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Hazardous Weather Outlook

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
854 PM CDT WED AUG 20 2014

ILZ003>006-008-010>014-019>023-032-033-039-INZ001-002-010-011-019-
220200-
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-
854 PM CDT WED AUG 20 2014 /954 PM EDT WED AUG 20 2014/

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

.DAY ONE...TONIGHT.

  WEATHER HAZARDS EXPECTED:

   SCATTERED THUNDERSTORMS...SOME COULD PRODUCE:
   WIND GUSTS TO 50 MPH.
   PEA TO NICKEL SIZE HAIL.
   HEAVY RAINFALL LEADING TO LOCALIZED FLOODING.
   FREQUENT CLOUD TO GROUND LIGHTNING.

  AREAS AFFECTED AND TIMING:

   ISOLATED THUNDERSTORMS WILL BE POSSIBLE ACROSS PORTIONS OF
   NORTHERN ILLINOIS AND NORTHWEST INDIANA OVERNIGHT...WITH
   THE POTENTIAL AND COVERAGE INCREASING DURING THE PRE-DAWN
   HOURS AND INTO THURSDAY MORNING.

  DISCUSSION:

   A WARM FRONT FROM NEBRASKA TO DOWNSTATE ILLINOIS WILL LIFT
   SLOWLY NORTH OVERNIGHT AND THURSDAY. ISOLATED SHOWERS AND
   THUNDERSTORMS WILL DEVELOP OVERNIGHT NORTH OF THE FRONT...
   WITH COVERAGE EXPECTED TO INCREASE DURING THE PRE-DAWN HOURS.
   AN AREA OF MORE SUBSTANTIAL SHOWERS AND STORMS IS EXPECTED
   TO DEVELOP OVER PORTIONS OF MINNESOTA AND NORTHWEST IOWA
   OVERNIGHT...WHICH ARE EXPECTED TO MOVE INTO THE OUTLOOK AREA
   EARLY THURSDAY MORNING. A VERY WARM AND HUMID LATE SUMMER
   AIR MASS IN PLACE ACROSS THE REGION WILL ALLOW STORMS TO
   PRODUCE LOCALLY HEAVY RAINFALL...WHICH COULD LEAD TO
   LOCALIZED FLOODING IF SEVERAL STORMS TRACK ACROSS THE SAME
   AREAS REPEATEDLY. IN ADDITION...WHILE NO WIDESPREAD SEVERE
   WEATHER IS EXPECTED...A FEW OF THE STRONGEST THUNDERSTORMS
   MAY BE CAPABLE OF PRODUCING WIND GUSTS UP TO 50 MPH AND
   SMALL HAIL.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY.

THUNDERSTORMS...SOME OF WHICH COULD BE STRONG TO SEVERE...ARE
LIKELY THURSDAY MORNING...AND AGAIN AND THURSDAY NIGHT WITH
HEAVY RAINFALL LIKELY OCCURRING WITH ANY STRONGER STORMS.

THERE WILL CONTINUE TO BE PERIODIC CHANCES FOR THUNDERSTORMS
FRIDAY THROUGH TUESDAY.

HEAT INDICES COULD EXCEED 100 DEGREES ON FRIDAY...PRIMARILY FOR
AREAS SOUTH OF INTERSTATE 80.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NECESSARY THROUGH TONIGHT.

&&

$$



Special Weather Statement

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHICAGO IL
827 PM CDT WED AUG 20 2014

ILZ003>006-008-010>014-019>023-032-033-039-INZ001-002-010-011-019-
210930-
WINNEBAGO-BOONE-MCHENRY-LAKE IL-OGLE-LEE-DE KALB-KANE-DUPAGE-COOK-
LA SALLE-KENDALL-GRUNDY-WILL-KANKAKEE-LIVINGSTON-IROQUOIS-FORD-
LAKE IN-PORTER-NEWTON-JASPER-BENTON-
INCLUDING THE CITIES OF...ROCKFORD...BELVIDERE...WOODSTOCK...
WAUKEGAN...OREGON...DIXON...DEKALB...AURORA...WHEATON...CHICAGO...
OTTAWA...OSWEGO...MORRIS...JOLIET...KANKAKEE...PONTIAC...
WATSEKA...PAXTON...GARY...VALPARAISO...MOROCCO...RENSSELAER...
FOWLER
827 PM CDT WED AUG 20 2014 /927 PM EDT WED AUG 20 2014/

...A PERIOD OR TWO OF HEAVY RAINFALL POSSIBLE ACROSS THE AREA
THROUGH FRIDAY MORNING...

AS A WARM FRONT LIFTS NORTH AND AN UPPER LEVEL DISTURBANCE MOVES
OVER THE AREA LATE TONIGHT INTO THURSDAY...SCATTERED THUNDERSTORMS
ARE EXPECTED TO DEVELOP ACROSS PORTIONS OF THE AREA. GIVEN THE
VERY MOIST AIR MASS IN PLACE OVER THE REGION...ANY THUNDERSTORMS
WILL BE CAPABLE OF PRODUCING TORRENTIAL DOWNPOURS. A SECOND ROUND
OF THUNDERSTORMS IS POSSIBLE THURSDAY NIGHT...AND THIS COULD AGAIN
LEAD TO TORRENTIAL DOWNPOURS...ALONG WITH THE POSSIBILITY OF
FLOODING. AT THIS TIME...CONFIDENCE IS LOW AS TO WHERE THE MOST
WIDESPREAD THUNDERSTORM ACTIVITY WILL FOCUS. HOWEVER...THE
INGREDIENTS ARE IN PLACE FOR AT LEAST MINOR URBAN AND SMALL STREAM
FLOODING FOR PARTS OF THE AREA LATE TONIGHT INTO THURSDAY MORNING
AND AGAIN THURSDAY NIGHT. CONCERN EXISTS FOR LOCALIZED FLASH
FLOODING OVER AREAS THAT EXPERIENCE CONTINUED THUNDERSTORM
ACTIVITY FOR A LONGER PERIOD OF TIME.

STAY TUNED TO LATER FORECASTS AND THE POSSIBLE ISSUANCE OF A FLASH
FLOOD WATCH AT WEATHER.GOV/CHICAGO.

$$

KJB

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