Illinois, 2015

Tornadoes and Hail in Illinois, April 9, 2015

April 9, 2015 · NWS LOT · 29 events in 11 counties and zones

Seven tornadoes were confirmed in north central Illinois in the NWS Chicago CWA. Six of the tornadoes formed from a single supercell.

Where it happened

Every event with a place to put it. Tap one for its entry below.

  • Tornadoes
  • Tropical storms and surge
  • Floods
  • Wind
  • Hail
  • Winter weather
  • Heat and drought
  • Cold
  • Fire, smoke and dust
  • Marine and coastal
  • Other

Open the live radar over this ground

The toll

Deaths
2
Injuries
11
Property damage
$19 million
Crop damage
None recorded
Events
29

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What happened

The episode as NWS LOT wrote it up.

Seven tornadoes were confirmed in north central Illinois in the NWS Chicago CWA. Six of the tornadoes formed from a single supercell. The atmosphere was ripe for severe weather due to highly anomalous moisture and instability for early April across the region. A strong low pressure system advanced into this favorable air mass. Combined with robust wind shear, this helped to trigger these potent storms. A long tracked violent tornado destroyed numerous homes and farmsteads along its path across north central Lee, eastern Ogle, northwest Dekalb, and southern Boone counties. This path included the far northwest side of Rochelle, Interstate-39, and a direct hit in the community of Fairdale where two fatalities occurred. This was the strongest tornado in the NWS Chicago CWA since the F5 tornado that struck Plainfield, IL on August 28th, 1990.

What forecasters said that day

The local office's own words before the first event, 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 the first event at Apr 9, 4:36 PM CST, 47 minutes earlier.

Area forecast discussion, Apr 9, 4:36 PM CST, 47 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
536 PM CDT THU APR 9 2015

.MESOSCALE DISCUSSION...
536 PM CDT

CONTINUE TO MONITOR COLD FRONT WITH STRONG CONVECTION OCCURRING
NEAR THE MISSISSIPPI RIVER THIS HOUR. AHEAD OF THE FRONT WITHIN
THE WARM SECTOR THUNDERSTORMS HAVE STRUGGLED TO REACH THEIR FULL
POTENTIAL WITH MODEST MID LEVEL LAPSE RATES BEING ONE OF THE
PRIMARY LIMITING FACTORS. WIDELY SCATTERED ACTIVITY WILL CONTINUE
AHEAD OF THE FRONT THROUGH MID EVENING...THOUGH GIVEN TRENDS SO
FAR THE THREAT FOR SEVERE WEATHER APPEARS LOW AHEAD OF THE FRONT.
WITH CIRRUS SHIELD OVERSPREADING THE REGION AND LOWERING SUN
ANGLE...THERE ARE RENEWED CONCERNS REGARDING
INSTABILITY...ESPECIALLY AS WE GET CLOSER TO SUNSET THIS EVENING.
EXPECT MODERATE INSTABILITY TO PERSIST THROUGH 00Z THEN FOR A
DIMINISHING TREND OF MLCAPE THEREAFTER.

BY 00Z/7PM CDT...EXPECT THE LINE OF THUNDERSTORMS ASSOCIATED WITH
THE COLD FRONT WHICH WILL MAINTAIN A HIGHER SEVERE THREAT TO BE
NEAR THE I-39 CORRIDOR...AND ENTERING THE WESTERN SUBURBS OF
CHICAGO CLOSER TO 01Z/8PM CDT. LOW LEVEL CONVERGENCE ALONG THE
FRONT REMAINS STRONG AND DEEP LAYER SHEAR REMAINS SUFFICIENT TO
SUSTAIN AT LEAST SOME ORGANIZED/SEVERE THREAT THROUGH THE HEART OF
THE FORECAST AREA...THOUGH DIMINISHING MLCAPE MAY EVENTUALLY LOWER
THAT THREAT.

DEUBELBEISS

&&

.SHORT TERM...
400 AM CDT

TODAY AND TONIGHT...

DENSE FOG CONTINUES IN COOL/SATURATED AIR MASS WITH NORTHEAST
WINDS OFF THE LAKE THIS MORNING...WILL MAINTAIN DENSE FOG ADVISORY
ALONG THE LAKE AS ISSUED.

CLUSTERS OF THUNDERSTORMS WERE OCCURRING EARLY THIS MORNING
ACROSS THE MIDWEST...IN A REGION OF BROAD SOUTHWESTERLY WARM/MOIST
ADVECTION ATOP NEARLY STATIONARY FRONTAL BOUNDARY WHICH STRETCHES
FROM THE CENTRAL PLAINS INTO SOUTHERN IOWA...THEN EAST ACROSS
CENTRAL ILLINOIS AND INDIANA. THESE CLUSTERS OF STORMS WERE
GENERALLY TIED TO INDIVIDUAL MINOR-AMPLITUDE MID-LEVEL SHORT WAVE
FEATURES...AND ASSOCIATED LOCALIZED ENHANCED MOISTURE TRANSPORT
AND ASCENT. TO THE WEST...STRONG UPPER TROUGH WAS MOVING ONTO THE
PLAINS EAST OF THE ROCKIES...AND IS PROGGED TO APPROACH THE MID-
UPPER MISSISSIPPI VALLEY LATE THIS AFTERNOON AS A COMPACT AND
SOMEWHAT NEGATIVELY-TILTED ENERGETIC DISTURBANCE. SURFACE LOW
PRESSURE IN THE VICINITY OF SOUTHWEST KANSAS AT THIS HOUR WILL
DEEPEN AND LIFT TO SOUTHWESTERN WISCONSIN/FAR NORTHWEST IL PER
COMPLIMENTING GUIDANCE SOLUTIONS...WITH THE FRONT LIFTING NORTH AS
A WARM FRONT ACROSS THE FORECAST AREA. THIS PATTERN HAS ALL THE
EARMARKS OF BEING A WIDESPREAD SEVERE WEATHER PRODUCER ACROSS THE
AREA THIS AFTERNOON AND EVENING.

WITH THAT SAID...QUESTIONS REMAIN WITH RESPECT TO EVOLUTION OF
STORMS LATER TODAY...MAINLY DUE TO THE EXPECTATION THAT SEVERAL
CLUSTERS OF STORMS WILL CONTINUE TO DEVELOP/PROPAGATE ACROSS THE
AREA THROUGH MUCH OF THE DAY DUE TO PERSISTENT WARM/MOIST
ADVECTION AND ASCENT IN REGION OF STEEP MID-LEVEL LAPSE RATES
AHEAD OF THE DEEPENING TROUGH AND SURFACE LOW. CONVECTION ALLOWING
GUIDANCE (HRRR/NMM/ARW RUNS) DEPICT SEVERAL CLUSTERS DEVELOPING
AND LIFTING ACROSS THE AREA THROUGH THE MORNING AND MIDDAY
HOURS...AND REGIONAL RADAR MOSAIC SEEMS TO INDICATE THIS WILL BE
THE TREND AT LEAST THROUGH THIS MORNING. THUS WHILE SYNOPTIC
FEATURES WILL BE STRONG...MESOSCALE BOUNDARIES AND FORCING REMAIN
UNCLEAR AT THIS TIME. STILL...STRONG FORCING IN ADVANCE OF COLD
FRONT COUPLED WITH STRONG ASCENT ASSOCIATED WITH COMPACT WAVE
SHOULD BE CAPABLE OF GENERATING ORGANIZED SEVERE STORMS LATER THIS
AFTERNOON. 00Z NAM FORECAST SOUNDINGS INDICATE WARM SECTOR MLCAPES
AROUND 1500-2000 J/KG...WITH AMPLE DEEP AND LOW LEVEL SHEAR. SPC
NOTES SOME UNCERTAINTY WITH RESPECT TO STORM MODE...LINE SEGMENTS
AS OPPOSED TO DISCRETE CELLS...THOUGH SUPERCELLULAR
CHARACTERISTICS ARE LIKELY GIVEN THE ENVIRONMENT. DAMAGING WINDS
FROM LINES/LINE SEGMENTS LOOKS TO BE THE MOST WIDESPREAD
THREAT...THOUGH NORTHERN IL/SOUTHERN WI...WHERE WINDS WILL MOST
LIKELY BE BACKED MORE STRONGLY AHEAD OF THE LOW...WILL STILL HAVE
A REAL TORNADO POTENTIAL. STORMS WILL LIKELY EVOLVE UPSCALE INTO
SQUALL-LINE AS COLD FRONT MOVES ACROSS THE AREA EARLY THIS
EVENING...WITH THUNDERSTORM/SEVERE THREAT QUICKLY WINDING DOWN
BEFORE MIDNIGHT AFTER FROPA.

RATZER

&&

.LONG TERM...
257 PM CDT

FRIDAY THROUGH THURSDAY...

FOLLOWING A PERIOD OF VERY ACTIVE WEATHER...FOLLOWING THE PASSAGE OF
THE COLD FRONT LATE THURSDAY NIGHT...A PERIOD OF RELATIVE CALM WILL
SET UP FOR FRIDAY INTO SUNDAY AS A COOL...DRY HIGH PRESSURE AREA
BUILDS ACROSS THE AREA.  TEMPERATURES WILL DROP BACK TO CLOSER TO
SEASONAL HIGHS NORMAL LEVELS WITH HIGHS IN THE UPPER 50S TO AROUND
60F UNDER MOSTLY SUNNY SKIES.  AS THE HIGH WILL BE RIGHT OVER THE
AREA FRIDAY NIGHT INTO SATURDAY MORNING...LIGHT WINDS AND A DRY
AIRMASS WILL ALLOW FOR SOME ENHANCED RADIATIVE COOLING OVERNIGHT FOR
LOWS TO DROP BACK INTO THE MIDDLE TO UPPER 30S SATURDAY MORNING.
WITH THE HIGH BEGINNING TO BUILD OFF TO THE EAST THROUGH SATURDAY
NIGHT AND SUNDAY...A RETURN FLOW OF MOISTURE AND WARMER AIR WILL
KEEP THE COOLING TREND VERY BRIEF WITH TEMPS REBOUNDING BACK TO
AROUND 60F OVER MUCH OF THE CWA...WITH THE EXCEPTION OF THE
IMMEDIATE LAKEFRONT...WHICH SHOULD REMAIN COOLER AS A WEAK PRESSURE
GRADIENT AND DIFFERENTIAL HEATING BETWEEN THE COOL LAKE WATER AND
WARMER LAKE SHOULD ALLOW A LAKE BREEZE TO DEVELOP.  HIGHS ON
SATURDAY ALONG THE LAKE FRONT TOPPING OUT IN THE MIDDLE 50S.
INCREASING SOUTHERLY FLOW ON THE WESTERN PERIPHERY OF THE HIGH
MOVING OFF TO THE EAST WILL LIKELY PREVENT A LAKE BREEZE FROM
DEVELOPING.

FOR SUNDAY...A NORTHERN STREAM SHORT WAVE MOVING OUT OF THE NRN
ROCKIES SHOULD BEGIN TO PHASE WITH A SOUTHERN STREAM SHORTWAVE
LIFTING INTO THE MIDDLE MISSISSIPPI VALLEY.  THIS PHASING SHOULD
RESULT IN AN AMPLIFYING LONG WAVE TROUGH OVER THE MIDDLE AND UPPER
MISSISSIPPI VALLEY AND BRINGING THE NEXT CHANCE OF PCPN TO THE
REGION.  THE LONGER RANGE GUIDANCE...IN GENERAL...AGREE ON THE
SCENARIO...BUT DIFFERENCES IN THE TIMING OF THE INDIVIDUAL SHORTWAVE
AND THE DEGREE OF PHASING AND THE RESULTANT STRENGTH OF THE LONG
WAVE TROUGH LEAD TO A RELATIVELY LOW CONFIDENCE FORECAST FOR THE
LATTER PORTIONS OF THE EXTENDED FORECAST PERIOD.  CURRENTLY FEEL
THAT A COLD FRONT MOVING ACROSS THE AREA SUNDAY INTO SUNDAY NIGHT
AND THEN SHUTTING OFF BY MONDAY MORNING AS ANOTHER HIGH PRESSURE
SYSTEM MOVES ACROSS THE AREA.  WHILE THERE IS MODERATE TO HIGH
CONFIDENCE IN A PERIOD OF PCPN SUNDAY AND SUNDAY NIGHT...START AND
END TIMES REMAIN UNCERTAIN AS WELL AS THE CHANCES FOR THUNDERSTORMS
WITH THE PCPN AND WILL LIKELY BE HIGHLY DEPENDENT ON THE SPEED OF AN
ASSOCIATED COLD FRONT MOVING THROUGH THE AREA.  FOR THE LATTER
PORTIONS OF THE FORECAST PERIOD...FROM TUESDAY THROUGH
THURSDAY...THERE COULD BE ANOTHER PERIOD OF UNSETTLED WEATHER AS THE
UPPER LEVEL FLOW PATTERN MAINTAINS A HIGH AMPLITUDE...QUICKLY
PROGRESSIVE PATTERN.  THE GFS/ECMWF ARE ACTUALLY SHOWING BETTER
CONSISTENCY FOR THE END OF THE LONGER TERM FORECAST PERIOD THAN
EARLIER...WITH ANOTHER LONG WAVE TROUGH DEVELOPING OVER THE CNTRL
PLAINS.  THE ECMWF IS TRENDING A BIT STRONGER AND DEVELOPING MORE OF
A NEGATIVE TILT TO THE TROUGH AND A CLOSED UPPER LOW BY WEDNESDAY
NIGHT...THE GFS IS REMARKABLY SIMILAR...BUT ABOUT 24 HOURS SLOWER IN
DEVELOPING THE NEGATIVE TILT UPPER TROUGH AND CLOSED UPPER LOW.
SHOULD THIS SCENARIO PAN OUT...THE MIDDLE OF NEXT WEAK COULD BE RIPE
FOR ANOTHER PERIOD OF ACTIVE WEATHER.

KREIN

&&

.AVIATION...

//ORD AND MDW CONCERNS...UPDATED 22Z...

* SCATTERED STORMS EXPECTED THIS AFTN...WITH THE FINAL ROUND OF
  STORMS MOVING THROUGH ARND 130-2Z. SOME OF THESE STORMS COULD BE
  SEVERE WITH GUSTY WINDS.

* GUSTY SSW WINDS WITH GUSTS ARND 25 KT.

* IFR VSBY EXPECTED WITH TSRA.

* IFR CIGS BEHIND THE LINE OF STORMS OVER NIGHT...BECOMING MVFR

* GUSTY WINDS BCMG SW TO W ARND MIDNIGHT WITH MAX GUSTS 30-35 KT.

JEE/KMD

//DISCUSSION...UPDATED 22Z...

STILL EXPECTING POP UP STORMS AHEAD OF THE MAIN LINE...THOUGH THE
MAIN ACTIVITY REACHES KRFD AROUND 0Z...0130Z AROUND KORD...AND
0200Z AT THE LAKEFRONT. IFR CIGS/VSBYS...GUSTY WINDS..AND HEAVY
DOWNPOURS WITH THIS LINE.

KMD

PREVIOUS DISCUSSION FROM 18Z...

STILL LOOKING AT A VERY MESSY FORECAST AS THE PIECES NECESSARY FOR
WIDESPREAD STORMS ARE NOT COMPLETELY LINING UP. THE SFC LOW IS
OVER IOWA WHILE ITS WARM FRONT STRETCHES FROM IOWA CITY IOWA
THROUGH ORD AND ITS COLD FRONT IS OVER WESTERN MO. THE LINGERING
CLOUD COVER IS INHIBITING DEVELOPMENT EARLY THIS AFTERNOON BUT
THINKING STRONG LIFT FROM THE LOW PRESSURE SYSTEM WILL ALLOW
STORMS TO DEVELOP. THINKING STORMS WILL GET STARTED OVER IOWA AND
CENTRAL IL AND REACH THE EASTERN TERMINALS LATE THIS AFTERNOON
INTO THE EARLY EVENING. FOR RFD...WILL LIKELY SEE STORMS A BIT
EARLIER IN THE MID TO LATE AFTN. ONCE AGAIN SOME OF THESE STORMS
MAY BE SVR WITH LARGE HAIL...DAMAGING WINDS...AND MAYBE AN
ISOLATED TORNADO.

THE COLD FRONT SWINGS THROUGH THIS EVENING WITH ANOTHER ROUND OF
ORGANIZED STORMS EXPECTED ALONG IT. IFR VSBY AND MVFR CIGS ARE
PSBL ONCE AGAIN. WINDS SHIFT TO THE SW AND W BEHIND THE FRONT WITH
GUSTS UP TO 30 KT. GUSTY WEST WINDS WITH VFR CIGS AND VSBY ARE
EXPECTED TOMORROW.

JEE

//ORD AND MDW CONFIDENCE...UPDATED 22Z...

* HIGH CONFIDENCE IN SCATTERED STORMS THIS AFTN FOLLOWED BY A
  SEGMENT OR LINE OF STORMS THIS EVENING. MEDIUM CONFIDENCE IN
  COVERAGE THIS AFTERNOON AND TIMING.

* MEDIUM CONFIDENCE IN WIND DIRECTION BEHIND THE SCATTERED STORMS.
  WINDS COULD BE CHAOTIC FOR A BRIEF PERIOD OF TIME.

* HIGH CONFIDENCE IN REDUCED VSBY UNDER STORMS...MEDIUM-LOW
  CONFIDENCE IN CIG HEIGHTS.

* HIGH CONFIDENCE IN LOWER CIGS TONIGHT...LOW ON SPECIFIC HEIGHTS
  AND HOW LONG IFR WILL LAST.

* MEDIUM CONFIDENCE IN WIND GUSTS OVERNIGHT AND TOMORROW...GUSTS
  COULD BE HIGHER.

JEE/KMD

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

* FRIDAY NIGHT...SLIGHT CHANCE OF SHRA. MVFR POSSIBLE. NORTHWEST
  WINDS.
* SATURDAY...DRY/VFR. SOUTHWEST WINDS. LAKE BREEZE POSSIBLE.
* SUNDAY...DRY/VFR. GUSTY SOUTH WINDS.
* MONDAY...DRY/VFR. EAST WINDS.
* TUESDAY...CHANCE OF SHRA/TSRA. MVFR POSSIBLE. SOUTH WINDS.
* WEDNESDAY...CHANCE OF SHRA. SOUTH WINDS.

&&

.MARINE...
315 PM CDT

CONDITIONS OVER LAKE MICHIGAN ARE DETERIORATING RAPIDLY
TODAY...FIRST WITH WAVES OF THUNDERSTORMS CROSSING THE SOUTHERN
PORTIONS OF THE LAKE AS A WARM FRONT LIFTS NORTHWARD.  AS OF 3PM
CDT...THE FRONT HAD MOVED UP TO THE CENTER OF THE LAKE AND SHOULD
CONTINUE TO LIFT NORTHWARD AS DEEPENING LOW PRESSURE OVER EASTERN
IOWA CONTINUES TO DEEPEN AND TRACKS INTO SOUTHERN WISCONSIN BY EARLY
THIS EVENING.  BY THIS POINT...THE SOUTHERLY FLOW WILL REACH ALMOST
TO THE NORTH END OF THE LAKE...BUT WITH STRONG PRESSURE FALLS AND A
STRENGTHENING PRESSURE GRADIENT OVER THE LAKE AS THE SFC LOW
APPROACHES...WINDS OVER THE SRN PORTIONS OF THE LAKE SHOULD INCREASE
TO GALE FORCE FOR THE NEARSHORE WATERS AND THE SOUTH HALF OF THE
LAKE.  THUNDERSTORMS WILL ALSO CONTINUE TO BE A CONCERN INTO THE
EVENING AS WELL.  THE SFC LOW IS EXPECTED TO TRACK ACROSS THE CNTRL
PORTIONS OF THE LAKE LATE THIS EVENING...WITH WINDS QUICKLY SHIFTING
TO WLY-NWLY.  A STRONG NORTHERLY GRADIENT BEHIND THE EXITING
LOW...INCREASING COLD ADVECTION ASSOCIATED WITH A COOL HIGH PRESSURE
SYSTEM DROPPING INTO THE NRN PLAINS AND STRONG PRESSURE RISES AS A
RESULT OF THE COMBINATION OF THE EXITING LOW AND APPROACHING
HIGH...SHOULD ALL COMBINE TO BRING SHORT PERIOD OF WEST TO NWLY
GALES TO THE LAKE INTO FRIDAY AFTERNOON.  THE APPROACHING HIGH
SHOULD BEGIN TO OVERSPREAD THE WESTERN GREAT LAKES BY FRIDAY
AFTERNOON...ALLOWING WINDS OVER THE LAKE TO DROP OFF RELATIVELY
QUICKLY.  FOR THE WEEKEND AND INTO EARLY NEXT WEEK...CONDITIONS OVER
THE LAKE SHOULD BE RELATIVELY QUIET.  ANOTHER COLD FRONT IS EXPECTED
TO SWEEP ACROSS THE LAKE SUNDAY NIGHT OR MONDAY...BUT THIS SHOULD BE
A LESS DYNAMIC SYSTEM...AND WINDS SHOULD NOT GET AS STRONG AS WITH
THE SYSTEM APPROACHING THE LAKE AT THE CURRENT TIME.

KREIN

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-
     LMZ779...10 PM THURSDAY TO 1 PM FRIDAY.

&&

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Hazardous weather outlook, Apr 9, 2:28 PM CST, 2 hours 55 minutes before
HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
328 PM CDT THU APR 9 2015

ILZ003>006-008-010>014-019>023-032-033-039-INZ001-002-010-011-019-
102030-
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-
328 PM CDT THU APR 9 2015

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

.DAY ONE...THIS AFTERNOON AND TONIGHT.

  WEATHER HAZARDS EXPECTED:

  THUNDERSTORMS...SOME MAY BE SEVERE AND PRODUCE:

   LOCALLY HEAVY RAINFALL RESULTING IN LOCALIZED FLOODING.
   HAIL UP TO THE SIZE OF QUARTERS
   DAMAGING WINDS UP TO 70 MPH.
   FREQUENT CLOUD TO GROUND LIGHTNING.
   AND POSSIBLY AN ISOLATED TORNADO.

  AREAS AFFECTED AND TIMING:

   A COLD FRONT WILL SWEEP WEST TO EAST ACROSS NORTHERN ILLINOIS
 AND NORTHWEST INDIANA LATE THIS AFTERNOON THROUGH THE EVENING.

  DISCUSSION:

A COLD FRONT WILL SWEEP ACROSS THE REGION THIS EVENING BRINGING
PRIMARILY A THREAT FOR STRONG AND DAMAGING WINDS ALONG WITH A
CONCERN FOR A TORNADO. AHEAD OF THE MAIN LINE OF THUNDERSTORMS...
SCATTERED THUNDERSTORMS ARE POSSIBLE LATE THIS AFTERNOON INTO THE
EARLY EVENING. THE SEVERE WEATHER THREAT SHOULD DIMINISH QUICKLY
BEHIND THE FRONT. IN ADDITION TO THE SEVERE WEATHER THREAT...SOME
AREAS HAVE ALREADY SEEN HEAVY RAIN TODAY WITH SOILS SATURATED.
ADDITIONAL HEAVY RAIN WILL QUICKLY BE CONVERTED TO RUNOFF WITH A
CONCERN FOR AT LEAST LOCALIZED FLOODING.

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

THERE IS A CHANCE OF THUNDERSTORMS LATE SUNDAY AFTERNOON INTO
SUNDAY NIGHT...AND AGAIN TUESDAY NIGHT THROUGH THURSDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NECESSARY THROUGH TONIGHT.

&&

LMZ740>745-102030-
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-
328 PM CDT THU APR 9 2015

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

.DAY ONE...THIS AFTERNOON AND TONIGHT.

SCATTERED THUNDERSTORMS ARE LIKELY THROUGH LATE THIS EVENING.
SOME THUNDERSTORMS MAY BE SEVERE LATE THIS AFTERNOON AND EARLY
THIS EVENING.

GALE FORCE WINDS ARE EXPECTED LATE THIS EVENING AND OVERNIGHT.

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

GALE FORCE WINDS ARE LIKELY THROUGH MIDDAY FRIDAY...WITH
WINDS AND WAVES REMAINING HAZARDOUS FOR SMALL CRAFT INTO FRIDAY
EVENING.

THERE IS A CHANCE OF THUNDERSTORMS SUNDAY NIGHT...AND AGAIN
TUESDAY NIGHT THROUGH THURSDAY.

&&

LMZ080-261-362-364-366-563-565-567-669-671-673-675-777-779-868-
870-872-874-876-878-102030-
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-
328 PM CDT THU APR 9 2015

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

.DAY ONE...THIS AFTERNOON AND TONIGHT.

THUNDERSTORMS ARE LIKELY ACROSS MAINLY THE SOUTH HALF OF THE LAKE
INTO THIS EVENING. SOME STORMS COULD BE SEVERE.

GALE FORCE WINDS ARE EXPECTED TONIGHT OVER THE SOUTHERN HALF OF
THE LAKE.

GALE FORCE WINDS ARE EXPECTED OVER THE NORTHERN HALF OF THE LAKE
AFTER MIDNIGHT TONIGHT.

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

GALE FORCE WINDS ARE LIKELY THROUGH MIDDAY THURSDAY ON THE
SOUTHERN HALF OF THE LAKE.

GALE FORCE WINDS ARE LIKELY THROUGH LATE THURSDAY AFTERNOON ON THE
NORTHERN HALF OF THE LAKE.

THERE IS A CHANCE OF THUNDERSTORMS ON SOUTHERN LAKE MICHIGAN
SUNDAY NIGHT...AND AGAIN TUESDAY NIGHT THROUGH THURSDAY.

&&

BMD/KREIN

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In the hours before

Local storm report, Apr 9, 11:56 AM CST, 5 hours 27 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
1256 PM CDT THU APR 09 2015

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

0900 AM     HEAVY RAIN       LIBERTYVILLE            42.28N 87.97W
04/09/2015  M1.61 INCH       LAKE               IL   TRAINED SPOTTER

            10 HOUR TOTAL, LAKE COUNTY SKYWARN

&&

KER

The radar

The Quad Cities radar (KDVN), 97 km away, was scanning. The volume nearest the first event began at 23:24 UTC.

Open the radar archive at this moment

Event by event

15 hail, 12 tornado, 2 thunderstorm wind. Local standard time, as filed.

Hail, Lee

When
April 9, 5:23 PM CST to 5:30 PM CST
Where
Lee County, Dixon Muni Arpt
Measured
1.75 in hail
Reported by
Amateur Radio
Coordinates
41.830, -89.450

Quarter to golf ball size hail was reported near Dixon.

Hail, Lee

When
April 9, 5:32 PM CST to 5:40 PM CST
Where
Lee County, 2.52 mi N of Franklin Grove to 5.06 mi WNW of Ashton
Measured
1.75 in hail
Reported by
Trained Spotter
Coordinates
41.866, -89.303

Tornado, Winnebago

When
April 9, 5:37 PM CST to 5:38 PM CST
Where
Winnebago County, 2.6 mi S of Cherry Vly to 2.2 mi SSE of Cherry Vly
Rating
EF0
Path length
0.87 mi
Path width
25 yd
Continued into
Boone, Il (LOT)
Reported by
Emergency Manager
Coordinates
42.193, -88.955

An emergency manager and trained spotters photographed a tornado that touched down south of Cherry Valley. The tornado did not produce any damage. The tornado continued into Boone County. (Tornado 1a of 7).

Tornado, Boone

When
April 9, 5:38 PM CST to 5:40 PM CST
Where
Boone County, 2.2 mi SSE of Cherry Vly to 2.2 mi ESE of Cherry Vly
Rating
EF0
Path length
1.97 mi
Path width
25 yd
Reported by
Emergency Manager
Coordinates
42.199, -88.940

This is a continuation of a tornado that began in Winnebago County. An emergency manager and trained spotters photographed a tornado that touched down south of Cherry Valley. The tornado did not produce any damage. (Tornado 1b of 7).

Tornado, Lee

When
April 9, 5:39 PM CST to 5:43 PM CST
Where
Lee County, 1.68 mi NNE of Franklin Grove to 1.59 mi NW of Ashton
Rating
EF1
Path length
3.62 mi
Path width
100 yd
Continued into
Ogle, Il (LOT)
Property damage
$1.0 million
Reported by
NWS Storm Survey
Coordinates
41.853, -89.290

This is the beginning of the Rochelle-Fairdale EF-4 tornado. At its strongest, peak winds were estimated to be 200 mph. The tornado touched down just northeast of Franklin Grove. A large sheet metal building on IL-38 collapsed with failure of column anchorage. Several smaller sheet metal buildings were destroyed along E Gurler Road. Peak winds in Lee County were estimated to 110 mph. The tornado continued into Ogle County. (Tornado 2a of 7).

Tornado, Ogle

When
April 9, 5:43 PM CST to 6:12 PM CST
Where
Ogle County, 4.74 mi ESE of Carthage to 3.14 mi E of Monroe Center
Rating
EF4
Path length
20.94 mi
Path width
700 yd
Continued into
De Kalb, Il (LOT)
Property damage
$10 million
Reported by
NWS Storm Survey
Coordinates
41.889, -89.238

This is the second segment of the Rochelle-Fairdale EF-4 tornado. At its strongest, peak winds were estimated to be 200 mph which occurred during this segment of the storm. The tornado entered Ogle County just west of IL-38 and moved northeast where it ripped the roof off of a small barn. A neighborhood was hit on S Skare Court where damage was consistent with EF-3. Some of the homes had large sections of the roofs ripped off while some less well constructed homes (nails instead of bolts) had collapsed walls. The tornado continued northeast and intensified to EF-4 where several well constructed homes along South Richard Road and East Kuehl Court were completely destroyed with the slab swept clean. Several outbuildings were destroyed along East Hemstock Road and South Center Road. A residence on East Bethal Road received heavy damage with most of the outer walls collapsing. The tornado once again intensified to EF-4 near IL-251 and IL-64 where well constructed homes were swept clean off their foundation. A farmstead just northeast of the aforementioned intersection was also swept clean to the foundation. A heavy barn was thrown and rolled on East Lindenwood Road. In total, around 30 homes were damaged or destroyed around Rochelle. The tornado continued into Dekalb County just north of East Quarry Road. (Tornado 2b of 7).

Hail, Ogle

When
April 9, 5:45 PM CST
Where
Ogle County, 2.05 mi E of Mt Morris
Measured
1.75 in hail
Reported by
Trained Spotter
Coordinates
42.050, -89.390

Hail, Cook

When
April 9, 5:45 PM CST
Where
Cook County, 2.29 mi WSW of Inverness
Measured
1 in hail
Reported by
Trained Spotter
Coordinates
42.103, -88.119

Hail, McHenry

When
April 9, 5:50 PM CST
Where
McHenry County, 0.98 mi SE of Huntley
Measured
1 in hail
Reported by
Trained Spotter
Coordinates
42.162, -88.405

Hail, McHenry

When
April 9, 5:56 PM CST
Where
McHenry County, 0.69 mi N of Lake in the Hills
Measured
0.88 in hail
Reported by
Trained Spotter
Coordinates
42.190, -88.320

Hail, McHenry

When
April 9, 5:58 PM CST
Where
McHenry County, Crystal Lake
Measured
0.88 in hail
Reported by
Trained Spotter
Coordinates
42.230, -88.330

Hail, Boone

When
April 9, 6:04 PM CST
Where
Boone County, 0.51 mi E of Capron
Measured
0.75 in hail
Reported by
CoCoRaHS
Coordinates
42.400, -88.740

Tornado, Ogle

When
April 9, 6:05 PM CST to 6:08 PM CST
Where
Ogle County, 2.87 mi ENE of Lindenwood to 3.32 mi ESE of Monroe Center
Rating
EF0
Path length
1.86 mi
Path width
100 yd
Reported by
NWS Storm Survey
Coordinates
42.058, -88.975

A brief satellite tornado formed over far eastern Ogle County. The tornado was confirmed during an aerial survey. (Tornado 3 of 7).

Tornado, De Kalb

When
April 9, 6:12 PM CST to 6:19 PM CST
Where
De Kalb County, 0.6 mi SW of Fairdale to 4.27 mi NNE of Fairdale
Rating
EF3
Path length
4.83 mi
Path width
700 yd
Continued into
Boone, Il (LOT)
Deaths
2 direct, 0 indirect
Injuries
11 direct, 0 indirect
Property damage
$8.0 million
Reported by
NWS Storm Survey
Coordinates
42.095, -88.939

This is the third segment of the Rochelle-Fairdale EF-4 tornado. At its strongest, peak winds were estimated to be 200 mph. The tornado entered the county just southwest of Fairdale before directly hitting the small community. Peak winds were estimated at 165 mph in Dekalb County, rating this section of the tornado a high end EF-3. Approximately 71 homes in the community had been damaged, 17 of which had been completely destroyed with all walls collapsed or removed from the buildings. Some homes that were only nailed to the foundation were swept clean. Two fatalities and 11 injuries occurred in Fairdale. A 67-year-old woman and her neighbor, a 69-year-old woman, were both killed in their homes. The tornado began to shift north (left) at this point during its lifecycle as it left Fairdale. Several homes were heavily damaged with large sections of the roofs removed along Wheeler road and dozens of trees were snapped and uprooted. A few trees were debarked. The second story was ripped off of a home near the intersection of McNeal Road and Irene Road. A two-story rebar reinforced cinder block silo was destroyed. The tornado continued into Boone County just east of Irene Road. (Tornado 2c of 7).

Tornado, De Kalb

When
April 9, 6:15 PM CST to 6:17 PM CST
Where
De Kalb County, 3.54 mi NE of Fairdale to 5.05 mi N of Kirkland
Rating
EF1
Path length
1.8 mi
Path width
100 yd
Continued into
Boone, Il (LOT)
Property damage
$5,000
Reported by
NWS Storm Survey
Coordinates
42.133, -88.878

This tornado was identified from a storm chaser video and survey. Heavy damage to two small outbuildings occurred on Paulson Road. Maximum winds speeds were estimated to be 110 mph. The tornado continued into Boone County. (Tornado 4a of 7).

Tornado, Boone

When
April 9, 6:17 PM CST to 6:21 PM CST
Where
Boone County, 2.61 mi ESE of Irene to 3.7 mi E of Irene
Rating
EF1
Path length
2.21 mi
Path width
100 yd
Property damage
$75,000
Reported by
NWS Storm Survey
Coordinates
42.153, -88.855

This is a continuation of a tornado that began in Dekalb County. This tornado was identified from a storm chaser video and survey. Three barns were destroyed on Pearl Street Road. Maximum winds speeds were estimated to be 110 mph. (Tornado 4b of 7).

Tornado, Boone

When
April 9, 6:19 PM CST to 6:20 PM CST
Where
Boone County, 1.36 mi SSE of Irene to 1.17 mi ESE of Irene
Rating
EF0
Path length
0.75 mi
Path width
25 yd
Reported by
NWS Storm Survey
Coordinates
42.153, -88.887

This is the fourth segment of the Rochelle-Fairdale EF-4 tornado. At its strongest, peak winds were estimated to be 200 mph. The tornado entered Boone County just east of Irene Road. No damage occurred and the tornado lifted shortly after entering the county. (Tornado 2d of 7).

Tornado, Boone

When
April 9, 6:24 PM CST to 6:25 PM CST
Where
Boone County, 3.32 mi S of Belvidere to 2.98 mi S of Belvidere
Rating
EF0
Path length
0.42 mi
Path width
30 yd
Property damage
$20,000
Reported by
NWS Storm Survey
Coordinates
42.202, -88.847

This was a satellite tornado that formed from the same storm that formed the long tracked EF-4 tornado. A small zoo was heavily damaged with walls collapsed on several outbuildings and small barns. Three animals were killed. Softwood trees 4 to 6 inches in diameter were snapped. The estimated peak wind was 85 mph. (Tornado 5 of 7).

Hail, Winnebago

When
April 9, 6:25 PM CST
Where
Winnebago County, 0.69 mi NNW of Cherry Vly
Measured
1.75 in hail
Reported by
Trained Spotter
Coordinates
42.239, -88.956

Tornado, Boone

When
April 9, 6:25 PM CST to 6:31 PM CST
Where
Boone County, 2.1 mi NW of Herbert to 0.6 mi SW of Garden Prairie
Rating
EF1
Path length
3.92 mi
Path width
50 yd
Property damage
$150,000
Reported by
NWS Storm Survey
Coordinates
42.194, -88.775

Witnesses said the tornado touched down in a field then moved northeast destroying a detached garage. The tornado ripped the roof off of a home though the walls mainly remained intact. Several hardwood trees were snapped. Maximum wind speeds were estimated to be 110 mph. (Tornado 6 of 7).

Tornado, McHenry

When
April 9, 6:50 PM CST to 6:51 PM CST
Where
McHenry County, 2.51 mi NW of Hartland to 2.6 mi NNW of Hartland
Rating
EF1
Path length
0.32 mi
Path width
30 yd
Reported by
NWS Storm Survey
Coordinates
42.398, -88.531

A brief tornado snapped and uprooted 6 to 7 trees at a property on McGuire Road southeast of Harvard. Minor tree damage occurred on the north side of the road before ending. Maximum winds were estimated to 90 mph. (Tornado 7 of 7).

Hail, McHenry

When
April 9, 7:08 PM CST
Where
McHenry County, 1.74 mi N of Union
Measured
1 in hail
Reported by
Trained Spotter
Coordinates
42.255, -88.529

Hail, La Salle

When
April 9, 7:15 PM CST
Where
La Salle County, 2.16 mi S of Lostant
Measured
1 in hail
Reported by
Trained Spotter
Coordinates
41.119, -89.075

Hail, McHenry

When
April 9, 7:15 PM CST to 7:20 PM CST
Where
McHenry County, 0.37 mi S of Woodstock to 2.11 mi SSE of Highland Shrs
Measured
1 in hail
Reported by
Trained Spotter
Coordinates
42.315, -88.449

Thunderstorm Wind, La Salle

When
April 9, 7:15 PM CST
Where
La Salle County, 0.86 mi SE of Lostant
Measured
61 kt (70 mph) measured gust
Reported by
Trained Spotter
Coordinates
41.140, -89.060

Hail, McHenry

When
April 9, 7:15 PM CST to 7:27 PM CST
Where
McHenry County, 1.35 mi SSE of Mc Cullom Lake to 1.97 mi S of Mc Henry
Measured
1 in hail
Reported by
Amateur Radio
Coordinates
42.331, -88.293

Thunderstorm Wind, Grundy

When
April 9, 7:59 PM CST
Where
Grundy County, 4 mi NNW of Coal City
Measured
54 kt (62 mph) measured gust
Reported by
NWS Employee
Coordinates
41.334, -88.309

Hail, Will

When
April 9, 8:23 PM CST
Where
Will County, 0.52 mi E of Channahon
Measured
1 in hail
Reported by
Trained Spotter
Coordinates
41.430, -88.220

Hail, Ford

When
April 9, 8:43 PM CST
Where
Ford County, 0.69 mi S of Paxton
Measured
1 in hail
Reported by
Trained Spotter
Coordinates
40.460, -88.100

The people who died

As the offices recorded each death: direct deaths were caused by the weather itself, indirect ones by something it set in motion.

EventDateAgeSexWhereKind
Tornado, De Kalb2015-04-0967FemalePermanent HomeDirect
Tornado, De Kalb2015-04-0969FemalePermanent HomeDirect

What these are

Hail
Hail three-quarters of an inch or larger, or smaller hail that caused damage, filed with the largest stone measured.
Tornado
A violently rotating column of air in contact with the ground and extending from a thunderstorm, filed with its path, width and Fujita or Enhanced Fujita rating from the damage survey.
Thunderstorm Wind
Winds from a thunderstorm of 50 knots (58 mph) or more, or lower winds that caused damage or casualties. Measured gusts are marked MG, estimated EG.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

More

Every storm in Illinois in 2015Every state in 2015This day in weather historyThe tornado archive for Illinois, 2015Warnings in Illinois, April 2015

Sources

NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 574228, 574231, 574249, 574247, 574336, 574337, 574232, 574233, 574234, 574235, 574236, 574237, 574248, 574338, 574250, 574251, 574339, 574333, 574238, 574334, 574335, 574239, 574240, 574241, 574242, 574243, 574530, 574245, 574246.