Alert archive / Illinois / Severe Thunderstorm Warnings in 2007

Severe Thunderstorm Warning 118, NWS Quad Cities, IA

August 12, 2007Stephenson County, Illinois

NWS Quad Cities, IA issued this severe thunderstorm warning at Aug 12, 2007, 1:44 AM CDT for Stephenson County, Illinois. It was in force for 61 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
Aug 12, 2007, 1:44 AM CDT (06:44 UTC)
Expired
Aug 12, 2007, 2:45 AM CDT
In force
61 min
Issued by
NWS Quad Cities, IA
Area
Counties, with a storm outline in the text

County Stephenson County, IL

The radar

The Quad Cities radar (KDVN), 112 km from the middle of the area, began a volume at 06:44 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

Davenport, (KDVN), launched 00:00Z, 6.7 hours before the alert went out and 107 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 2007-08-12Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1137 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 2007-08-12The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 62 square meters per square second.193958Sfc1 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
1137 J/kg
Mixed-layer CIN
-105 J/kg
Mixed-layer LCL
1520 m above ground
0-6 km bulk shear
27 kt
0-1 km storm-relative helicity
62 m²/s²
0-3 km storm-relative helicity
120 m²/s²
Significant tornado parameter
0.1
Supercell composite
1.9

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 Aug 11, 2:45 PM CDT, 10 hours 59 minutes earlier.

Area forecast discussion, Aug 11, 2:45 PM CDT, 10 hours 59 minutes before
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Hazardous weather outlook, Aug 11, 5:03 AM CDT, 20 hours 41 minutes before
HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
503 AM CDT SAT AUG 11 2007

IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007-
009-015>018-024>026-034-035-MOZ009-010-121015-
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-
503 AM CDT SAT AUG 11 2007

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...TODAY AND TONIGHT...

TEMPERATURES IN THE LOW TO MID 90S AND INCREASING HUMIDITY TODAY
WILL COMBINE TO PRODUCE HEAT INDICES OF AROUND 100 DEGREES IN
PORTIONS OF SOUTHEAST IOWA...FAR WEST CENTRAL ILLINOIS AND
NORTHEAST MISSOURI.

A FRONTAL SYSTEM WILL DROP SOUTH TOWARD THE DUBUQUE...TO CEDAR
RAPIDS AREA BY LATE TONIGHT. OUT AHEAD OF IT...THERE WILL BE A
CHANCE FOR SOME THUNDERSTORMS THIS EVENING AND OVERNIGHT GENERALLY
ALONG AND NORTH OF A LINE FROM WEST OF CEDAR RAPIDS... TO FREEPORT
IN NORTHWEST ILLINOIS. IF STORMS DO MANAGE TO GET DOWN INTO THESE
AREAS TONIGHT...THERE WILL BE A LOW CHANCE THAT A FEW STORMS WILL
PRODUCE DAMAGING WINDS.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY...

SUNDAY THE COLD FRONT CONTINUES TO MOVE SOUTHEAST ACROSS THE
OUTLOOK AREA IN THE MORNING. BY THIS TIME NO STORMS ARE EXPECTED
IN THE FORECAST AREA...THOUGH ISOLATED CELLS ARE POSSIBLE CLOSE TO
THE BOUNDARY.

A SECOND FRONT IS EXPECTED TO MOVE THROUGH THE AREA ON TUESDAY
WITH LOW CHANCES OF SHOWERS AND THUNDERSTORMS. LATER IN THE
WEEK...SHOWERS AND THUNDERSTORMS ARE EXPECTED LATE TUESDAY NIGHT
THROUGH WEDNESDAY AND WEDNESDAY NIGHT. IT IS TOO EARLY TO
DETERMINE THE POTENTIAL FOR SEVERE WEATHER OR HEAVY RAINS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED TODAY OR TONIGHT.

In the hours before

Special weather statement, Aug 12, 1:40 AM CDT, 4 minutes before
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
140 AM CDT SUN AUG 12 2007

ILZ001-002-120815-
JO DAVIESS-STEPHENSON-
INCLUDING THE CITIES OF...GALENA...FREEPORT
140 AM CDT SUN AUG 12 2007

...A LINE OF STRONG THUNDERSTORMS PUSHING OUT OF SOUTHERN
WISCONSIN AND INTO NORTHWEST ILLINOIS...

A LINE OF STRONG THUNDERSTORMS WILL MOVE QUICKLY SOUTHEAST OUT OF
SOUTHERN WISCONSIN AND REACH A STOCKTON...TO FREEPORT LINE BY 220 AM.
THESE STORMS WILL BE CAPABLE OF PRODUCING WIND GUSTS UP TO 50
MPH...FREQUENT AND INTENSE CLOUD TO GROUND LIGHTNING...AND
TORRENTIAL DOWNPOURS AT RATES OF OVER AN INCH AN HOUR. HEAVY
RAINS MAY FLOOD LOW LYING AREAS SUCH AS DITCHES AND UNDERPASSES.
IF YOU LIVE IN NORTHEAST PORTIONS OF JO DAVIESS AND NORTHERN
STEPHENSON COUNTIES...MOVE INDOORS AS THESE STORMS APPROACH YOUR
AREA.

12

Nearby

Severe Thunderstorm Warnings in Illinois, 2007Every severe thunderstorm warning in 2007

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.