Alert archive / Iowa / Severe Thunderstorm Warnings in 2002
Severe Thunderstorm Warning 112, NWS Quad Cities, IA
NWS Quad Cities, IA issued this severe thunderstorm warning at Aug 21, 2002, 3:35 PM CDT for Iowa County, Johnson County, Washington County, Iowa. It was in force for 40 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 21, 2002, 3:35 PM CDT (20:35 UTC)
- Expired
- Aug 21, 2002, 4:15 PM CDT
- In force
- 40 min
- Issued by
- NWS Quad Cities, IA
- Area
- Counties, with a storm outline in the text
Counties Iowa County, IA, Johnson County, IA, Washington County, IA
The radar
The Quad Cities radar (KDVN), 101 km from the middle of the area, began a volume at 20:37 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 21, 4:00 PM CDT | Thunderstorm Wind 61 E | Wellman, IA | Several large trees blown down, barn on 540th Street Southwest heavily damaged, and corn flattened in spots on Angle Road Southwest. |
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.
Did it verify
Not verified. The Iowa Environmental Mesonet's Cow found no qualifying storm report inside this severe thunderstorm warning while it was in force. That is not proof nothing happened: reports are thin where few people live.
Cow counts a report within 15 km of the polygon while the warning was in force: a tornado for a tornado warning; hail of 1 inch or more, a gust of 58 mph or more or wind damage for a severe thunderstorm warning; a flash flood report for a flash flood warning.
The watch it was issued in
The SPC watch in force over the same counties when this warning went out.
| Issued | Product | Office | Lasted |
|---|---|---|---|
| Aug 21, 2:25 PM CDT | Severe Thunderstorm Watch | SPC | 6 hr |
The nearest sounding before it
Davenport, (KDVN), launched 12:00Z, 8.6 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.
- Mixed-layer CAPE
- 1748 J/kg
- Mixed-layer CIN
- -90 J/kg
- Mixed-layer LCL
- 760 m above ground
- 0-6 km bulk shear
- 32 kt
- 0-1 km storm-relative helicity
- 173 m²/s²
- 0-3 km storm-relative helicity
- 150 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 3.6
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 21, 1:51 PM CDT, 1 hour 44 minutes earlier.
Area forecast discussion, Aug 21, 1:51 PM CDT, 1 hour 44 minutes before
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE QUAD CITIES IA IL 151 PM CDT WED AUG 21 2002 SYNOPSIS... MORNING UA AND SURFACE ANALISIS SHOWS THE AREA IS NOW IN THE WARM AND MOIST SECTOR. THE SURFACE WARM FRONT AT 15Z EXTENDS FROM NEAR FSD TO ALO TO VYS. WELL DEFINED SHORT WAVE JUST WEST OF MCI AT 12Z...NOW APPROACHING THE UPPER MIDWEST FROM THE SOUTHWEST. THIS WAVE HAS SPAWNED OVERNIGHT CONVECTION FROM KANSAS THROUGH NORTHWEST IOWA. MUCH OF THIS IS NOW DECAYING AS EXPECTED...WITH THE EXCEPTION OF PORTION NEAR MCI. THIS WILL BE THE CONVECTIVE CLUSTER TO WATCH AS IT APPROACHES THE CWA THIS AFTERNOON. CIRRUS AND DEBRIS CLOUDS CONTINUE TO SLOWLY THIN NORTH OF INTERSTATE 80...WITH MODERATED INSOLATION ALREADY IN PLACE SOUTH OF THE INTERSTATE. THIS WILL ALLOW ADEQUATE HEATING FOR STORMS TO INTENSIFY IN OUR AREA THIS AFTERNOON. SHORT TERM... SEVERE WEATHER THREAT WILL MAINLY AFFECT THE AREA THIS EVENING...WITH HEAVY RAIN EXPECTED LATE EVENING AND OVERNIGHT. PWAT VALUES IN EXCESS OF TWO INCHES NOTED ON THE OMA 12Z SOUNDING AND NEAR 2 INCHES ON 18Z DVN SOUNDING...SHOW TROPICAL AIRMASS OVER THE REGION. DESPITE MODEL DIFFERENCES...ALL SHORT TERM MODELS INDICATE DIFFLUENT THICKNESS OVER THE CWA TONIGHT THROUGH THURSDAY MORNING. TRAINING CELLS APPEAR TO BE LIKELY GIVEN NEARY STATIONARY BOUNDARY OVER THE CWA. ALL THIS SAID... COUNTY FFG GUIDANCE VALUES ARE RUNNING RATHER HIGH AND CROPS ARE MATURE. THEREFORE I FEEL WIDESPREAD FLOODING PROBLEMS DO NOT WARRANT A FLOOD WATCH AT THIS TIME. URBAN FLOODING MAY BECOME AN ISSUE...IF STORMS PICK ON ONE AREA REPEATEDLY. THE FRONT BECOMES QUASI-STATIONARY THURSDAY AND FRIDAY...WITH SEVERAL ROUNDS OF HEAVY RAIN AND THUNDESTORMS EXPECTED THROUGH FRIDAY NIGHT. IF HEAVY RAIN DOES MATERIALIZE TONIGHT...A FLOOD WATCH MAY BE NEEDED FOR THURSDAY NIGHT AND FRIDAY FOR AREAS THAT RECIEVE HEAVY RAIN TONIGHT. EXTENDED... NO MAJOR CHANGES EXPECTED IN EXTENDED AS CANADIAN HIGH SETTLES SOUTH ACROSS THE AREA FOR SEVERAL DAYS OF PLEASANT WEATHER. MRF AND UKMET CONTINUE TO INDICATE A LOBE UPPER LEVEL VORTICITY WORKING SOUTH ACROSS THE AREA MONDAY. FOR NOW...I WILL NOT CHANGES THE GOING FORECAST...BUT SHOWERS MAY NEED TO BE ADDED IF THIS FEATURE MOVES OVER THE AREA DURING PEAK HEATING. OTHERWISE...DRY WEATHER WILL CONTINUE THROUGH WEDNESDAY...WITH SLOWLY MODERATING TEMPERATURES. .DVN... IA...NONE. IL...NONE. MO...NONE. ERVIN/DVN LAST/OMA NEXT
The office that day
Everything else NWS Quad Cities, IA issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 21, 4:53 PM CDT | Severe Thunderstorm Warning | DVN | Cedar | 52 min |
| Aug 21, 5:27 PM CDT | Severe Thunderstorm Warning | DVN | Jackson | 33 min |
| Aug 21, 6:03 PM CDT | Severe Thunderstorm Warning | DVN | Muscatine | 42 min |
| Aug 21, 6:05 PM CDT | Severe Thunderstorm Warning | DVN | Muscatine | 40 min |
| Aug 21, 6:13 PM CDT | Tornado Warning | DVN | Muscatine | 32 min |
| Aug 21, 6:39 PM CDT | Tornado Warning | DVN | Scott | 66 min |
Nearby
Severe Thunderstorm Warnings in Iowa, 2002Every severe thunderstorm warning in 2002
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.