Alert archive / Illinois / Severe Thunderstorm Warnings in 1997

Severe Thunderstorm Warning 120, NWS Quad Cities, IA

August 4, 1997Carroll County, Jo Daviess County, Illinois

NWS Quad Cities, IA issued this severe thunderstorm warning at Aug 4, 1997, 4:54 PM CDT for Carroll County, Jo Daviess County, Illinois. It was in force for 36 min. 1 report came from inside the area while it was in force.

The area

The counties it named, with what was reported inside it.

The facts

Issued: Aug 4, 1997, 4:54 PM CDT (21:54 UTC)
Expired: Aug 4, 1997, 5:30 PM CDT
In force: 36 min
Issued by: NWS Quad Cities, IA
Area: Whole counties

Counties Carroll County, IL, Jo Daviess County, IL

The radar

The Quad Cities radar (KDVN), 79 km from the middle of the area, began a volume at 21:58 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.

What was reported inside it

Time	Report	Where	Remark
Aug 4, 5:08 PM CDT	Thunderstorm Wind 57	Savanna, IL	A line of strong to severe thunderstorms pushed through the area. Winds at Savanna were measured with a peak wind gust to 65 mph.

NCEI Storm Data entries that began inside the alert's area while it was in force. Before 2003 the local storm report archive is thin, so this is the record of what happened rather than what was phoned in.

The nearest sounding before it

Davenport, (KDVN), launched 12:00Z, 9.9 hours before the alert went out and 75 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 519 J/kg
Mixed-layer CIN: -81 J/kg
Mixed-layer LCL: 990 m above ground
0-6 km bulk shear: 38 kt
0-1 km storm-relative helicity: -36 m²/s²
0-3 km storm-relative helicity: 51 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.9

Open this sounding in Storm Lab

The text

The text of this product is not in the archive. The NWS text archive before 2002 is incomplete.

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 4, 1:07 PM CDT, 3 hours 47 minutes earlier.

Area forecast discussion, Aug 4, 1:07 PM CDT, 3 hours 47 minutes before

AREA FORECAST DISCUSSION...CORRECTION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
105 PM CDT MON AUG 4 1997

SFC TROF LOCATED NR IA/MN BORDER INTO SRN WI AT 17Z. ALOFT... FEATURE
SHOWS UP BEST AT 70H AND EXTENDS FRM SRN MN INTO NRN WI. MOISTURE
POOLING ALONG SFC TROF AS PER UPR 60S TO LWR 70S DEWPOINTS ON IOWA
MESONET. LATEST 1KM VISIBLE SNAPSHOT DEPICTED NMRS CU/TCU DEVELOPING
ALONG BOUNDARY W\ A FEW SHRA/TSRA ON KARX WSR-88D NORTH OF MADISON. SFC
TROF HEADED TOWARD UNSTABLE ENVIRONMENT OVR ERN IA AND NW IL W\ LI'S TO
-6 AND NO CAP. KARX WSR-88D STORM TRACK ALGORITHM BRINGS SHRA INTO RFD
AREA BY 1830Z OR SO. APPEARS AREAS EAST OF MS RVR HAVE LEGIT CHC. BIG
QUESTION IS WILL ANYTHING FIRE FURTHER WEST ALONG BOUNDARY. LACK OF CU
IN NE IA ON SATELLITE TROUBLING BUT QUICK PEEK OUT WINDOW REVEALED
DECENT TCU FORMING NORTHWEST OF AIRPORT. IN ADDITION... SPEED MAX AT 50H
AND DECENT 30H JET FOR AUGUST TO PROVIDE UPR SUPPORT. THUS... CURRENT 30
POPS ACRS THE BOARD COVERS SITUATION NICELY. OF COURSE... PCPN TO FADE
W\ LOSS OF HTG. RECOMMEND MENTION OF EARLY EVE SHRA... PSBL TSRA.

ONCE PCPN FADES AWAY... HIGH PRES IN CONTROL AND FORECAST RATHER
STRAIGHT-FOREWARD. RELIEF FROM THE BRIEF STINT OF HUMID WX TO COME TO AN
END AS MUCH DRIER AND COOLER AIR INVADES THE AREA. LUKS LIKE
COMFORTABLE SLEEPING WX NEXT COUPLE NIGHTS W\ A BEAUTIFUL DAY SANDWICHED
IN BETWEEN.

FAN AND FWC CLOSE W\ MINS... BUT FWC BETTER W\ AFT MAXS BASED ON
TRAJECTORY.

CID  58/30  DBQ  55/30   MLI  58/30  BRL 60/30

HENDRICKS

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 3, 8:15 PM CDT	Severe Thunderstorm Warning	DVN	Dubuque	65 min
Aug 3, 9:50 PM CDT	Severe Thunderstorm Warning	DVN	Henry	50 min
Aug 3, 10:41 PM CDT	Severe Thunderstorm Warning	DVN	Hancock	49 min
Aug 4, 5:13 PM CDT	Severe Thunderstorm Warning	DVN	Carroll	47 min
Aug 4, 6:10 PM CDT	Severe Thunderstorm Warning	DVN	Putnam	50 min

Nearby

Severe Thunderstorm Warnings in Illinois, 1997 Every severe thunderstorm warning in 1997

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; verification from NCEI's Storm Data; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.