Alert archive / Iowa / Tornado Watches in 2002

Tornado Watch 160

April 27, 20028 counties in Illinois; 24 counties in Iowa; 4 counties in Missouri

The Storm Prediction Center issued this tornado watch at Apr 27, 2002, 7:45 PM CDT for 8 counties in Illinois; 24 counties in Iowa; 4 counties in Missouri. It was in force for 4 hr.

The area

The outline as issued.

The facts

Issued: Apr 27, 2002, 7:45 PM CDT (00:45 UTC)
Expired: Apr 28, 2002, 12:00 AM CDT
In force: 4 hr
Issued by: the Storm Prediction Center

All 36 counties

Appanoose County, IA, Cedar County, IA, Davis County, IA, Des Moines County, IA, Henry County, IA, Iowa County, IA, Jasper County, IA, Jefferson County, IA, Johnson County, IA, Keokuk County, IA, Lee County, IA, Louisa County, IA, Lucas County, IA, Mahaska County, IA, Marion County, IA, Monroe County, IA, Muscatine County, IA, Polk County, IA, Poweshiek County, IA, Scott County, IA, Van Buren County, IA, Wapello County, IA, Washington County, IA, Wayne County, IA, Fulton County, IL, Hancock County, IL, Henderson County, IL, Knox County, IL, McDonough County, IL, Mercer County, IL, Rock Island County, IL, Warren County, IL, Clark County, MO, Putnam County, MO, Schuyler County, MO, Scotland County, MO

The radar

The Quad Cities radar (KDVN), 91 km from the middle of the area, began a volume at 00:47 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.

Warnings issued inside it

2 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

Issued	Product	Office	Counties	Lasted
Apr 27, 8:38 PM CDT	Severe Thunderstorm Warning	DVN	Hancock	52 min
Apr 27, 10:19 PM CDT	Severe Thunderstorm Warning	ILX	Fulton, Peoria	41 min

The nearest sounding before it

Davenport, (KDVN), launched 00:00Z, 0.8 hours before the alert went out and 98 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: 5 J/kg
Mixed-layer CIN: 0 J/kg
Mixed-layer LCL: 438 m above ground
0-6 km bulk shear: 78 kt
0-1 km storm-relative helicity: 403 m²/s²
0-3 km storm-relative helicity: 461 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.4

Open this sounding in Storm Lab

The text

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

000
WWUS20 KWNS 280029
SEL0  
SPC WW 280025
IAZ000-ILZ000-MOZ000-280500-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 160
STORM PREDICTION CENTER NORMAN OK
725 PM CDT SAT APR 27 2002

THE STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF

   SOUTHEAST IOWA                               
   WEST CENTRAL ILLINOIS                           
   EXTREME NORTHEAST MISSOURI                           

EFFECTIVE THIS SATURDAY NIGHT AND SUNDAY MORNING FROM 745 PM UNTIL
MIDNIGHT CDT.

TORNADOES...HAIL TO 1 INCH IN DIAMETER...THUNDERSTORM WIND GUSTS TO
70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE TORNADO WATCH AREA IS ALONG AND 85 STATUTE MILES EAST AND WEST
OF A LINE FROM 55 MILES NORTH NORTHEAST OF OTTUMWA IOWA TO 40 MILES
SOUTHWEST OF BURLINGTON IOWA.

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA. 
PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING
WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE
WARNINGS.

OTHER WATCH INFORMATION...THIS TORNADO WATCH REPLACES TORNADO WATCH
NUMBER 158.  WATCH NUMBER 158 WILL NOT BE IN EFFECT AFTER 745 PM
CDT.  CONTINUE...WW 159...

DISCUSSION...ISOLATED SEVERE THUNDERSTORMS REMAIN POSSIBLE AHEAD OF
VORT MAX OVER SOUTHWEST IA...WITH SUFFICIENT VERTICAL SHEAR
PROFILES FOR SUPERCELLS AND TORNADOES.  SURFACE AIRMASS IS RAPIDLY
DESTABILIZING OVER THIS REGION...SUGGESTING THAT THREAT MAY EXTEND
EASTWARD INTO WESTERN IL BY MIDNIGHT.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 1 INCH...EXTREME TURBULENCE AND SURFACE WIND
GUSTS TO 60 KNOTS.  A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. 
MEAN STORM MOTION VECTOR 24045.

...HART

414,0902 402,0900 402,0931 414,0934

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 27, 10:00 PM CDT	Tornado Watch	SPC	Alexander, Bond, Champaign, Christian, Clark, Clay and 56 more	5 hr
Apr 28, 2:00 AM CDT	Tornado Watch	SPC	Hardin, Massac, Pope	5 hr
Apr 27, 11:15 PM CDT	Tornado Watch	SPC	Bollinger, Butler, Carter, Howell, Iron, Madison and 7 more	5 hr

Nearby

Tornado Watches in Iowa, 2002 Tornado Watches in Illinois, 2002 Tornado Watches in Missouri, 2002 Every tornado watch 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.