Alert archive / Illinois / Severe Thunderstorm Warnings in 2008

Severe Thunderstorm Warning 241, NWS Quad Cities, IA

July 21, 2008McDonough County, Illinois

NWS Quad Cities, IA issued this severe thunderstorm warning at Jul 21, 2008, 8:31 PM CDT for McDonough County, Illinois. It was in force for 34 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued
Jul 21, 2008, 8:31 PM CDT (01:31 UTC)
Expired
Jul 21, 2008, 9:05 PM CDT
In force
34 min
Issued by
NWS Quad Cities, IA
Area
Storm-based polygon

County McDonough County, IL

The radar

The Lincoln radar (KILX), 119 km from the middle of the area, began a volume at 01:32 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 watch it was issued in

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

IssuedProductOfficeLasted
Jul 21, 5:10 PM CDTSevere Thunderstorm WatchSPC7 hr

The nearest sounding before it

Davenport, (KDVN), launched 00:00Z, 1.5 hours before the alert went out and 130 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Davenport, at 00:00Z on 2008-07-22Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 721 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Davenport, at 00:00Z on 2008-07-22The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 102 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
721 J/kg
Mixed-layer CIN
-258 J/kg
Mixed-layer LCL
1280 m above ground
0-6 km bulk shear
41 kt
0-1 km storm-relative helicity
102 m²/s²
0-3 km storm-relative helicity
143 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.6

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Quad Cities, IA wrote its last area forecast discussion before this severe thunderstorm warning went out at Jul 21, 2:57 PM CDT, 5 hours 34 minutes earlier.

Area forecast discussion, Jul 21, 2:57 PM CDT, 5 hours 34 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
257 PM CDT MON JUL 21 2008

.SYNOPSIS...
FRONTAL BOUNDARY ACROSS SOUTHERN IOWA WILL BE THE FOCUS FOR
CONVECTION TONIGHT...WITH FRONT GRADUALLY SHIFTING SOUTHWARD. HIGH
PRESSURE BUILDING INTO THE GREAT LAKES REGION SHOULD BRING MORE
PLEASANT CONDITIONS FOR MID WEEK. FOR THURSDAY AND FRIDAY WARM FRONT
RETURNS TO THE REGION BRINGING BACK THUNDERSTORM CHANCES. ANOTHER
HIGH PRESSURE SYSTEM DROPS SOUTHWARD INTO THE UPPER MIDWEST FOR THIS
UPCOMING WEEKEND...WITH ACTIVE FRONTAL BOUNDARY NEARBY IN MO.

&&

.SHORT TERM...TONIGHT AND TUESDAY...
FRONTAL BOUNDARY LIES ACROSS SOUTHERN IOWA AND WILL BE THE FOCUS FOR
INTENSE THUNDERSTORMS TOWARDS EVENING. STRONG TEMPERATURE CONTRAST
EXISTS WITH TEMPERATURES WELL INTO THE 90S TO NEAR 100 IN KS AND MO
WHILE READINGS ONLY IN THE 70S IN SOUTHERN WI. AIRMASS IS CAPPED
SOUTH OF BOUNDARY BUT SHOULD WEAKEN BY EVENING. 18Z SPECIAL BALLOON
LAUNCH AT KDVN SHOWED 500 MB WIND SPEED OF 60 KNOTS WHICH WILL
SUPPORT DAMAGING WINDS IN THE STRONGER STORMS. WILL NEED TO KEEP AN
EYE OUT FOR BOWING SEGMENTS WHICH WILL ENHANCE WIND DAMAGE. WILL
HAVE MENTION OF SEVERE IN THE GRIDS. BULK OF SEVERE WEATHER SHOULD
BE OVER WITH BY MIDNIGHT WITH FRONT SAGGING FARTHER SOUTHWARD. WILL
KEEP SLIGHT CHANCE OF STORMS FOR TUESDAY IN OUR FAR SOUTHERN CWA
WITH FRONTAL BOUNDARY IN NORTHERN MO. OTHERWISE BULK OF THE CWA WILL
HAVE QUIET WEATHER WITH GRADUALLY LOWERING HUMIDITIES.

..HAASE..

.LONG TERM...TUESDAY NIGHT THROUGH MONDAY...
TUE NIGHT THROUGH WED STILL LOOKS TO BE A QUIET WEATHER PERIOD WITH
AREA IN UPPER LEVEL NW FLOW BETWEEN NORTHERN PLAINS RIDGE AXIS AND
LOW OVER EASTERN GREAT LAKES. AT SURFACE...HIGH PRESSURE OVER
WESTERN GREAT LAKES WILL FEED SEASONABLY COOL AND DRY AIR INTO THE
REGION. THIS WILL MINS LOWS TO DROP INTO THE 50S NORTH OF I-80 WITH
HIGHS IN UPPER 70S TO LOWER 80S.

BEST CHANCE FOR THUNDERSTORMS THROUGHOUT WILL BE LATE WED NIGHT INTO
THU NIGHT AS UPPER LEVEL SHORTWAVE TOPS THE RIDGE AXIS AND PASSES SE
ACROSS THE REGION. THIS ALLOWS DEEPER MOISTURE TO SURGE NORTH INTO
THE CENTRAL PLAINS. WILL KEEP LOW POPS WED NIGHT IN THE ESPECIALLY
THE WESTERN CWFA FOR ELEVATED CONVECTION ON THE DEVELOPING
NOCTURNAL JET. MODELS DEPICT MAIN SHORTWAVE AND STRONGEST FORCING
ACROSS EASTERN IA THU MORNING AND HAVE NARROWED CHANCE POPS TO
MAINLY THIS PERIOD. SLIGHT CHANCES MAINTAINED FOR THU NIGHT INTO FRI
AS MODELS SUGGESTING LOW POTENTIAL FOR ADDITIONAL THUNDERSTORMS WITH
PASSAGE OF WEAK COLD FRONT.

FRI NIGHT THROUGH MON...NW FLOW CONTINUES WITH ECMWF MAINTAINING THE
SYNOPTIC FRONT FURTHER SOUTH THAN THE GFS AND THUS KEEPING ANY
POTENTIAL PRECIPITATION SOUTH OF THE AREA. HAVE MAINTAINED CONTINUITY
WITH THIS SOLUTION WITH HIGHS IN 80S AND LOWS IN 60S THROUGHOUT.
..SHEETS..

&&

.AVIATION...
THUNDERSTORMS SHOULD INCREASE IN COVERAGE AND INTENSITY LATER THIS
AFTERNOON AND INTO EARLY TONIGHT...ESPECIALLY SOUTH OF HIGHWAY 30.
MVFR TO OCNL IFR CONDITIONS IN THUNDERSTORMS. STORMS SHOULD
GRADUALLY SHIFT SOUTH AND EAST OF THE TAF SITES BY MIDNIGHT. VFR
CONDITIONS EXPECTED LATER TONIGHT AND TUESDAY AS HIGH PRESSURE
BUILDS INTO THE GREAT LAKES. LIGHT AND VARIABLE WINDS LATER TONIGHT
WITH NORTHEAST WINDS AROUND 10 KNOTS ON TUESDAY.

..HAASE..

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.

&&

HAASE/SHEETS
Hazardous weather outlook, Jul 21, 3:12 PM CDT, 5 hours 19 minutes before
HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
312 PM CDT MON JUL 21 2008

IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007-
009-015>018-024>026-034-035-MOZ009-010-221000-
BUCHANAN-DELAWARE-DUBUQUE-BENTON-LINN-JONES-JACKSON-IOWA-JOHNSON-
CEDAR-CLINTON-MUSCATINE-SCOTT-KEOKUK-WASHINGTON-LOUISA-JEFFERSON-
HENRY IA-DES MOINES-VAN BUREN-LEE-JO DAVIESS-STEPHENSON-CARROLL-
WHITESIDE-ROCK ISLAND-HENRY IL-BUREAU-PUTNAM-MERCER-HENDERSON-
WARREN-HANCOCK-MCDONOUGH-SCOTLAND-CLARK-
312 PM CDT MON JUL 21 2008

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH CENTRAL
ILLINOIS...NORTHWEST ILLINOIS...WEST CENTRAL ILLINOIS...EAST
CENTRAL IOWA...NORTHEAST IOWA...SOUTHEAST IOWA AND NORTHEAST
MISSOURI.

.DAY ONE...THIS AFTERNOON AND TONIGHT
THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS LATE THIS AFTERNOON
AND INTO EARLY TONIGHT ALONG AND SOUTH OF HIGHWAY 34. WIDESPREAD
DAMAGING WINDS IN EXCESS OF 70 MPH IS THE MAIN THREAT.

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS LATE THIS AFTERNOON
AND INTO EARLY TONIGHT BETWEEN HIGHWAY 30 AND HIGHWAY 34. THE MAIN
THREAT FROM THESE STORMS WILL BE DAMAGING WINDS IN EXCESS OF 60 MPH.
LARGE HAIL AND LOCALLY HEAVY RAIN IS A SECONDARY THREAT.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY
THERE IS A CHANCE OF THUNDERSTORMS ON THURSDAY. IT IS TOO EARLY TO
DETERMINE THE SEVERE WEATHER POTENTIAL.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL BE NEEDED LATE THIS AFTERNOON INTO EARLY
TONIGHT.

HAASE

In the hours before

Special weather statement, Jul 21, 5:35 PM CDT, 2 hours 56 minutes before
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
535 PM CDT MON JUL 21 2008

IAZ067-076>078-087>089-ILZ024-220200-
DES MOINES IA-HENRY IA-JEFFERSON IA-KEOKUK IA-LOUISA IA-MERCER IL-
MUSCATINE IA-WASHINGTON IA-
535 PM CDT MON JUL 21 2008

...THUNDERSTORMS...SOME STRONG EXPECTED BETWEEN 6 PM AND 8 AM...

AT 520 PM CDT...A LINE OF INTESIFYING THUNDERSTORMS AND SHOWERS EXTENDED
ALONG THE I-80 CORRIDOR THAT WAS MOVING EAST SOUTHEAST AT 25 TO 30 MPH.
THIS LINE IS CAPABLE OF STRONG WINDS OF 30 TO OVER 45 MPH AND PEA SIZED
HAIL. THESE STORMS MAY ALSO PRODUCE HEAVY RAINFALL RATES OF OVER TWO
INCHES AN HOUR. WIDESPREAD MODERATE TO HEAVY RAINFALL AMOUNTS OF A HALF
INCH TO AN INCH IS EXPECTED WITH LOCALIZED AMOUNTS WELL OVER AN INCH
POSSIBLE. LOCATIONS THAT RECEIVE WELL OVER AN INCH OF RAIN MAY BE
SUSCEPTIBLE TO SIGNIFICANT PONDING OF WATER.

NICHOLS
Special weather statement, Jul 21, 5:38 PM CDT, 2 hours 53 minutes before
SPECIAL WEATHER STATEMENT...CORRECTED TYPO
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
538 PM CDT MON JUL 21 2008

IAZ067-076>078-087>089-ILZ024-220200-
DES MOINES IA-HENRY IA-JEFFERSON IA-KEOKUK IA-LOUISA IA-MERCER IL-
MUSCATINE IA-WASHINGTON IA-
538 PM CDT MON JUL 21 2008

...THUNDERSTORMS...SOME STRONG EXPECTED BETWEEN 6 PM AND 8 PM...

AT 520 PM CDT...A LINE OF INTESIFYING THUNDERSTORMS AND SHOWERS EXTENDED
ALONG THE I-80 CORRIDOR THAT WAS MOVING EAST SOUTHEAST AT 25 TO 30 MPH.
THIS LINE IS CAPABLE OF STRONG WINDS OF 30 TO OVER 45 MPH AND PEA SIZED
HAIL. THESE STORMS MAY ALSO PRODUCE HEAVY RAINFALL RATES OF OVER TWO
INCHES AN HOUR. WIDESPREAD MODERATE TO HEAVY RAINFALL AMOUNTS OF A HALF
INCH TO AN INCH IS EXPECTED WITH LOCALIZED AMOUNTS WELL OVER AN INCH
POSSIBLE. LOCATIONS THAT RECEIVE WELL OVER AN INCH OF RAIN MAY BE
SUSCEPTIBLE TO SIGNIFICANT PONDING OF WATER.

NICHOLS
Special weather statement, Jul 21, 6:50 PM CDT, 1 hour 41 minutes before
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
650 PM CDT MON JUL 21 2008

IAZ089-ILZ025-026-220200-
DES MOINES IA-HENDERSON IL-WARREN IL-
650 PM CDT MON JUL 21 2008

...THUNDERSTORMS...SOME STRONG EXPECTED BETWEEN 7 PM AND 9 PM...

AT 645 PM CDT...A LINE OF INTENSIFYING THUNDERSTORMS AND SHOWERS
EXTENDED FROM NEAR BURLINGTON TO GALESBURG THAT ARE MOVING EAST
SOUTHEAST AT 25 TO 30 MPH. THIS LINE IS CAPABLE OF PEA SIZED HAIL AND
STRONG WINDS 30 TO OVER 45 MPH. THESE STORMS MAY ALSO PRODUCE HEAVY
RAINFALL RATES OF OVER TWO INCHES AN HOUR. AREAS OF MODERATE TO HEAVY
RAINFALL AMOUNTS OF A HALF INCH TO AN INCH IS EXPECTED WITH LOCALIZED
AMOUNTS WELL OVER AN INCH POSSIBLE. LOCATIONS THAT RECEIVE WELL OVER AN
INCH OF RAIN MAY BE SUSCEPTIBLE TO SIGNIFICANT PONDING OF WATER.

NICHOLS
Local storm report, Jul 21, 7:43 PM CDT, 48 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
743 PM CDT MON JUL 21 2008

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

0735 PM     HAIL             3 S NEW LONDON          40.88N 91.41W
07/21/2008  E0.50 INCH       HENRY              IA   PUBLIC

            ESTIMATED SIZE, OCCURRED AT 735PM.

&&

WE
Local storm report, Jul 21, 8:14 PM CDT, 17 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
814 PM CDT MON JUL 21 2008

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

0812 PM     HEAVY RAIN       1 N BURLINGTON          40.82N 91.12W
07/21/2008  M1.00 INCH       DES MOINES         IA   PUBLIC

            WATER IN STREETS.

&&

BILLN
Local storm report, Jul 21, 8:29 PM CDT, 2 minutes before
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The office that day

Everything else NWS Quad Cities, IA issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 21, 7:13 PM CDTSevere Thunderstorm WarningDVNWarren43 min

Nearby

Severe Thunderstorm Warnings in Illinois, 2008Every severe thunderstorm warning in 2008

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.