Alert archive / Illinois / Flash Flood Warnings in 2015

Flash Flood Warning 35, NWS Chicago, IL

August 17, 2015Cook County, DuPage County, Illinois

NWS Chicago, IL issued this flash flood warning at Aug 17, 2015, 9:34 PM CDT for Cook County, DuPage County, Illinois. It was in force for 6 hr. 2 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
Aug 17, 2015, 9:34 PM CDT (02:34 UTC)
Expired
Aug 18, 2015, 3:30 AM CDT
In force
6 hr
Issued by
NWS Chicago, IL
Area
Storm-based polygon
Flood severity
None

Counties Cook County, IL, DuPage County, IL

The radar

The Chicago radar (KLOT), 46 km from the middle of the area, began a volume at 02:34 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

What was reported inside it

TimeReportWhereRemark
Aug 17, 9:55 PM CDTFLASH FLOOD3 Nw Berwyn, ILALL LANES AND SHOULDERS ARE CLOSED ON EAST BOUND I-290/EISENHOWER ESPRESSWAY AT DES PLAINES AVE. DUE TO FLOODING
Aug 17, 10:30 PM CDTHEAVY RAIN 1.951 Sw Oak Park, ILRAINFALL TOTAL THUS FAR

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

Did it verify

Verified. The Iowa Environmental Mesonet's Cow matched one storm report to this flash flood warning; the first came 21 minutes after it went out.

Cow counts a report within 15 km of the polygon while the warning was in force: a tornado for a tornado warning; hail of 1 inch or more, a gust of 58 mph or more or wind damage for a severe thunderstorm warning; a flash flood report for a flash flood warning.

The nearest sounding before it

Lincoln, IL (KILX), launched 00:00Z, 2.6 hours before the alert went out and 206 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Lincoln, IL at 00:00Z on 2015-08-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 546 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Lincoln, IL at 00:00Z on 2015-08-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 8 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
546 J/kg
Mixed-layer CIN
-8 J/kg
Mixed-layer LCL
1518 m above ground
0-6 km bulk shear
11 kt
0-1 km storm-relative helicity
8 m²/s²
0-3 km storm-relative helicity
95 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

346 
WGUS53 KLOT 180234
FFWLOT
ILC031-043-180830-
/O.NEW.KLOT.FF.W.0035.150818T0234Z-150818T0830Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
934 PM CDT MON AUG 17 2015

THE NATIONAL WEATHER SERVICE IN CHICAGO  HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  EAST CENTRAL COOK COUNTY IN NORTHEASTERN ILLINOIS...
  EAST CENTRAL DUPAGE COUNTY IN NORTHEASTERN ILLINOIS...

* UNTIL 330 AM CDT
    
* AT 933 PM CDT...DOPPLER RADAR INDICATED THUNDERSTORMS PRODUCING 
  HEAVY RAIN ACROSS THE WARNED AREA. UP TO TWO INCHES OF RAIN HAS 
  ALREADY FALLEN. ANOTHER ONE TO TWO INCHES OF RAIN IS POSSIBLE. 
  FLASH FLOODING IS EXPECTED TO BEGIN SHORTLY.

* SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE...
  CHICAGO...CICERO...BERWYN...OAK PARK...DOWNERS GROVE...ELMHURST...
  LOMBARD...WESTMONT...MAYWOOD...VILLA PARK...BROOKFIELD...FRANKLIN
  PARK...HINSDALE...WESTCHESTER...LA GRANGE...FOREST PARK...RIVER
  FOREST...SUMMIT...LYONS AND BURR RIDGE.

INCLUDING THE FOLLOWING INTERSTATES...
 I-55 BETWEEN MILE MARKERS 281 AND 294.
 I-88 BETWEEN MILE MARKERS 134 AND 140.
 I-94 BETWEEN MILE MARKERS 45 AND 59.
 I-290 BETWEEN MILE MARKERS 14 AND 29.
 I-294 BETWEEN MILE MARKERS 45 AND 59.

THIS INCLUDES...  
BROOKFIELD ZOO...LINCOLN PARK ZOO...TRITON COLLEGE...UNIVERSITY OF
CHICAGO...HAWTHORNE PARK...SOLDIER FIELD...UNIVERSITY OF ILLINOIS
CHICAGO...US CELLULAR FIELD...IL INSTITUTE OF TECHNOLOGY...WRIGLEY
FIELD...THE LOOP...MUSEUM OF SCIENCE AND INDUSTRY...MUSEUM CAMPUS...
AND NORTHERLY ISLAND.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

BE ESPECIALLY CAUTIOUS AT NIGHT WHEN IT IS HARDER TO RECOGNIZE THE
DANGERS OF FLOODING.

&&

LAT...LON 4177 8757 4178 8801 4188 8802 4198 8765
      4197 8763 4196 8764 4191 8762 4190 8762
      4190 8760 4188 8762 4187 8762 4187 8761
      4185 8761 4180 8758 4178 8757 4178 8756

$$

CMS
4 follow-up statements
450 
WGUS73 KLOT 180334
FFSLOT

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1034 PM CDT MON AUG 17 2015

ILC031-043-180830-
/O.CON.KLOT.FF.W.0035.000000T0000Z-150818T0830Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
COOK IL-DUPAGE IL-
1034 PM CDT MON AUG 17 2015

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 330 AM CDT FOR
EAST CENTRAL COOK AND EAST CENTRAL DUPAGE COUNTIES...

AT 1030 PM CDT...DOPPLER RADAR INDICATED THUNDERSTORMS PRODUCING
HEAVY RAIN ACROSS THE WARNED AREA. UP TO THREE INCHES OF RAIN HAVE 
ALREADY FALLEN. AN ADDITIONAL HALF INCH OF RAIN IS POSSIBLE THROUGH
MIDNIGHT. FLASH FLOODING IS EXPECTED TO BEGIN SHORTLY.

SEVERAL VIADUCTS WERE REPORTED FLOODED BETWEEN ROOSEVELT ROAD AND 
NORTH AVENUE.

SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE...
CHICAGO...CICERO...BERWYN...OAK PARK...DOWNERS GROVE...ELMHURST...
LOMBARD...WESTMONT...MAYWOOD...VILLA PARK...BROOKFIELD...FRANKLIN
PARK...HINSDALE...WESTCHESTER...LA GRANGE...FOREST PARK...RIVER
FOREST...SUMMIT...LYONS AND BURR RIDGE.

INCLUDING THE FOLLOWING INTERSTATES...
 I-55 BETWEEN MILE MARKERS 281 AND 294.
 I-88 BETWEEN MILE MARKERS 134 AND 140.
 I-94 BETWEEN MILE MARKERS 45 AND 59.
 I-290 BETWEEN MILE MARKERS 14 AND 29.
 I-294 BETWEEN MILE MARKERS 45 AND 59.

THIS INCLUDES...  
BROOKFIELD ZOO...LINCOLN PARK ZOO...TRITON COLLEGE...UNIVERSITY OF
CHICAGO...HAWTHORNE PARK...SOLDIER FIELD...UNIVERSITY OF ILLINOIS
CHICAGO...US CELLULAR FIELD...IL INSTITUTE OF TECHNOLOGY...WRIGLEY
FIELD...THE LOOP...MUSEUM OF SCIENCE AND INDUSTRY...MUSEUM CAMPUS...
AND NORTHERLY ISLAND.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

BE ESPECIALLY CAUTIOUS AT NIGHT WHEN IT IS HARDER TO RECOGNIZE THE
DANGERS OF FLOODING.

TURN AROUND...DONT DROWN WHEN ENCOUNTERING FLOODED ROADS. MOST FLOOD
DEATHS OCCUR IN VEHICLES.

&&

LAT...LON 4177 8757 4178 8801 4188 8802 4198 8765
      4197 8763 4196 8764 4191 8762 4190 8762
      4190 8760 4188 8762 4187 8762 4187 8761
      4185 8761 4180 8758 4178 8757 4178 8756

$$

CMS
262 
WGUS73 KLOT 180450
FFSLOT

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1150 PM CDT MON AUG 17 2015

ILC031-043-180830-
/O.CON.KLOT.FF.W.0035.000000T0000Z-150818T0830Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
COOK IL-DUPAGE IL-
1150 PM CDT MON AUG 17 2015

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 330 AM CDT FOR
EAST CENTRAL COOK AND EAST CENTRAL DUPAGE COUNTIES...

AT 1147 PM CDT...DOPPLER RADAR INDICATED THUNDERSTORMS PRODUCING
HEAVY RAIN ACROSS THE WARNED AREA. UP TO THREE INCHES OF RAIN HAVE 
ALREADY FALLEN. AN ADDITIONAL HALF INCH TO INCH OF RAIN IS POSSIBLE 
THROUGH THE NEXT FEW HOURS.

SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE...
CHICAGO...CICERO...BERWYN...OAK PARK...DOWNERS GROVE...ELMHURST...
LOMBARD...WESTMONT...MAYWOOD...VILLA PARK...BROOKFIELD...FRANKLIN
PARK...HINSDALE...WESTCHESTER...LA GRANGE...FOREST PARK...RIVER
FOREST...SUMMIT...LYONS AND BURR RIDGE.

INCLUDING THE FOLLOWING INTERSTATES...
 I-55 BETWEEN MILE MARKERS 281 AND 294.
 I-88 BETWEEN MILE MARKERS 134 AND 140.
 I-94 BETWEEN MILE MARKERS 45 AND 59.
 I-290 BETWEEN MILE MARKERS 14 AND 29.
 I-294 BETWEEN MILE MARKERS 45 AND 59.

THIS INCLUDES...  
BROOKFIELD ZOO...LINCOLN PARK ZOO...TRITON COLLEGE...UNIVERSITY OF
CHICAGO...HAWTHORNE PARK...SOLDIER FIELD...UNIVERSITY OF ILLINOIS
CHICAGO...US CELLULAR FIELD...IL INSTITUTE OF TECHNOLOGY...WRIGLEY
FIELD...THE LOOP...MUSEUM OF SCIENCE AND INDUSTRY...MUSEUM CAMPUS...
AND NORTHERLY ISLAND.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

BE ESPECIALLY CAUTIOUS AT NIGHT WHEN IT IS HARDER TO RECOGNIZE THE
DANGERS OF FLOODING.

TURN AROUND...DONT DROWN WHEN ENCOUNTERING FLOODED ROADS. MOST FLOOD
DEATHS OCCUR IN VEHICLES.

&&

LAT...LON 4177 8757 4178 8801 4188 8802 4198 8765
      4197 8763 4196 8764 4191 8762 4190 8762
      4190 8760 4188 8762 4187 8762 4187 8761
      4185 8761 4180 8758 4178 8757 4178 8756

$$

ENDERLEN
147 
WGUS73 KLOT 180617
FFSLOT

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
117 AM CDT TUE AUG 18 2015

ILC031-043-180830-
/O.CON.KLOT.FF.W.0035.000000T0000Z-150818T0830Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
COOK IL-DUPAGE IL-
117 AM CDT TUE AUG 18 2015

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 330 AM CDT FOR
EAST CENTRAL COOK AND EAST CENTRAL DUPAGE COUNTIES...

AT 115 AM CDT...DOPPLER RADAR INDICATED LIGHT TO MODERATE RAIN OVER 
THE FLASH FLOOD WARNING AREA. EARLIER THIS EVENING...THUNDERSTORMS  
ACROSS THE WARNED AREA PRODUCED UP TO THREE INCHES OF RAIN. UP TO AN 
ADDITIONAL HALF INCH OF RAIN IS EXPECTED OVERNIGHT.

SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE...
CHICAGO...CICERO...BERWYN...OAK PARK...DOWNERS GROVE...ELMHURST...
LOMBARD...WESTMONT...MAYWOOD...VILLA PARK...BROOKFIELD...FRANKLIN
PARK...HINSDALE...WESTCHESTER...LA GRANGE...FOREST PARK...RIVER
FOREST...SUMMIT...LYONS AND BURR RIDGE.

INCLUDING THE FOLLOWING INTERSTATES...
 I-55 BETWEEN MILE MARKERS 281 AND 294.
 I-88 BETWEEN MILE MARKERS 134 AND 140.
 I-94 BETWEEN MILE MARKERS 45 AND 59.
 I-290 BETWEEN MILE MARKERS 14 AND 29.
 I-294 BETWEEN MILE MARKERS 45 AND 59.

THIS INCLUDES...  
BROOKFIELD ZOO...LINCOLN PARK ZOO...TRITON COLLEGE...UNIVERSITY OF
CHICAGO...HAWTHORNE PARK...SOLDIER FIELD...UNIVERSITY OF ILLINOIS
CHICAGO...US CELLULAR FIELD...IL INSTITUTE OF TECHNOLOGY...WRIGLEY
FIELD...THE LOOP...MUSEUM OF SCIENCE AND INDUSTRY...MUSEUM CAMPUS...
AND NORTHERLY ISLAND.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

BE ESPECIALLY CAUTIOUS AT NIGHT WHEN IT IS HARDER TO RECOGNIZE THE
DANGERS OF FLOODING.

TURN AROUND...DONT DROWN WHEN ENCOUNTERING FLOODED ROADS. MOST FLOOD
DEATHS OCCUR IN VEHICLES.

&&

LAT...LON 4177 8757 4178 8801 4188 8802 4198 8765
      4197 8763 4196 8764 4191 8762 4190 8762
      4190 8760 4188 8762 4187 8762 4187 8761
      4185 8761 4180 8758 4178 8757 4178 8756

$$

ENDERLEN
887 
WGUS73 KLOT 180827
FFSLOT

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
327 AM CDT TUE AUG 18 2015

ILC031-043-180836-
/O.EXP.KLOT.FF.W.0035.000000T0000Z-150818T0830Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
COOK IL-DUPAGE IL-
327 AM CDT TUE AUG 18 2015

...THE FLASH FLOOD WARNING FOR EAST CENTRAL COOK AND EAST CENTRAL
DUPAGE COUNTIES WILL EXPIRE AT 330 AM CDT...

ALTHOUGH LIGHT TO LOCALLY MODERATE RAIN WILL BE POSSIBLE ACROSS THE 
WARNED AREA MAINLY PRIOR TO SUNRISE THIS MORNING...HEAVY RAINFALL 
HAS ENDED AND WATER WILL CONTINUE TO RECEDE.

LAT...LON 4177 8757 4178 8801 4188 8802 4198 8765
      4197 8763 4196 8764 4191 8762 4190 8762
      4190 8760 4188 8762 4187 8762 4187 8761
      4185 8761 4180 8758 4178 8757 4178 8756

$$

RATZER

What forecasters said that day

The local office's own words before this flash flood warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Chicago, IL wrote its last area forecast discussion before this flash flood warning went out at Aug 17, 9:21 PM CDT, 13 minutes earlier.

Area forecast discussion, Aug 17, 9:21 PM CDT, 13 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
921 PM CDT MON AUG 17 2015

.UPDATE...
847 PM CDT

THUNDERSTORMS CONTINUE TO FIRE THIS EVENING ALONG VARIOUS
BOUNDARIES. THE MAIN BOUNDARY EXTENDS FROM CENTRAL COOK COUNTY
THROUGH SOUTHERN DUPAGE INTO NORTHERN KENDALL. LATEST RAP
ANALYSIS INDICATES WE HAVE AROUND 500 J/KG OF CAPE TO WORK WITH
ALONG THE BOUNDARY SO ADDITIONAL ISOLATED TO SCATTERED STORMS ARE
POSSIBLE. THIS IS ESPECIALLY TRUE AS THE CURRENT STORMS PRODUCE
THEIR OWN BOUNDARIES. WITH LONG SKINNY CAPE VALUES IN FORECAST AND
00Z SOUNDINGS...EXPECTING ONLY THE STRONGEST STORMS TO PRODUCE
WIND GUSTS UP TO 50-60 MPH AND SMALL HAIL. ALL STORMS HOWEVER WILL
PRODUCE TORRENTIAL RAINFALL. THUS FAR MOST OF THE STORMS HAVE
EITHER BEEN MOVING OR WEAKENING JUST FAST ENOUGH TO AVOID FLOODING
ISSUES...BUT WILL CONTINUE TO MONITOR FOR TRAINING STORMS THAT
COULD PRODUCE FLASH FLOODING AND STANDING WATER.

STILL HAVE LOW CONFIDENCE IN EXACTLY HOW THE REST OF THE EVENING
WILL PROGRESS IN REGARDS TO STORMS. THE HRRR HAS DONE A VERY GOOD
JOB AT CAPTURING MOST OF WHAT HAS HAPPENED THUS FAR SO POP
FORECAST IS MOSTLY BASED OFF OF IT. EXPECTING MORE SCATTERED PULSE
CONVECTION ALONG THE OUTFLOW BOUNDARIES WHILE THE AREA OF
CONVECTION OVER WESTERN IL SPREADS EAST. THINKING THE STORMS OVER
WESTERN IL WILL WEAKEN AS THEY SHIFT EAST...BUT MORE STORMS WILL
PROBABLY FORM ALONG ANY OUTFLOW BOUNDARIES THE ORIGINAL STORMS
PRODUCE. IN ADDITION..A SHORTWAVE TROUGH IS OVER EASTERN IOWA SO
THINKING THAT WILL HELP FORCE WAVES OF CONVECTION THROUGH THE
NIGHT. HAD A VERY DIFFICULT TIME BEING MORE DETERMINISTIC IN MY
FORECAST SIMPLY BECAUSE OF THE MESOSCALE NATURE OF THE STORMS.
THEREFORE HAVE HIGH CONFIDENCE IN SCATTERED STORMS MAINLY
NORTHWEST OF A DE MOTTE THROUGH GIBSON CITY LINE...BUT LOW
CONFIDENCE IN EXACT TIMING AND COVERAGE AT ANY GIVEN TIME.

WITH THE AMPLE MOISTURE FROM THE STORMS...KEPT PATCHY FOG GOING
AFTER MIDNIGHT.

JEE

&&

.SHORT TERM...
340 PM CDT

THROUGH TUESDAY...

SCATTERED SHOWERS AND THUNDERSTORMS CONTINUE THIS AFTERNOON. SEVERAL
OF THE STRONGER STORMS HAVE REPORTED WIND GUSTS AROUND 50 MPH AND
SMALL HAIL...ALONG WITH MODERATE TO HEAVY DOWNPOURS AND LIKELY
LOCALLY 1 INCH PLUS RAINFALL TOTALS.

THIS ACTIVITY IS COURTESY OF SEVERAL FEATURES...THE FIRST AN UPPER
LEVEL DISTURBANCE PUSHING INTO CENTRAL INDIANA WITH A WELL DEFINED
CLOSED CIRCULATION ON WATER VAPOR SATELLITE IMAGERY. THE SECOND IS A
COLD FRONT STRETCHED SOUTHWEST FROM NORTHERN LAKE MICHIGAN...THROUGH
CENTRAL WISCONSIN...THEN ORIENTED WEST-EAST IN MOST OF IOWA. SPC
MESOANALYSIS SHOWS MODERATE INSTABILITY WITH GOOD LOW LEVEL LAPSE
RATES...BUT POOR SHEAR...AND MODEST PW VALUES. THEREFORE LOCALLY
HEAVY RAINFALL AND GUSTY WINDS WILL REMAIN THE PREDOMINANT HAZARDS
THROUGH THE AFTERNOON AND EARLY EVENING HOURS. THESE STORMS ARE
PRODUCING OUTFLOW BOUNDARIES THAT WILL LOCALLY INCREASE
CONVERGENCE SUGGESTING SCATTERED STORMS REMAIN POSSIBLE AREA-WIDE.

WHILE THE CONVECTIVE EVOLUTION IS STILL A BIT UNCERTAIN...EXPECT A
DIURNAL DECREASE IN THE COVERAGE AWAY FROM THE COLD FRONT AS THE
UPPER LEVEL LOW ENTERS INDIANA EXITS TO THE EAST...ESPECIALLY INTO
EASTERN ILLINOIS AND NORTHWEST INDIANA. ADDITIONALLY...MODEL
GUIDANCE STALLS THE FRONT OUT ALONG A DUBUQUE TO ROCKFORD TO
MILWAUKEE LINE. THE NEXT SET OF DISTURBANCES PROPAGATE PARALLEL TO
THE COLD FRONTAL BOUNDARY...THUS HAVE RETAINED HIGHEST POPS IN NORTH
CENTRAL ILLINOIS AND ALONG THE WISCONSIN BORDER. A TRAILING
DISTURBANCE IN WESTERN IOWA WILL MOVE THROUGH THE AREA OVERNIGHT
WHICH MAY ALLOW SOME FURTHER EASTWARD PROGRESSION OVERNIGHT.

HEIGHT RISES AND SUBSIDENCE IN WAKE OF THE DEPARTING DISTURBANCE BUT
BROAD SW MOIST LOWER LEVEL FLOW SUPPORTS LOWER POPS BUT A QUIETER
PERIOD IN GENERAL. A STRONG UPPER LEVEL LOW WILL BE WORKING EASTWARD
THROUGH THE CENTRAL PLAINS ON TUESDAY. WHILE THE STRONGEST STORMS
APPEAR TO BE IN IOWA...SOME MAY SNEAK INTO OUR AREA AS WELL LATER IN
THE DAY...BUT MORE LIKELY IN THE EVENING. WEAK INSTABILITY WILL BE
PRESENT DURING THE DAY COUPLED WITH INCREASING SHEAR AND MAY SUPPORT
SCATTERED DEVELOPMENT AGAIN DURING THE AFTERNOON.

KMD

&&

.LONG TERM...
310 PM CDT

TUESDAY NIGHT THROUGH THURSDAY...

THE PERIOD WILL BEGIN FAIRLY ACTIVE AS A NOW CLOSED UPPER LEVEL
SYSTEM CONTINUES TO SLOWLY PROGRESS EAST THROUGH THE NORTHERN
PLAINS AND UPPER MIDWEST. GUIDANCE IN FAIR AGREEMENT WITH OVERALL
EVOLUTION/PLACEMENT OF THIS SYSTEM AS WELL SEVERAL IMPULSES
LIFTING NORTHEAST ACROSS THE CWA/REGION...WHILE SURFACE LOW AND
BOUNDARY REMAIN WELL TO THE NORTHWEST AND WEST DURING THIS TIME.
ALTHOUGH PLACEMENT OF STRONGER AND MORE WIDESPREAD THUNDERSTORM
DEVELOPMENT WILL INITIALLY BE SITUATED WEST OF THE
CWA...INCREASING MOISTURE AND INSTABILITY OUT AHEAD OF THIS SYSTEM
TUESDAY/TUESDAY NIGHT WHILE PERSISTENT FORCING IS PRESENT COULD
ALLOW FOR SCATTERED DEVELOPMENT ACROSS THE CWA. FOCUS WILL THEN
SHIFT TOWARDS MORE WIDESPREAD DEVELOPMENT APPROACHING OUT AHEAD OF
EASTWARD MOVING FRONTAL BOUNDARY OVER IOWA. THESE
THUNDERSTORMS...DEVELOPING THROUGHOUT THE DAY TUESDAY...WILL BE
APPROACHING THE CWA BY THE MID TO LATE EVENING TIME FRAME. WITH
PERSISTENT FORCING THROUGHOUT THE NIGHT...WOULD EXPECT SHOWERS AND
THUNDERSTORMS TO BE POSSIBLE OVER MUCH OF THE CWA. ALTHOUGH
CONFIDENCE IS HIGHER WITH COVERAGE...CONFIDENCE IS LOWER WITH
REGARD TO INTENSITY OF THESE STORMS. QUESTIONS AS TO HOW MUCH THE
ATMOSPHERE WILL DESTABILIZE ON TUESDAY WILL PLAY A FACTOR WITH
INTENSITY MAINTAINING ITSELF WEDNESDAY EVENING. DO THINK AT LEAST
A FEW/ISOLATED STRONGER STORMS WILL BE POSSIBLE...BUT WILL NEED TO
MONITOR FOR POSSIBLE HIGHER COVERAGE OF THESE STRONGER STORMS.

WHILE FRONTAL BOUNDARY WILL CONTINUE TO PUSH EAST WEDNESDAY
MORNING...THUNDERSTORM CHANCES WILL BE ENDING FROM WEST TO EAST
WITH THE ARRIVAL OF MUCH DRIER AIR ON BACKSIDE OF THIS SYSTEM.
HOWEVER...THERE IS SOME VARIABILITY WITH HOW QUICKLY THIS FRONT
PUSHES THROUGH. WITH THIS SYSTEM CLOSING ITSELF OFF...I AM A
LITTLE CONCERNED THAT A MORE PREFERRED SOLUTION WOULD BE FOR A
SLOWER TIME FRAME. IF THIS WERE TO OCCUR...THEN THERE WOULD BE AN
ADDITIONAL CHANCE FOR STRONG TO SEVERE THUNDERSTORMS ACROSS THE
EASTERN CWA WEDNESDAY AS MOISTURE/INSTABILITY WOULD CONTINUE TO
STREAM NORTHWARD OUT AHEAD OF IT. HOWEVER...WOULD THINK ALREADY
PRESENT CLOUD COVER AND PRECIP WOULD LIMIT HOW UNSTABLE THE CWA
WOULD BE...WITH BETTER INSTABILITY LIKELY STAYING EAST OF THE CWA.
THUNDERSTORM CHANCES WILL LIKELY DIMINISH FROM WEST TO EAST IN THE
AFTERNOON AND ALTHOUGH PRECIP CHANCES MAY LINGER IN THE
EVENING...THUNDER SHOULD STAY TO THE EAST. HIGH TEMPERATURES ON
WEDNESDAY WILL LIKELY OCCUR EARLY IN THE DAY WEDNESDAY AND WHILE
STRONGER WESTERLY WINDS INCREASE INTO THE AFTERNOON. DESPITE SOME
TIMING DIFFERENCE WITH THE EVOLUTION OF THIS LARGE SYSTEM...WITH
DRIER AIR WORKING IN AND BETTER FORCING EXITING...THURSDAY IS
APPEARING TO BE DRY.

RODRIGUEZ

THURSDAY NIGHT THROUGH MONDAY

THE MAIN POINT OF INTEREST FOR THE REST OF THIS WEEK AND INTO THE
WEEKEND IS AN UPPER LEVEL DISTURBANCE AND ASSOCIATED SFC LOW.
WATER VAPOR SATELLITE SHOWS A MID-LEVEL TROUGH DEVELOPING OVER THE
DAKOTAS THAT WILL PROGRESS EAST THROUGH THE UPPER GREAT LAKES
REGION THE NEXT COUPLE OF DAYS. BOTH NAM AND GFS GUIDANCE ARE IN
RATHER GOOD AGREEMENT WITH THE TIMING AND INTENSITY OF THIS
DISTURBANCE. THIS TAKES THE CENTER OF THE LOW NORTH OF THE CWA
THROUGH MN AND WI. POPS ARE PROBABLE WITH THIS SETUP WITH EMBEDDED
WAVES WITHIN THE TROUGH, HOWEVER THERE IS UNCERTAINTY AS TO THE
AMOUNT OF POPS THE AREA WILL SEE WITH THIS DISTURBANCE. SATURDAY
LOOKS TO BE THE FAVORABLE DAY FOR CONVECTION WITH AN ISOLATED
THUNDERSTORM. COVERAGE OF TSRA WILL LIKELY BE SMALL. EXPECT TEMPS
TO DROP WITH FROPA BUT RECOVER BACK INTO THE 80S WITH SWLY FLOW AT
THE SFC. DEWPOINTS LOOK TO STAY PUT IN THE LOWER TO MID 60S. THE
SFC LOW WILL LEAD TO DEVELOPMENT OF STRONG PRESSURE GRADIENT
FAVORING STRONG WIND GUSTS AS THIS DISTURBANCE PROGRESSES ACROSS
THE REGION.

KRULL

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 00Z...

* CHANCE OF TSRA MID/LATE THIS EVENING.
* CHANCE OF TSRA OVERNIGHT/TUESDAY MORNING.
* CHANCE OF TSRA TUESDAY EVENING.
* POSSIBLE MVFR CIGS/VIS OVERNIGHT/TUESDAY MORNING. CMS

//DISCUSSION...UPDATED 00Z...

PRIMARY FORECAST CONCERN/CHALLENGE THRU THE PERIOD IS THE CHANCE
AND TIMING OF THUNDERSTORMS. OVERALL...FAIRLY LOW CONFIDENCE WITH
CONVECTIVE TRENDS. CURRENT ACTIVITY HAS REMAINED OUTSIDE OF THE
IMMEDIATE CHICAGO METRO AREA BUT ACTIVITY TO THE SOUTH AND WEST
MAY HOLD TOGETHER TO REACH THE CHICAGO AREA BY 02Z. MOVED UP THE
VICINITY TIMING BUT TRENDS WILL NEED TO BE MONITORED. GUSTY/
ERRATIC WINDS CAN BE EXPECTED IF ANY THUNDERSTORMS DO REACH THE
TERMINALS. ACTIVITY THIS EVENING WILL LIKELY HAVE SOME IMPACT ON
ACTIVITY OVERNIGHT INTO TUESDAY MORNING...BUT ANOTHER PERIOD OF
THUNDERSTORMS IS POSSIBLE TOWARD DAYBREAK TUESDAY. BEYOND THIS...
IT APPEARS MUCH OF THE DAYTIME TUESDAY COULD BE RATHER QUIET...AT
LEAST THRU EARLY AFTERNOON. CONVECTION IS LIKELY TO DEVELOP WEST
OF THE TERMINALS DURING THE AFTERNOON AND THEN SPREAD ACROSS THE
AREA LATE IN THE AFTERNOON OR MORE LIKELY DURING THE EVENING.

WITH TODAYS RAIN AND LIGHT WINDS OVERNIGHT...AS TEMPS COOL TOWARD
THE DEWPOINTS...COULD SEE SOME PATCHY FOG ESPECIALLY IN THE
FAVORED/OUTLYING AREAS IN ADDITION TO MVFR CIGS. CONFIDENCE ON HOW
WIDESPREAD FOG AND CIGS MAY BECOME IS LOW. TRENDS WILL NEED TO BE
MONITORED AGAIN OVERNIGHT. ANY CIGS/FOG THAT DO DEVELOP SHOULD
LIFT AND SCATTER MID/LATE TUESDAY MORNING.

LIGHT SOUTHWESTERLY WINDS THIS EVENING WILL LIKELY BECOME VARIABLE
OVERNIGHT AND THEN TURN SOUTHEASTERLY TUESDAY MORNING. SPEEDS MAY
APPROACH 10KTS DURING THE AFTERNOON. CMS

//ORD AND MDW CONFIDENCE...UPDATED 00Z...

* LOW FOR TSRA CHANCES/TIMING THRU THE PERIOD.
* LOW FOR MVFR CIGS/VIS OVERNIGHT/TUESDAY MORNING. CMS

//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...

* WEDNESDAY...CHANCE OF TSRA. STRONG/GUSTY SOUTHWEST WINDS.
* THURSDAY...DRY/VFR. STRONG/GUSTY WESTERLY WINDS.
* FRIDAY...DRY/VFR. SOUTH/SOUTHWEST WINDS.
* SATURDAY...DRY/VFR. SOUTH/SOUTHEAST WINDS.
* SUNDAY...CHANCE OF TSRA. SOUTHWEST WINDS.

&&

.MARINE...
344 PM CDT

VARYING WINDS ACROSS THE LAKE THIS AFTERNOON ARE DUE TO LINGERING
BOUNDARY SITUATED OVER THE LAKE WHILE SURFACE LOW/TROUGH REMAINS
TO THE WEST. THESE VARYING WINDS WILL LIKELY PERSIST ON TUESDAY
AND INTO A PORTION OF TUESDAY NIGHT...BEFORE WINDS ACROSS THE
ENTIRE LAKE TURN MORE SOUTHERLY TUESDAY NIGHT INTO WEDNESDAY. THIS
WILL BE IN RESPONSE TO APPROACHING AND STRENGTHENING SURFACE LOW
OVER THE UPPER MIDWEST. EXPECT SPEEDS TO BE INCREASING TUESDAY
NIGHT BUT EXPECT SPEEDS TO REALLY RAMP UP ON WEDNESDAY AND
ESPECIALLY WEDNESDAY NIGHT AS THIS LOW FURTHER
STRENGTHENS/APPROACHES. HAVE MAINTAINED TO 30 KT WINDS ACROSS THE
LAKE...BUT AM A LITTLE CONCERNED THAT A PERIOD OF AT LEAST GALE
FORCE GUSTS WILL BE POSSIBLE...ESPECIALLY WEDNESDAY NIGHT. THESE
STRONGER WINDS WILL LIKELY BE PRESENT ACROSS THE NEARSHORE
WEDNESDAY INTO WEDNESDAY EVENING...BUT THESE HIGHER GUSTS MAY BE
POSSIBLE WELL INTO WEDNESDAY NIGHT. ALTHOUGH THESE STRONGER WINDS
MAY STILL BE OCCURRING THURSDAY MORNING...EXPECT SPEEDS TO BE
LOWERING INTO THE AFTERNOON.

RODRIGUEZ

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&

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

FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
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Hazardous weather outlook, Aug 17, 4:38 PM CDT, 4 hours 56 minutes before
HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
438 PM CDT MON AUG 17 2015

ILZ003>006-008-010>014-019>023-032-033-039-INZ001-002-010-011-019-
182145-
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-
438 PM CDT MON AUG 17 2015

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

.DAY ONE...TONIGHT.

  WEATHER HAZARDS EXPECTED:

 SCATTERED THUNDERSTORMS...THE STRONGEST OF WHICH MAY PRODUCE:

 WIND GUSTS OF 50-60 MPH.
 SMALL HAIL.
 FREQUENT LIGHTNING.
 HEAVY DOWNPOURS WITH LOCALIZED MINOR FLOODING.

  AREAS AFFECTED AND TIMING:

 NORTHERN ILLINOIS THROUGH MID EVENING...AND THEN ALL OF NORTHERN
 ILLINOIS AND NORTHWEST INDIANA AFTER MIDNIGHT.

  DISCUSSION:

 SCATTERED THUNDERSTORMS WILL REMAIN POSSIBLE THROUGH MID EVENING
 AS AN UPPER LEVEL SYSTEM ENCOUNTERS A MOIST AND UNSTABLE
 ENVIRONMENT. WITH INSTABILITY QUICKLY DIMINISHING...EXPECT STORM
 COVERAGE AND INTENSITY TO ALSO QUICKLY DIMINISH THIS EVENING.
 THEN EXPECT ADDITIONAL THUNDERSTORMS TO REMAIN POSSIBLE
 OVERNIGHT AS ANOTHER SYSTEM APPROACHES FROM THE WEST.

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

THERE ARE PERIODIC CHANCES FOR THUNDERSTORMS TUESDAY THROUGH
WEDNESDAY...AND AGAIN SATURDAY THROUGH SUNDAY. A FEW OF THE
THUNDERSTORMS TUESDAY AND WEDNESDAY COULD BECOME STRONG TO SEVERE
AND PRODUCE HEAVY DOWNPOURS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NECESSARY THROUGH TONIGHT.

&&

LMZ740>745-182145-
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-
438 PM CDT MON AUG 17 2015

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

.DAY ONE...TONIGHT.

SCATTERED THUNDERSTORMS ARE POSSIBLE. THE STRONGEST STORMS MAY
PRODUCE GUSTY WINDS AND HEAVY DOWNPOURS.

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

WINDS HAZARDOUS TO SMALL CRAFT ARE LIKELY WEDNESDAY AND WEDNESDAY
NIGHT.

THERE ARE PERIODIC CHANCES FOR THUNDERSTORMS TUESDAY AND
WEDNESDAY...AND AGAIN SATURDAY THROUGH SUNDAY. SOME STRONGER
STORMS MAY PRODUCE GUSTY WINDS AND HEAVY DOWNPOURS TUESDAY
AFTERNOON AND EVENING.

&&

LMZ080-261-362-364-366-563-565-567-669-671-673-675-777-779-868-
870-872-874-876-878-182145-
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-
438 PM CDT MON AUG 17 2015

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

.DAY ONE...TONIGHT.

THUNDERSTORMS ARE POSSIBLE. THE STRONGEST STORMS MAY PRODUCE
GUSTY WINDS AND HEAVY DOWNPOURS.

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

THERE ARE PERIODIC CHANCES FOR THUNDERSTORMS TUESDAY AND
WEDNESDAY...AND AGAIN SATURDAY THROUGH SUNDAY. SOME STRONGER
STORMS MAY PRODUCE GUSTY WINDS AND HEAVY DOWNPOURS TUESDAY
AFTERNOON AND EVENING.

&&

RODRIGUEZ

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

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

In the hours before

Local storm report, Aug 17, 4:41 PM CDT, 4 hours 53 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
441 PM CDT MON AUG 17 2015

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0411 PM     HAIL             NORTHBROOK              42.13N 87.83W
08/17/2015  M0.50 INCH       COOK               IL   AMATEUR RADIO

            HAIL LASTED 4 MINUTES.

&&

ACS
Special weather statement, Aug 17, 4:50 PM CDT, 4 hours 44 minutes before
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
450 PM CDT MON AUG 17 2015

ILZ004-005-011-012-172245-
BOONE IL-KANE IL-MCHENRY IL-DE KALB IL-
450 PM CDT MON AUG 17 2015

...SPECIAL WEATHER STATEMENT FOR NORTHEASTERN DE KALB...BOONE...
MCHENRY AND NORTHERN KANE COUNTIES UNTIL 545 PM CDT...

AT 450 PM CDT...DOPPLER RADAR WAS TRACKING A LINE OF STRONG
THUNDERSTORMS ALONG A LINE EXTENDING FROM SHARON TO NEAR MARENGO TO
NEAR HAMPSHIRE...AND MOVING NORTHEAST AT 20 MPH.

HALF INCH HAIL AND WIND GUSTS UP TO 50 MPH WILL BE POSSIBLE WITH
THESE STORMS.

LOCATIONS IMPACTED INCLUDE...
ELGIN...               CARPENTERSVILLE...     ALGONQUIN...
MCHENRY...             BELVIDERE...           WOODSTOCK...
LOVES PARK...          HARVARD...             ISLAND LAKE...
MARENGO...             GENOA...               WONDER LAKE...
SLEEPY HOLLOW...       EAST DUNDEE...         LAKE IN THE HILLS...
HUNTLEY...             WEST DUNDEE...         GILBERTS...
JOHNSBURG...           LAKEMOOR...

INCLUDING THE FOLLOWING INTERSTATE...
 I-90 BETWEEN MILE MARKERS 26 AND 57.

THIS INCLUDES...
BOONE COUNTY FAIRGROUNDS...MCHENRY COUNTY COLLEGE...MCHENRY COUNTY
FAIRGROUNDS...AND MORAINE HILLS STATE PARK.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TORRENTIAL RAINFALL IS ALSO OCCURRING WITH THESE STORMS...AND MAY
LEAD TO FLASH FLOODING. DO NOT DRIVE YOUR VEHICLE THROUGH FLOODED
ROADWAYS.

&&

LAT...LON 4248 8824 4216 8820 4215 8824 4212 8824
      4196 8850 4212 8879 4230 8894 4239 8894
      4249 8880 4250 8827
TIME...MOT...LOC 2150Z 230DEG 18KT 4249 8872 4227 8854 4208 8846

RODRIGUEZ
Special weather statement, Aug 17, 6:12 PM CDT, 3 hours 22 minutes before
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
612 PM CDT MON AUG 17 2015

ILZ022-023-180000-
WILL IL-KANKAKEE IL-
612 PM CDT MON AUG 17 2015

...SPECIAL WEATHER STATEMENT FOR SOUTHWESTERN WILL AND WESTERN
KANKAKEE COUNTIES UNTIL 700 PM CDT...

AT 611 PM CDT...DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM OVER
LAKEWOOD SHORES...OR NEAR WILMINGTON...MOVING NORTH AT 25 MPH.

HALF INCH HAIL AND WIND GUSTS UP TO 50 MPH WILL BE POSSIBLE WITH THIS
STORM.

LOCATIONS IMPACTED INCLUDE...
JOLIET...              NEW LENOX...           BOURBONNAIS...
MANTENO...             UNIVERSITY PARK...     PEOTONE...
WILMINGTON...          MANHATTAN...           BRAIDWOOD...
MONEE...               ELWOOD...              ROCKDALE...
LAKEWOOD SHORES...     ESSEX...               BONFIELD...
SYMERTON...            IRWIN...               PRESTON HEIGHTS...

INCLUDING THE FOLLOWING INTERSTATES...
 I-57 BETWEEN MILE MARKERS 318 AND 336.
 I-80 BETWEEN MILE MARKERS 130 AND 131.

THIS INCLUDES... CHICAGOLAND SPEEDWAY ROUTE 66 RACEWAY AND KANKAKEE
RIVER STATE PARK.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TORRENTIAL RAINFALL IS ALSO OCCURRING WITH THIS STORM...AND MAY LEAD
TO FLASH FLOODING. DO NOT DRIVE YOUR VEHICLE THROUGH FLOODED
ROADWAYS.

&&

LAT...LON 4115 8823 4152 8814 4144 8774 4103 8795
TIME...MOT...LOC 2311Z 192DEG 23KT 4125 8810

RODRIGUEZ
Special weather statement, Aug 17, 6:15 PM CDT, 3 hours 19 minutes before
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
615 PM CDT MON AUG 17 2015

ILZ003-004-008-011-180000-
BOONE IL-OGLE IL-WINNEBAGO IL-DE KALB IL-
615 PM CDT MON AUG 17 2015

...SPECIAL WEATHER STATEMENT FOR NORTHWESTERN DE KALB...SOUTHWESTERN
BOONE...NORTHEASTERN OGLE AND SOUTHERN WINNEBAGO COUNTIES UNTIL 700
PM CDT...

AT 615 PM CDT...DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM OVER
ROCKFORD AIRPORT...MOVING NORTHEAST AT 25 MPH.

HALF INCH HAIL AND WIND GUSTS UP TO 50 MPH WILL BE POSSIBLE WITH THIS
STORM.

LOCATIONS IMPACTED INCLUDE...
ROCKFORD...            BELVIDERE...           LOVES PARK...
MACHESNEY PARK...      GENOA...               ROCKFORD AIRPORT...
ROSCOE...              POPLAR GROVE...        BYRON...
CHERRY VALLEY...       WINNEBAGO...           KIRKLAND...
KINGSTON...            STILLMAN VALLEY...     TIMBERLANE...
CALEDONIA...           DAVIS JUNCTION...      NEW MILLFORD...

INCLUDING THE FOLLOWING INTERSTATES...
 I-39 BETWEEN MILE MARKERS 108 AND 123.
 I-90 BETWEEN MILE MARKERS 51 AND 73.

THIS INCLUDES...
BOONE COUNTY FAIRGROUNDS...ROCK CUT STATE PARK...ROCK VALLEY
COLLEGE...ROCKFORD AVIATORS BASEBALL...AND ROCKFORD SPEEDWAY.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TORRENTIAL RAINFALL IS ALSO OCCURRING WITH THIS STORM...AND MAY LEAD
TO FLASH FLOODING. DO NOT DRIVE YOUR VEHICLE THROUGH FLOODED
ROADWAYS.

&&

LAT...LON 4245 8891 4216 8871 4215 8871 4215 8870
      4211 8867 4202 8922 4226 8933
TIME...MOT...LOC 2315Z 242DEG 23KT 4220 8911

RODRIGUEZ
Special weather statement, Aug 17, 8:40 PM CDT, 54 minutes before
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
840 PM CDT MON AUG 17 2015

ILZ013-014-180215-
DUPAGE IL-COOK IL-
840 PM CDT MON AUG 17 2015

...SPECIAL WEATHER STATEMENT FOR NORTHEASTERN COOK AND NORTHEASTERN
DUPAGE COUNTIES UNTIL 915 PM CDT...

AT 839 PM CDT...DOPPLER RADAR WAS TRACKING A STRONG THUNDERSTORM OVER
MAYWOOD...MOVING NORTHEAST AT 20 MPH.

HALF INCH HAIL AND WINDS IN EXCESS OF 40 MPH WILL BE POSSIBLE WITH
THIS STORM.

LOCATIONS IMPACTED INCLUDE...
CHICAGO...             CICERO...              EVANSTON...
SKOKIE...              DES PLAINES...         BERWYN...
MOUNT PROSPECT...      OAK PARK...            GLENVIEW...
ELMHURST...            WHEELING...            PARK RIDGE...
ADDISON...             NORTHBROOK...          WILMETTE...
MAYWOOD...             MORTON GROVE...        VILLA PARK...
BROOKFIELD...          FRANKLIN PARK...

INCLUDING THE FOLLOWING INTERSTATES...
 I-55 BETWEEN MILE MARKERS 284 AND 292.
 I-88 BETWEEN MILE MARKERS 136 AND 140.
 I-94 NEAR MILE MARKER 28...AND BETWEEN MILE MARKERS 30 AND 53.
 I-290 BETWEEN MILE MARKERS 11 AND 29.
 I-294 NEAR MILE MARKER 28...AND BETWEEN MILE MARKERS 30 AND 53.

THIS INCLUDES...
BROOKFIELD ZOO...LINCOLN PARK ZOO...LOYOLA UNIVERSITY...OAKTON
COMMUNITY COLLEGE...TRITON COLLEGE...HAWTHORNE PARK...NORTHEASTERN
ILLINOIS UNIVERSITY...NORTHWESTERN UNIVERSITY...UNIVERSITY OF
ILLINOIS CHICAGO...AND WRIGLEY FIELD.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TORRENTIAL RAINFALL IS ALSO OCCURRING WITH THIS STORM...AND MAY LEAD
TO FLASH FLOODING. DO NOT DRIVE YOUR VEHICLE THROUGH FLOODED
ROADWAYS.

&&

LAT...LON 4214 8775 4210 8771 4208 8768 4206 8767
      4203 8767 4201 8766 4198 8765 4197 8763
      4196 8764 4191 8762 4190 8762 4177 8769
      4184 8799 4215 8791
TIME...MOT...LOC 0139Z 203DEG 20KT 4188 8785

CMS
Local storm report, Aug 17, 9:14 PM CDT, 20 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
914 PM CDT MON AUG 17 2015

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0845 PM     MARINE TSTM WIND 4 NE CHICAGO            41.92N 87.57W
08/17/2015  M47 MPH          LMZ741             IL   C-MAN STATION

            47 MPH GUST AT HARRISON DEVER CRIB.

&&

The office that day

Everything else NWS Chicago, IL issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 17, 8:40 PM CDTSpecial Weather StatementLOTCook35 min
Aug 17, 8:46 PM CDTSpecial Marine WarningLOT59 min
Aug 17, 9:08 PM CDTAreal Flood AdvisoryLOTCook, DuPage3 hr
Aug 18, 3:41 AM CDTAreal Flood AdvisoryLOTCook, Kankakee, Livingston, Will6 hr
Aug 18, 4:03 AM CDTAreal Flood AdvisoryLOTKankakee6 hr
Aug 18, 7:55 AM CDTAreal Flood AdvisoryLOTFord, Iroquois, Livingston3 hr
Aug 18, 4:18 PM CDTTornado WarningLOTLivingston42 min
Aug 18, 5:07 PM CDTTornado Warning Tornado observedLOTLivingston38 min
Aug 18, 6:19 PM CDTSevere Thunderstorm WarningLOTGrundy, Kendall, LaSalle, Livingston56 min
Aug 18, 6:53 PM CDTSpecial Weather StatementLOTGrundy, Kendall, Livingston52 min

Nearby

Flash Flood Warnings in Illinois, 2015Every flash flood warning in 2015

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.