURE A VERY MOIST ENVIRONMENT. AS A RESULT
  SOME OF THE THUNDERSTORMS HAVE THE POTENTIAL TO PRODUCE LOCALLY
  HEAVY RAINFALL...POSSIBLY TORRENTIAL DOWNPOURS. THIS COULD LEAD TO
  LOCALIZED FLOODING...ESPECIALLY IN LOW LYING AND POOR DRAINAGE AREAS.


.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY.

SCATTERED THUNDERSTORMS WILL BE POSSIBLE TUESDAY THROUGH WEDNESDAY
NIGHT...WITH THE POTENTIAL FOR SEVERE WEATHER TUESDAY ACROSS THE
ENTIRE AREA. THE MAIN SEVERE WEATHER THREATS WILL BE DAMAGING
WIND GUSTS AND LARGE HAIL.

HEAVY RAIN WILL ALSO BE POSSIBLE FROM ANY OF THE THUNDERSTORMS
THAT FORM TUESDAY NIGHT INTO WEDNESDAY MORNING. HEAVY RAINFALL COULD
LEAD TO LOCALIZED FLOODING...ESPECIALLY IN LOW LYING AND POOR
DRAINAGE AREAS.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS MAY BE NEEDED THIS AFTERNOON THROUGH TONIGHT.

&&

$$

LMZ740>745-210915-
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-
408 AM CDT MON MAY 20 2013

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.

THERE IS A CHANCE OF THUNDERSTORMS TODAY THROUGH TONIGHT FOR THE
ILLINOIS AND NORTHWEST INDIANA NEARSHORE. SOME OF THE STORMS MAY
PRODUCE WIND GUSTS GREATER THAN 35 KNOTS.

STRONG WINDS MAY CREATE HAZARDOUS CONDITIONS FOR SMALL CRAFT
TODAY.

PATCHY FOG WILL BE POSSIBLE.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY.

SCATTERED THUNDERSTORMS WILL BE POSSIBLE TUESDAY THROUGH WEDNESDAY WITH
THE POTENTIAL FOR SEVERE WEATHER TUESDAY. THE MAIN SEVERE WEATHER
THREATS WILL BE WIND GUSTS GREATER THAN 35 KNOTS AND LARGE HAIL.

STRONG WINDS AND HIGH WAVES MAY CREATE HAZARDOUS CONDITIONS FOR
SMALL CRAFT THURSDAY THROUGH FRIDAY.

&&

$$

LMZ080-261-362-364-366-563-565-567-669-671-673-675-777-779-868-
870-872-874-876-878-210915-
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-
408 AM CDT MON MAY 20 2013

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

.DAY ONE...TODAY AND TONIGHT.

PATCHY DENSE FOG WILL BE POSSIBLE ACROSS THE ENTIRE LAKE.

THERE IS A CHANCE OF THUNDERSTORMS. SOME OF THE STORMS MAY
PRODUCE WIND GUSTS GREATER THAN 35 KNOTS TODAY THROUGH
TONIGHT.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY.

AREAS OF DENSE FOG WILL BE POSSIBLE MONDAY THROUGH TUESDAY ACROSS
THE ENTIRE LAKE.

SCATTERED THUNDERSTORMS WILL BE POSSIBLE TUESDAY THROUGH WEDNESDAY WITH
THE POTENTIAL FOR SEVERE WEATHER TUESDAY. THE MAIN SEVERE WEATHER
THREATS WILL BE WIND GUSTS GREATER THAN 35 KNOTS AND LARGE HAIL.

&&

$$

BEACHLER

VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO