Alert archive / Illinois / Wind Advisories in 2012

Wind Advisory 14, NWS Chicago, IL

December 21, 20125 counties in Illinois; Benton County, Jasper County, Newton County, Indiana

NWS Chicago, IL issued this wind advisory at Dec 21, 2012, 12:00 AM CST for 5 counties in Illinois; Benton County, Jasper County, Newton County, Indiana. It was in force for 6 hr.

The area

The counties it named.

The facts

Issued
Dec 21, 2012, 12:00 AM CST (06:00 UTC)
Expired
Dec 21, 2012, 6:00 AM CST
In force
6 hr
Issued by
NWS Chicago, IL

Counties Ford County, IL, Iroquois County, IL, Kankakee County, IL, LaSalle County, IL, Livingston County, IL, Benton County, IN, Jasper County, IN, Newton County, IN

The radar

The Chicago radar (KLOT), 78 km from the middle of the area, began a volume at 06:00 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.

The nearest sounding before it

Lincoln, IL (KILX), launched 00:00Z, 6.0 hours before the alert went out and 104 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 2012-12-21Temperature 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, Lincoln, IL at 00:00Z on 2012-12-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 445 square meters per square second.19395878Sfc1 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
536 m above ground
0-6 km bulk shear
27 kt
0-1 km storm-relative helicity
445 m²/s²
0-3 km storm-relative helicity
488 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.

213 
WWUS73 KLOT 210600
NPWLOT

URGENT - WEATHER MESSAGE
NATIONAL WEATHER SERVICE CHICAGO IL
1200 AM CST FRI DEC 21 2012


ILZ023-032-033-039-INZ010-011-019-211200-
/O.CAN.KLOT.HW.W.0003.000000T0000Z-121221T0600Z/
/O.NEW.KLOT.WI.Y.0014.121221T0600Z-121221T1200Z/
KANKAKEE-LIVINGSTON-IROQUOIS-FORD-NEWTON-JASPER-BENTON-
INCLUDING THE CITIES OF...KANKAKEE...PONTIAC...WATSEKA...PAXTON...
MOROCCO...RENSSELAER...FOWLER
1200 AM CST FRI DEC 21 2012 /100 AM EST FRI DEC 21 2012/

...WIND ADVISORY IN EFFECT UNTIL 6 AM CST /7 AM EST/ FRIDAY...
...HIGH WIND WARNING IS CANCELLED...

THE NATIONAL WEATHER SERVICE IN CHICAGO HAS ISSUED A WIND
ADVISORY...WHICH IS IN EFFECT UNTIL 6 AM CST /7 AM EST/ FRIDAY.
THE HIGH WIND WARNING HAS BEEN CANCELLED. 

* TIMING...THROUGH TONIGHT. 

* WINDS...WEST TO NORTHWEST 25 TO 35 MPH GUSTING TO AROUND 45 MPH.

* IMPACTS...BE CERTAIN THAT ANY LOOSE ITEMS SUSCEPTIBLE TO HIGH
  WINDS ARE SECURED. WINDS MAY ADVERSELY IMPACT HIGH PROFILE
  VEHICLES.

* OTHER IMPACTS...LIGHT SNOW ACCUMULATION MAY RESULT IN SOME
  BLOWING SNOW WHICH MAY STICK TO ROADWAYS. USE EXTRA CAUTION AND
  BE ALERT FOR SLIPPERY AREAS.  

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WIND ADVISORY MEANS THAT SUSTAINED WINDS OF 30 TO 39 MPH...OR
GUSTS BETWEEN 45 AND 57 MPH...ARE LIKELY. WINDS THIS STRONG CAN
CAUSE MINOR PROPERTY DAMAGE UNLESS PRECAUTIONS ARE TAKEN. DRIVING
MAY BE DIFFICULT...ESPECIALLY IN HIGH PROFILE VEHICLES. MOTORISTS
SHOULD BE ALERT AND USE CAUTION.

&&

$$

ILZ019-211200-
/O.NEW.KLOT.WI.Y.0014.121221T0600Z-121221T1200Z/
LA SALLE-
INCLUDING THE CITY OF...OTTAWA
1200 AM CST FRI DEC 21 2012

...WIND ADVISORY IN EFFECT UNTIL 6 AM CST FRIDAY...

THE NATIONAL WEATHER SERVICE IN CHICAGO HAS ISSUED A WIND
ADVISORY...WHICH IS IN EFFECT UNTIL 6 AM CST FRIDAY. 

* TIMING...THROUGH TONIGHT. 

* WINDS...WEST TO NORTHWEST 25 TO 35 MPH GUSTING TO AROUND 45 MPH.

* IMPACTS...BE CERTAIN THAT ANY LOOSE ITEMS SUSCEPTIBLE TO HIGH
  WINDS ARE SECURED. WINDS MAY ADVERSELY IMPACT HIGH PROFILE
  VEHICLES.

* OTHER IMPACTS...LIGHT SNOW ACCUMULATION MAY RESULT IN SOME
  BLOWING SNOW WHICH MAY STICK TO ROADWAYS. USE EXTRA CAUTION AND
  BE ALERT FOR SLIPPERY AREAS.  

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WIND ADVISORY MEANS THAT SUSTAINED WINDS OF 30 TO 39 MPH...OR
GUSTS BETWEEN 45 AND 57 MPH...ARE LIKELY. WINDS THIS STRONG CAN
CAUSE MINOR PROPERTY DAMAGE UNLESS PRECAUTIONS ARE TAKEN. DRIVING
MAY BE DIFFICULT...ESPECIALLY IN HIGH PROFILE VEHICLES. MOTORISTS
SHOULD BE ALERT AND USE CAUTION.

&&

$$

MDB
2 follow-up statements
830 
WWUS73 KLOT 210852
NPWLOT

URGENT - WEATHER MESSAGE
NATIONAL WEATHER SERVICE CHICAGO IL
252 AM CST FRI DEC 21 2012

INZ002-211700-
/O.NEW.KLOT.HW.W.0004.121221T0852Z-121221T1800Z/
PORTER-
INCLUDING THE CITY OF...VALPARAISO
252 AM CST FRI DEC 21 2012

...HIGH WIND WARNING IN EFFECT UNTIL NOON CST TODAY NEAR THE LAKE...

THE NATIONAL WEATHER SERVICE IN CHICAGO HAS ISSUED A HIGH WIND
WARNING FOR THE PORTER COUNTY LAKESHORE...WHICH IS IN EFFECT
UNTIL NOON CST TODAY.

* TIMING...VERY STRONG WINDS AND POTENTIALLY DAMAGING WINDS ARE
  LIKELY THIS MORNING.

* WINDS...GUSTS UP TO 60 MPH ARE EXPECTED.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A HIGH WIND WARNING MEANS A HAZARDOUS HIGH WIND EVENT IS EXPECTED
OR OCCURRING. SUSTAINED WIND SPEEDS OF AT LEAST 40 MPH OR GUSTS
OF 58 MPH OR MORE CAN LEAD TO PROPERTY DAMAGE.

&&

$$

ILZ019-023-032-033-039-INZ010-011-019-211200-
/O.CON.KLOT.WI.Y.0014.000000T0000Z-121221T1200Z/
LA SALLE-KANKAKEE-LIVINGSTON-IROQUOIS-FORD-NEWTON-JASPER-BENTON-
INCLUDING THE CITIES OF...OTTAWA...KANKAKEE...PONTIAC...WATSEKA...
PAXTON...MOROCCO...RENSSELAER...FOWLER
252 AM CST FRI DEC 21 2012 /352 AM EST FRI DEC 21 2012/

...WIND ADVISORY REMAINS IN EFFECT UNTIL 6 AM CST /7 AM EST/
EARLY THIS MORNING...

* TIMING...THROUGH SUNRISE.

* WINDS...WEST TO NORTHWEST 25 TO 35 MPH GUSTING TO AROUND 45 
  MPH.

* IMPACTS...BE CERTAIN THAT ANY LOOSE ITEMS SUSCEPTIBLE TO HIGH 
  WINDS ARE SECURED. WINDS MAY ADVERSELY IMPACT HIGH PROFILE 
  VEHICLES. 

* OTHER IMPACTS...LIGHT SNOW ACCUMULATION MAY RESULT IN SOME 
  BLOWING SNOW WHICH MAY STICK TO ROADWAYS. USE EXTRA CAUTION 
  AND BE ALERT FOR SLIPPERY AREAS. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WIND ADVISORY MEANS THAT SUSTAINED WINDS OF 30 TO 39 MPH...OR
GUSTS BETWEEN 45 AND 57 MPH...ARE LIKELY. WINDS THIS STRONG CAN
CAUSE MINOR PROPERTY DAMAGE UNLESS PRECAUTIONS ARE TAKEN. DRIVING
MAY BE DIFFICULT...ESPECIALLY IN HIGH PROFILE VEHICLES. MOTORISTS
SHOULD BE ALERT AND USE CAUTION.

&&

$$

IZZI
922 
WWUS73 KLOT 211152
NPWLOT

URGENT - WEATHER MESSAGE
NATIONAL WEATHER SERVICE CHICAGO IL
552 AM CST FRI DEC 21 2012

ILZ019-023-032-033-039-INZ010-011-019-211300-
/O.EXP.KLOT.WI.Y.0014.000000T0000Z-121221T1200Z/
LA SALLE-KANKAKEE-LIVINGSTON-IROQUOIS-FORD-NEWTON-JASPER-BENTON-
INCLUDING THE CITIES OF...OTTAWA...KANKAKEE...PONTIAC...WATSEKA...
PAXTON...MOROCCO...RENSSELAER...FOWLER
552 AM CST FRI DEC 21 2012 /652 AM EST FRI DEC 21 2012/

...WIND ADVISORY WILL EXPIRE AT 6 AM CST /7 AM EST/ EARLY THIS
MORNING...

WEST NORTHWEST WINDS WILL REMAIN GUSTY UP TO 40 MPH THIS MORNING.
HOWEVER...WIND SPEEDS WILL GRADUALLY DIMINISH THROUGH THE DAY. 

$$

INZ002-211800-
/O.CON.KLOT.HW.W.0004.000000T0000Z-121221T1800Z/
PORTER-
INCLUDING THE CITY OF...VALPARAISO
552 AM CST FRI DEC 21 2012

...HIGH WIND WARNING REMAINS IN EFFECT UNTIL NOON CST TODAY...

* TIMING...VERY STRONG WINDS AND POTENTIALLY DAMAGING WINDS ARE 
  LIKELY THIS MORNING. 

* WINDS...GUSTS UP TO 60 MPH ARE EXPECTED.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A HIGH WIND WARNING MEANS A HAZARDOUS HIGH WIND EVENT IS EXPECTED
OR OCCURRING. SUSTAINED WIND SPEEDS OF AT LEAST 40 MPH OR GUSTS
OF 58 MPH OR MORE CAN LEAD TO PROPERTY DAMAGE.

&&

$$

KJB

What forecasters said that day

The local office's own words before this wind advisory 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 wind advisory went out at Dec 20, 8:54 PM CST, 3 hours 6 minutes earlier.

Area forecast discussion, Dec 20, 8:54 PM CST, 3 hours 6 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
854 PM CST THU DEC 20 2012

.MESOSCALE DISCUSSION...
652 PM CST

THROUGH EARLY TONIGHT...

SURFACE LOW CONTINUES TO MOVE NORTHEASTWARD INTO SOUTHWEST LOWER
MICHIGAN WITH THE PRESSURE STARTING TO COME UP SLIGHTLY. RADAR
IMAGERY SHOWS A BAND OF PRECIPITATION WITH DUAL POL PRODUCTS AND
SURFACE REPORTS INDICATING THE LEADING PORTION FALLING AS RAIN
WITH A VERY NARROW CORRIDOR OF SLEET FOLLOWED BY LIGHT-MODERATE SNOW.
THE BACK EDGE OF THE MORE INTENSE SNOW CONTINUES TO WORK
SOUTHEASTWARD FROM ROUGHLY EVANSTON TO WILMINGTON AT 645 PM CST. COLD
AIR CONTINUES TO WRAP INTO NORTHWEST INDIANA FROM THE SOUTH SO AM
CONCERNED THAT THE BAND WILL TURN TO ALL SNOW AS IT MOVES ACROSS
AREAS FROM KANKAKEE TO GARY AND POINTS SOUTH AND EAST OVER THE
NEXT FEW HOURS. FORCING ASSOCIATED WITH TROUGH OF WARM AIR ALOFT
/TROWAL/ LOOKS TO REMAIN WELL ORGANIZED OVER THE NEXT FEW HOURS AS
IT PIVOTS ACROSS NORTHWEST INDIANA. BEHIND THE BAND....ACROSS THE
WESTERN CHI METRO AND BACK TO NEAR THE RFD AREA ECHOES HAVE WANED
WITH WITH NEAR TERM GUIDANCE SUPPORTING THIS WITH A WEAKENING IN
FRONTOGENETIC FORCING. HOWEVER...FURTHER WEST...ANOTHER WELL
ORGANIZED BUT BROAD BAND CONTINUES ORIENTED FROM NORTH TO SOUTH
AND IS MOVING EAST. BETWEEN RADAR TRENDS AND NEAR TERM PROGS
INCLUDING 700-600 MP FRONTOGENESIS THIS BAND WILL CONTINUE
EASTWARD BUT MAY WANE A BIT OVER THE NEXT COUPLE HOURS BEFORE
BECOMING BETTER FOCUSED CLOSER TO THE CHICAGO METRO LATE THIS
EVENING. WILL NEED TO EVALUATE TIMING OF THE END OF THE WINTER
STORM WARNING IN NORTHWEST INDIANA AND THIS BAND MAY AFFECT THAT
AREA THROUGH THE WEE HOURS OF THE MORNING.

IN TERMS OF WINDS...BEST PRESSURE RISE AREA IS STILL POSITIONED
ACROSS WESTERN AND CENTRAL ILLINOIS WITH STRONGEST ALONG AND SOUTH
OF A LINE FROM THE QUAD CITIES TO PRINCETON TO PONTIAC. WITH THE
LOW LIFTING NORTHEASTWARD THE PRESSURE RISE/FALL COUPLET WILL ALSO
LIFT NORTHEAST SO WIND SPEEDS WILL COME UP THROUGH THE EVENING
INTO THE 40-50 KT RANGE.

WILL KEEP CURRENT HEADLINES AS-IS BUT ADJUST WORDING/SNOW AMOUNTS TO
FIT THE EXPECTED TRENDS THROUGH THE EVENING AND WILL HAVE THOSE
ISSUED SHORTLY.

TO SUMMARIZE...THE CHICAGO METRO PRECIP BAND WILL CONTINUE
SOUTHEASTWARD ACROSS AREAS FROM KANKAKEE TO WATSEKA AND NORTHWEST
INDIANA AND PROBABLY TURN TO MORE SNOW THAN RAIN IF NOT ALL SNOW.
THE MOST INTENSE PRECIP WITH THIS WILL LIKELY BE FOCUSED ALONG AND
NORTH OF INTERSTATE 80 AND HIGHWAY 30. A LULL IN FALLING SNOW WILL
OCCUR BEHIND THE BAND ACROSS NORTHEAST ILLINOIS FOR THE NEXT
SEVERAL HOURS...THOUGH SOME LIGHT SNOW WILL PROBABLY CONTINUE WITH
MINOR ADDITIONAL ACCUMS. A HEAVIER BAND OF LIGHT TO MODERATE SNOW
WILL RETURN TO THE ROCKFORD/I-39 CORRIDOR AND DOWN TO PONTIAC IN
THE NEXT HOUR THEN CONTINUE EASTWARD. THIS WILL LIKELY DROP
ANOTHER 1 TO PERHAPS 2 INCHES OF SNOW...ESPECIALLY ACROSS AREAS
ALONG AND NORTH OF INTERSTATE 80. THIS BAND MAY THEN RE-FOCUS
SOMEWHAT CLOSER TO OR OVER THE CHICAGO METRO AREA AFTER 10 OR 11
PM THIS EVENING BRINGING AN INCREASE IN SNOWFALL INTENSITY AND
SOME ADDITIONAL ACCUMULATION...PROBABLY IN THE 1 TO POSSIBLY 2
INCH RANGE BUT WILL NEED TO SEE HOW INTENSITY EVOLVES OVER THE
NEXT HOUR OR TWO AS THIS MAY BE A BIT HIGH. WINDS WILL INTENSIFY
TO THE 40-50 KT RANGE THROUGH THE EVENING LEADING TO BLOWING SNOW
AND REDUCED VSBY WHICH WILL CONTINUE OVERNIGHT.

MDB

&&

.DISCUSSION...
412 PM CST

APOLOGIES FOR THE LATE DISCUSSION

NEAR TERM...STORM IMPACTS TONIGHT

THE STRONG WINTER SYSTEM IS FOR THE MOST PART UNFOLDING SO FAR AS TO
PLAN. THE WINTER STORM WARNING FOR LASALLE AND DEKALB COUNTY HAS
BEEN UPGRADED TO A BLIZZARD WARNING...WITH ALL OTHER EXISTING
HEADLINES UNCHANGED.

IMPRESSIVELY DEEP MID LEVEL LOW CONTINUES TO TRACK ACROSS NRN
IL WITH DEFORMATION ZONE CONTINUING TO STRENGTHEN ACROSS WI/NRN IL.
OVER THE PAST FEW HOURS THE SURFACE PRESSURE HAS DROPPED AT 5 MB
ACROSS MI ACCORDING TO SFC OBS AS THE SUB 985 MB SURFACE LOW
PRESSURE HAS EMERGED FROM CHICAGO OVER THE SOUTHERN END OF LAKE
MICHIGAN. DUE TO THIS STRENGTHENING...PRECIPITATION HAS BEGUN TO
FILL IN NORTH OF THE SURFACE LOW. CURRENTLY THE COLDEST CLOUD
TOPS AND BEST ENHANCEMENT ON INFRARED SATELLITE ARE LOCATED ACROSS
EXTREME NORTHEAST IOWA AND WISCONSIN AND WITH THE HEAVIER SNOWFALL
RATES GETTING INTO NORTH CENTRAL AND NORTHWEST ILLINOIS WITH COLD
AIR WRAPPING INTO THE CIRCULATION.

...RAIN TO SNOW TIMING...
RAIN HAS CHANGED TO SNOW ALONG AND WEST OF A MCHENRY COUNTY TO
SYCAMORE TO MENDOTA TO CHAMPAIGN LINE AS OF THIS WRITING.  THE
CHANGE SHOULD PICK UP IN PROGRESSION SPEED IN THE WAKE OF THE
SURFACE LOW AND UNDERNEATH THE RAPID COOLING OF THE UPPER LOW LATE
THIS AFTERNOON AND EVENING. THE FAR WESTERN CHICAGO METRO WILL BEGIN
TO SEE SNOW WITHIN THE NEXT 1 TO 2 HOURS...WITH THE CITY AND POINTS
SOUTH CHANGING OVER WITHIN THE 6PM TO 8PM TIME FRAME. FINALLY
NORTHWEST INDIANA SHOULD SEE ALL SNOW BY ROUGHLY 8PM TO 9PM.

...SNOWFALL AND WIND...

WITH CURRENT RADAR AND SATELLITE TRENDS AND THE PROJECTED PATH OF
THE LOW AND ASSOCIATED DEFORMATION...THE MOST INTENSE SNOWFALL
AREA/BANDS WITH RATES POTENTIALLY AS HIGH AS ONE INCH OR GREATER PER
HOUR SHOULD START TO SLOWLY WORK EASTWARD PRIMARILY ALONG AND NORTH
OF I-80 THROUGH THE EVENING.  WHILE NOT WIDESPREAD...CANT RULE OUT
SOME LOCAL 1 TO 2 INCH PER HOUR RATES IN MORE INTENSE BANDING
FEATURES. THERE IS ONE WELL DEFINED FRONTOGENETIC BAND OVER
NORTHEAST ILLINOIS THAT IS FILLING IN BACK TO THE
SOUTHWEST...INCLUDING AFOREMENTIONED AREAS THAT HAVE CHANGED TO
SNOW.

AS THE COLD ADVECTION GOES TO WORK...AREAS UNDER THIS BAND
SHOULD SEE A GOOD BURST OF SNOW AS IT PIVOTS EASTWARD LATE THIS
AFTERNOON THROUGH THIS EVENING. WINDS HAVE BEEN GUSTING IN EXCESS OF
40 MPH ACROSS NORTH CENTRAL/NW IL AND CENTRAL IL WITH THE DEEPENING
OF THE SYSTEM AND CONTINUED STRENGTHENING COLD AIR ADVECTION. THESE
GUSTS WILL ONLY INCREASE AS THEY ROTATE EAST INTO THE AREA WHICH
CONTINUES TO MATCH UP WELL WITH THE 50-60 MPH WINDS SEEN IN THE
BOUNDARY LAYER FORECAST SOUNDINGS. GIVEN THE LATEST TRENDS WITH WIND
AND SNOW...UPGRADED THE WSW TO A BLIZZARD WARNING FOR DEKALB AND
LASALLE.

IN ADDITION...A DEFORMATION BAND EXTENDING FROM SOUTHWEST
WISCONSIN AND NORTHEAST IOWA DOWN ALL THE WAY TO THE ST LOUIS AREA
IS PRODUCING...COMBINED WITH INCREASING WINDS...WIDESPREAD LESS THAN
A MILE VISIBILITY AS OF THIS WRITING. WHILE SNOWFALL AMOUNTS ARE
EXPECTED TO BE FAIRLY LIGHT IN THE IN THE HIGH WIND WARNING AREA OF
THE SOUTHERN CWA... BLOWING SNOW IS A CONTINUED SECONDARY IMPACT
MENTIONED IN THE NPW. TOTAL FORECAST SNOWFALL AMOUNTS REMAIN FAIRLY
SIMILAR TO PREVIOUS FORECAST...SO FOR THE RUNDOWN ON THIS...REFER TO
WSW STATEMENTS. SOME OF THE MOST SEVERE CONDITIONS MAY OCCUR ONCE
LAKEFRONT AREAS IN NORTHWEST INDIANA CHANGE OVER TO SNOW...AS WINDS
WILL BE GUSTING TO IN EXCESS OF 60 MPH THERE AND SNOW INCLUDING SOME
POSSIBLE LAKE ENHANCEMENT AIMED TOWARD NORTHEAST PORTER COUNTY WILL
CONTINUE AFTER MIDNIGHT. MAY NEED TO CONSIDER EXTENDING WINTER STORM
WARNING THERE UNTIL DAYBREAK.

...CONFIDENCE IN STORM IMPACTS TONIGHT...

SNOWFALL AMOUNTS...MEDIUM.

HIGH WINDS...HIGH.

BLIZZARD/NEAR BLIZZARD CONDITIONS...HIGH.

RC/MTF

FRIDAY AND FRIDAY NIGHT...

BY 12Z FRIDAY THE STORM SYSTEM IS TO HAVE MOVED SLOWLY EAST TO
FAR SOUTHERN LOWER MICHIGAN AND BECOME VERTICALLY STACKED. WHILE
THE SURFACE LOW CENTRAL PRESSURE WILL BE GRADUALLY INCREASING
THERE WILL STILL BE A VERY TIGHT PRESSURE GRADIENT SURROUNDING
THE STORM KEEPING STRONG WINDS GOING. NORTHWEST WINDS WILL STILL
BE GUSTING TO AROUND 40 MPH AT DAYBREAK AND THEN ONLY VERY
GRADUALLY DIMINISH DURING THE DAY AS THE THE STORM SYSTEM
CONTINUES OFF TO THE EAST TO THE UPPER ST. LAWRENCE VALLEY BY 00Z
SATURDAY. THE CONTINUED STRONG WINDS WILL LIKELY CAUSE DRIFTING
AND SOME BLOWING SNOW UNTIL THE WINDS DROP OFF LATER IN THE
AFTERNOON.

BESIDES FLURRIES AND A BIT OF LINGERING LIGHT SNOW ACROSS THE
EASTERN PORTION OF THE FORECAST AREA DURING THE FIRST PART OF THE
DAY FRIDAY...ANY ACCUMULATING SNOW WILL BE OVER EXCEPT FOR
POSSIBLY SOME MINOR ADDITIONAL ACCUMULATION DUE TO LAKE EFFECT IN
PORTER AND PORTIONS OF JASPER COUNTIES UNTIL WINDS BACK FURTHER
AND SHIFT THE WESTERN EDGE OF ANY LAKE EFFECT FURTHER TO THE EAST
AND OUT OF THE LOCAL FORECAST AREA BY EARLY TO MID AFTERNOON.
CLOUDS WILL BE CLEARING FROM WEST TO EAST DURING THE DAY AS THE
STORM SYSTEM PULLS AWAY.

STRONG COLD AIR ADVECTION CURRENTLY UNDER WAY OVER THE AREA WILL
CONTINUE THROUGH THE NIGHT. FORECAST TEMPERATURE PROFILES SHOWING
SOME WARMING IN LOW LEVELS DUE TO SUBSIDENCE AS RIDGING SURFACE
AND ALOFT MOVE EAST FROM THE PLAINS TOWARD THE UPPER AND MID
MISSISSIPPI VALLEY LATER FRIDAY. BELOW THIS WARMING IS AN
INVERSION UP TO AROUND 2K FT AGL TRAPPING THE COLD AIR OVER FRESH
SNOWFALL. TEMPERATURES DURING THE DAY FRIDAY ARE EXPECTED TO ONLY
RECOVER A FEW DEGREES FROM EARLY MORNING LOWS...MAINLY NO MORE
THAN THE LOWER AND MID 20S. WIND CHILLS WILL BE IN THE ZERO TO 10
ABOVE RANGE MUCH OF THE DAY.

THE SURFACE RIDGE IS PROGGED TO MOVE EAST OF THE MISSISSIPPI
RIVER AND BE OVER THE LOCAL AREA BY 12Z SATURDAY. MAINLY CLEAR
SKIES AND A CONTINUED DECREASE IN WINDS FRIDAY NIGHT WILL ALLOW
GOOD RADIATIONAL COOLING WITH LOWS AROUND 10 ABOVE IN NORTH
CENTRAL ILLINOIS AND TEENS ELSEWHERE.

SATURDAY THROUGH SUNDAY NIGHT...

WARM AIR ADVECTION CONTINUES SATURDAY HELPING TEMPERATURES TO
REACH HIGHS FROM THE MID 20S TO THE LOWER 30S. THEN...A WEAK
TROUGH/COLD FRONT DROPS SOUTH ACROSS THE AREA SATURDAY NIGHT WITH
TEENS AND LOWER 20S COMMON FOR OVERNIGHT LOWS FOLLOWED BY MID 20S
TO LOWER 30S FOR HIGHS SUNDAY. WITH ONLY VERY WEAK FEATURES
PROGGED AT THE SURFACE AND ALOFT THE THREAT OF PRECIPITATION
DURING THIS PERIOD IS VERY LOW.

MONDAY THROUGH THURSDAY...

SOME SIGNIFICANT MODEL DIFFERENCES STILL EXIST AT THIS RANGE WITH
THE 20.12Z OPERATIONAL GFS BRINGING AN UPPER LOW AND ASSOCIATED
SURFACE LOW ACROSS FROM THE NORTHERN PLAINS EAST ACROSS THE UPPER
MIDWEST MONDAY THROUGH MONDAY NIGHT KEEPING THE BETTER CHANCES OF
SOME LIGHT CHRISTMAS EVE SNOW TO THE NORTH OF THE LOCAL AREA. IN
CONTRAST...THE 20.12Z ECMWF TAKES A SHARPER UPPER TROUGH FROM THE
CENTRAL PLAINS EAST ACROSS THE MID AND LOWER MISSOURI VALLEY AND
THE UPPER AND MID MISSISSIPPI VALLEY DURING THE SAME PERIOD. THIS
TRACK PUTS THE LOCAL AREA UNDER THE THREAT OF A SOMEWHAT MORE
INTENSE SNOWFALL RESULTING IN ACCUMULATIONS OF UP TO A FEW INCHES
POSSIBLE DURING LATER MONDAY AND MONDAY EVENING. MEANWHILE THE
GFS ENSEMBLE MEAN TAKES THE SURFACE LOW ACROSS FAR SOUTHERN
ILLINOIS TO THE LOWER OHIO VALLEY WHICH WOULD KEEP ANY
SIGNIFICANT CHANCES FOR PRECIPITATION TO THE SOUTH OF THE LOCAL
AREA. WITH MUCH DISAGREEMENT AMONGST MODELS AT THIS POINT FOR NOW
HAVE FORECAST JUST A CHANCE OF LIGHT SNOW DURING MONDAY AND
MONDAY NIGHT.

MODEL DISCREPANCIES CONTINUE TUESDAY THROUGH THURSDAY BUT SOME
CONSENSUS ON UPPER TROUGHY-NESS ACROSS THE CENTRAL U.S. SO SLIGHT
CHANCE TO LOW END CHANCE POPS FOR LIGHT SNOW CARRIED FROM
TUESDAY...CHRISTMAS DAY...INTO THURSDAY. SOME INDICATION THAT
HIGH PRESSURE BUILDING FROM SOUTH CENTRAL CANADA ACROSS THE
NORTHERN AND CENTRAL PLAINS MAY BRING LAKE EFFECT SNOW SHOWERS TO
AREAS NEAR THE LAKE IN BOTH NORTHEAST ILLINOIS AND FAR NORTHWEST
INDIANA SO HAVE SOMEWHAT HIGHER CHANCE POPS FOR THESE LOCATIONS.

TRS

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 03Z...

* VARIABLE IFR/MVFR CIGS/VSBY TONIGHT.
* NW WINDS WITH GUSTS TO AROUND 45 KT.
* A SECOND BAND OF LIGHT TO MODERATE SNOW RESTRICTING VSBY TO
  BETWEEN 1-2 MILES...BLOWING SNOW CONTRIBUTING TO LOW VIS. BMD

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

OVERALL FORECAST SEEMS ON TRACK THIS EVENING THUS DID NOT MAKE ANY
SIGNIFICANT CHANGES TO LATEST TAF PACKAGE. PRECIP CONTINUES TO
TRANSITION TO SNOW THIS EVENING...TAKING PLACE OVER THE CHICAGO AREA
NOW THROUGH THE NEXT HOUR OR SO AS WINDS TURN NORTHWESTERLY. WIND
GUSTS SHOULD QUICKLY INCREASE...AND CONTINUE TO EXPECT GUSTS IN
EXCESS OF 40 KT THROUGH MUCH OF TONIGHT AS THE HIGH CONTINUES TO
MOVE EAST WITH THE TIGHTEST GRADIENT TRAILING...AND VERY STRONG
PRESSURE RISES CONTRIBUTING TO THE SHARP INCREASE IN WINDS.

RADAR IMAGERY SHOWS TWO BANDS OF HEAVIER PRECIP...ONE STRETCHING
FROM ROUGHLY KENV SSW TO KC09 THIS HOUR. THIS FIRST BAND IS
ASSOCIATED WITH THE TRANSITION ZONE FROM RAIN TO SNOW...BUT MAY ALSO
INCLUDE OCCASIONAL BURSTS OF MODERATE TO HEAVY SNOW WITH VSBY
REDUCED TO AROUND 1/2 MILE. THE SECOND BAND STRETCHES FROM KEFT
SOUTH TO JUST WEST OF KSQI THIS HOUR. THIS BAND WILL MOVE OVER THE
ROCKFORD AREA OVER THE NEXT COUPLE HOURS CONTRIBUTING TO HALF MILE
OR LESS VSBY AT TIME. RUC/NAM GUIDANCE BOTH SHOW A SECONDARY PEAK OF
OMEGA AS THIS BAND MOVES ACROSS THE CHICAGO AREA...WITH THE BETTER
FORCING CENTERED WITHIN THE SNOW GROWTH ZONE. SHOULD THIS BAND HOLD
TOGETHER...MAY SEE A SECONDARY PERIOD AROUND 5-6Z WHERE VSBY COULD
BE LESS THAN A MILE. DESPITE THIS PEAK IN OMEGA...OVERALL THE
FORCING IS LESS THAN THE FIRST BAND TO MOVE ACROSS THE AREA...WITH
STRONG WINDS LIKELY TO BREAK DENDRITES AND WEAKENING PVU INDICATING
DIMINISHED BANDING POTENTIAL. WILL HAVE TO MONITOR THE EVOLUTION
OVER NEXT HOUR OR SO...

EXPECT SNOWFALL TO TAPER 08-10Z THEN END WITH CIGS RETURNING TO VFR
DURING THE DAY FRIDAY. WINDS ARE EXPECTED TO REMAIN ELEVATED...BUT
NOT AS STRONG AS OVERNIGHT WITH GUSTS ABOVE 20 KT CONTINUING.

BMD

//ORD AND MDW CONFIDENCE...UPDATED 03Z...

* MEDIUM CONFIDENCE IN CIG TRENDS.
* HIGH CONFIDENCE IN -SN...MEDIUM CONFIDENCE IN VSBY.
* HIGH CONFIDENCE IN WIND DIRECTION...MEDIUM CONFIDENCE IN WIND
  SPEEDS.
* HIGH CONFIDENCE IN CIGS IMPROVING TOMORROW...MEDIUM CONFIDENCE
  IN TIMING. BMD

//OUTLOOK FOR ORD/MDW FOR 12Z SATURDAY-12Z THURSDAY...UPDATED 00Z...

* SATURDAY THROUGH SUNDAY...DRY. VFR.
* MONDAY AND TUESDAY...SLIGHT CHANCE OF SNOW. MVFR POSSIBLE.
* WEDNESDAY...CHANCE OF SNOW. MVFR LIKELY.

BMD

&&

.MARINE...

207 PM...MINIMAL ADJUSTMENTS TO CURRENT FORECAST...AND HEADLINES
WILL REMAIN IN PLACE. STORM WARNING WILL REMAIN IN PLACE FOR LATE
THIS AFTERNOON THROUGH FRIDAY AFTERNOON. STORM FORCE CONDITIONS
WILL BEGIN ACROSS THE SOUTHERN HALF OF LAKE MICHIGAN FIRST...THEN
COVER ALL OF LAKE MICHIGAN LATER THIS EVENING.

THE SURFACE LOW PRESSURE THIS AFTERNOON WAS APPROACHING
CHICAGO...AND BASED ON GUIDANCE WILL SLIDE EAST/NORTHEAST ACROSS THE
SOUTHERN TIP OF LAKE MICHIGAN. AS THIS LOW SLIDES EAST THE WINDS
WILL DIMINISH...HOWEVER ALONG THE BACKSIDE OF THE LOW PRESSURE
SYSTEM WINDS WILL RAPIDLY INCREASE TO STORM FORCE GUSTS TO 55 KT BY
TONIGHT FROM THE NORTH/NORTHWEST. AT THIS TIME IT REMAINS POSSIBLE
FOR AN OCCASIONAL GUST TO 60-65 KT...HOWEVER CONFIDENCE REMAINS LOW.
THE TIGHTEST WIND GRADIENT THAT COULD PRODUCE THIS TYPE OF GUST
WOULD BE LATE THIS EVENING THROUGH EARLY FRIDAY MORNING.

THE LOW WILL MOVE EAST AND MERGE WITH ANOTHER LOW MOVING UP THE EAST
COAST SATURDAY. THE COMBINED LOW WILL SLOW AND AND AS HIGH PRESSURE
BUILDS ACROSS THE PLAINS...THE GRADIENT WILL REMAIN STRONG INTO
FRIDAY NIGHT AND FINALLY RELAX SATURDAY. THEN WITH HIGH PRESSURE
SLIDING ACROSS THE OHIO VALLEY FOR THE WEEKEND...WINDS WILL
DIMINISH. THE NEXT SYSTEM APPEARS TO SLIDE ACROSS THE MISSOURI
VALLEY MONDAY ARRIVING ACROSS THE CENTRAL GREAT LAKES MONDAY
NIGHT/CHRISTMAS DAY.

CONFIDENCE IN THE STORM FORCE GUSTS...HIGH.

CONFIDENCE IN THE SYSTEM EARLY NEXT WEEK...MEDIUM.

BEACHLER

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...BLIZZARD WARNING...ILZ003-ILZ004-ILZ008-ILZ010-ILZ011-ILZ019
     UNTIL MIDNIGHT FRIDAY.

     WINTER STORM WARNING...ILZ006-ILZ012-ILZ013-ILZ014-ILZ020-ILZ021-
     ILZ022 UNTIL 3 AM FRIDAY.

     WINTER STORM WARNING...ILZ005 UNTIL MIDNIGHT FRIDAY.

     HIGH WIND WARNING...ILZ023-ILZ032-ILZ033-ILZ039 UNTIL MIDNIGHT
     FRIDAY.

IN...LAKESHORE FLOOD WARNING...INZ001-INZ002...MIDNIGHT FRIDAY TO 3
     AM SATURDAY.

     WINTER STORM WARNING...INZ001-INZ002 UNTIL 3 AM FRIDAY.

     HIGH WIND WARNING...INZ010-INZ011-INZ019 UNTIL MIDNIGHT FRIDAY.

LM...STORM WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
     LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ740-LMZ741-LMZ742-
     LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-
     LMZ874-LMZ876-LMZ878 UNTIL 4 PM FRIDAY.

&&
Hazardous weather outlook, Dec 20, 9:33 PM CST, 2 hours 27 minutes before
HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
933 PM CST THU DEC 20 2012

ILZ003>006-008-010>014-019>023-032-033-039-INZ001-002-010-011-019-
220345-
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-
933 PM CST THU DEC 20 2012 /1033 PM EST THU DEC 20 2012/

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

.DAY ONE...OVERNIGHT.

LIGHT SNOW WILL CONTINUE TO MOVE EASTWARD ACROSS THE OUTLOOK AREA
WITH PERIODIC BANDS OF MODERATE SNOW AT TIMES. SNOW WILL TAPER OFF
FROM WEST TO EAST FROM LATE EVENING THROUGH THE OVERNIGHT HOURS
THOUGH SOME LIGHT SNOW WILL LINGER ACROSS PORTER COUNTY INDIANA
THROUGH DAYBREAK.

NORTHWEST WINDS OF 30 TO 45 MPH WILL CONTINUE THIS EVENING WITH
GUSTS UP TO 55 OR 60 MPH THROUGH EARLY TONIGHT...ESPECIALLY NEAR
THE INDIANA SHORELINE OF LAKE MICHIGAN. DOWNED TREE LIMBS AND
POWER LINES COULD CAUSE POWER OUTAGES.

THE COMBINATION OF THE SNOWFALL AND VERY STRONG WINDS WILL
SIGNIFICANTLY REDUCE VISIBILITIES AT TIMES.

THE VERY STRONG NORTHWEST WINDS WILL GENERATE WAVES HIGH ENOUGH
TO CAUSE FLOODING AND BEACH EROSION ALONG THE INDIANA SHORES OF
LAKE MICHIGAN BY LATE TONIGHT.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY.

STRONG WINDS WILL PERSIST INTO FRIDAY AFTERNOON. WINDS GUSTING TO
45 MPH WILL CONTINUE TO CAUSE LOCAL AREAS OF BLOWING AND DRIFTING
SNOW.

HIGH WAVES WILL POSE A THREAT OF FLOODING AND BEACH EROSION ALONG
THE INDIANA SHORES OF LAKE MICHIGAN THROUGH FRIDAY NIGHT.

THERE IS A CHANCE OF SOME PERIODS OF LIGHT SNOW ACCUMULATION
ACROSS MUCH OF THE AREA MONDAY NIGHT THROUGH WEDNESDAY NIGHT.
SOMEWHAT HEAVIER ACCUMULATIONS DUE TO LAKE EFFECT SNOW SHOWERS
ARE POSSIBLE NEAR THE ILLINOIS AND INDIANA LAKE SHORES TUESDAY
NIGHT INTO THURSDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS ARE ENCOURAGED TO REPORT SNOWFALL TOTALS TO THE NATIONAL
WEATHER SERVICE CHICAGO.

&&

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

LMZ740>745-220345-
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-
933 PM CST THU DEC 20 2012

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

.DAY ONE...OVERNIGHT.

STORM FORCE WINDS WILL OCCUR TONIGHT.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY.

STORM FORCE WINDS WILL PERSIST INTO FRIDAY AFTERNOON AND THEN
DIMINISH TO GALE FORCE BY LATE AFTERNOON. THE GALE FORCE WINDS
WILL PERSIST INTO FRIDAY NIGHT.

HAZARDOUS WINDS AND WAVES WILL POSE HAZARDOUS CONDITIONS FOR
SMALL CRAFT OVERNIGHT FRIDAY AND THROUGH SATURDAY.

&&

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-
870-872-874-876-878-220345-
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-
933 PM CST THU DEC 20 2012

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

.DAY ONE...OVERNIGHT.

STORM FORCE WINDS WILL OCCUR TONIGHT.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY.

STORM FORCE WINDS WILL PERSIST THROUGH FRIDAY AND THEN DIMINISH
TO GALE FORCE FRIDAY EVENING. THE GALE FORCE WINDS CONTINUE
THROUGH THE OVERNIGHT HOURS OF FRIDAY NIGHT.

&&

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

MDB

In the hours before

Local storm report, Dec 20, 8:55 PM CST, 3 hours 5 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
855 PM CST THU DEC 20 2012

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

0659 PM     NON-TSTM WND DMG MORRIS                  41.37N 88.43W
12/20/2012                   GRUNDY             IL   PUBLIC

            WIRES AND TREE LIMBS DOWN

&&

ED F
Local storm report, Dec 20, 8:56 PM CST, 3 hours 4 minutes before
PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
856 PM CST THU DEC 20 2012

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

0830 PM     SNOW             2 N WINNEBAGO           42.30N 89.24W
12/20/2012  M3.9 INCH        WINNEBAGO          IL   BROADCAST MEDIA

            WREX-TV

0756 PM     SNOW             2 NE ROSCOE             42.44N 88.98W
12/20/2012  M3.5 INCH        WINNEBAGO          IL   BROADCAST MEDIA

0703 PM     SNOW             MACHESNEY PARK          42.36N 89.04W
12/20/2012  E0.0 INCH        WINNEBAGO          IL   AMATEUR RADIO

            MODERATE SNOW FALLING... NEAR WHITE OUT CONDITIONS.

0700 PM     HEAVY SNOW       MOUNT MORRIS            42.05N 89.43W
12/20/2012  M3.3 INCH        OGLE               IL   CO-OP OBSERVER

0700 PM     SNOW             GRAYSLAKE               42.35N 88.04W
12/20/2012  M1.2 INCH        LAKE               IL   CO-OP OBSERVER

0659 PM     NON-TSTM WND DMG MORRIS                  41.37N 88.43W
12/20/2012                   GRUNDY             IL   PUBLIC

            WIRES AND TREE LIMBS DOWN

0640 PM     SNOW             CLARENDON HILLS         41.80N 87.96W
12/20/2012  M0.5 INCH        DUPAGE             IL   PUBLIC

0636 PM     SNOW             2 NE MIDWAY AIRPORT     41.80N 87.72W
12/20/2012  E0.0 INCH        COOK               IL   TRAINED SPOTTER

            SNOW BEGAN 630 PM

0635 PM     NON-TSTM WND GST PONTIAC                 40.88N 88.64W
12/20/2012  M55.00 MPH       LIVINGSTON         IL   AWOS

            SUSTAINED WINDS AT 44 MPH.

0632 PM     NON-TSTM WND DMG ELBURN                  41.89N 88.47W
12/20/2012                   KANE               IL   FIRE DEPT/RESCUE

            POWER LINES DOWN

0630 PM     SNOW             N HUNTLEY               42.17N 88.42W
12/20/2012  M1.0 INCH        MCHENRY            IL   COCORAHS

            ONE INCH OF SNOW ON THE GROUND. ROADS ARE SLUSHY.
            FLURRIES AND WIND CURRENTLY.

0625 PM     SNOW             PALATINE                42.11N 88.04W
12/20/2012  M0.5 INCH        COOK               IL   NWS EMPLOYEE

0617 PM     NON-TSTM WND DMG DWIGHT                  41.10N 88.42W
12/20/2012                   LIVINGSTON         IL   PUBLIC

            POWER LINES DOWN

0555 PM     SNOW             ROCKFORD AIRPORT        42.20N 89.10W
12/20/2012  M0.5 INCH        WINNEBAGO          IL   OFFICIAL NWS OBS

0550 PM     SNOW             OAK BROOK               41.84N 87.95W
12/20/2012  E0.0 INCH        DUPAGE             IL   TRAINED SPOTTER

            CAR TOPS COVERED... SNOW STARTING TO STICK TO GRASS...
            LARGE FLAKES. RAIN SNOW MIX CHANGED TO ALL SNOW AT 545
            PM.

0548 PM     SNOW             2 N WINNEBAGO           42.30N 89.24W
12/20/2012  M2.5 INCH        WINNEBAGO          IL   BROADCAST MEDIA

            MEASURED AT WREX-TV

0540 PM     SNOW             MORTON GROVE            42.04N 87.79W
12/20/2012  E0.0 INCH        COOK               IL   TRAINED SPOTTER

            RAIN TRANSITIONING TO SNOW AT 530 PM.

0516 PM     SNOW             ELGIN                   42.04N 88.29W
12/20/2012  E0.0 INCH        KANE               IL   TRAINED SPOTTER

            RAIN BEGAN TRANSITIONING TO SNOW AROUND 420 PM.

0502 PM     HEAVY SNOW       ELBURN                  41.89N 88.47W
12/20/2012  M0.5 INCH        KANE               IL   TRAINED SPOTTER

            MODERATE TO HEAVY SNOW COMING DOWN

0440 PM     SNOW             1 W BEACH PARK          42.42N 87.88W
12/20/2012  M0.1 INCH        LAKE               IL   COCORAHS

            SNOW RAIN MIX AT 430 PM AND CHANGED TO ALL SNOW BY 440
            PM. MODERATE SNOWFALL RATE. VERY LARGE FLAKES.
            ACCUMULATING QUITE QUICKLY ON ALL SURFACES.

0440 PM     HEAVY RAIN       LIBERTYVILLE            42.28N 87.97W
12/20/2012  M1.50 INCH       LAKE               IL   EMERGENCY MNGR

0355 PM     SNOW             ANTIOCH                 42.47N 88.08W
12/20/2012  E0.0 INCH        LAKE               IL   AMATEUR RADIO

            LARGE SNOW FLAKES NEAR ROUTE 59/173. RAIN SNOW MIXTURE
            TRANSITIONING OVER.

0339 PM     SNOW             ROCKFORD                42.27N 89.06W
12/20/2012  E2.0 INCH        WINNEBAGO          IL   AMATEUR RADIO

            LOW VISIBLITY ALSO.

0330 PM     HEAVY RAIN       N HUNTLEY               42.17N 88.42W
12/20/2012  M1.31 INCH       MCHENRY            IL   COCORAHS

            LOTS OF PONDING BECAUSE MOST OF RAIN FELL THIS AFTERNOON.
            RAIN IS JUST NOW CHANGING TO SLEET AND SNOW.

0326 PM     SNOW             RICHMOND                42.48N 88.31W
12/20/2012  E0.0 INCH        MCHENRY            IL   TRAINED SPOTTER

            RAIN ENDED, SNOW BEGAN 214 PM.

0321 PM     HEAVY SNOW       CAPRON                  42.40N 88.74W
12/20/2012  M1.0 INCH        BOONE              IL   TRAINED SPOTTER

            ONE INCH OF NEW SNOWFALL OVER THE PAST HOUR. RAIN TURNED
            TO SNOW 220 PM SNOW COVERING ROADS, POWERLINES, TREE
            BRANCHES, ROADS SLIPPERY AND POWER FLICKERING. TENDENCY
            TO SLIDE ON ROADWAYS.

0305 PM     HEAVY SNOW       ROCKFORD                42.27N 89.06W
12/20/2012  E0.0 INCH        WINNEBAGO          IL   AMATEUR RADIO

            POWER OUTAGE DUE TO SNOW. ONE INCH MEASURED SNOW. SNOW
            STILL FALLING.

0248 PM     SNOW             BELVIDERE               42.25N 88.85W
12/20/2012  E0.0 INCH        BOONE              IL   AMATEUR RADIO

            SNOW COVERED SLICK ROADS.

0230 PM     SNOW             CHERRY VALLEY           42.24N 88.96W
12/20/2012  E0.0 INCH        WINNEBAGO          IL   AMATEUR RADIO

            SNOW STARTED

0220 PM     HEAVY SNOW       ROCKFORD                42.27N 89.06W
12/20/2012  E0.0 INCH        WINNEBAGO          IL   AMATEUR RADIO

            EXTREMELY HEAVY SNOW FALL RATE, SNOW BEGINNING TO COVER
            GROUND, VISIBILITY ABOUT 1/4 MILE. A FEW REPORTED SNOW

            COVERED ROADS. RAIN CHANGED TO SNOW APPROXIMATELY 145 PM.

0211 PM     SNOW             DIXON                   41.85N 89.48W
12/20/2012  E0.0 INCH        LEE                IL   EMERGENCY MNGR

            STARTING TO SNOW IN DIXON.

0200 PM     SNOW             ROCKFORD                42.27N 89.06W
12/20/2012  E0.0 INCH        WINNEBAGO          IL   BROADCAST MEDIA

            WTVO REPORTED SNOWING AT THE STATION AND BEGINNING TO
            ACCUMULATE ON CARS.

0159 PM     SNOW             ROCKFORD                42.27N 89.06W
12/20/2012  E0.0 INCH        WINNEBAGO          IL   PUBLIC

            HALF DOLLAR SIZED FLAKES BEGAN TO FALL.

0159 PM     SNOW             ROCKFORD                42.27N 89.06W
12/20/2012  E0.0 INCH        WINNEBAGO          IL   BROADCAST MEDIA

            WREX REPORTED, STARTING TO SEE A COATING ON THE TOPS OF
            BUILDINGS AND SIDEWALKS IN DOWNTOWN.

&&

ED F
Local storm report, Dec 20, 10:21 PM CST, 1 hour 39 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1021 PM CST THU DEC 20 2012

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

1000 PM     SNOW             POLO                    41.98N 89.58W
12/20/2012  M3.9 INCH        OGLE               IL   CO-OP OBSERVER

            1/2 MILE VISIBILITY...MAINLY DUE TO BLOWING SNOW.

&&

RC
Local storm report, Dec 20, 10:25 PM CST, 1 hour 35 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1025 PM CST THU DEC 20 2012

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

0955 PM     SNOW             CARY                    42.21N 88.25W
12/20/2012  M0.9 INCH        MCHENRY            IL   PUBLIC

&&

RC
Local storm report, Dec 20, 11:03 PM CST, 57 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1103 PM CST THU DEC 20 2012

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

0818 PM     NON-TSTM WND GST GIBSON CITY             40.47N 88.38W
12/20/2012  M56 MPH          FORD               IL   PUBLIC

&&

RC
Local storm report, Dec 20, 11:14 PM CST, 46 minutes before
PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1114 PM CST THU DEC 20 2012

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

0159 PM     SNOW             ROCKFORD                42.27N 89.06W
12/20/2012  E0.0 INCH        WINNEBAGO          IL   BROADCAST MEDIA

            WREX REPORTED, STARTING TO SEE A COATING ON THE TOPS OF
            BUILDINGS AND SIDEWALKS IN DOWNTOWN.

0159 PM     SNOW             ROCKFORD                42.27N 89.06W
12/20/2012  E0.0 INCH        WINNEBAGO          IL   PUBLIC

            HALF DOLLAR SIZED FLAKES BEGAN TO FALL.

0200 PM     SNOW             ROCKFORD                42.27N 89.06W
12/20/2012  E0.0 INCH        WINNEBAGO          IL   BROADCAST MEDIA

            WTVO REPORTED SNOWING AT THE STATION AND BEGINNING TO
            ACCUMULATE ON CARS.

0211 PM     SNOW             DIXON                   41.85N 89.48W
12/20/2012  E0.0 INCH        LEE                IL   EMERGENCY MNGR

            STARTING TO SNOW IN DIXON.

0220 PM     HEAVY SNOW       ROCKFORD                42.27N 89.06W
12/20/2012  E0.0 INCH        WINNEBAGO          IL   AMATEUR RADIO

            EXTREMELY HEAVY SNOW FALL RATE, SNOW BEGINNING TO COVER
            GROUND, VISIBILITY ABOUT 1/4 MILE. A FEW REPORTED SNOW

            COVERED ROADS. RAIN CHANGED TO SNOW APPROXIMATELY 145 PM.

0230 PM     SNOW             CHERRY VALLEY           42.24N 88.96W
12/20/2012  E0.0 INCH        WINNEBAGO          IL   AMATEUR RADIO

            SNOW STARTED

0248 PM     SNOW             BELVIDERE               42.25N 88.85W
12/20/2012  E0.0 INCH        BOONE              IL   AMATEUR RADIO

            SNOW COVERED SLICK ROADS.

0305 PM     HEAVY SNOW       ROCKFORD                42.27N 89.06W
12/20/2012  E0.0 INCH        WINNEBAGO          IL   AMATEUR RADIO

            POWER OUTAGE DUE TO SNOW. ONE INCH MEASURED SNOW. SNOW
            STILL FALLING.

0321 PM     HEAVY SNOW       CAPRON                  42.40N 88.74W
12/20/2012  M1.0 INCH        BOONE              IL   TRAINED SPOTTER

            ONE INCH OF NEW SNOWFALL OVER THE PAST HOUR. RAIN TURNED
            TO SNOW 220 PM SNOW COVERING ROADS, POWERLINES, TREE
            BRANCHES, ROADS SLIPPERY AND POWER FLICKERING. TENDENCY
            TO SLIDE ON ROADWAYS.

0326 PM     SNOW             RICHMOND                42.48N 88.31W
12/20/2012  E0.0 INCH        MCHENRY            IL   TRAINED SPOTTER

            RAIN ENDED, SNOW BEGAN 214 PM.

0330 PM     HEAVY RAIN       N HUNTLEY               42.17N 88.42W
12/20/2012  M1.31 INCH       MCHENRY            IL   COCORAHS

            LOTS OF PONDING BECAUSE MOST OF RAIN FELL THIS AFTERNOON.
            RAIN IS JUST NOW CHANGING TO SLEET AND SNOW.

0339 PM     SNOW             ROCKFORD                42.27N 89.06W
12/20/2012  E2.0 INCH        WINNEBAGO          IL   AMATEUR RADIO

            LOW VISIBLITY ALSO.

0355 PM     SNOW             ANTIOCH                 42.47N 88.08W
12/20/2012  E0.0 INCH        LAKE               IL   AMATEUR RADIO

            LARGE SNOW FLAKES NEAR ROUTE 59/173. RAIN SNOW MIXTURE
            TRANSITIONING OVER.

0440 PM     HEAVY RAIN       LIBERTYVILLE            42.28N 87.97W
12/20/2012  M1.50 INCH       LAKE               IL   EMERGENCY MNGR

0440 PM     SNOW             1 W BEACH PARK          42.42N 87.88W
12/20/2012  M0.1 INCH        LAKE               IL   COCORAHS

            SNOW RAIN MIX AT 430 PM AND CHANGED TO ALL SNOW BY 440
            PM. MODERATE SNOWFALL RATE. VERY LARGE FLAKES.
            ACCUMULATING QUITE QUICKLY ON ALL SURFACES.

0502 PM     HEAVY SNOW       ELBURN                  41.89N 88.47W
12/20/2012  M0.5 INCH        KANE               IL   TRAINED SPOTTER

            MODERATE TO HEAVY SNOW COMING DOWN

0516 PM     SNOW             ELGIN                   42.04N 88.29W
12/20/2012  E0.0 INCH        KANE               IL   TRAINED SPOTTER

            RAIN BEGAN TRANSITIONING TO SNOW AROUND 420 PM.

0540 PM     SNOW             MORTON GROVE            42.04N 87.79W
12/20/2012  E0.0 INCH        COOK               IL   TRAINED SPOTTER

            RAIN TRANSITIONING TO SNOW AT 530 PM.

0548 PM     SNOW             2 N WINNEBAGO           42.30N 89.24W
12/20/2012  M2.5 INCH        WINNEBAGO          IL   BROADCAST MEDIA

            MEASURED AT WREX-TV

0550 PM     SNOW             OAK BROOK               41.84N 87.95W
12/20/2012  E0.0 INCH        DUPAGE             IL   TRAINED SPOTTER

            CAR TOPS COVERED... SNOW STARTING TO STICK TO GRASS...
            LARGE FLAKES. RAIN SNOW MIX CHANGED TO ALL SNOW AT 545
            PM.

0555 PM     SNOW             ROCKFORD AIRPORT        42.20N 89.10W
12/20/2012  M0.5 INCH        WINNEBAGO          IL   OFFICIAL NWS OBS

0617 PM     NON-TSTM WND DMG DWIGHT                  41.10N 88.42W
12/20/2012                   LIVINGSTON         IL   PUBLIC

            POWER LINES DOWN

0625 PM     SNOW             PALATINE                42.11N 88.04W
12/20/2012  M0.5 INCH        COOK               IL   NWS EMPLOYEE

0630 PM     SNOW             N HUNTLEY               42.17N 88.42W
12/20/2012  M1.0 INCH        MCHENRY            IL   COCORAHS

            ONE INCH OF SNOW ON THE GROUND. ROADS ARE SLUSHY.
            FLURRIES AND WIND CURRENTLY.

0632 PM     NON-TSTM WND DMG ELBURN                  41.89N 88.47W
12/20/2012                   KANE               IL   FIRE DEPT/RESCUE

            POWER LINES DOWN

0635 PM     NON-TSTM WND GST PONTIAC                 40.88N 88.64W
12/20/2012  M55.00 MPH       LIVINGSTON         IL   AWOS

            SUSTAINED WINDS AT 44 MPH.

0636 PM     SNOW             2 NE MIDWAY AIRPORT     41.80N 87.72W
12/20/2012  E0.0 INCH        COOK               IL   TRAINED SPOTTER

            SNOW BEGAN 630 PM

0640 PM     SNOW             CLARENDON HILLS         41.80N 87.96W
12/20/2012  M0.5 INCH        DUPAGE             IL   PUBLIC

0659 PM     NON-TSTM WND DMG MORRIS                  41.37N 88.43W
12/20/2012                   GRUNDY             IL   PUBLIC

            WIRES AND TREE LIMBS DOWN

0700 PM     SNOW             GRAYSLAKE               42.35N 88.04W
12/20/2012  M1.2 INCH        LAKE               IL   CO-OP OBSERVER

0700 PM     HEAVY SNOW       MOUNT MORRIS            42.05N 89.43W
12/20/2012  M3.3 INCH        OGLE               IL   CO-OP OBSERVER

0703 PM     SNOW             MACHESNEY PARK          42.36N 89.04W
12/20/2012  E0.0 INCH        WINNEBAGO          IL   AMATEUR RADIO

            MODERATE SNOW FALLING... NEAR WHITE OUT CONDITIONS.

0756 PM     SNOW             2 NE ROSCOE             42.44N 88.98W
12/20/2012  M3.5 INCH        WINNEBAGO          IL   BROADCAST MEDIA

0818 PM     NON-TSTM WND GST GIBSON CITY             40.47N 88.38W
12/20/2012  M56.00 MPH       FORD               IL   PUBLIC

0830 PM     SNOW             2 N WINNEBAGO           42.30N 89.24W
12/20/2012  M3.9 INCH        WINNEBAGO          IL   BROADCAST MEDIA

            WREX-TV

0955 PM     SNOW             CARY                    42.21N 88.25W
12/20/2012  M0.9 INCH        MCHENRY            IL   PUBLIC

1000 PM     SNOW             POLO                    41.98N 89.58W
12/20/2012  M3.9 INCH        OGLE               IL   CO-OP OBSERVER

            1/2 MILE VISIBILITY...MAINLY DUE TO BLOWING SNOW.

&&

RC

The office that day

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

IssuedProductOfficeCountiesLasted
Dec 20, 11:53 PM CSTWinter Weather AdvisoryLOTBoone, DeKalb, Lee, Ogle, Winnebago10 hr
Dec 21, 9:25 AM CSTGale WarningLOT6 hr
Dec 21, 3:11 PM CSTGale WarningLOT9 hr
Dec 21, 3:11 PM CSTSmall Craft AdvisoryLOT24 hr
Dec 21, 2:52 AM CSTHigh Wind WarningLOTPorter9 hr

Nearby

Wind Advisories in Illinois, 2012Wind Advisories in Indiana, 2012Every wind advisory 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.