Alert archive / Illinois / Winter Storm Warnings in 2012

Winter Storm Warning 3, NWS Chicago, IL

March 2, 20125 counties in Illinois

NWS Chicago, IL issued this winter storm warning at Mar 2, 2012, 10:29 AM CST for 5 counties in Illinois. It took effect at Mar 2, 2012, 3:00 PM CST. It was in force for 6 hr. 21 reports came from inside the area while it was in force.

The area

The counties it named, with what was reported inside it.

The facts

Issued
Mar 2, 2012, 10:29 AM CST (16:29 UTC)
In effect from
Mar 2, 2012, 3:00 PM CST
Expired
Mar 2, 2012, 8:34 PM CST
In force
6 hr
Issued by
NWS Chicago, IL

Counties Boone County, IL, Lake County, IL, McHenry County, IL, Ogle County, IL, Winnebago County, IL

The radar

The Milwaukee radar (KMKX), 78 km from the middle of the area, began a volume at 16:29 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
Mar 2, 3:03 PM CSTSNOW 0Rochelle, ILTHUNDERSNOW REPORTED IN ROCHELLE, AT NIU IN DE KALB, MARENGO, BELVIDERE, CORTLAND AND SYCAMORE. RELAYED BY BROADCAST MEDIA.
Mar 2, 3:08 PM CSTSNOW 1Roscoe, ILSNOW TOTAL SO FAR. RELAYED BY WREX.
Mar 2, 3:18 PM CSTSNOW 0Belvidere, ILTHUNDER IS BEING OBSERVED WITH SNOW. REPORT RELAYED BY WREX.
Mar 2, 3:20 PM CSTSNOW 0Crystal Lake, ILTHUNDER WAS BEING OBSERVED AS IT WAS SNOWING. FINE SNOW FLAKES ARE FALLING COMBINED WITH SLEET.
Mar 2, 3:49 PM CSTSNOW 2.5Winnebago, ILREPORTED AT WREX-TV.
Mar 2, 4:12 PM CSTSNOW 4Forreston, IL
Mar 2, 4:13 PM CSTSNOW 2.45 Wnw Rockford, IL2.4 INCHES AT WIFR.
Mar 2, 4:16 PM CSTSNOW 3Huntley, IL3 INCHES OF SNOW FELL SO FAR AT REED ROAD AND HALIGUS RD.
Mar 2, 4:18 PM CSTSNOW 1.5E Harvard, ILSNOWING QUITE HEAVY. 1 TO 1.5 INCHES ON GROUND.
Mar 2, 4:20 PM CSTSNOW 24 W Huntley, IL2 INCHES OF SNOW FELL IN THE PAST HOUR. HEAVY SNOW IS STILL FALLING WITH LARGE SNOW FLAKES. THUNDER ACCOMPANIED THE SNOW WHEN THE SNOW INITIALLY BEGAN TO FALL.
Mar 2, 4:30 PM CSTSNOW 1.7N Huntley, IL1.7 INCHES OF SNOW FELL OVER THE PAST 75 MINUTES. 2 INCHES OF SNOW ON THE GROUND. VERY HEAVY SNOW STILL FALLING.
Mar 2, 5:10 PM CSTSNOW 2.54 Nw Rockford, IL2.5 INCHES OF WET SNOW HAVE FALLEN THUS FAR.
Mar 2, 5:13 PM CSTSNOW 1.3Capron, ILRELAYED BY BROADCAST MEDIA.
Mar 2, 5:13 PM CSTSNOW 2.8W Rockford, ILMEASURED AT WTVO. FAR WEST SIDE OF ROCKFORD.
Mar 2, 5:30 PM CSTSNOW 3.4E Harvard, IL3.4 INCHES OF SNOW HAVE FALLEN OVER THE PAST 2 HOURS.
Mar 2, 6:00 PM CSTSNOW 1.52 Ne Gurnee, ILRAIN CHANGED TO SNOW AT 4 PM AND SNOWING PRETTY HEAVY SINCE THEN. WET AND HEAVY SNOW.
Mar 2, 6:09 PM CSTSNOW 2.8Rockford Airport, IL
Mar 2, 7:30 PM CSTSNOW 1Island Lake, ILSTORM TOTAL SO FAR.
Mar 2, 7:30 PM CSTSNOW 4.92 Wnw Bull Valley, ILSTORM TOTAL SO FAR. LIGHT SNOW FALLING. 32F.
Mar 2, 7:44 PM CSTSNOW 3.2Capron, ILSTORM TOTAL SO FAR. SNOW SEEMS TO HAVE STOPPED FOR NOW. HEAVY SNOW ON TREES AND WIRES, SLIPPERY SIDE STREETS.
Mar 2, 8:00 PM CSTSNOW 4.41 N Huntley, ILSTORM REPORT

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

The nearest sounding before it

Davenport, (KDVN), launched 12:00Z, 4.5 hours before the alert went out and 164 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, Davenport, at 12:00Z on 2012-03-02Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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, Davenport, at 12:00Z on 2012-03-02The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 42 square meters per square second.1939587897117136Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
868 m above ground
0-6 km bulk shear
87 kt
0-1 km storm-relative helicity
42 m²/s²
0-3 km storm-relative helicity
124 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.

473 
WWUS43 KLOT 021629
WSWLOT

URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE CHICAGO IL
1029 AM CST FRI MAR 2 2012

...A PERIOD OF HEAVY SNOWFALL EXPECTED ACROSS FAR NORTHERN
ILLINOIS LATE THIS AFTERNOON AND THIS EVENING...

.A RAPIDLY DEVELOPING STORM SYSTEM WILL LIFT NORTHEASTWARD
THROUGH CENTRAL ILLINOIS BY AROUND NOON. AS THE SYSTEM CONTINUES
TO THE NORTHEAST...THROUGH NORTHERN INDIANA AND INTO SOUTHERN
LOWER MICHIGAN...IT WILL RAPIDLY DEEPEN AS COLDER AIR IS DRAWN INTO
THE SYSTEM. RAIN OVERSPREADING THE AREA WILL TRANSITION OVER TO
SNOW AND A RAIN SNOW MIX BY MID AFTERNOON AND ALL SNOW BY LATE
THIS AFTERNOON AND EARLY EVENING. THERE IS THE POSSIBILITY OF
SNOWFALL RATES ONE INCH PER HOUR. STRONG NORTHERLY WINDS ARE ALSO
EXPECTED TO DEVELOP AS THE SYSTEM INTENSIFIES. THE SNOW WILL TAPER
OFF THIS EVENING AS THE MAIN LOW PRESSURE SYSTEM PULLS OFF TO THE
NORTHEAST.

ILZ003-004-008-030030-
/O.UPG.KLOT.WS.A.0004.120302T2100Z-120303T0600Z/
/O.NEW.KLOT.WS.W.0003.120302T2100Z-120303T0300Z/
WINNEBAGO-BOONE-OGLE-
INCLUDING THE CITIES OF...ROCKFORD...BELVIDERE...OREGON
1029 AM CST FRI MAR 2 2012

...WINTER STORM WARNING IN EFFECT FROM 3 PM THIS AFTERNOON TO
9 PM CST THIS EVENING...

THE NATIONAL WEATHER SERVICE IN CHICAGO HAS ISSUED A WINTER STORM
WARNING FOR HEAVY SNOW...WHICH IS IN EFFECT FROM 3 PM THIS
AFTERNOON TO 9 PM CST THIS EVENING. THE WINTER STORM WATCH IS NO
LONGER IN EFFECT.

* TIMING...RAIN WILL CHANGE TO SNOW BY MID TO LATE AFTERNOON. THE
  SNOW WILL IS EXPECTED TO BE HEAVY AT TIMES...WITH AN INCH OR
  MORE PER HOUR ACCUMULATIONS POSSIBLE DURING THE AFTERNOON AND
  EVENING RUSH. THE SNOW WILL CONTINUE THIS EVENING BEFORE
  TAPERING OFF.

* ACCUMULATIONS...TOTAL SNOW ACCUMULATIONS OF 4 TO 7 INCHES ARE
  EXPECTED ACROSS THE WARNING AREA.

* MAIN IMPACT...THE SNOW MAY BE HEAVY AT TIMES. THIS WILL ALLOW
  SNOW TO QUICKLY ACCUMULATE ON AREA ROADS MAKING TRAVEL HAZARDS BY
  LATE THIS AFTERNOON AND INTO THE EVENING. 

* OTHER IMPACTS...DUE TO THE HIGH LIQUID CONTENT OF THE SNOW... 
  THOSE WITH HEALTH CONCERNS SHOULD USE CAUTION WHEN SHOVELING. 
  THE HEAVY WET SNOW MAY ALSO LEAD TO WEIGHTED DOWN BRANCHES AND 
  POWER LINES. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WINTER STORM WARNING MEANS SIGNIFICANT AMOUNTS OF SNOW ARE
EXPECTED. STRONG WINDS ARE ALSO POSSIBLE. THIS WILL MAKE TRAVEL
VERY HAZARDOUS.

&&

$$

ILZ005-006-030030-
/O.UPG.KLOT.WS.A.0004.120302T2100Z-120303T0600Z/
/O.NEW.KLOT.WS.W.0003.120302T2100Z-120303T0600Z/
MCHENRY-LAKE IL-
INCLUDING THE CITIES OF...WOODSTOCK...WAUKEGAN
1029 AM CST FRI MAR 2 2012

...WINTER STORM WARNING IN EFFECT FROM 3 PM THIS AFTERNOON TO
MIDNIGHT CST TONIGHT...

THE NATIONAL WEATHER SERVICE IN CHICAGO HAS ISSUED A WINTER STORM
WARNING FOR HEAVY SNOW...WHICH IS IN EFFECT FROM 3 PM THIS
AFTERNOON TO MIDNIGHT CST TONIGHT. THE WINTER STORM WATCH IS NO
LONGER IN EFFECT.

* TIMING...RAIN WILL CHANGE TO SNOW BY MID TO LATE AFTERNOON. THE
  SNOW WILL IS EXPECTED TO BE HEAVY AT TIMES...WITH AN INCH OR
  MORE PER HOUR ACCUMULATIONS POSSIBLE DURING THE AFTERNOON AND
  EVENING RUSH. THE SNOW WILL CONTINUE THIS EVENING BEFORE
  TAPERING OFF.

* ACCUMULATIONS...TOTAL SNOW ACCUMULATIONS OF 4 TO 7 INCHES ARE
  EXPECTED ACROSS THE WARNING AREA.

* MAIN IMPACT...THE SNOW MAY BE HEAVY AT TIMES. THIS WILL ALLOW
  SNOW TO QUICKLY ACCUMULATE ON AREA ROADS MAKING TRAVEL HAZARDS BY
  LATE THIS AFTERNOON AND INTO THE EVENING. 

* OTHER IMPACTS...DUE TO THE HIGH LIQUID CONTENT OF THE SNOW... 
  THOSE WITH HEALTH CONCERNS SHOULD USE CAUTION WHEN SHOVELING. 
  THE HEAVY WET SNOW MAY ALSO LEAD TO WEIGHTED DOWN BRANCHES AND 
  POWER LINES. 



PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WINTER STORM WARNING MEANS SIGNIFICANT AMOUNTS OF SNOW ARE
EXPECTED. STRONG WINDS ARE ALSO POSSIBLE. THIS WILL MAKE TRAVEL
VERY HAZARDOUS.

&&

$$

ILZ013-014-030030-
/O.NEW.KLOT.WW.Y.0007.120302T2100Z-120303T0600Z/
DUPAGE-COOK-
INCLUDING THE CITIES OF...WHEATON...CHICAGO
1029 AM CST FRI MAR 2 2012

...WINTER WEATHER ADVISORY IN EFFECT FROM 3 PM THIS AFTERNOON TO
MIDNIGHT CST TONIGHT...

THE NATIONAL WEATHER SERVICE IN CHICAGO HAS ISSUED A WINTER
WEATHER ADVISORY FOR SNOW...WHICH IS IN EFFECT FROM 3 PM THIS
AFTERNOON TO MIDNIGHT CST TONIGHT.

* TIMING...RAIN WILL CHANGE TO SNOW ACROSS DUPAGE AND NORTHERN
  COOK COUNTY LATE THIS AFTERNOON. THE SNOW WILL CONTINUE THIS
  EVENING BEFORE TAPERING OFF BY LATE EVENING.

* ACCUMULATIONS...TOTAL SNOW ACCUMULATIONS WILL VARY WIDELY ACROSS
  COOK COUNTY. ACROSS NORTHERN COOK COUNTY 3 TO 5 INCHES ARE
  EXPECTED. AMOUNTS WILL DROP QUICKLY TO AN INCH OR TWO IN THE
  CITY OF CHICAGO...AND UNDER AN INCH ACROSS FAR SOUTHERN COOK
  COUNTY.

* MAIN IMPACT...THE SNOW MAY BE HEAVY AT TIMES. THIS WILL ALLOW
  SNOW TO QUICKLY ACCUMULATE ON AREA ROADS MAKING TRAVEL HAZARDS BY
  LATE THIS AFTERNOON AND INTO THE EVENING. 

* OTHER IMPACTS...DUE TO THE HIGH LIQUID CONTENT OF THE SNOW... 
  THOSE WITH HEALTH CONCERNS SHOULD USE CAUTION WHEN SHOVELING. 
  THE HEAVY WET SNOW MAY ALSO LEAD TO WEIGHTED DOWN BRANCHES AND 
  POWER LINES. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WINTER WEATHER ADVISORY FOR SNOW MEANS THAT PERIODS OF SNOW
WILL CAUSE PRIMARILY TRAVEL DIFFICULTIES. BE PREPARED FOR SNOW
COVERED ROADS AND LIMITED VISIBILITIES...AND USE CAUTION WHILE
DRIVING.

&&

$$

ILZ010>012-030030-
/O.NEW.KLOT.WW.Y.0007.120302T2100Z-120303T0300Z/
LEE-DE KALB-KANE-
INCLUDING THE CITIES OF...DIXON...DEKALB...AURORA
1029 AM CST FRI MAR 2 2012

...WINTER WEATHER ADVISORY IN EFFECT FROM 3 PM THIS AFTERNOON TO
9 PM CST THIS EVENING...

THE NATIONAL WEATHER SERVICE IN CHICAGO HAS ISSUED A WINTER
WEATHER ADVISORY FOR SNOW...WHICH IS IN EFFECT
FROM 3 PM THIS AFTERNOON TO 9 PM CST THIS EVENING. 

* TIMING...RAIN WILL CHANGE TO SNOW BY MID TO LATE AFTERNOON. THE
  SNOW WILL CONTINUE EARLY THIS EVENING BEFORE TAPERING OFF.
  PERIODS OF HEAVY SNOW WITH ACCUMULATIONS UP TO AN INCH AN HOUR
  ARE POSSIBLE DURING THE AFTERNOON.

* ACCUMULATIONS...TOTAL SNOW ACCUMULATIONS OF 3 TO 6 INCHES ARE
  EXPECTED ACROSS THE ADVISORY AREA.

* MAIN IMPACT...THE SNOW MAY BE HEAVY AT TIMES. THIS WILL ALLOW
  SNOW TO QUICKLY ACCUMULATE ON AREA ROADS MAKING TRAVEL HAZARDS BY
  LATE THIS AFTERNOON AND INTO THE EVENING. 

* OTHER IMPACTS...DUE TO THE HIGH LIQUID CONTENT OF THE SNOW...
  THOSE WITH HEALTH CONCERNS SHOULD USE CAUTION WHEN SHOVELING.
  THE HEAVY WET SNOW MAY ALSO LEAD TO WEIGHTED DOWN BRANCHES AND
  POWER LINES. 


PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WINTER WEATHER ADVISORY FOR SNOW MEANS THAT PERIODS OF SNOW
WILL CAUSE PRIMARILY TRAVEL DIFFICULTIES. BE PREPARED FOR SNOW
COVERED ROADS AND LIMITED VISIBILITIES...AND USE CAUTION WHILE
DRIVING.

&&

$$

KJB/RC
3 follow-up statements
620 
WWUS43 KLOT 022145
WSWLOT

URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE CHICAGO IL
345 PM CST FRI MAR 2 2012

...A PERIOD OF HEAVY SNOWFALL ACROSS FAR NORTHERN ILLINOIS INTO
THIS EVENING...

.AN INTENSE STORM SYSTEM IS CONTINUING TO LIFT RAPIDLY NORTHEASTWARD
INTO SOUTHWEST LOWER MICHIGAN. COLDER AIR MOVING IN BEHIND THE
SYSTEM HAS CHANGED PRECIPITATION QUICKLY OVER TO HEAVY SNOW ACROSS
NORTHWEST AND NORTH CENTRAL ILLINOIS. THE CHANGEOVER LINE WILL
PROGRESS QUICKLY EASTWARD THROUGH THE LATE AFTERNOON AND EARLY
EVENING. SNOWFALL RATES OF 1 INCH PER HOUR AND THUNDERSNOW HAVE
ALREADY BEEN REPORTED IN THE GREATER ROCKFORD AREA. NORTHWESTERLY
WINDS ARE ALSO STRENGTHENING AS THE SYSTEM INTENSIFIES. THE SNOW
WILL TAPER OFF THIS EVENING AS THE MAIN LOW PRESSURE SYSTEM PULLS
OFF TO THE NORTHEAST.

ILZ003-004-008-030300-
/O.CON.KLOT.WS.W.0003.000000T0000Z-120303T0300Z/
WINNEBAGO-BOONE-OGLE-
INCLUDING THE CITIES OF...ROCKFORD...BELVIDERE...OREGON
345 PM CST FRI MAR 2 2012

...WINTER STORM WARNING REMAINS IN EFFECT UNTIL 9 PM CST THIS
EVENING...

* TIMING...HEAVY SNOW WILL CONTINUE INTO THE EARLY EVENING...WITH
  AN INCH OR MORE PER HOUR ACCUMULATIONS POSSIBLE THROUGH THE
  AFTERNOON AND EVENING RUSH. THE SNOW WILL TAPER OFF BY MID EVENING.

* ACCUMULATIONS...TOTAL SNOW ACCUMULATIONS OF 4 TO 7 INCHES ARE 
  EXPECTED ACROSS THE WARNING AREA. 

* MAIN IMPACT...THE SNOW WILL BE HEAVY AT TIMES...ALLOWING SNOW TO
  QUICKLY ACCUMULATE ON AREA ROADS AND MAKING TRAVEL VERY
  HAZARDOUS. STRONG WINDS WILL FURTHER REDUCE THE VISIBILITY IN
  HEAVY SNOW.

* OTHER IMPACTS...DUE TO THE HIGH LIQUID CONTENT OF THE SNOW... 
  THOSE WITH HEALTH CONCERNS SHOULD USE CAUTION WHEN SHOVELING. 
  THE HEAVY WET SNOW MAY ALSO LEAD TO WEIGHTED DOWN BRANCHES AND 
  POWER LINES. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WINTER STORM WARNING MEANS SIGNIFICANT AMOUNTS OF SNOW ARE
EXPECTED. STRONG WINDS ARE ALSO POSSIBLE. THIS WILL MAKE TRAVEL
VERY HAZARDOUS.

&&

$$

ILZ005-006-030545-
/O.CON.KLOT.WS.W.0003.000000T0000Z-120303T0600Z/
MCHENRY-LAKE IL-
INCLUDING THE CITIES OF...WOODSTOCK...WAUKEGAN
345 PM CST FRI MAR 2 2012

...WINTER STORM WARNING REMAINS IN EFFECT UNTIL MIDNIGHT CST
TONIGHT...

* TIMING...PRECIPITATION WILL RAPIDLY CHANGE TO ALL SNOW FROM
  WEST TO EAST BY LATE AFTERNOON. THE SNOW WILL BE HEAVY AT
  TIMES...WITH AN INCH OR MORE PER HOUR ACCUMULATIONS POSSIBLE
  DURING THE AFTERNOON AND EVENING RUSH. THE SNOW WILL TAPER OFF
  LATE THIS EVENING.

* ACCUMULATIONS...TOTAL SNOW ACCUMULATIONS OF 4 TO 7 INCHES ARE
  EXPECTED ACROSS THE WARNING AREA.

* MAIN IMPACT...THE SNOW WILL BE HEAVY AT TIMES...ALLOWING SNOW TO
  QUICKLY ACCUMULATE ON AREA ROADS...MAKING TRAVEL VERY HAZARDOUS.
  STRONG WINDS WILL FURTHER REDUCE THE VISIBILITY IN HEAVY SNOW.

* OTHER IMPACTS...DUE TO THE HIGH LIQUID CONTENT OF THE SNOW... 
  THOSE WITH HEALTH CONCERNS SHOULD USE CAUTION WHEN SHOVELING. 
  THE HEAVY WET SNOW MAY ALSO LEAD TO WEIGHTED DOWN BRANCHES AND 
  POWER LINES. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WINTER STORM WARNING MEANS SIGNIFICANT AMOUNTS OF SNOW ARE
EXPECTED. STRONG WINDS ARE ALSO POSSIBLE. THIS WILL MAKE TRAVEL
VERY HAZARDOUS.

&&

$$

ILZ013-014-030545-
/O.CON.KLOT.WW.Y.0007.000000T0000Z-120303T0600Z/
DUPAGE-COOK-
INCLUDING THE CITIES OF...WHEATON...CHICAGO
345 PM CST FRI MAR 2 2012

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL MIDNIGHT CST
TONIGHT...

* TIMING...RAIN WILL CHANGE TO SNOW ACROSS DUPAGE AND NORTHERN
  COOK COUNTY BY LATE THIS AFTERNOON. THE SNOW WILL TAPER OFF BY
  LATE EVENING.

* ACCUMULATIONS...TOTAL SNOW ACCUMULATIONS WILL VARY WIDELY ACROSS
  THE METRO AREA. ACROSS NORTHERN DUPAGE AND NORTHERN COOK COUNTY
  2 TO 5 INCHES ARE EXPECTED. AMOUNTS WILL DROP QUICKLY TO AN INCH
  OR TWO IN THE CITY OF CHICAGO...AND UNDER AN INCH ACROSS FAR
  SOUTHERN COOK COUNTY.

* MAIN IMPACT...THE SNOW MAY BE HEAVY AT TIMES. THIS WILL ALLOW
  SNOW TO QUICKLY ACCUMULATE ON AREA ROADS MAKING TRAVEL HAZARDOUS
  BY LATE THIS AFTERNOON AND INTO THE EVENING. STRONG WINDS WILL
  FURTHER REDUCE THE VISIBILITY IN MODERATE TO HEAVY SNOW.

* OTHER IMPACTS...DUE TO THE HIGH LIQUID CONTENT OF THE SNOW... 
  THOSE WITH HEALTH CONCERNS SHOULD USE CAUTION WHEN SHOVELING. 
  THE HEAVY WET SNOW MAY ALSO LEAD TO WEIGHTED DOWN BRANCHES AND 
  POWER LINES. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WINTER WEATHER ADVISORY FOR SNOW MEANS THAT PERIODS OF SNOW
WILL CAUSE PRIMARILY TRAVEL DIFFICULTIES. BE PREPARED FOR SNOW
COVERED ROADS AND LIMITED VISIBILITIES...AND USE CAUTION WHILE
DRIVING.

&&

$$

ILZ010>012-030300-
/O.CON.KLOT.WW.Y.0007.000000T0000Z-120303T0300Z/
LEE-DE KALB-KANE-
INCLUDING THE CITIES OF...DIXON...DEKALB...AURORA
345 PM CST FRI MAR 2 2012

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 9 PM CST THIS
EVENING...

* TIMING...PERIODS OF MODERATE TO HEAVY SNOW WITH ACCUMULATIONS UP
  TO AN INCH AN HOUR ARE EXPECTED INTO THE EVENING. THE SNOW WILL
  TAPER OFF BY MID EVENING.

* ACCUMULATIONS...TOTAL SNOW ACCUMULATIONS OF 3 TO 6 INCHES ARE 
  EXPECTED ACROSS THE ADVISORY AREA. 

* MAIN IMPACT...THE SNOW MAY BE HEAVY AT TIMES. THIS WILL ALLOW
  SNOW TO QUICKLY ACCUMULATE ON AREA ROADS MAKING TRAVEL
  HAZARDOUS. STRONG WINDS WILL FURTHER REDUCE VISIBILITY IN
  MODERATE TO HEAVY SNOW.

* OTHER IMPACTS...DUE TO THE HIGH LIQUID CONTENT OF THE SNOW... 
  THOSE WITH HEALTH CONCERNS SHOULD USE CAUTION WHEN SHOVELING. 
  THE HEAVY WET SNOW MAY ALSO LEAD TO WEIGHTED DOWN BRANCHES AND 
  POWER LINES. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WINTER WEATHER ADVISORY FOR SNOW MEANS THAT PERIODS OF SNOW
WILL CAUSE PRIMARILY TRAVEL DIFFICULTIES. BE PREPARED FOR SNOW
COVERED ROADS AND LIMITED VISIBILITIES...AND USE CAUTION WHILE
DRIVING.

&&

$$

RC
604 
WWUS43 KLOT 030149
WSWLOT

URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE CHICAGO IL
749 PM CST FRI MAR 2 2012

...A BAND OF LIGHT TO MODERATE SNOWFALL ACROSS FAR NORTHERN
ILLINOIS INTO THIS EVENING...

.A FINAL BAND OF LIGHT TO MODERATE SNOW IS MAKING ITS WAY THROUGH
NORTHERN ILLINOIS THIS EVENING. THE PARENT LOW THAT CAUSED THE
PRECIPITATION TODAY HAS MOVED OVER SOUTH-CENTRAL MICHIGAN. 

ILZ003-004-008-030300-
/O.CAN.KLOT.WS.W.0003.000000T0000Z-120303T0300Z/
WINNEBAGO-BOONE-OGLE-
INCLUDING THE CITIES OF...ROCKFORD...BELVIDERE...OREGON
749 PM CST FRI MAR 2 2012

...WINTER STORM WARNING IS CANCELLED...

THE NATIONAL WEATHER SERVICE IN CHICAGO HAS CANCELLED THE WINTER
STORM WARNING AS THE SNOW HAS MOVED EAST OF THE AREA.

$$

ILZ010-011-030300-
/O.CAN.KLOT.WW.Y.0007.000000T0000Z-120303T0300Z/
LEE-DE KALB-
INCLUDING THE CITIES OF...DIXON...DEKALB
749 PM CST FRI MAR 2 2012

...WINTER WEATHER ADVISORY IS CANCELLED...

THE NATIONAL WEATHER SERVICE IN CHICAGO HAS CANCELLED THE WINTER
WEATHER ADVISORY AS SNOW HAS MOVED EAST OF THE AREA.

$$

ILZ005-006-030600-
/O.CON.KLOT.WS.W.0003.000000T0000Z-120303T0600Z/
MCHENRY-LAKE IL-
INCLUDING THE CITIES OF...WOODSTOCK...WAUKEGAN
749 PM CST FRI MAR 2 2012

...WINTER STORM WARNING REMAINS IN EFFECT UNTIL MIDNIGHT CST
TONIGHT...

* TIMING...A FINAL BAND OF LIGHT TO MODERATE SNOW WILL MOVE
  THROUGH THE AREA OVER THE NEXT COUPLE OF HOURS.

* ACCUMULATIONS...ADDITIONAL SNOW ACCUMULATION OF AROUND 1 INCH IS
  EXPECTED ACROSS THE WARNING AREA. STORM TOTAL SNOWFALL BETWEEN 4
  AND 7 INCHES OF SNOW IS EXPECTED.

* MAIN IMPACT...THE SNOW WILL FALL AS A VERY WET SNOW...CREATING
  SLICK ROADS AND HAZARDOUS TRAVEL. STRONG WINDS WILL FURTHER
  REDUCE THE VISIBILITY IN MODERATE SNOW.

* OTHER IMPACTS...DUE TO THE HIGH LIQUID CONTENT OF THE SNOW... 
  THOSE WITH HEALTH CONCERNS SHOULD USE CAUTION WHEN SHOVELING. 
  THE HEAVY WET SNOW MAY ALSO LEAD TO WEIGHTED DOWN BRANCHES AND 
  POWER LINES. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WINTER STORM WARNING MEANS SIGNIFICANT AMOUNTS OF SNOW ARE
EXPECTED. STRONG WINDS ARE ALSO POSSIBLE. THIS WILL MAKE TRAVEL
VERY HAZARDOUS.

&&

$$

ILZ012-030300-
/O.CON.KLOT.WW.Y.0007.000000T0000Z-120303T0300Z/
KANE-
INCLUDING THE CITY OF...AURORA
749 PM CST FRI MAR 2 2012

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 9 PM CST THIS
EVENING...

* TIMING...A FINAL BAND OF LIGHT TO MODERATE SNOW WILL MOVE
  THROUGH THE AREA OVER THE NEXT HOUR.

* ACCUMULATIONS...LITTLE TO NO ADDITIONAL ACCUMULATION IS
  EXPECTED. TOTAL STORM ACCUMULATION OF 3 TO 5 INCHES IS EXPECTED.

* MAIN IMPACT...THE SNOW WILL FALL AS A VERY WET SNOW...CREATING
  SLICK ROADS AND HAZARDOUS TRAVEL. STRONG WINDS WILL FURTHER REDUCE THE
  VISIBILITY IN MODERATE SNOW.

* OTHER IMPACTS...DUE TO THE HIGH LIQUID CONTENT OF THE SNOW... 
  THOSE WITH HEALTH CONCERNS SHOULD USE CAUTION WHEN SHOVELING. 
  THE HEAVY WET SNOW MAY ALSO LEAD TO WEIGHTED DOWN BRANCHES AND 
  POWER LINES. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WINTER WEATHER ADVISORY FOR SNOW MEANS THAT PERIODS OF SNOW
WILL CAUSE PRIMARILY TRAVEL DIFFICULTIES. BE PREPARED FOR SNOW
COVERED ROADS AND LIMITED VISIBILITIES...AND USE CAUTION WHILE
DRIVING.

&&

$$

ILZ013-014-030600-
/O.CON.KLOT.WW.Y.0007.000000T0000Z-120303T0600Z/
DUPAGE-COOK-
INCLUDING THE CITIES OF...WHEATON...CHICAGO
749 PM CST FRI MAR 2 2012

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL MIDNIGHT CST
TONIGHT...

* TIMING...A FINAL BAND OF LIGHT TO MODERATE SNOW IS MOVING ACROSS
  NORTHERN ILLINOIS THIS EVENING. THE BAND IS EXPECTED TO MOVE
  THROUGH FAR NORTHEASTERN ILLINOIS WITHIN THE NEXT COUPLE OF HOURS.

* ACCUMULATIONS...LESS THAN INCH OF ADDITIONAL ACCUMULATION IS
  EXPECTED. TOTAL SNOW ACCUMULATIONS WILL VARY WIDELY ACROSS THE
  METRO AREA. ACROSS NORTHERN DUPAGE AND NORTHERN COOK COUNTY 2 TO
  5 INCHES ARE EXPECTED. AMOUNTS WILL DROP QUICKLY TO AROUND AN
  INCH IN THE CITY OF CHICAGO...AND UNDER AN INCH ACROSS FAR
  SOUTHERN COOK COUNTY.

* MAIN IMPACT...THE SNOW WILL FALL AS A VERY WET SNOW...CREATING
  SLICK ROADS AND HAZARDOUS TRAVEL. STRONG WINDS WILL FURTHER
  REDUCE THE VISIBILITY IN MODERATE SNOW. 

* OTHER IMPACTS...DUE TO THE HIGH LIQUID CONTENT OF THE SNOW... 
  THOSE WITH HEALTH CONCERNS SHOULD USE CAUTION WHEN SHOVELING. 
  THE HEAVY WET SNOW MAY ALSO LEAD TO WEIGHTED DOWN BRANCHES AND 
  POWER LINES. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WINTER WEATHER ADVISORY FOR SNOW MEANS THAT PERIODS OF SNOW
WILL CAUSE PRIMARILY TRAVEL DIFFICULTIES. BE PREPARED FOR SNOW
COVERED ROADS AND LIMITED VISIBILITIES...AND USE CAUTION WHILE
DRIVING.

&&

$$

JEE
220 
WWUS43 KLOT 030234
WSWLOT

URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE CHICAGO IL
834 PM CST FRI MAR 2 2012

...THE LAST BAND OF LIGHT SNOW IS MOVING EASTWARD OUT OF NORTHEAST
ILLINOIS AND NORTHWEST INDIANA...

ILZ005-006-030345-
/O.CAN.KLOT.WS.W.0003.000000T0000Z-120303T0600Z/
MCHENRY-LAKE IL-
INCLUDING THE CITIES OF...WOODSTOCK...WAUKEGAN
834 PM CST FRI MAR 2 2012

...WINTER STORM WARNING IS CANCELLED...

THE NATIONAL WEATHER SERVICE IN CHICAGO HAS CANCELLED THE WINTER
STORM WARNING. LIGHT SNOW HAS MOVED OUT OF MCHENRY COUNTY AND
WILL CONTINUE TO MOVE EASTWARD OUT OF LAKE COUNTY.

$$

ILZ013-014-030345-
/O.CAN.KLOT.WW.Y.0007.000000T0000Z-120303T0600Z/
DUPAGE-COOK-
INCLUDING THE CITIES OF...WHEATON...CHICAGO
834 PM CST FRI MAR 2 2012

...WINTER WEATHER ADVISORY IS CANCELLED...

THE NATIONAL WEATHER SERVICE IN CHICAGO HAS CANCELLED THE WINTER
WEATHER ADVISORY. LIGHT SNOW HAS MOVED EAST OF THE AREA.

$$

ILZ012-030345-
/O.CAN.KLOT.WW.Y.0007.000000T0000Z-120303T0300Z/
KANE-
INCLUDING THE CITY OF...AURORA
834 PM CST FRI MAR 2 2012

...WINTER WEATHER ADVISORY IS CANCELLED...

THE NATIONAL WEATHER SERVICE IN CHICAGO HAS CANCELLED THE WINTER
WEATHER ADVISORY. LIGHT SNOW HAS MOVED EAST OF THE AREA.

$$

JEE

What forecasters said that day

The local office's own words before this winter storm 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 winter storm warning went out at Mar 2, 10:10 AM CST, 19 minutes earlier.

Area forecast discussion, Mar 2, 10:10 AM CST, 19 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1010 AM CST FRI MAR 2 2012

.DISCUSSION...
357 AM CST

A VERY DIFFICULT FORECAST SITUATION SHAPING UP FOR TODAY AND TONIGHT
WITH A COMBINATION OF WINTER WEATHER AND CONVECTIVE WEATHER TO
AFFECT NORTHERN ILLINOIS AND NORTHWEST INDIANA.

A SOUTHERN STREAM LOW IS TAKING SHAPE OVER THE SOUTHERN PLAINS.  THE
MODELS ARE FINALLY SETTING INTO A SOLUTION OF TRACKING THE SFC LOW
FROM CENTRAL OKLAHOMA...THROUGH SOUTHERN MISSOURI THIS MORNING AND
INTO CENTRAL ILLINOIS BY AROUND NOON AND THROUGH NORTHERN INDIANA
AND INTO SOUTHERN LOWER MICHIGAN BY EARLY THIS EVENING.  THE
SITUATION IS COMPLICATED BY A NORTHERN STREAM SHORT WAVE DROPPING
OUT OF THE NORTHERN PLAINS AND INTO THE WESTERN GREAT LAKES.  THE
GUIDANCE IS ADVERTISING PHASING OF THE NORTHERN STREAM SYSTEM WITH
THE SOUTHERN STREAM LOW WHICH WILL LEAD TO RAPID DEEPENING OF THE
SYSTEM.  THE RAPID DEEPENING OF THE LOW SHOULD NOT TAKE PLACE UNTIL
LATE THIS AFTERNOON AND INTO THE EVENING...WHEN THE LOW IS MOVING
THROUGH NORTHERN INDIANA AND INTO LOWER MICHIGAN.  FOR THE
THUNDERSTORM THREAT...THE MOST LIKELY TIMING AND LOCATION OF THUNDER
WILL BE OVER THE SOUTHERN AND EASTERN PORTIONS OF THE CWA...THOUGH
THERE IS A CHANCE THAT SOME THUNDER CAN DEVELOP AS FAR NORTH AS THE
FAR SOUTHEASTERN CHICAGO SUBURBS.  GIVEN THE VERY DYNAMIC SITUATION
SETTING UP...THE FAR SOUTHEASTERN PORTIONS OF THE CWA...ROUGHLY
SOUTH OF THE KANKAKEE RIVER ARE IN A SLIGHT RISK AREA FOR SEVERE
WEATHER WITH POSSIBLE DISCRETE SUPERCELL DEVELOPMENT AND THE MOST
LIKELY TIMING FOR STRONG TO SEVERE THUNDERSTORMS WILL BE DURING THE
LATE AFTERNOON HOURS.

THE WINTER WEATHER PICTURE IS A LITTLE MUDDLED BY SURFACE
TEMPERATURES AND THE GUIDANCE IS SHOWING SOME UNCERTAINTY TO THE
LOCATION OF THE RAIN/SNOW LINE.  THIS MORNING...HAVE TRENDED CLOSELY
TO THE NAM SOLUTION...THOUGH THE TRACK OF THE MAIN SFC LOW IS VERY
SIMILAR SIMILAR IN MUCH OF THE SHORT RANGE GUIDANCE.  FEEL FAIRLY
CONFIDENT IN A DEFORMATION ZONE FORMING NORTHWEST OF THE SFC LOW
TRACK...INITIALLY OVER ERN IOWA BY ARND NOON AND THEN SHIFT EWD INTO
THE ROCKFORD AREA THROUGH THE AFTERNOON.  WITH PRECIPITABLE WATER
AMOUNTS EXPECTED TO APPROACH THREE QUARTERS OF AN INCH INVOF THE
DEFORMATION BAND...QPF VALUES SHOULD BE RELATIVELY HIGH...AND
ANTICIPATE CLOSE TO AN INCH OF STORM TOTAL LIQUID QPF FOR THE
DURATION OF THE EVENT.  TOTAL SNOWFALL IN THE MAIN DEFORMATION BAND
HAS BEEN TOUGH TO GET A HANDLE ON GIVEN THE UNCERTAINTY IN THE
LOCATION OF THE RAIN/SNOW LINE AND HOW LARGE OF A TRANSITION ZONE
THERE WILL BE BETWEEN THE AREA OF ALL RAIN AND ALL SNOW.  HAVE
MAINTAINED A FAIRLY BROAD TRANSITION ZONE IN THE GRIDS TO REFLECT
THE UNCERTAINTY.  ONE LIMITING FACTOR FOR TOTAL ACCUMULATION WILL BE
THE INITIAL RELATIVELY WARM ENVIRONMENT AND THE TIME IT WILL TAKE
FOR THE COLDER AIR TO FILTER IN BEHIND THE SFC LOW.  AT THIS POINT
HAVE GONE WITH RELATIVELY LOW RAIN/SNOW RATIOS.  AT THIS
POINT...ANTICIPATE THAT THE BAND OF HEAVIEST ACCUMULATION WILL
EXTEND FROM NEAR DIXON TO ROCKFORD...WITH A BAND OF 3 TO 5 INCHES
POSSIBLE.  LIGHTER AMOUNTS SHOULD EXTEND TO THE SOUTH AND
EAST...WITH 1 TO 2 INCHES NEAR THE I-88 CORRIDOR...INCLUDING THE
CHICAGO AREA.  SOME LIGHTER AMOUNTS ARE POSSIBLE AS FAR SOUTH AS
I-80.  GIVEN THE UNCERTAINTY OF THE TOTAL SNOWFALL AMOUNTS...WILL
LET THE WINTER STORM WATCH RIDE FOR NOW...AND WAIT TO SEE HOW
QUICKLY THE SYSTEM DEEPENS BEFORE MAKING A FINAL DECISION ON WHETHER
TO GO WITH A WINTER STORM WARNING OR AN ADVISORY.

STRONG WINDS SHOULD ALSO BE A CONCERN LATE THIS AFTERNOON AND EARLY
THIS EVENING...ESPECIALLY FOR LOCATIONS EAST OF THE I-55 CORRIDOR AS
THE SFC LOW DEEPENS AS IT TRACKS THROUGH INDIANA.  AT THIS
POINT...DO NOT ANTICIPATE THE NEED FOR A WIND ADVISORY...BUT GUSTS
OF 30 TO 35 MPH...AND AN OCCASIONAL GUST TO 40 MPH...ARE LIKELY.

THIS WEEKEND THROUGH MID WEEK...

CYCLONIC FLOW WILL BE THE DOMINANT WEATHER WORD THROUGH THE WEEKEND.
BEHIND THE SYSTEM THAT WILL IMPACT THE REGION TODAY WILL BE A
SHEARED VORT LOBE THAT WILL MOVE FROM NORTHWEST TO SOUTHEAST ACROSS
THE CWA BY SATURDAY MORNING. THIS MAY BRING SOME LIGHT SNOW SHOWERS
TO AREAS NORTH OF INTERSTATE 80 THROUGHOUT THE DAY ON SATURDAY AND
SATURDAY NIGHT. MOISTURE WILL BE RELATIVELY SHALLOW AND FORCING WILL
BE WEAK...AND NOT EXPECTING MUCH BEYOND LIGHT SNOW SHOWERS TO A
LIGHT DUSTING. THE COLD NORTHWEST FLOW WILL KEEP TEMPERATURES DOWN
AND BELOW NORMAL THROUGH THE WEEKEND...AND A CONSTANT STRATUS DECK
WILL KEEP THOSE TEMPERATURES LOCKED AS IS. THE OFF AND ON CHANCES
FOR LIGHT SNOW SHOWERS WILL ALSO CONTINUE SUNDAY AS ANOTHER RIPPLE
IN THE FLOW SHOOTS DOWN THROUGH THE NORTHERN PLAINS AND ACROSS
NORTHERN ILLINOIS AND NORTHWESTERN INDIANA THROUGH THAT TIME. THE
FLIP BACK TO SPRING WILL COME CHARGING IN JUST IN
TIME FOR THE WORK WEEK. BY MONDAY AFTERNOON...AN EXPANSIVE AREA OF
HIGH PRESSURE WILL SHIFT EAST OF THE MID MISSISSIPPI VALLEY REGION
AND ACROSS THE OHIO VALLEY...ALLOWING WINDS TO BECOME SOUTHERLY.
TIGHTENING GRADIENT FLOW AT THE  SURFACE AND STRONG WAA WILL SUPPORT
HIGHS TUESDAY QUICKLY JUMPING TO THE UPPER 50S TO LOW TO MID 60S.
WITH OVERNIGHT LOWS IN THE LOWER 40S. CURRENT RECORDS FOR ROCKFORD
AND OHARE FOR TUESDAY AND WEDNESDAY ARE 70 AND 78 RESPECTIVELY AND
DONT EXPECT ANY THREAT TO THOSE NUMBERS.

THE NEXT UPPER LEVEL WAVE WILL APPROACH THE REGION CLOSER TO
WEDNESDAY EVENING /SLOWER THAN EARLIER FORECASTS/ BRINGING WITH IT
THE INCREASED CHANCES FOR SHOWERS. A WEAKENING UPPER LEVEL TROUGH
WILL HELP TO PUSH THROUGH A COLD FRONT OVERNIGHT ON THURSDAY. AT
THIS POINT IT IS LOOKING LIKE ANY THUNDER THREAT WILL BE MARGINAL.

KREIN/SHEA

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 16Z...

* CIGS LOWERING TO IFR BY MID AFTERNOON AND PERSISTING INTO
  EVENING IN PRECIPITATION.

* RAIN SPREADING ACROSS TERMINALS SHORTLY AFTER 17Z.

* RAIN CHANGING TO SNOW LATE THIS AFTERNOON...WITH SNOW BEING
  MODERATE TO POSSIBLY HEAVY AT TIMES INTO EARLY EVENING.

* A SMALL CHANCE FOR ICE PELLETS DURING THE RAIN TO SNOW
  CHANGEOVER LATE THIS AFTERNOON.

* WINDS BACKING TO THE NORTH THIS AFTERNOON THEN BECOMING GUSTY
  AND BACKING TO THE WEST BY MID EVENING.

//DISCUSSION...UPDATED 16Z...

ONLY MADE SOME MINOR CHANGES TO GOING FORECAST IN NEAR
TERM...MAINLY WITH RESPECT MOVING TIMING OF RAIN UP A COUPLE OF
HOURS WITH RAIN ALREADY SPREADING INTO THE SOUTHERN PARTS OF
CHICAGO METRO FROM THE SOUTH. TIMING OF RAIN/SNOW CHANGEOVER...
THE POTENTIAL FOR A PERIOD OF MODERATE/HEAVY SNOW INTO EARLY
EVENING...AND IFR/LIFR CONDITIONS ALL CONTINUE TO LOOK APPROPRIATE
BASED ON 12Z NAM WHICH REMAINS CONSISTENT WITH PREVIOUS THINKING.

THUNDER WILL BE LIKELY JUST OFF TO THE SOUTH OF THE TERMINALS
MIDDAY THROUGH AFTERNOON. RECENT HRRR RUNS THIS MORNING CONTINUE
TO DEPICT SOME POTENTIAL FOR CELLULAR CONVECTION INTO CHI AREA
AROUND 20Z...BUT BETTER POTENTIAL LOOKS TO BE ALONG/SOUTH OF A
PNT-GYY LINE AT THIS TIME.

RATZER

PREVIOUS DISCUSSION FROM 12Z...

A VERY ACTIVE PERIOD OF WEATHER IMPACTING AVIATION IS EXPECTED
ACROSS THE REGION THIS AFTERNOON AND EVENING. THIS WILL BE DUE TO
DEEPENING LOW PRESSURE MOVING NORTHEAST FROM SOUTHERN MO THIS
MORNING TO LOWER MI BY EVENING. THROUGH THIS MORNING...THERE WILL
BE MINIMAL IMPACTS WITH MID-LEVEL CLOUD COVER AND POSSIBLY A
PASSING SPRINKLE OR ISOLATED LIGHT SHOWER.

AS THE ENTIRE WEATHER SYSTEM BECOMES SIGNIFICANTLY BETTER
ORGANIZED THIS AFTERNOON...PRECIPITATION WILL SPREAD OVER NORTHERN
IL AND NORTHWEST IN. THIS WILL START AS RAIN AT ALL TAF SITES.
CIGS SHOULD QUICKLY DROP TO IFR OR LOW MVFR WITHIN AN HOUR OR TWO
OF THE PRECIP BEGINNING. WITH THE SYSTEM DEEPENING...COOLER AIR
WILL ALSO BE MORE RAPIDLY ENTRAINED INTO THE SYSTEM...AS WELL AS
DYNAMIC COOLING OCCURRING. THIS WILL TRANSITION RAIN TO A WET AND
POTENTIALLY HEAVY SNOW ACROSS NORTH CENTRAL IL...INCLUDING
RFD...DURING THE MIDDLE OF THIS AFTERNOON...AND ACROSS CHICAGO
AREA AIRPORTS LATE THIS AFTERNOON. THERE EVEN COULD BE A BRIEF
PERIOD OF ICE PELLETS DURING THE CHANGEOVER...BUT CONFIDENCE IN
THIS IS LOW. IN ADDITION...THUNDER IS POSSIBLE AT CHICAGO AREA
AIRPORTS AND GARY DURING THIS TIME. THE MOST ROBUST THUNDERSTORMS
ARE EXPECTED TO REMAIN SOUTH AND SOUTHEAST OF CHICAGO.

SNOWFALL RATES DURING THE TWO TO THREE HOURS AFTER TRANSITION WILL
BE MODERATE TO POTENTIALLY HEAVY...ESPECIALLY AT RFD. THE QUICK
FORWARD PROGRESS OF THE SYSTEM WILL HELP TO TAPER SNOW QUICKLY BY
MID EVENING FROM WEST TO EAST. WHILE SNOWFALL MAY ONLY LAST A FEW
HOURS...THE MODERATE TO POTENTIALLY HEAVY /GREATER THAN ONE INCH
PER HOUR/ RATES WILL LEAD TO QUICK ACCUMULATION. THIS IS
ESPECIALLY TRUE AT RFD...WHERE FOUR TO SIX INCHES ARE EXPECTED. AS
FOR AMOUNTS ANTICIPATED AT OTHER AIRFIELDS...TWO TO FOUR AT
DPA...ONE TO THREE AT ORD...AROUND ONE AT MDW...AND LESS THAN ONE
AT GYY.

WITH THE SIGNIFICANT INTENSIFICATION OF THE ENTIRE LOW PRESSURE
AREA THIS AFTERNOON AND EVENING...THE ENTIRE ATMOSPHERIC WIND
FIELD WILL RESPOND WITH A RAPID INCREASE IN MAGNITUDE. SURFACE
WINDS WILL BACK TO THE NORTH THEN NORTHWEST THROUGH THIS
AFTERNOON. THESE WILL BECOME GUSTY...ESPECIALLY LATE IN THE
AFTERNOON AND EVENING. HAVE GONE ABOVE MODEL FORECASTS FOR WINDS
WITH SUCH A RAPIDLY DEEPENING SYSTEM AND THE PATH IT IS TAKING.
WINDS ALOFT...IN THE 2000 TO 4000 FT LAYER LATE THIS AFTERNOON AND
EVENING...WILL LIKELY BE BETWEEN 35 AND 50 KTS ACROSS CHICAGO INTO
NORTHWEST INDIANA.

CIGS ARE EXPECTED TO IMPROVE LATER THIS EVENING...AND MAY COME UP
EVEN FASTER THAN THE TAF INDICATES.

//ORD AND MDW CONFIDENCE...UPDATED 16Z...

* HIGH CONFIDENCE IN IFR CIGS DEVELOPING BY LATE AFTERNOON.

* HIGH CONFIDENCE IN RAIN CHANGING TO SNOW. HIGH CONFIDENCE IN AT
  LEAST MODERATE RATES OF SNOWFALL AT ORD...WITH MEDIUM CONFIDENCE
  AT MDW. MEDIUM CONFIDENCE IN TIMING OF TRANSITION AT BOTH
  AIRPORTS.

* LOW CONFIDENCE IN ICE PELLET CHANCES. HIGH CONFIDENCE THAT IF
  ICE PELLETS OCCUR THAT THE PERIOD WOULD BE BRIEF.

* HIGH CONFIDENCE IN WIND TRENDS. MEDIUM CONFIDENCE IN SPEEDS AND
  GUSTS.

//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...

* SUNDAY...CHANCE OF MVFR WITH SNOW SHOWERS.
* MONDAY AND TUESDAY...VFR.
* WEDNESDAY...GUSTY SOUTHERLY WINDS. CHANCE OF RAIN SHOWERS.
* THURSDAY...CHANCE OF MVFR IN RAIN.

MTF

&&

.MARINE...
241 AM CST

STRONG LOW PRESSURE SYSTEM TO IMPACT THE REGION TODAY BRINGING
STRONG GALES AND POSSIBLY STORM FORCE WINDS TO THE LOWER HALF OF
LAKE MICHIGAN. THIS MORNING LOW PRESSURE IS CENTERED OVER CENTRAL
OKLAHOMA AND IS FORECAST TO LIFT NORTHEAST AND RAPIDLY DEEPEN. THIS
LOW WILL PASS JUST SOUTH OF LAKE MICHIGAN LATE THIS EVENING...
CONTINUING TO DEEPEN AS IT PUSHES ACROSS MICHIGAN TONIGHT. TIGHT
PRESSURE GRADIENT DEVELOPS ON THE NORTHWEST QUADRANT OF THE LOW WITH
VERY STRONG PRESSURE FALL/RISE COUPLET HELPING TO FURTHER ENHANCE
WINDS ACROSS THE SOUTHERN HALF OF THE LAKE. GUIDANCE SUGGESTS WINDS
OF 50 TO 55 KTS AT THE TOP OF THE MIXED LAYER FOR A BRIEF PERIOD
WHICH COULD MIX DOWN TO THE LAKE SURFACE. OUTSIDE OF THIS VERY SHORT
WINDOW WHERE STORM FORCE WINDS ARE POSSIBLE...MAINLY LOOKING AT HIGH
END GALE EVENT WITH WINDS 40 TO 45 KT FROM THIS EVENING THROUGH
EARLY SATURDAY MORNING. WILL UPGRADE THE GALE WATCH TO A WARNING AND
ALSO EXPAND INTO THE NEARSHORE WATERS.

WINDS DIMINISH SUNDAY AND MONDAY AS SURFACE RIDGE MOVES ACROSS THE
LAKE. WINDS INCREASE AGAIN TUESDAY AND WEDNESDAY AS ANOTHER LOW
PRESSURE SYSTEM PUSHES EAST ACROSS THE CANADIAN PRAIRIES THEN INTO
HUDSON BAY. BROAD HIGH PRESSURE WILL THEN DEVELOP ACROSS THE PLAINS
AND UPPER MIDWEST TO END OUT THE WEEK. BMD

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ013-ILZ014...3 PM FRIDAY TO
     MIDNIGHT SATURDAY.

     WINTER WEATHER ADVISORY...ILZ010-ILZ011-ILZ012...3 PM FRIDAY TO
     9 PM FRIDAY.

     WINTER STORM WATCH...ILZ003-ILZ004-ILZ008...3 PM FRIDAY TO 9 PM
     FRIDAY.

     WINTER STORM WATCH...ILZ005-ILZ006...3 PM FRIDAY TO MIDNIGHT
     SATURDAY.

IN...NONE.
LM...GALE WARNING...LMZ080-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-
     LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...5 PM
     FRIDAY TO 3 PM SATURDAY.

     GALE WARNING...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745...5 PM
     FRIDAY TO 3 AM SATURDAY.

     SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 5 PM FRIDAY.

     SMALL CRAFT ADVISORY...LMZ743-LMZ744-LMZ745...3 PM FRIDAY TO 5
     PM FRIDAY.

&&
Hazardous weather outlook, Mar 2, 5:07 AM CST, 5 hours 22 minutes before
HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
507 AM CST FRI MAR 2 2012

ILZ003>006-008-010>014-019>023-032-033-039-INZ001-002-010-011-019-
031030-
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-
507 AM CST FRI MAR 2 2012 /607 AM EST FRI MAR 2 2012/

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

.DAY ONE...TODAY AND TONIGHT.

  WEATHER HAZARDS EXPECTED:

 STRONG TO SEVERE THUNDERSTORMS...THE STRONGEST MAY PRODUCE:

  HAIL TO ONE INCH.

  STRONG DAMAGING WIND GUSTS IN EXCESS OF 60 MPH.

  LOCALLY HEAVY RAINFALL.

  FREQUENT CLOUD TO GROUND LIGHTNING.

 HEAVY SNOW...

  THREE TO FIVE INCHES...WITH LOCALLY HIGHER AMOUNTS IN EXCESS OF
  SIX INCHES.

  AREAS AFFECTED AND TIMING:

  THUNDERSTORMS ARE EXPECTED TO MOVE INTO THE AREA SOUTH OF A LINE
  FROM PONTIAC TO RENSSELAER BY LATE THIS MORNING. THE
  THUNDERSTORM ACTIVITY MAY SPREAD AS FAR NORTH AS TO THE
  INTERSTATE 80 CORRIDOR BY AROUND NOON. THE MOST LIKELY LOCATION
  FOR SEVERE THUNDERSTORMS WILL BE OVER THE FAR SOUTHEASTERN
  PORTIONS OF THE OUTLOOK AREA...SOUTH OF A LINE FROM HEBRON...TO
  FAIRBURY.

  RAIN WILL BEGIN TO OVERSPREAD THE AREA LATER THIS MORNING. THE
  RAIN WILL TRANSITION OVER TO SNOW DURING THE AFTERNOON HOURS
  ACROSS NORTHWESTERN ILLINOIS...WITH THE TRANSITION LINE FROM
  RAIN TO SNOW SPREADING TO THE SOUTH AND EAST THROUGH THE LATE
  AFTERNOON AND INTO THE EVENING. SEVERAL INCHES...POTENTIALLY
  GREATER THAN SIX INCHES...ARE EXPECTED IN FAR NORTHERN ILLINOIS.
  THE SNOW SHOULD COME TO AN END BY AROUND MIDNIGHT.

  DISCUSSION:

  A RAPIDLY DEEPENING LOW PRESSURE SYSTEM WILL TRACK THROUGH
  SOUTHERN MISSOURI...INTO CENTRAL ILLINOIS BY AROUND NOON AND
  THEN CONTINUE OFF TO THE NORTHEAST. THERE IS A RISK THAT SOME
  THUNDERSTORMS MAY BECOME SEVERE...PRODUCING DAMAGING WIND AND
  LARGE HAIL. LOCALLY HEAVY RAINFALL AND FREQUENT LIGHTNING ARE
  LIKELY AS WELL.

  FARTHER NORTH...A BAND OF HEAVY SNOW IS POSSIBLE AS THE LOW
  PRESSURE SYSTEM LIFTS NORTHEASTWARD...DRAWING COLDER AIR INTO
  NORTHERN ILLINOIS. SNOW MAY BECOME HEAVY AT TIMES...WITH
  ACCUMULATION RATES OF ONE INCH PER HOUR POSSIBLE.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS ACROSS THE SOUTHEAST PART OF THE OUTLOOK AREA MAY BE
NEEDED THIS AFTERNOON.

&&

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

LMZ740>745-031030-
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-
507 AM CST FRI MAR 2 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.

GALE FORCE WINDS TO 40 KT ARE EXPECTED THIS AFTERNOON THROUGH LATE
TONIGHT FOR THE ILLINOIS NEARSHORE WATERS. GALE FORCE WINDS TO 45
KT ARE EXPECTED THIS AFTERNOON THROUGH LATE TONIGHT FOR THE
INDIANA NEARSHORE WATERS.

THERE IS A CHANCE FOR THUNDERSTORMS TODAY FOR THE ILLINOIS AND
INDIANA NEARSHORE WATERS.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

WINDS AND WAVES HAZARDOUS TO SMALL CRAFT ARE LIKELY TO CONTINUE
THROUGH SATURDAY EVENING FOR THE ILLINOIS NEARSHORE WATERS AND
THROUGH LATE SATURDAY NIGHT FOR THE NORTHWEST INDIANA NEARSHORE
WATERS.

&&

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-
870-872-874-876-878-031030-
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-
507 AM CST FRI MAR 2 2012

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

.DAY ONE...TODAY AND TONIGHT.

NORTHERLY GALE FORCE WINDS TO 35 KT ARE EXPECTED TO OVERSPREAD
THE SOUTHERN HALF OF LAKE MICHIGAN BY THIS AFTERNOON. THIS
EVENING AND TONIGHT...GALES WILL BECOME WESTERLY AND INCREASE TO
45 KT. A FEW STORM FORCE GUSTS TO 50 KT ARE POSSIBLE.

THERE IS A CHANCE FOR THUNDERSTORMS FOR FAR SOUTHERN PORTIONS OF
LAKE MICHIGAN TODAY.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

GALE FORCE WINDS WILL CONTINUE THROUGH SATURDAY AFTERNOON FOR THE
SOUTHERN HALF OF LAKE MICHIGAN.

GALE FORCE WINDS ARE POSSIBLE AGAIN ON TUESDAY.

&&

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

KREIN

In the hours before

Special weather statement, Mar 2, 4:59 AM CST, 5 hours 30 minutes before
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHICAGO IL
459 AM CST FRI MAR 2 2012

ILZ023-033-039-INZ001-002-010-011-019-021700-
KANKAKEE-IROQUOIS-FORD-LAKE IN-PORTER-NEWTON-JASPER-BENTON-
INCLUDING THE CITIES OF...KANKAKEE...WATSEKA...PAXTON...GARY...
VALPARAISO...MOROCCO...RENSSELAER...FOWLER
459 AM CST FRI MAR 2 2012 /559 AM EST FRI MAR 2 2012/

...STRONG WINDS AND A RISK FOR SEVERE THUNDERSTORMS THIS AFTERNOON...

A POTENT LOW PRESSURE SYSTEM TRACKING ACROSS CENTRAL ILLINOIS INTO
NORTHWEST INDIANA TODAY WILL BRING STRONG AND GUSTY WINDS TO THE
REGION AS WELL AS A THREAT FOR SEVERE WEATHER. WINDS ARE EXPECTED
TO INCREASE TO 20 TO 25 MPH WITH GUSTS TO 40 MPH THIS AFTERNOON
AND EVENING. THIS WILL CAUSE LOOSE ITEMS TO BE BLOWN AROUND AND
POSSIBLY ALSO MAKE DRIVING HAZARDOUS...PARTICULARLY FOR HIGH
PROFILE VEHICLES DRIVING ON NORTH SOUTH ORIENTED ROADS.

IN ADDITION TO THE STRONG WINDS...STRONG TO SEVERE THUNDERSTORMS
MAY ALSO DEVELOP THIS AFTERNOON ACROSS EAST CENTRAL ILLINOIS AND
NORTHWEST INDIANA. THUNDERSTORMS MAY BE CAPABLE OF PRODUCING
DAMAGING STRAIGHT LINE WINDS AND HAIL.

BMD
Special weather statement, Mar 2, 6:14 AM CST, 4 hours 15 minutes before
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHICAGO IL
614 AM CST FRI MAR 2 2012

ILZ012>014-021700-
KANE-DUPAGE-COOK-
INCLUDING THE CITIES OF...AURORA...WHEATON...CHICAGO
614 AM CST FRI MAR 2 2012

...RAIN CHANGING OVER TO SNOW LATER TODAY...

A DEEPENING LOW PRESSURE SYSTEM TRACKING THROUGH CENTRAL ILLINOIS
WILL SPREAD RAIN ACROSS THE AREA SHORTLY BEFORE NOON. AS THE LOW
MOVES OFF TO THE NORTHEAST...COLDER AIR WILL FILTER ACROSS THE
AREA AND THE RAIN WILL BEGIN TO MIX WITH SNOW THIS
AFTERNOON...BEFORE CHANGING OVER TO ALL SNOW IN TIME FOR THE
EVENING RUSH HOURS ACROSS THE CHICAGO METRO AREA. SNOWFALL RATES
MAY BE HEAVY FOR BRIEF PERIODS OF TIME CAUSING SOME TRAVEL
DIFFICULTIES. SOME ACCUMULATION OF WET...HEAVY SNOW IS POSSIBLE.

KREIN

The office that day

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

IssuedProductOfficeCountiesLasted
Mar 1, 9:01 PM CSTWinter Storm WatchLOTBoone, Lake, McHenry, Ogle, Winnebago13 hr
Mar 2, 3:21 AM CSTGale WarningLOT33 hr
Mar 2, 10:29 AM CSTWinter Weather AdvisoryLOTDeKalb, DuPage, Kane, Lee10 hr
Mar 2, 11:44 AM CSTWind AdvisoryLOTFord, Iroquois, Kankakee12 hr
Mar 2, 3:11 PM CSTGale WarningLOT18 hr
Mar 2, 3:11 PM CSTGale WarningLOT24 hr
Mar 2, 3:11 PM CSTStorm WarningLOT12 hr

Nearby

Winter Storm Warnings in Illinois, 2012Every winter storm 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.