Alert archive / Iowa / Tornado Watches in 1997

Tornado Watch 439

June 15, 199757 counties in Iowa; Otoe County, Nebraska

The Storm Prediction Center issued this tornado watch at Jun 15, 1997, 1:30 PM CDT for 57 counties in Iowa; Otoe County, Nebraska. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued
Jun 15, 1997, 1:30 PM CDT (18:30 UTC)
Expired
Jun 15, 1997, 7:00 PM CDT
In force
6 hr
Issued by
the Storm Prediction Center
All 58 counties

Adair County, IA, Adams County, IA, Allamakee County, IA, Audubon County, IA, Black Hawk County, IA, Boone County, IA, Bremer County, IA, Butler County, IA, Calhoun County, IA, Carroll County, IA, Cass County, IA, Cerro Gordo County, IA, Chickasaw County, IA, Clarke County, IA, Dallas County, IA, Decatur County, IA, Fayette County, IA, Floyd County, IA, Franklin County, IA, Fremont County, IA, Greene County, IA, Grundy County, IA, Guthrie County, IA, Hamilton County, IA, Hancock County, IA, Hardin County, IA, Howard County, IA, Humboldt County, IA, Jasper County, IA, Kossuth County, IA, Lucas County, IA, Madison County, IA, Marion County, IA, Marshall County, IA, Mills County, IA, Mitchell County, IA, Montgomery County, IA, Page County, IA, Palo Alto County, IA, Pocahontas County, IA, Polk County, IA, Pottawattamie County, IA, Poweshiek County, IA, Ringgold County, IA, Sac County, IA, Shelby County, IA, Story County, IA, Tama County, IA, Taylor County, IA, Union County, IA, Warren County, IA, Wayne County, IA, Webster County, IA, Winnebago County, IA, Winneshiek County, IA, Worth County, IA, Wright County, IA, Otoe County, NE

The radar

The Des Moines radar (KDMX), 43 km from the middle of the area, began a volume at 18:29 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

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

IssuedProductOfficeCountiesLasted
Jun 15, 2:38 PM CDTSevere Thunderstorm WarningARXChickasaw, Floyd47 min
Jun 15, 3:02 PM CDTSevere Thunderstorm WarningARXAllamakee48 min
Jun 15, 3:02 PM CDTSevere Thunderstorm WarningARXWinneshiek48 min
Jun 15, 3:49 PM CDTSevere Thunderstorm WarningARXAllamakee, Clayton, Fayette, Winneshiek61 min
Jun 15, 4:51 PM CDTSevere Thunderstorm WarningARXClayton, Fayette69 min
Jun 15, 6:42 PM CDTSevere Thunderstorm WarningDMXTama33 min

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 6.5 hours before the alert went out and 186 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, Omaha, NE at 12:00Z on 1997-06-15Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 381 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, Omaha, NE at 12:00Z on 1997-06-15The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 162 square meters per square second.19395878Sfc1 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
381 J/kg
Mixed-layer CIN
-141 J/kg
Mixed-layer LCL
1120 m above ground
0-6 km bulk shear
28 kt
0-1 km storm-relative helicity
162 m²/s²
0-3 km storm-relative helicity
143 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

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

918 
WWUS9 KMKC 151748
SEL9  
MKC WW 151748
IAZ000-160000-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 439
STORM PREDICTION CENTER NORMAN OK
1248 PM CDT SUN JUN 15 1997

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

   IOWA                               

EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 130 PM UNTIL 700
PM CDT.

TORNADOES...HAIL TO 2 3/4 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 80 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.

THE TORNADO WATCH AREA IS ALONG AND 80 STATUTE MILES EAST AND WEST
OF A LINE FROM 40 MILES WEST OF LAMONI IOWA TO 40 MILES NORTHEAST
OF MASON CITY 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.


DISCUSSION...THUNDERSTORMS ARE BEGINNING TO DEVELOP ALONG PRE-
FRONTAL TROUGH. INTENSE HEATING ALONG WITH LOW LEVEL
THERMAL/MOISTURE ADVECTION HAVE RESULTED IN A VERY UNSTABLE AIRMASS
WITH SURFACE-BASED CAPES NOW EXCEEDING 3000 J/KG. STRONG FLOW ALOFT
AND SUFFICENT VEERING AT LOW LEVELS WILL ALLOW FOR THE DEVELOPMENT
OF A FEW SUPERCELLS BEFORE ACTIVITY BECOMES LINEAR IN NATURE LATE
THIS AFTERNOON.


AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 2 3/4 INCHES.  EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 70 KNOTS.  A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
520.  MEAN STORM MOTION VECTOR 26030.


...VESCIO

403,0961 433,0942 433,0911 403,0930

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jun 15, 4:00 PM CDTSevere Thunderstorm WatchSPCAllamakee, Clayton, Delaware, Dubuque5 hr
Jun 15, 4:15 PM CDTSevere Thunderstorm WatchSPCPage6 hr
Jun 15, 6:30 PM CDTTornado WatchSPCAdair, Adams, Appanoose, Benton, Cedar, Clarke and 39 more7 hr

Nearby

Tornado Watches in Iowa, 1997Tornado Watches in Nebraska, 1997Every tornado watch 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.