Alert archive / Iowa / Severe Thunderstorm Warnings in 2002

Severe Thunderstorm Warning 116, NWS Quad Cities, IA

August 21, 2002Muscatine County, Iowa

NWS Quad Cities, IA issued this severe thunderstorm warning at Aug 21, 2002, 6:05 PM CDT for Muscatine County, Iowa. It was in force for 40 min. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
Aug 21, 2002, 6:05 PM CDT (23:05 UTC)
Expired
Aug 21, 2002, 6:45 PM CDT
In force
40 min
Issued by
NWS Quad Cities, IA
Area
Counties, with a storm outline in the text

County Muscatine County, IA

The radar

The Quad Cities radar (KDVN), 47 km from the middle of the area, began a volume at 23:05 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

TimeReportWhereRemark
Aug 21, 6:15 PM CDTTornado F1Muscatine, IAAn F1 tornado touched down north of Muscatine near Highway 38 doing extensive damage to a machine shed that housed a tractor, disk, planter and field cultivator. Damage to the shed and equipment was estimated at over $200,000. Nearby, the roof was partially

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.

IssuedProductOfficeLasted
Aug 21, 2:25 PM CDTSevere Thunderstorm WatchSPC6 hr

The nearest sounding before it

Davenport, (KDVN), launched 12:00Z, 11.1 hours before the alert went out and 54 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 12:00Z on 2002-08-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1748 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 12:00Z on 2002-08-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 173 square meters per square second.1939Sfc1 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
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

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

000 
WUUS53 KDVN 212305 CCA
SVRMLI
IAC139-212345-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING...CORRECTED SEVERE REPORT AT NICHOLS...
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
603 PM CDT WED AUG 21 2002

THE NATIONAL WEATHER SERVICE IN THE QUAD CITIES HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  MUSCATINE COUNTY IN EAST CENTRAL IOWA

* UNTIL 645 PM CDT

* AT 600 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM WITH DAMAGING WINDS 6 MILES NORTHWEST OF
  MUSCATINE...MOVING NORTHEAST AT 35 MPH.

* THE SEVERE THUNDERSTORM IS EXPECTED TO BE NEAR...
   MUSCATINE NOW.
   WILTON BY 620 PM CDT.
   STOCKTON BY 630 PM CDT.

AT 556 PM CDT LOCAL LAW ENFORCEMENT REPORTED...8 INCH DIAMETER LIMBS 
DOWN IN NICHOLS.

THIS SEVERE THUNDERSTORM IS CAPABLE OF PRODUCING WINDS IN EXCESS OF 
70 MPH. TAKE COVER IN A STURDY STRUCTURE AND GO INTO AN INTERIOR 
ROOM OR BASEMENT UNTIL THE STORM PASSES.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 800 PM CDT
WEDNESDAY EVENING FOR EASTERN IOWA AND NORTHWESTERN ILLINOIS.

LAT...LON 4158 9137 4137 9130 4146 9081 4159 9081

$$
86

&

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, 4 hours 14 minutes earlier.

Area forecast discussion, Aug 21, 1:51 PM CDT, 4 hours 14 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

In the hours before

Local storm report, Aug 21, 3:36 PM CDT, 2 hours 29 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
336 PM CDT WED AUG 21 2002

TIME(CDT)  .....CITY LOCATION..... STATE  ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0324 PM    12 E FAIRBANK             IA   50-55 MPH TSTM GUST
08/21/02   BUCHANAN                       WIND SPEEDS ESTIMATED.
                                          REPORTED BY STORM
                                          SPOTTER.
Local storm report, Aug 21, 4:05 PM CDT, 2 hours before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
405 PM CDT WED AUG 21 2002

TIME(CDT)  .....CITY LOCATION..... STATE  ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0400 PM    WELLMAN                   IA   WIND DAMAGE
08/21/02   WASHINGTON                     LARGE TREES DOWNED DUE
                                          TO VERY HIGH WINDS.
                                          REPORTED BY LAW
                                          ENFORCEMENT OFFICIAL.
Local storm report, Aug 21, 5:04 PM CDT, 1 hour 1 minute before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
504 PM CDT WED AUG 21 2002

TIME(CDT)  .....CITY LOCATION..... STATE  ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0459 PM    2 S OXFORD JCT            IA   51 MPH TSTM GUST
08/21/02   JONES                          WIND SPEEDS MEASURED.
                                          SMALL BRACHES BLOWN
                                          DOWN.  REPORTED BY
                                          STORM SPOTTER.

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 21, 3:35 PM CDTSevere Thunderstorm WarningDVNIowa, Johnson, Washington40 min
Aug 21, 4:53 PM CDTSevere Thunderstorm WarningDVNCedar52 min
Aug 21, 5:27 PM CDTSevere Thunderstorm WarningDVNJackson33 min
Aug 21, 6:03 PM CDTSevere Thunderstorm WarningDVNMuscatine42 min
Aug 21, 6:13 PM CDTTornado WarningDVNMuscatine32 min
Aug 21, 6:39 PM CDTTornado WarningDVNScott66 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.