Alert archive / Illinois / Severe Thunderstorm Warnings in 2012

Severe Thunderstorm Warning 88, NWS Chicago, IL

July 24, 2012Lake County, Indiana; 6 counties in Illinois

NWS Chicago, IL issued this severe thunderstorm warning at Jul 24, 2012, 6:09 AM CDT for Lake County, Indiana; 6 counties in Illinois. It was in force for 66 min. 18 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
Jul 24, 2012, 6:09 AM CDT (11:09 UTC)
Expired
Jul 24, 2012, 7:15 AM CDT
In force
66 min
Issued by
NWS Chicago, IL
Area
Storm-based polygon
Hail
0.5 in
Wind
70.0 mph

Counties Cook County, IL, DuPage County, IL, Grundy County, IL, Kankakee County, IL, Kendall County, IL, Will County, IL, Lake County, IN

The radar

The Chicago radar (KLOT), 39 km from the middle of the area, began a volume at 11:11 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
Jul 24, 6:18 AM CDTTSTM WND DMGOak Brook, IL5 INCH DIAMETER TREE SHEARED OFF. 30 FEET IN LENGTH.
Jul 24, 6:20 AM CDTTSTM WND DMG5 Sw Plainfield, IL2 TREES SPLIT NEAR SOUTHWORTH CIRCLE AND TOWNSEND BLVD.
Jul 24, 6:20 AM CDTTSTM WND DMGMinooka, ILTREES AND BRANCHES DOWN ON THE NORTH SIDE OF MINOOKA. TIME ESTIMATED.
Jul 24, 6:24 AM CDTTSTM WND DMG4 S Naperville, ILTREE DOWN AT WASHINGTON STREET AND 87TH STREET.
Jul 24, 6:25 AM CDTTSTM WND DMGOak Brook, ILMEASURED 45 MPH GUST - 5 INCH TREE LIMB DOWN.
Jul 24, 6:25 AM CDTTSTM WND GST 65Morris, ILMEAURED AT DRESDEN NUCLEAR POWER STATION. OUTFLOW WINDS FROM NEARBY THUNDERSTORMS.
Jul 24, 6:30 AM CDTTSTM WND GST 70Joliet, IL10 INCH DIAMETER TREE LIMB SNAPPED FROM TREE. TIME ESTIMATED BY RADAR.
Jul 24, 6:32 AM CDTTSTM WND GST 55Romeoville, IL
Jul 24, 6:32 AM CDTTSTM WND GST 61Midway Airport, IL
Jul 24, 6:33 AM CDTTSTM WND GST 65Plainfield, IL
Jul 24, 6:35 AM CDTTSTM WND GST 653 Sw Midway Airport, IL
Jul 24, 6:36 AM CDTTSTM WND GST 60Chicago, ILAUGUSTA AND DAMEN. POWER OUT.
Jul 24, 6:40 AM CDTTSTM WND DMGChicago Ridge, ILAT 103RD STREET AND CENTRAL AVENUE - 1/4 TO 1/2 INCH TREE BRANCHES DOWN.
Jul 24, 6:44 AM CDTTSTM WND DMGOak Forest, ILLIGHT POLE BLOWN DOWN. ESTIMATED 60 MPH WINDS. INTERSTATE 57 AND 167TH ST.
Jul 24, 6:50 AM CDTTSTM WND GST 63Lansing, IL
Jul 24, 6:55 AM CDTTSTM WND DMGBradley, IL12 TO 14 INCH DIAMETER TREE DOWN ON U.S. 45 AT NORTH STREET. TIME ESTIMATED WITH RADAR.
Jul 24, 6:55 AM CDTTSTM WND GST 60Homewood, ILMANY SMALL BRANCHES DOWN.
Jul 24, 7:03 AM CDTTSTM WND GST 75Griffith, INTREE LIMBS DOWN. VERY HEAVY RAIN.

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 17 storm reports to this severe thunderstorm warning; the first came 9 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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

IssuedProductOfficeLasted
Jul 24, 4:47 AM CDTSevere Thunderstorm WatchSPC4 hr

The nearest sounding before it

Lincoln, IL (KILX), launched 00:00Z, 11.2 hours before the alert went out and 190 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 2012-07-24Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 545 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 2012-07-24The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 79 square meters per square second.193958Sfc1 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
545 J/kg
Mixed-layer CIN
-149 J/kg
Mixed-layer LCL
2710 m above ground
0-6 km bulk shear
27 kt
0-1 km storm-relative helicity
79 m²/s²
0-3 km storm-relative helicity
79 m²/s²
Significant tornado parameter
0.0
Supercell composite
2.9

Open this sounding in Storm Lab

The text

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

438 
WUUS53 KLOT 241109
SVRLOT
ILC031-043-063-091-093-197-INC089-241215-
/O.NEW.KLOT.SV.W.0088.120724T1109Z-120724T1215Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
609 AM CDT TUE JUL 24 2012

THE NATIONAL WEATHER SERVICE IN CHICAGO HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  SOUTHEASTERN COOK COUNTY IN NORTHEAST ILLINOIS...
  SOUTHEASTERN DUPAGE COUNTY IN NORTHEAST ILLINOIS...
  NORTHEASTERN GRUNDY COUNTY IN NORTHEAST ILLINOIS...
  KANKAKEE COUNTY IN NORTHEAST ILLINOIS...
  SOUTHERN KENDALL COUNTY IN NORTHEAST ILLINOIS...
  WILL COUNTY IN NORTHEAST ILLINOIS...
  NORTHERN LAKE COUNTY IN NORTHWEST INDIANA...

* UNTIL 715 AM CDT

* AT 606 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING DESTRUCTIVE WINDS
  IN EXCESS OF 70 MPH.  THESE STORMS WERE LOCATED ALONG A LINE
  EXTENDING FROM LAKE FOREST TO MEDINAH TO YORKVILLE...AND MOVING
  SOUTHEAST AT 55 MPH.

* SEVERE THUNDERSTORMS WILL BE NEAR...
  MORRIS...WOODRIDGE...PLAINFIELD AND OAK BROOK AROUND 615 AM CDT.
  MINOOKA...WESTMONT...WESTERN SPRINGS AND WESTCHESTER AROUND 620 AM
  CDT.
  MONTROSE HARBOR...COAL CITY...WILLOW SPRINGS AND SUMMIT AROUND 625
  AM CDT.
  WILMINGTON...DIAMOND AND BRAIDWOOD AROUND 630 AM CDT.

  THIS INCLUDES THE CITY OF CHICAGO.

OTHER LOCATIONS AFFECTED...
ARGONNE NATIONAL LABORATORY...BROOKFIELD ZOO...CHANNAHON STATE
PARK...CHICAGOLAND SPEEDWAY ROUTE 66 RACEWAY...FIRST MIDWEST BANK
AMPHITHEATRE...GOVERNORS STATE UNIVERSITY...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

SEEK SHELTER IN A STURDY STRUCTURE AND STAY AWAY FROM WINDOWS UNTIL
THESE STORMS HAVE PASSED.

&&

LAT...LON 4163 8723 4148 8734 4102 8786 4130 8835
      4148 8857 4199 8775 4208 8768 4197 8763
      4191 8762 4190 8760 4184 8760 4175 8753
      4170 8751 4168 8745 4169 8742 4167 8741
      4165 8742
TIME...MOT...LOC 1108Z 307DEG 47KT 4225 8780 4195 8804
          4163 8834
WIND...HAIL 70MPH <.50IN

$$

BMD
5 follow-up statements
290 
WWUS53 KLOT 241125
SVSLOT

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
625 AM CDT TUE JUL 24 2012

ILC031-043-063-091-093-197-INC089-241215-
/O.CON.KLOT.SV.W.0088.000000T0000Z-120724T1215Z/
KANKAKEE IL-KENDALL IL-WILL IL-GRUNDY IL-DUPAGE IL-COOK IL-LAKE IN-
625 AM CDT TUE JUL 24 2012

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT FOR NORTHERN
LAKE...SOUTHEASTERN COOK...SOUTHEASTERN DUPAGE...NORTHEASTERN
GRUNDY...WILL...SOUTHEASTERN KENDALL AND KANKAKEE COUNTIES UNTIL 715
AM CDT...

AT 619 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING DESTRUCTIVE WINDS
IN EXCESS OF 70 MPH.  THESE STORMS WERE LOCATED ALONG A LINE
EXTENDING FROM 6 MILES NORTHEAST OF KENILWORTH TO WESTCHESTER TO
SHOREWOOD...MOVING SOUTHEAST AT 55 MPH.

IN ADDITION...AT 616 AM CDT WINDS TO 58 MPH WERE REPORTED AT OHARE 
INTERNATIONAL AIRPORT. 

SEVERE THUNDERSTORMS WILL BE NEAR...
  WILMINGTON...BRAIDWOOD...WORTH AND PALOS HILLS AROUND 630 AM CDT.
  LAKEWOOD SHORES...TINLEY PARK...OAK FOREST AND MOKENA AROUND 635 AM
  CDT.
  POSEN...PHOENIX...MATTESON AND MARKHAM AROUND 640 AM CDT.
  UNIVERSITY PARK...THORNTON AND SOUTH HOLLAND AROUND 645 AM CDT.


LAT...LON 4163 8723 4148 8734 4102 8786 4130 8835
      4148 8857 4199 8775 4208 8768 4197 8763
      4191 8762 4190 8760 4184 8760 4175 8753
      4170 8751 4168 8745 4169 8742 4167 8741
      4165 8742
TIME...MOT...LOC 1123Z 307DEG 47KT 4213 8759 4183 8783
          4151 8814
WIND...HAIL 70MPH <.50IN

$$

BMD
833 
WWUS53 KLOT 241136
SVSLOT

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
636 AM CDT TUE JUL 24 2012

ILC031-043-063-091-093-197-INC089-241215-
/O.CON.KLOT.SV.W.0088.000000T0000Z-120724T1215Z/
KANKAKEE IL-KENDALL IL-WILL IL-GRUNDY IL-DUPAGE IL-COOK IL-LAKE IN-
636 AM CDT TUE JUL 24 2012

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT FOR NORTHERN
LAKE...SOUTHEASTERN COOK...SOUTHEASTERN DUPAGE...NORTHEASTERN
GRUNDY...WILL...SOUTHEASTERN KENDALL AND KANKAKEE COUNTIES UNTIL 715
AM CDT...

AT 632 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING DESTRUCTIVE WINDS
IN EXCESS OF 70 MPH.  THESE STORMS WERE LOCATED ALONG A LINE
EXTENDING FROM 11 MILES EAST OF ROGERS PARK TO ENGLEWOOD TO
MANHATTAN...MOVING SOUTHEAST AT 55 MPH.

IN ADDITION...AT 632 AM CDT...WINDS TO 61 MPH WERE REPORTED AT 
MIDWAY AIRPORT.

SEVERE THUNDERSTORMS WILL BE NEAR...
  POSEN...PHOENIX...MATTESON AND MARKHAM AROUND 640 AM CDT.
  UNIVERSITY PARK...THORNTON...SOUTH HOLLAND AND RICHTON PARK AROUND
  645 AM CDT.
  BRADLEY...BOURBONNAIS...STEGER AND SAUK VILLAGE AROUND 650 AM CDT.
  KANKAKEE...BEECHER AND ST. JOHN AROUND 655 AM CDT.


LAT...LON 4163 8723 4148 8734 4102 8786 4130 8835
      4148 8857 4199 8775 4208 8768 4197 8763
      4191 8762 4190 8760 4184 8760 4175 8753
      4170 8751 4168 8745 4169 8742 4167 8741
      4165 8742
TIME...MOT...LOC 1135Z 307DEG 47KT 4203 8742 4173 8766
          4141 8798
WIND...HAIL 70MPH <.50IN

$$

BMD
871 
WWUS53 KLOT 241142
SVSLOT

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
642 AM CDT TUE JUL 24 2012

ILC031-043-063-091-093-197-INC089-241215-
/O.CON.KLOT.SV.W.0088.000000T0000Z-120724T1215Z/
KANKAKEE IL-KENDALL IL-WILL IL-GRUNDY IL-DUPAGE IL-COOK IL-LAKE IN-
642 AM CDT TUE JUL 24 2012

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT FOR NORTHERN
LAKE...SOUTHEASTERN COOK...SOUTHEASTERN DUPAGE...NORTHEASTERN
GRUNDY...WILL...SOUTHEASTERN KENDALL AND KANKAKEE COUNTIES UNTIL 715
AM CDT...

AT 637 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING DAMAGING WINDS IN
EXCESS OF 60 MPH.  THESE STORMS WERE LOCATED ALONG A LINE EXTENDING
FROM 13 MILES EAST OF MONTROSE HARBOR TO CHATHAM TO MANHATTAN...
MOVING SOUTHEAST AT 55 MPH.

IN ADDITION...AT 632 AM CDT...61 MPH WINDS WERE RECORDED AT MIDWAY 
AIRPORT...AND AT 635 AM CDT...65 MPH WINDS WERE RECORDED 3 MILES 
SOUTHWEST OF MIDWAY.

SEVERE THUNDERSTORMS WILL BE NEAR...
  BOURBONNAIS...STEGER...SAUK VILLAGE AND MANTENO AROUND 650 AM CDT.
  KANKAKEE...BRADLEY...BEECHER AND ST. JOHN AROUND 655 AM CDT.
  AROMA PARK AND GRANT PARK AROUND 700 AM CDT.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

SEVERE THUNDERSTORMS PRODUCE DAMAGING WIND IN EXCESS OF 60 MILES PER
HOUR. FOR YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON THE LOWEST
FLOOR OF YOUR HOME OR BUSINESS.

&&

LAT...LON 4163 8723 4148 8734 4102 8786 4130 8835
      4148 8857 4199 8775 4208 8768 4197 8763
      4191 8762 4190 8760 4184 8760 4175 8753
      4170 8751 4168 8745 4169 8742 4167 8741
      4165 8742
TIME...MOT...LOC 1141Z 307DEG 47KT 4198 8734 4169 8758
          4137 8789
WIND...HAIL 60MPH <.50IN

$$

BMD
598 
WWUS53 KLOT 241155
SVSLOT

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
655 AM CDT TUE JUL 24 2012

ILC043-093-241204-
/O.CAN.KLOT.SV.W.0088.000000T0000Z-120724T1215Z/
KENDALL IL-DUPAGE IL-
655 AM CDT TUE JUL 24 2012


...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN DUPAGE AND
SOUTHEASTERN KENDALL COUNTIES IS CANCELLED...

THE LINE OF STORMS WHICH PROMPTED THE WARNING HAVE MOVED OUT OF THE 
WARNED AREA.

LAT...LON 4163 8723 4148 8734 4102 8786 4130 8835
      4154 8809 4191 8762 4190 8760 4184 8760
      4175 8753 4170 8751 4168 8745 4169 8742
      4167 8741 4165 8742
TIME...MOT...LOC 1154Z 307DEG 47KT 4187 8716 4158 8740
          4127 8771

$$

ILC031-063-091-197-INC089-241215-
/O.CON.KLOT.SV.W.0088.000000T0000Z-120724T1215Z/
KANKAKEE IL-WILL IL-GRUNDY IL-COOK IL-LAKE IN-
655 AM CDT TUE JUL 24 2012

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT FOR NORTHERN
LAKE...SOUTHEASTERN COOK...EAST CENTRAL GRUNDY...WILL AND KANKAKEE
COUNTIES UNTIL 715 AM CDT...

AT 650 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING DAMAGING WINDS IN
EXCESS OF 60 MPH.  THESE STORMS WERE LOCATED ALONG A LINE EXTENDING
FROM 19 MILES NORTHWEST OF BEVERLY SHORES TO HAMMOND TO PEOTONE...
MOVING SOUTHEAST AT 55 MPH.

SEVERE THUNDERSTORMS WILL BE NEAR...
  AROMA PARK AND GRANT PARK AROUND 700 AM CDT.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

SEVERE THUNDERSTORMS PRODUCE DAMAGING WIND IN EXCESS OF 60 MILES PER
HOUR. FOR YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON THE LOWEST
FLOOR OF YOUR HOME OR BUSINESS.

&&

LAT...LON 4163 8723 4148 8734 4102 8786 4130 8835
      4154 8809 4191 8762 4190 8760 4184 8760
      4175 8753 4170 8751 4168 8745 4169 8742
      4167 8741 4165 8742
TIME...MOT...LOC 1154Z 307DEG 47KT 4187 8716 4158 8740
          4127 8771
WIND...HAIL 60MPH <.50IN

$$

BMD
262 
WWUS53 KLOT 241215
SVSLOT

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
715 AM CDT TUE JUL 24 2012

ILC031-063-091-197-INC089-241224-
/O.EXP.KLOT.SV.W.0088.000000T0000Z-120724T1215Z/
KANKAKEE IL-WILL IL-GRUNDY IL-COOK IL-LAKE IN-
715 AM CDT TUE JUL 24 2012


...THE SEVERE THUNDERSTORM WARNING FOR NORTHERN LAKE...WILL AND 
KANKAKEE COUNTIES HAS BEEN REISSUED...

PLEASE REFER TO THAT BULLETIN FOR THE LATEST SEVERE WEATHER
INFORMATION...HOWEVER GUSTY WINDS ARE STILL POSSIBLE WITH THESE
THUNDERSTORMS.

REMEMBER...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT FOR
PORTIONS OF LAKE...WILL...AND KANKAKEE COUNTIES...UNTIL 8 AM CDT.

LAT...LON 4163 8723 4148 8734 4102 8786 4130 8835
      4154 8809 4191 8762 4190 8760 4184 8760
      4175 8753 4170 8751 4168 8745 4169 8742
      4167 8741 4165 8742
TIME...MOT...LOC 1214Z 307DEG 47KT 4171 8688 4142 8712
          4111 8743

$$

BMD

What forecasters said that day

The local office's own words before this severe thunderstorm 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 severe thunderstorm warning went out at Jul 24, 5:56 AM CDT, 13 minutes earlier.

Area forecast discussion, Jul 24, 5:56 AM CDT, 13 minutes before
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
556 AM CDT TUE JUL 24 2012

.MESOSCALE DISCUSSION...

ONGOING LINEAR COMPLEX OF SEVERE STORMS HAS A HISTORY OF 50-65 MPH
GUSTS AND OBSERVATIONAL AND ENVIRONMENTAL TRENDS FAVOR THIS TO
CONTINUE THROUGH CHICAGOLAND. OCCASIONAL FINGERS OF 70-75
KT INBOUND VELOCITY DATA CONTINUES TO SHOW UP WITHIN THE STORM
AREA...ALONG WITH PERIODIC DRY PUNCHES AND AN OVERALL TIGHT FRONT
EDGE REFLECTIVITY GRADIENT. ALL OF THESE ARE INDICATIVE OF STRONG
WINDS PUNCHING DOWN TO THE SURFACE. COMPLEX OF STORMS ALSO
APPEARS TO HAVE A WAKE LOW/MESO HIGH ASSOCIATED WITH IT NOW ALONG
WITH THE COLD POOL...EVEN A BETTER SIGN THAT THIS WILL CONTINUE.
THE BRIEF HEAVY RAINFALL RATES MAY ALSO BE PROBLEMATIC FOR PARTS
OF THE CHICAGO METRO AREA DURING THE MORNING COMMUTE.

MTF

&&

.PREV MESOSCALE DISCUSSION...
329 AM CDT

CONVECTION WILL BE MOVING OVER THE NORTHERN AND EASTERN FORECAST
AREA INCLUDING CHICAGO AND ROCKFORD THROUGH MID-MORNING. THERE IS
A CHANCE FOR ISOLATED SEVERE STORMS AND EXCESSIVE RAIN...WITH THE
LATTER PRIMARILY IN THE METRO AREAS.

SEVERAL SHORT WAVES ARE RIDING ATOP THE NORTHERN PERIPHERY OF THE
UPPER LEVEL RIDGE THIS MORNING...INCLUDING ONE MOVING ACROSS
SOUTHERN MN AS OF 3 AM. THIS HAS HELPED TO FOCUS THE ELEVATED
WARM AIR ADVECTION AND IMPROVE THE EFFECTIVE DEEP LAYER SHEAR
/40-45 KT/ IN ADVANCE OF IT. A VEERING LOW-LEVEL JET OF AROUND 40
KT IS ORIENTING MORE NORTHEAST AND SHOULD CONTINUE DOING SO
THROUGH DAYBREAK BEFORE WEAKENING. ALONG THE NOSE OF THIS IS STEEP
ISENTROPIC ASCENT INTO QUITE AN UNSTABLE AIR MASS CHARACTERIZED BY
MUCAPE VALUES OF 1500 TO 3000 J/KG FROM SOUTHWEST WI TO FAR
NORTHERN IL. THE ONGOING CONVECTION IN SOUTHWEST WI HAS GENERALLY
FOLLOWED THE STEERING WINDS NICELY...BUT LATEST SFC OBS AND ARX
PROFILER INDICATED THIS HAS DEVELOPED A COLD POOL AND MAY WORK
MORE SOUTH OF EAST IN THE UPCOMING COUPLE HOURS. EXPECT TO SEE
THIS CONVECTION CONTINUE GIVEN THE ORGANIZATION AND THE
SATELLITE/RADAR/ENVIRONMENTAL TRENDS. SCATTERED CONVECTION MAY
DEVELOP AHEAD OF THIS...SIMILAR TO WHAT HAS BEEN SEEN BEHIND IT
WITHIN THE GENERAL WARM AIR ADVECTION ZONE. SO OVERALL FEEL
CONFIDENT WITH BASICALLY CATEGORICAL POPS FOR A PERIOD THIS
MORNING EAST OF A BYRON TO MORRIS TO FOWLER LINE. THERE HAVE BEEN
NO SEVERE WEATHER REPORTS WITH ONGOING CONVECTION AND JUST ONE
RECENT WARNING THUS FAR. CANNOT RULE OUT A FLARE UP OF AN INTENSE
STORM OR TWO GIVEN THE SHEAR/INSTABILITY SPECTRUM...BUT IT WOULD
SEEM MOST FAVORED PRIOR TO 14Z GIVEN THE PROJECTIONS OF THE LLJ
AND EXPLICIT CONVECTION MODELS WHICH SHOW A RAPID WEAKENING OF THE
DBZ AFTER THAT TIME. HIGH PRECIPITABLE WATER AIR NEAR TWO INCHES
SHOULD MAKE FOR CONTINUE EFFICIENT RAIN PRODUCTION...ALTHOUGH THE
MOST ANY UPSTREAM AUTOMATED SITES HAVE SHOWN IS THREE-QUARTERS OF
AN INCH PER HOUR. THIS MOISTURE MAY ALSO AID IN WATER LOADING FOR
A SEVERE GUST OR TWO. THE CONVECTION IS FAVORED TO SHOW A DOWNWARD
TREND FROM MID TO LATE MORNING WITH A WEAKENING LOW-LEVEL JET AND
ASSOCIATED MOISTURE TRANSPORT.

MTF

&&

.DISCUSSION...
329 AM CDT

FORECAST CHALLENGES AFTER MORNING STORMS ARE CONVECTIVE
REDEVELOPMENT POTENTIAL THIS AFTERNOON AND AGAIN
TONIGHT...FOLLOWED BY HOT WEATHER ON WEDNESDAY.

THE UPPER LEVEL RIDGE WILL CONTINUE TO DOMINATE THE WEATHER FOR
TWO MORE DAYS BEFORE BEING DAMPENED BY AN UPPER LEVEL WAVE
CENTERED OVER ALBERTA THIS MORNING. AT THE SURFACE THIS
MORNING...THE COOL FRONT IS DRAPED FROM WEST-TO-EAST NEAR THE
IL/WI BORDER AND WILL BE USHERED SOUTHWARD IN PART BY CONVECTION
THROUGH THE MORNING. AS HEIGHT FALLS ASSOCIATED WITH THE
AFOREMENTIONED UPPER LEVEL LOW SPREAD EASTWARD OVER THE NORTHERN
PLAINS TONIGHT...FAIRLY STRONG CYCLOGENESIS FOR SUMMERTIME WILL
OCCUR HELPING TO STRENGTHEN THE BOUNDARY AS A WARM FRONT ACROSS
IA INTO CENTRAL IL AND IN. THIS WILL LIKELY EVOLVE NORTH RAPIDLY
EARLY WEDNESDAY PLACING AT LEAST PART IF NOT THE WHOLE AREA IN A
CAPPED AND VERY TOASTY WARM SECTOR. THE COOL FRONT FROM THE LOW
WILL PUSH INTO THE AREA EITHER LATE WEDNESDAY NIGHT OR EARLY
THURSDAY AND SHIFT EASTWARD. A SECONDARY COOL FRONTAL BOUNDARY
WITH DRIER AIR LOOKS TO PASS EARLY FRIDAY BRINGING IN HIGH
PRESSURE TO START THE WEEKEND.

CONCERNS THIS AFTERNOON CENTER ON THE FRONTAL BOUNDARY AND REMNANT
OUTFLOWS. DEW POINTS LAST NIGHT INTO EARLY THIS MORNING IN
IMMEDIATE ADVANCE OF THE SFC FRONT HAVE POOLED IN THE MID 70S.
WITH SOME MORNING RAIN ACTIVITY AND LIMITED MIXING DUE TO RESIDUAL
CLOUD COVER...BELIEVE THAT DEW POINTS WILL NOT DROP MUCH. THIS
SHOULD SUPPORT POOLED MODEST MIXED LAYER INSTABILITY OF 1000 TO
2500 J/KG WHERE SOME HEATING CAN OCCUR. THE CONVERGENCE ALONG ANY
BOUNDARIES LOOKS TO BE FAIRLY WEAK BY AFTERNOON HOWEVER...SO TOUGH
TO SUPPORT ANY POPS HIGHER THAN CHANCE BY AFTERNOON. THIS IS
FURTHER THE CASE WITH SHORT WAVE ENERGY...WHICH IS ALSO
CHALLENGING TO DEDUCE IN GUIDANCE BY AFTERNOON. IT APPEARS CURRENT
WAVE OVER SD EARLY THIS MORNING MAY BE MOVING NEAR THE AREA THIS
AFTERNOON. WITH THE MID-LEVEL JET AXIS OVER THE AREA...DEEP LAYER
SHEAR REMAINS FAVORABLE FOR ISOLATED SEVERE POTENTIAL IN ANY
STORMS THAT CAN DEVELOP. THE MAIN THREAT WOULD SEEM TO BE WIND
WITH ANY ORGANIZED CLUSTERS...ALTHOUGH HAIL AND LOCALLY HEAVY
RAIN ARE CERTAINLY POSSIBLE AS WELL. FOR TEMPERATURES...THE
SOUTHWEST AREA IS FAVORED TO FLIRT WITH THE LOWER 90S
AGAIN...ALTHOUGH CONFIDENCE IS LOWERED SOME BECAUSE OF POTENTIAL
CLOUDS AND OUTFLOW. ONSHORE FLOW WILL KEEP TEMPERATURES COOLER IN
CHICAGO...WHERE SOME PLACES MAY ONLY HOLD STEADY THROUGH THE
MORNING.

FOR TONIGHT...THE ELEVATED WARM AIR ADVECTION WILL INCREASE
RAPIDLY NORTH OF THE BOUNDARY...MOST FOCUSED OVER MN AND WI. THERE
IS SOME VARIANCE IN GUIDANCE ON HOW FAR SOUTH THE WARM AIR
ADVECTION ZONE AND ELEVATED INSTABILITY GRADIENT IS DEFINED...BUT
CAN SEE SOME SCATTERED CONVECTION DEVELOP WITHIN THAT REGION
TONIGHT AS THE LOW-LEVEL WINDS INCREASE AND MOISTENING OCCURS NEAR
THE BOTTOM OF THE EML. AGAIN...ISOLATED SEVERE POTENTIAL WILL
EXIST...MAYBE TRANSITIONING MORE TOWARD HAIL AND WIND WITH SOME
ELEVATED SUPERCELL PARAMETERS SHOWING UP.

GUIDANCE IS IN IMPROVING AGREEMENT WITH WEDNESDAY BRINGING THE
HEAT BACK...AND POTENTIALLY RECORD HEAT AT THAT. THE SYNOPTIC
REGIME CONTINUES TO FAVOR 100 DEGREE ANALOGS FOR CHICAGO WITH THE
850 MB AND 925 MB TEMPERATURE MAGNITUDES AND THERMAL RIDGE
ORIENTATION. THIS ADVECTION AND SETUP IS HELPED BY AN ANOMALOUS
DEEP SURFACE LOW /2 TO 3 STANDARDIZED ANOMALIES BELOW NORMAL FOR
JULY/ TO THE NORTH OF THE AREA ON WEDNESDAY AFTERNOON. THE
CHALLENGE IS 1. HOW MUCH ANY MORNING CLOUD COVER IN NORTHEAST
AREAS WOULD LIMIT INITIAL WARMING AND 2. HOW WILL DEW POINTS
TREND THROUGH THE DAY. HAVE BEEN A LITTLE SLOWER TO CLEAR CLOUDS
IN NORTHEAST AREAS THAN WHAT GUIDANCE WOULD SAY WITH THE NOCTURNAL
WARM AIR ADVECTION AND ANY RAIN POSSIBLY LEADING TO LINGERING
CLOUDS. AT THIS POINT THAT PROVIDES A FORECAST OF MID TO UPPER 90S
FOR CHICAGO...CLIMBING TO LOW 100S FOR THE FAR SOUTH AND WEST. IF
THE MORNING WERE TO BEGIN SUNNY HOWEVER...COULD VERY WELL SEE
LOWER 100S IN CHICAGO. FOR DEW POINTS...HAVE ADAPTED A MIXING FROM
THE NAM MODEL TO 750 MB FOR THE AFTERNOON...ALONG WITH A BLEND OF
THE BETTER PERFORMING MODELS DURING RECENT AFTERNOONS. CONFIDENCE
OVERALL ON DEW POINTS THOUGH IS LOWER THAN TEMPERATURES. FORECAST
HEAT INDICES CURRENTLY FALL OUT AROUND 105 TO 108 IN SOUTHWEST
AREAS TO 100 TO 105 ELSEWHERE. HAVE COLLABORATED WITH NEIGHBORING
WFOS TO THE SOUTH AND WEST TO HOLD BACK HERE FOR THE HEAT ADVISORY
AT THIS TIME UNTIL CONFIDENCE IS HIGHER...BUT COULD SEE A HEADLINE
NEEDED FOR WEDNESDAY. OF NOTE...ITS POSSIBLE SOME AREAS IN THE
WEST AND SOUTH APPROACH 105 AIR TEMPERATURE IF BOUNDARY LAYER
WINDS ARE HIGH ENOUGH AND ASSOCIATED MIXING OCCURS.

THE SURFACE LOW WILL STEER THE COOL FRONT TOWARD THE AREA
WEDNESDAY NIGHT AND THROUGH ON THURSDAY. GUIDANCE HAS STRONG
MOISTURE TRANSPORT AND SLIGHT COOLING TEMPERATURES ALOFT CONFINED
TO NEAR THIS BOUNDARY ON WEDNESDAY EVE...AND GIVEN CAPPED
PROFILES OVER THE AREA THE BETTER RAIN CHANCES MAY HOLD BACK TO
OVERNIGHT WEDNESDAY NIGHT AND REMAIN IN THE WESTERN AND NORTHERN
CWA. AHEAD OF THE BOUNDARY ON THU...ANY DESTABILIZATION THAT CAN
OCCUR WILL BE FAVORED FOR POTENTIAL STRONG TO SEVERE STORM
DEVELOPMENT...WHICH AT THIS TIME IS ACROSS THE EASTERN FORECAST
AREA.

HAVE MADE LITTLE CHANGES TO THE EXTENDED WITH AN ACTIVE FIRST 72
HOURS OF THE FORECAST. HAVE BLENDED TEMPERATURES IN WHAT APPEARS
TO BE WARMER PERIODS...SUNDAY AND MONDAY...TOWARDS BIAS-CORRECTED
GUIDANCE.

MTF

&&

.CLIMATE...
329 AM CDT

RECORDS HIGHS FOR WEDNESDAY JULY 25TH ARE:

CHICAGO  101 /1940/
ROCKFORD 105 /1934/

RECORD WARM LOWS FOR WEDNESDAY JULY 25TH ARE:

CHICAGO   77 /1892/
ROCKFORD  76 /1940/

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 09Z...

* SHRA/TSRA EARLY-MID THIS MORNING.
* WIND GUSTS OF 35 TO 50+ KT POSSIBLE WITH BOWING THUNDERSTORMS
  MOVING INTO NORTHERN ILLINOIS.
* MVFR...POSSIBLY LOWER...VSBY IN TSRA THIS MORNING. POTENTIAL FOR
  MVFR/IFR CIGS IN HEAVIER TSRA.
* TSRA TUESDAY AFTERNOON AND NIGHT.
* WIND TRENDS.

BMD

//DISCUSSION...UPDATED 06Z...

FOCUS IN THE NEAR TERM IS NW TO SE ORIENTED CLUSTER OF SHRA/TSRA
EXTENDING INTO SE MN/SW WI. A COOL FRONT CONTINUES TO SLOWLY SAG
SOUTH THROUGH WISCONSIN AS WELL. RADAR TRENDS AND LATEST GUIDANCE
POINT TO MN/WI ACTIVITY HOLDING TOGETHER AND MOVING SOUTHEAST OVER
THE TERMINALS EARLY THROUGH MID THIS MORNING...ROUGHLY 9Z-13Z IN
RFD AREA AND 10Z-14Z IN ORD/MDW/DPA/GYY AREA. TIMING MAY NEED
REFINING IN 09Z UPDATE OR SOONER...BUT HAVE DECENT CONFIDENCE
THAT TERMINALS WILL SEE BOTH SHRA AND TSRA DUE TO LOW LEVEL JET
DIRECTING INTO AREA AND PLENTY OF ELEVATED INSTABILITY. THE FRONT
DROPPING SOUTH MAY ALSO PROVIDE A FOCUS FOR MAINTAINING THE
ACTIVITY. IT IS TOO EARLY TO TELL IF TSRA WILL DEVELOP
VARIABLE/GUSTY WINDS...THUS BIGGEST CONCERN IS AT LEAST TEMPORARY
MVFR VSBY IN TSRA AND POSSIBLY A FURTHER LOWERING OF CIGS THAN
INDICATED IN TAFS IN VERY MOIST AIRMASS. PRIOR TO ARRIVAL OF
SHRA/TSRA...CANNOT RULE OUT LIGHT SHRA BREAKING OUT...AND AM ALSO
CONCERNED ACTIVITY COULD LINGER LONGER SO CARRIED -SHRA TO 16/17Z
AT TAF SITES. WILL NEED TO MONITOR TRENDS. AFTER THE MORNING
ACTIVITY...THERE COULD BE ADDITIONAL SHRA/TSRA DURING THE
DAY...BUT NOT CONFIDENT ENOUGH FOR MENTION DURING THIS TIME. A
BETTER CHANCE MAY EXIST LATER IN THE EVENING AS THE FRONTAL
BOUNDARY LIFTS BACK NORTH. INDICATED PROB30 FOR TSRA IN RFD AND
ORD TAFS WITH THIS IN MIND.

WINDS CURRENTLY ARE VERY LIGHT OUT OF THE WEST WHERE THEY ARE NOT
COMPLETELY CALM AND SHOULD REMAIN FAIRLY LIGHT EVEN AS FRONT
PUSHES SOUTH THROUGH THE TERMINALS...TURNING WINDS NORTHEAST. WITH
SOME SITES NORTH OF MKE REPORTING SLIGHTLY STRONGER NORTHEAST
WINDS...WILL NEED TO WATCH FOR THIS OCCURRING AT ORD/MDW/GYY.
WINDS WILL STAY MORE NORTHEASTERLY AT THE EASTERN TAF SITES
BEFORE BECOMING EAST SOUTHEAST LATE TUESDAY EVENING. THE RFD AREA
IS LIKELY TO SEE WINDS EAST-NORTHEAST FOR A TIME AFTER THE FRONTAL
PASSAGE...BUT THEN BECOME EASTERLY BY LATE MORNING AND REMAIN SO
UNTIL POSSIBLY BECOMING MORE EAST-SOUTHEAST TOMORROW EVENING.

RC

//ORD AND MDW CONFIDENCE...UPDATED 09Z...

* HIGH CONFIDENCE IN SHRA/TSRA OCCURRING AT TERMINALS EARLY
  THROUGH MID THIS MORNING...MEDIUM CONFIDENCE IN EXACT TIMING AND
  DURATION.
* MEDIUM CONFIDENCE THAT GUSTY NW WINDS WILL REACH TERMINALS...LOW
  CONFIDENCE ON EXACTLY HOW STRONG THE WINDS WILL BE.
* MEDIUM/HIGH CONFIDENCE IN AT LEAST TEMPO MVFR VSBY IN SHRA/TSRA
  EARLY THROUGH MID THIS MORNING...LOW CONFIDENCE IN IFR VSBY AND
  LOW CONFIDENCE IN MVFR/IFR CIGS.
* LOW CONFIDENCE IN TSRA THIS AFTERNOON AND LOW/MEDIUM CONFIDENCE
  IN TSRA LATE THIS EVENING.
* MEDIUM CONFIDENCE IN WIND TRENDS...WITH LOW CONFIDENCE IN
  NEEDING TO ADD GUSTS TO TSRA ACTIVITY THIS MORNING. BMD

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

WEDNESDAY THROUGH FRIDAY...CHANCES FOR OCCASIONAL TSRA...OTHERWISE
VFR.

SATURDAY...VFR.

SUNDAY...CHANCE FOR TSRA...ESPECIALLY LATE. OTHERWISE VFR.

RC

&&

.MARINE...
250 AM CDT

A COLD FRONT DROPPING SOUTH ACROSS THE REGION HAS ALL BUT CLEARED
FAR SOUTHERN LAKE MICHIGAN WITH NORTHERLY WINDS TAKING HOLD IN THE
WAKE OF THE FRONT. THIS MORNING...SHOWERS AND THUNDERSTORMS ARE
EXPECTED DEVELOP ALONG AND NORTH OF THE FRONT...IMPACTING THE
SOUTHERN THIRD OR SO OF LAKE MICHIGAN. HIGH PRESSURE WILL BUILD
ACROSS NORTHERN LAKE MICHIGAN TODAY ALLOWING WINDS TO SUBSIDE
ACROSS THE NORTH. WEDNESDAY...LOW PRESSURE WILL DEEPEN OVER THE
NORTHERN PLAINS AS IT MOVES INTO THE UPPER MIDWEST AND WESTERN
GREAT LAKES REGION. THE FRONTAL ZONE WILL LIFT BACK NORTH WITH
SOUTH TO SOUTHEASTERLY WINDS MOVING BACK UP THE LAKE. THE LOW IS
FORECAST TO CROSS MIDLAKE LATE WEDNESDAY EVENING CAUSING WINDS TO
BECOME NORTHEASTERLY ACROSS THE NORTHERN PORTIONS OF THE LAKE.
SOUTHWESTERLY WINDS THE SOUTHERN HALF OF THE LAKE WILL BECOME
NORTHWEST AFTER A TRAILING COLD FRONT SWEEPS ACROSS. WINDS WILL
INCREASE WEDNESDAY AND WEDNESDAY NIGHT...ESPECIALLY ACROSS THE
NORTHERN PART OF THE LAKE WHERE NORTHEAST WINDS TO 30 KT ARE
EXPECTED. ACROSS SOUTHERN LAKE MICHIGAN...20 TO 25 KT OF OFFSHORE
FLOW IS POSSIBLE WEDNESDAY EVENING...BUT A STABLE MARINE LAYER
SHOULD HELP KEEP WINDS IN CHECK OVER THE OPEN WATERS. A SMALL
CRAFT ADVISORY MAY BE NEEDED FOR THE INDIANA AND ILLINOIS
NEARSHORE WATERS. ANOTHER WEAKER LOW PRESSURE SYSTEM WILL CROSS
THE LAKE THURSDAY NIGHT CAUSING ADDITIONAL SHIFTS IN THE WIND
FIELD. HIGH PRESSURE IS EXPECTED TO BUILD INTO THE REGION THIS
WEEKEND OFFERING AT LEAST A BRIEF REPRIEVE FROM THE ACTIVE
WEATHER. BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
Hazardous weather outlook, Jul 24, 4:00 AM CDT, 2 hours 9 minutes before
HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
400 AM CDT TUE JUL 24 2012

ILZ003>006-008-010>014-019>023-032-033-039-INZ001-002-010-011-019-
250900-
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-
400 AM CDT TUE JUL 24 2012 /500 AM EDT TUE JUL 24 2012/

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

.DAY ONE...TODAY AND TONIGHT.

  WEATHER HAZARDS EXPECTED:

  THUNDERSTORMS...SOME MAY PRODUCE:

  DAMAGING WINDS IN EXCESS OF 60 MPH.
  HAIL TO THE SIZE OF QUARTERS.
  HEAVY RAINFALL.

  AREAS AFFECTED AND TIMING:

  MORNING THUNDERSTORMS WILL MOVE ACROSS NORTHERN ILLINOIS AND
  NORTHWEST INDIANA...PRIMARILY NORTH AND EAST OF AN OREGON TO
  MORRIS ILLINOIS...TO FOWLER INDIANA LINE. THERE IS A RISK OF
  SEVERE WEATHER WITH THESE STORMS...NAMELY SEVERE WINDS. IN
  ADDITION...THERE IS A HEAVY RAIN THREAT...WITH THE EXCESSIVE
  RAIN MORE FAVORED IN URBAN AREAS. FOR THIS AFTERNOON...THE BEST
  CHANCE FOR THUNDERSTORMS WILL BE MAINLY WEST AND SOUTH OF THE
  CHICAGOLAND AREA...INCLUDING NORTHWEST INDIANA. THERE IS AGAIN A
  SLIGHT RISK OF SEVERE STORMS. TONIGHT THE CHANCE FOR STORMS WILL
  SPREAD BACK NORTH ACROSS THE ENTIRE AREA. ONCE AGAIN ISOLATED
  SEVERE POTENTIAL WILL EXIST.

  DISCUSSION:

  A COOL FRONT MOVING INTO THE AREA THIS MORNING ALONG WITH STRONG
  WARM AIR ADVECTION IN ADVANCE OF IT WILL CONTINUE SERVING AS A
  FOCUS FOR STORMS THROUGH THE MORNING HOURS. SUFFICIENT WIND SHEAR
  AND INSTABILITY ALOFT ALONG WITH ANOMALOUSLY HIGH MOISTURE WILL
  ALLOW FOR SEVERE STORM AND HEAVY RAIN THREATS. THIS IS
  ESPECIALLY TRUE IN ANY CLUSTERS OF STORMS WHICH WOULD HAVE THE
  BEST POTENTIAL FOR PRODUCING SEVERE WINDS. THE FRONT ALONG WITH
  ANY REMNANT OUTFLOW BOUNDARIES COULD SERVE AS A FOCUS FOR
  AFTERNOON STORM REDEVELOPMENT WHICH MAY LAST INTO THE EVENING
  HOURS. LATE TONIGHT...WARM AIR RETURNING NORTHWARD AHEAD OF THE
  FRONTAL BOUNDARY WILL SERVE AS A FOCUS FOR POSSIBLE SCATTERED
  STORM DEVELOPMENT.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.

THERE ARE CHANCES FOR THUNDERSTORMS WEDNESDAY MORNING AND AGAIN
WEDNESDAY NIGHT THROUGH FRIDAY. THERE IS A SMALL CHANCE FOR SEVERE
STORMS WEDNESDAY MORNING IN AREAS OF FAR NORTHERN AND NORTHEASTERN
ILLINOIS. THE POTENTIAL FOR SEVERE WEATHER AND HEAVY RAINFALL WILL
BE MAINLY ACROSS NORTHERN ILLINOIS ON WEDNESDAY NIGHT. FOR
THURSDAY THE CHANCE FOR SEVERE STORMS WILL SPREAD BACK ACROSS THE
ENTIRE AREA.

HEAT INDICES TOPPING 105 DEGREES ARE BECOMING MORE LIKELY ACROSS
THE AREA ON WEDNESDAY.

CHANCES FOR STORMS RETURN LATER SUNDAY INTO MONDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED TODAY AND TONIGHT.

&&

COMPLETE FORECAST INFORMATION IS AVAILABLE ON THE NWS CHICAGO
WEBPAGE: WEATHER.GOV/CHICAGO

LMZ740>745-250900-
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-
400 AM CDT TUE JUL 24 2012

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.

THUNDERSTORMS WILL OCCUR THIS MORNING WITH A CHANCE THIS
AFTERNOON AND TONIGHT. SOME OF THE STORMS...ESPECIALLY THIS
MORNING...WILL HAVE THE POTENTIAL TO PRODUCE GUSTS UP TO 50 KNOTS.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.

PERIODIC THUNDERSTORM CHANCES WILL EXIST WEDNESDAY THROUGH
FRIDAY...WITH SOME OF THE STORMS HAVING THE POTENTIAL TO BE
SEVERE WITH WIND GUSTS OVER 50 KNOTS POSSIBLE. CHANCES FOR
THUNDERSTORMS RETURN SUNDAY NIGHT INTO MONDAY.

&&

COMPLETE FORECAST INFORMATION IS AVAILABLE ON THE NWS CHICAGO
WEBPAGE: WEATHER.GOV/CHICAGO

LMZ080-261-362-364-366-563-565-567-669-671-673-675-777-779-868-
870-872-874-876-878-250900-
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-
400 AM CDT TUE JUL 24 2012

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

.DAY ONE...TODAY AND TONIGHT.

THUNDERSTORMS WILL OCCUR THIS MORNING ACROSS THE SOUTHERN HALF OF
THE LAKE WITH A CHANCE THIS AFTERNOON. THUNDERSTORM CHANCES WILL
SPREAD ACROSS THE ENTIRE LAKE TONIGHT. SOME OF THE
STORMS...ESPECIALLY THIS MORNING ACROSS THE SOUTHERN PART OF THE
LAKE...WILL HAVE THE POTENTIAL TO PRODUCE GUSTS UP TO 50 KNOTS.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.

PERIODIC THUNDERSTORM CHANCES WILL EXIST WEDNESDAY THROUGH
FRIDAY...WITH SOME OF THE STORMS HAVING THE POTENTIAL TO BE
SEVERE WITH WIND GUSTS OVER 50 KNOTS POSSIBLE. CHANCES FOR
THUNDERSTORMS RETURN SUNDAY NIGHT INTO MONDAY.

&&

COMPLETE FORECAST INFORMATION IS AVAILABLE ON THE NWS CHICAGO
WEBPAGE: WEATHER.GOV/CHICAGO

MTF

In the hours before

Local storm report, Jul 24, 5:37 AM CDT, 32 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
537 AM CDT TUE JUL 24 2012

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

0531 AM     TSTM WND GST     HARVARD                 42.42N 88.62W
07/24/2012  M67 MPH          MCHENRY            IL   TRAINED SPOTTER

            NEAR INTERSECTION OF MCGUIRE AND ALDEN ROADS.

&&

MDB
Local storm report, Jul 24, 5:43 AM CDT, 26 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
543 AM CDT TUE JUL 24 2012

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

0505 AM     TSTM WND DMG     SOUTH BELOIT            42.48N 89.03W
07/24/2012                   WINNEBAGO          IL   BROADCAST MEDIA

            SWING SET BLOWN ACROSS YARD AND LANDED UPSIDE DOWN.
            RELAYED BY BORADCAST MEDIA. TIME ESTIMATED WITH RADAR.

&&

MDB
Local storm report, Jul 24, 5:45 AM CDT, 24 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
545 AM CDT TUE JUL 24 2012

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

0540 AM     TSTM WND GST     2 NE WOODSTOCK          42.33N 88.41W
07/24/2012  E65 MPH          MCHENRY            IL   TRAINED SPOTTER

&&

MDB
Local storm report, Jul 24, 5:48 AM CDT, 21 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
548 AM CDT TUE JUL 24 2012

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

0527 AM     TSTM WND GST     ROCHELLE                41.92N 89.06W
07/24/2012  M58 MPH          OGLE               IL   AWOS

&&

MDB
Local storm report, Jul 24, 5:57 AM CDT, 12 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
557 AM CDT TUE JUL 24 2012

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

0535 AM     TSTM WND DMG     2 NW DE KALB            41.95N 88.78W
07/24/2012                   DEKALB             IL   EMERGENCY MNGR

            ESTIMATED 60 MPH WINDS DOWNED POWER LINES. LOST POWER AND
            LAND-LINE PHONES.

&&

BN
Local storm report, Jul 24, 6:09 AM CDT, 0 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
609 AM CDT TUE JUL 24 2012

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

0535 AM     NON-TSTM WND DMG DE KALB                 41.93N 88.75W
07/24/2012                   DEKALB             IL   EMERGENCY MNGR

            TREE AND POWER LINES DOWN BLOCKING INTERSECTION OF
            BETHANY ROAD AND FIRST STREET. WINDS ESTIMATED AT 70 MPH
            AT KISHWAUKEE HOSPITAL IN DEKALB.

&&

MDB

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 24, 6:09 AM CDTAreal Flood AdvisoryLOTLake3 hr
Jul 24, 7:04 AM CDTSevere Thunderstorm WarningLOTJasper, Lake, Newton, Porter56 min
Jul 24, 3:31 PM CDTHeat AdvisoryLOTBenton, Jasper, Lake, Newton, Porter30 hr
Jul 24, 4:42 AM CDTSevere Thunderstorm WarningLOTBoone, DeKalb, McHenry, Ogle, Winnebago63 min
Jul 24, 4:58 AM CDTSpecial Marine WarningLOT3 hr
Jul 24, 5:30 AM CDTSevere Thunderstorm WarningLOTCook, DeKalb, DuPage, Kane, Kendall, Lake and 2 more60 min
Jul 24, 3:07 PM CDTSmall Craft AdvisoryLOT31 hr

Nearby

Severe Thunderstorm Warnings in Illinois, 2012Severe Thunderstorm Warnings in Indiana, 2012Every severe thunderstorm warning in 2012

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.