Rainfall Amounts From Sunday Into Early Monday; Dual-Pol Radar Estimates on Track

    Sunday afternoon and night brought a rapid increase in deep moisture to central Illinois into northwest Indiana.  As multiple upper level disturbances moved within this moist flow, thunderstorms developed, and in those areas had ample moisture to produce localized efficient and heavy rainfall rates.  Some thunderstorms tracked over the same portion of southern and southeast Iroquois County into southern Newton County during the late afternoon and early evening.  A rainfall amount of 2.80 inches was recorded near Milford, IL through late Monday morning, with much of that occurring between 4:30 and 6:00 pm with those storms on Sunday.  In addition, a CoCoRaHS observer in Kentland, IN logged 2.23 inches.

Rainfall Amounts from Automated Sensors

The above map displays precipitation reports from various automated sensors.  Note that several of these are not quality controlled.  Almost three inches was observed just east southeast of Milford.

 Text Listing of Rainfall Amounts

   The NWS Chicago Doppler Radar estimated precipitation quite well in this area.  With dual-polarization technology, which the radar was upgraded to six months ago, rainfall estimates are anticipated to likely be more accurate in some scenarios.  The dual-polarization radar utilizes various base data reflected back to the radar that describe the shapes, similarity, and concentration of the precipitation particles.  From that, its algorithms deduce the likely precipitation type.  With a more accurate type of precipitation identified, improved estimates on amounts are expected. Below is a look at the algorithm output from the 0.5° radar scan around 430 pm Sunday afternoon, indicating heavy rain near Milford.  This was indicated over the same area through 600 pm.  This output was based on the indication of large drops, high concentration, and all mainly liquid (as opposed to hail or a mix).

 

NWS Dual-Polarization Algorithm Indicated Precipitation:  April 29, 4:30 pm

Dual-Polarization Algorithm

 

Below are the dual-polarization precipitation estimates from Sunday afternoon and early evening, with the two highest rainfall amounts overlaid.

Dual-Pol vs Legacy Precipitation


PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE CHICAGO IL
1017 AM CDT MON APR 30 2012

...MORNING RAINFALL ROUNDUP...

   THE FOLLOWING ARE RAIN AMOUNTS FOR THE PREVIOUS 24-HOURS
   AS MEASURED IN THE MORNING BY NWS COOPERATIVE OBSERVERS
   AND COCORAHS OBSERVERS.
   OBSERVATIONS ARE USUALLY TAKEN BETWEEN 6 AND 8 AM.

   24-HOUR RAINFALL AMOUNTS
       FOR MONDAY(04/30/12)...


ILLINOIS                                       RAIN
  LOCATION (COUNTY):                           FALL (IN)

  ST ANNE (KANKAKEE)...........................1.48
  MILFORD (IROQUOIS)...........................1.35
  PAXTON (FORD)................................1.00
  MENDOTA (LA SALLE)...........................0.99
  MENDOTA 2SE (LA SALLE).......................0.91
  MENDOTA 1N (LA SALLE)........................0.90
  MOMENCE 3NE (KANKAKEE).......................0.80
  PIPER CITY (FORD)............................0.76
  CHATSWORTH (LIVINGSTON)......................0.70
  CHATSWORTH (LIVINGSTON)......................0.70
  GENOA (DE KALB)..............................0.64
  PERU 1SW (LA SALLE)..........................0.64
  MALTA (DE KALB)..............................0.63
  HUNTLEY 4W (MCHENRY).........................0.61
  LA SALLE (LA SALLE)..........................0.60
  EARLVILLE 3S (LA SALLE)......................0.58
  WATSEKA 5W (IROQUOIS)........................0.56
  KANKAKEE 3SE (KANKAKEE)......................0.56
  HARVARD (MCHENRY)............................0.56
  PERU (LA SALLE)..............................0.55
  ELGIN 1WSW (KANE)............................0.54
  KANKAKEE (KANKAKEE)..........................0.53
  DE KALB (DE KALB)............................0.53
  PAW PAW (LEE)................................0.53
  STEWARD (LEE)................................0.53
  SYCAMORE 2NNE (DE KALB)......................0.52
  DE KALB (DE KALB)............................0.51
  ELBURN (KANE)................................0.51
  HARVARD (MCHENRY)............................0.50
  WOODSTOCK 1WSW (MCHENRY).....................0.50
  ST CHARLES 7NW (KANE)........................0.50
  ELGIN (KANE).................................0.49
  ELGIN 1S (KANE)..............................0.49
  ELBURN 3NNE (KANE)...........................0.49
  ST. CHARLES 6NW (KANE).......................0.49
  STERLING 4NE (LEE)...........................0.49
  CARY 2NE (MCHENRY)...........................0.49
  CARY (MCHENRY)...............................0.49
  HARVARD (MCHENRY)............................0.49
  WAUCONDA (LAKE)..............................0.48
  WOODSTOCK 5NW (MCHENRY)......................0.48
  CORTLAND (DE KALB)...........................0.47
  SUBLETTE (LEE)...............................0.47
  WOODSTOCK 1SSW (MCHENRY).....................0.47
  WOODSTOCK (MCHENRY)..........................0.46
  GENEVA 2ENE (KANE)...........................0.45
  ELGIN 2W (KANE)..............................0.45
  HEBRON 1WNW (MCHENRY)........................0.45
  ROCKFORD 3NE (WINNEBAGO).....................0.45
  ST CHARLES 1SW (KANE)........................0.44
  ROCHELLE (OGLE)..............................0.44
  WINFIELD (DU PAGE)...........................0.44
  HOFFMAN ESTATES 5W (COOK)....................0.43
  WEST CHICAGO 3N (DU PAGE)....................0.43
  BATAVIA 1WSW (KANE)..........................0.43
  BATAVIA 1WNW (KANE)..........................0.43
  ST. CHARLES (KANE)...........................0.43
  GENEVA 1SSW (KANE)...........................0.43
  AMBOY (LEE)..................................0.43
  OGLESBY 1ESE (LA SALLE)......................0.43
  HEBRON (MCHENRY).............................0.43
  OTTAWA (LA SALLE)............................0.43
  ST CHARLES (KANE)............................0.43
  HANOVER PARK 2SSW (DU PAGE)..................0.42
  ELGIN 2WNW (KANE)............................0.42
  BATAVIA 2WNW (KANE)..........................0.42
  PINGREE GROVE 1NW (KANE).....................0.42
  LAKEMOOR 2SE (LAKE)..........................0.42
  MUNDELEIN (LAKE).............................0.42
  ROCKFORD (WINNEBAGO).........................0.42
  ROCKFORD 4NW (WINNEBAGO).....................0.42
  ASHTON (LEE).................................0.41
  WHEATON (DU PAGE)............................0.40
  AMBOY 3SE (LEE)..............................0.40
  DIXON 2SW (LEE)..............................0.40
  LAKE VILLA 1SSW (LAKE).......................0.40
  ZION (LAKE)..................................0.40
  OTTAWA 1NW (LA SALLE)........................0.40
  BULL VALLEY 2WNW (MCHENRY)...................0.40
  BARRINGTON (LAKE)............................0.39
  GENEVA 1WNW (KANE)...........................0.39
  SHERIDAN (LA SALLE)..........................0.39
  ROCKFORD 2ENE (WINNEBAGO)....................0.39
  BATAVIA (KANE)...............................0.38
  ROLLING MEADOWS 1ESE (COOK)..................0.38
  STREAMWOOD (COOK)............................0.38
  MUNDELEIN (LAKE).............................0.38
  OTTAWA 2N (LA SALLE).........................0.38
  ALGONQUIN 1N (MCHENRY).......................0.38
  SPRING GROVE 2N (MCHENRY)....................0.38
  SCHAUMBURG 2SW (COOK)........................0.37
  BARTLETT 1SSE (DU PAGE)......................0.37
  GENEVA 3WSW (KANE)...........................0.37
  GENEVA 2WSW (KANE)...........................0.37
  HAWTHORN WOODS 1N (LAKE).....................0.37
  ROCKFORD 1NW (WINNEBAGO).....................0.37
  LOMBARD 1NNW (DU PAGE).......................0.36
  OHARE (COOK).................................0.36
  ARLINGTON HEIGHTS 1SW (COOK).................0.35
  ELK GROVE VILLAGE 2WSW (COOK)................0.35
  LOMBARD 1NNW (DU PAGE).......................0.35
  GRANT PARK 6ENE (KANKAKEE)...................0.35
  NORTH AURORA 2NE (KANE)......................0.35
  SUGAR GROVE 1ENE (KANE)......................0.35
  SUGAR GROVE 1NE (KANE).......................0.34
  SUGAR GROVE 2ENE (KANE)......................0.34
  LINCOLNSHIRE 1.3WSW (LAKE)...................0.34
  MACHESNEY PARK 3ENE (WINNEBAGO)..............0.34
  WAUKEGAN (LAKE)..............................0.34
  ELK GROVE VILLAGE 1ESE (COOK)................0.33
  WEST CHICAGO 1SE (DU PAGE)...................0.33
  AURORA 4NE (DU PAGE).........................0.33
  ROSELLE 1ESE (DU PAGE).......................0.33
  ROSCOE 2ESE (WINNEBAGO)......................0.33
  ROCHELLE (OGLE)..............................0.33
  ROSCOE 2SE (WINNEBAGO).......................0.33
  AURORA (KANE)................................0.32
  BOTANIC GARDENS (COOK).......................0.32
  WEST CHICAGO (DU PAGE).......................0.32
  INVERNESS 2S (COOK)..........................0.32
  WINNETKA 1ESE (COOK).........................0.32
  WARRENVILLE 1NNW (DU PAGE)...................0.32
  BUFFALO GROVE 2N (LAKE)......................0.32
  OTTAWA 1ESE (LA SALLE).......................0.32
  WONDER LAKE 1WNW (MCHENRY)...................0.32
  PECATONICA 2S (WINNEBAGO)....................0.32
  PALATINE 1E (COOK)...........................0.31
  HARWOOD HEIGHTS 2NNE (COOK)..................0.31
  GLENCOE (COOK)...............................0.31
  BEACH PARK 1W (LAKE).........................0.31
  WINTHROP HARBOR (LAKE).......................0.31
  ROCKTON 1ESE (WINNEBAGO).....................0.31
  MONTGOMERY 2SSE (KENDALL)....................0.30
  GURNEE 2NE (LAKE)............................0.30
  WINTHROP HARBOR 1SSW (LAKE)..................0.30
  RIVERWOODS (LAKE)............................0.30
  MONTGOMERY 1SSE (KENDALL)....................0.29
  DIXON 3NNW (LEE).............................0.29
  MARSEILLES (LA SALLE)........................0.29
  SHIRLAND (WINNEBAGO).........................0.28
  GLEN ELLYN 2SSE (DU PAGE)....................0.27
  VILLA PARK 1NW (DU PAGE).....................0.27
  LISBON 4NE (KENDALL).........................0.27
  MARSEILLES 6WNW (LA SALLE)...................0.27
  GLEN ELLYN 1SE (DU PAGE).....................0.26
  HIGHWOOD (LAKE)..............................0.26
  OAK PARK 1NE (COOK)..........................0.25
  AURORA 4SE (DU PAGE).........................0.24
  NAPERVILLE 1NW (DU PAGE).....................0.24
  LISLE MORTON ARB (DU PAGE)...................0.24
  YORKVILLE 1W (KENDALL).......................0.23
  BYRON 3N (OGLE)..............................0.23
  AURORA 4SE (DU PAGE).........................0.22
  OAK PARK 1SW (COOK)..........................0.21
  WESTMONT 1SSE (DU PAGE)......................0.21
  LISLE (DU PAGE)..............................0.21
  SENECA 1NE (LA SALLE)........................0.21
  NEWARK (KENDALL).............................0.21
  OAK PARK 1NNE (COOK).........................0.20
  EVANSTON 1SSE (COOK).........................0.20
  BOLINGBROOK 3NE (DU PAGE)....................0.20
  LISLE (DU PAGE)..............................0.20
  LINCOLNWOOD 2E (COOK)........................0.19
  NAPERVILLE 2ESE (DU PAGE)....................0.19
  CHENOA 4NNW (LIVINGSTON).....................0.19
  WESTMONT (DU PAGE)...........................0.19
  YORKVILLE 2SE (KENDALL)......................0.19
  OAK PARK 2S (COOK)...........................0.18
  YORKVILLE 1NE (KENDALL)......................0.18
  PONTIAC 1SE (LIVINGSTON).....................0.18
  PONTIAC 1ESE (LIVINGSTON)....................0.18
  BEECHER 3SSE (WILL)..........................0.18
  OAK BROOK (DU PAGE)..........................0.18
  BONFIELD 4WSW (KANKAKEE).....................0.17
  PONTIAC (LIVINGSTON).........................0.17
  STREATOR (LIVINGSTON)........................0.17
  LA GRANGE (COOK).............................0.16
  MIDWAY 3SW (COOK)............................0.16
  BOURBONNAIS (KANKAKEE).......................0.15
  CHICAGO 6ESE (COOK)..........................0.15
  DOWNERS GROVE 2SE (DU PAGE)..................0.15
  NAPERVILLE 3ESE (DU PAGE)....................0.15
  BURR RIDGE 2SW (DU PAGE).....................0.15
  MORRIS 1SW (GRUNDY)..........................0.15
  OSWEGO 5SSE (KENDALL)........................0.15
  BONFIELD 2NW (KANKAKEE)......................0.15
  MANTENO 2SSE (KANKAKEE)......................0.15
  SENECA 2SSW (LA SALLE).......................0.15
  HOMER GLEN 4WNW (WILL).......................0.15
  NAPERVILLE 4SSW (WILL).......................0.15
  WHEELING (COOK)..............................0.15
  MORRIS (GRUNDY)..............................0.14
  CHICAGO RIDGE (COOK).........................0.14
  COUNTRYSIDE 1ENE (COOK)......................0.14
  COUNTRYSIDE 1NNE (COOK)......................0.14
  BONFIELD 4NNE (KANKAKEE).....................0.14
  NAPERVILLE 4SSW (WILL).......................0.14
  PLAINFIELD 1SW (WILL)........................0.14
  LA GRANGE PARK 1SSW (COOK)...................0.13
  PLAINFIELD 5SW (KENDALL).....................0.13
  PLAINFIELD (WILL)............................0.13
  WORTH (COOK).................................0.12
  BOURBONNAIS 2NNE (KANKAKEE)..................0.12
  HOMER GLEN 1ENE (WILL).......................0.12
  PLAINFIELD 3ESE (WILL).......................0.12
  FRANKFORT 2NNE (WILL)........................0.12
  JOLIET 2N (WILL).............................0.12
  MORRIS (GRUNDY)..............................0.12
  OAK LAWN 2SE (COOK)..........................0.11
  ALSIP (COOK).................................0.11
  PARK FOREST 1NNE (COOK)......................0.11
  MINOOKA (GRUNDY).............................0.11
  CHANNAHON 1NNE (WILL)........................0.11
  PEOTONE (WILL)...............................0.11
  LOCKPORT 1SE (WILL)..........................0.11
  ORLAND PARK 5WNW (WILL)......................0.11
  MIDWAY (COOK)................................0.11
  OAK LAWN 1N (COOK)...........................0.10
  ODELL 4SE (LIVINGSTON).......................0.10
  CRETE 3E (WILL)..............................0.10
  PEOTONE (WILL)...............................0.10
  NEW LENOX 4SE (WILL).........................0.10
  WILMINGTON 6NW (WILL)........................0.10
  JOLIET LOCK/DAM (WILL).......................0.10
  PARK FOREST (COOK)...........................0.10
  DRESDEN LOCK/DAM (GRUNDY)....................0.09
  ORLAND HILLS 1S (COOK).......................0.09
  MORRIS 6ESE (GRUNDY).........................0.09
  PEOTONE (WILL)...............................0.09
  ROMEOVILLE (WILL)............................0.09
  MONEE (WILL).................................0.09
  PEOTONE (WILL)...............................0.09
  COAL CITY 4NNW (GRUNDY)......................0.08
  DWIGHT (LIVINGSTON)..........................0.08
  ORLAND HILLS 1SE (COOK)......................0.08
  CHICAGO 5NE (COOK)...........................0.08
  LANSING (COOK)...............................0.08
  COAL CITY (GRUNDY)...........................0.07
  BRACEVILLE (GRUNDY)..........................0.07
  MANHATTAN 5ENE (WILL)........................0.07
  JOLIET (WILL)................................0.07
  MANHATTAN (WILL).............................0.07
  WILMINGTON 3SE (WILL)........................0.06
  NEW LENOX 2SE (WILL).........................0.04
  LANSING (COOK)...............................0.01

INDIANA                                        RAIN
  LOCATION (COUNTY):                           FALL (IN)

  KENTLAND (NEWTON)............................2.23
  DE MOTTE 3SE (JASPER)........................1.48
  KENTLAND 2SSE (NEWTON).......................1.45
  DE MOTTE 6S (JASPER).........................1.18
  LAKE VILLAGE (NEWTON)........................1.14
  RENSSELAER (JASPER)..........................1.04
  EARL PARK 2SSE (BENTON)......................1.00
  RENSSELAER 4N (JASPER).......................0.98
  (W9OPR)WHEATFIELD 1ENE (JASPER)..............0.94
  WHEATFIELD 2ENE (JASPER).....................0.93
  DE MOTTE 1NNW (JASPER).......................0.92
  DE MOTTE 1SSW (JASPER).......................0.90
  RENSSELAER 6SE (JASPER)......................0.89
  MOROCCO (NEWTON).............................0.89
  DE MOTTE 4SW (JASPER)........................0.86
  MOUNT AYR 2NNE (NEWTON)......................0.81
  LOWELL (LAKE)................................0.80
  RENSSELAER 5NW (JASPER)......................0.78
  RENSSELAER 5E (JASPER).......................0.70
  REMINGTON (JASPER)...........................0.68
  WHEATFIELD 3S (JASPER).......................0.65
  RENSSELAER 10NE (JASPER).....................0.65
  VALPARAISO 6SSW (PORTER).....................0.57
  (KB9F)VALPARAISO 4S (PORTER).................0.57
  CHESTERTON 4E (PORTER).......................0.57
  RENSSELAER 2SSW (JASPER).....................0.56
  RENSSELAER 10NNE (JASPER)....................0.56
  HEBRON 4NE (PORTER)..........................0.56
  KOUTS 2WSW (PORTER)..........................0.56
  REMINGTON (JASPER)...........................0.55
  HEBRON 1NW (PORTER)..........................0.51
  VALPARAISO (PORTER)..........................0.51
  VALPARAISO 6S (PORTER).......................0.45
  VALPARAISO 2ESE (PORTER).....................0.35
  LAKES OF THE FOUR SEASONS (PORTER)...........0.34
  VALPARAISO 5NNE (PORTER).....................0.31
  VALPARAISO 5NNE (PORTER).....................0.31
  (KB9UUO)NEW CHICAGO 1SSE (LAKE)..............0.29
  GARY 4SSW (LAKE).............................0.28
  PORTER 1S (PORTER)...........................0.28
  CROWN POINT 8E (PORTER)......................0.26
  LAKES OF THE FOUR SEASONS 2NNE (PORTER)......0.26
  CROWN POINT 2WSW (LAKE)......................0.25
  MERRILLVILLE 2ESE (LAKE).....................0.25
  VALPARAISO 6WSW (PORTER).....................0.24
  VALPARAISO (PORTER)..........................0.24
  VALPARAISO 7WSW (PORTER).....................0.24
  INDIANA DUNES (PORTER).......................0.23
  VALPARAISO 4SW (PORTER)......................0.23
  PORTAGE 3E (PORTER)..........................0.23
  CROWN POINT 1N (LAKE)........................0.22
  PORTAGE 1ESE (PORTER)........................0.22
  CROWN POINT (LAKE)...........................0.21
  VALPARAISO 2NW (PORTER)......................0.21
  VALPARAISO 1NNW (PORTER).....................0.21
  VALPARAISO 1ENE (PORTER).....................0.20
  DYER 1WNW (LAKE).............................0.18
  VALPARAISO 2N (PORTER).......................0.18
  VALPARAISO 1SE (PORTER)......................0.16
  ST. JOHN (LAKE)..............................0.10
  (WV90)HOBART 1ENE (LAKE).....................0.10
  HAMMOND 3SW (LAKE)...........................0.09
  SCHERERVILLE 2WSW (LAKE).....................0.06

$$


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