Alert archive / Nebraska / Tornado Watches in 1997

Tornado Watch 491

June 20, 199755 counties in Nebraska

The Storm Prediction Center issued this tornado watch at Jun 20, 1997, 8:00 PM CDT for 55 counties in Nebraska. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued: Jun 20, 1997, 8:00 PM CDT (01:00 UTC)
Expired: Jun 21, 1997, 2:00 AM CDT
In force: 6 hr
Issued by: the Storm Prediction Center

All 55 counties

Adams County, NE, Antelope County, NE, Blaine County, NE, Boone County, NE, Buffalo County, NE, Burt County, NE, Butler County, NE, Cass County, NE, Clay County, NE, Colfax County, NE, Cuming County, NE, Custer County, NE, Dawson County, NE, Dodge County, NE, Douglas County, NE, Fillmore County, NE, Franklin County, NE, Gage County, NE, Garfield County, NE, Greeley County, NE, Hall County, NE, Hamilton County, NE, Harlan County, NE, Howard County, NE, Jefferson County, NE, Johnson County, NE, Kearney County, NE, Lancaster County, NE, Loup County, NE, Madison County, NE, Merrick County, NE, Nance County, NE, Nemaha County, NE, Nuckolls County, NE, Otoe County, NE, Pawnee County, NE, Phelps County, NE, Pierce County, NE, Platte County, NE, Polk County, NE, Richardson County, NE, Saline County, NE, Sarpy County, NE, Saunders County, NE, Seward County, NE, Sherman County, NE, Stanton County, NE, Thayer County, NE, Thurston County, NE, Valley County, NE, Washington County, NE, Wayne County, NE, Webster County, NE, Wheeler County, NE, York County, NE

The radar

The Omaha radar (KOAX), 108 km from the middle of the area, began a volume at 01:04 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

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

Issued	Product	Office	Counties	Lasted
Jun 20, 8:24 PM CDT	Severe Thunderstorm Warning	GID	Greeley	51 min
Jun 20, 8:25 PM CDT	Severe Thunderstorm Warning	OAX	Burt	50 min
Jun 20, 8:29 PM CDT	Severe Thunderstorm Warning	GID	Howard, Merrick, Nance	46 min
Jun 20, 8:35 PM CDT	Severe Thunderstorm Warning	OAX	Thurston	50 min
Jun 20, 8:43 PM CDT	Severe Thunderstorm Warning	OAX	Cuming, Dodge	47 min
Jun 20, 8:48 PM CDT	Severe Thunderstorm Warning	OAX	Boone	62 min
Jun 20, 9:00 PM CDT	Tornado Warning	GID	Merrick	45 min
Jun 20, 9:00 PM CDT	Severe Thunderstorm Warning	LBF	Blaine, Thomas	65 min
Jun 20, 9:12 PM CDT	Severe Thunderstorm Warning	OAX	Antelope	63 min
Jun 20, 9:24 PM CDT	Severe Thunderstorm Warning	OAX	Cuming, Stanton	51 min
Jun 20, 9:29 PM CDT	Severe Thunderstorm Warning	LBF	Custer	61 min
Jun 20, 9:40 PM CDT	Severe Thunderstorm Warning	OAX	Madison, Pierce	50 min
Jun 20, 9:42 PM CDT	Tornado Warning	GID	Dawson	48 min
Jun 20, 9:45 PM CDT	Tornado Warning	GID	Merrick, Polk	30 min
Jun 20, 9:51 PM CDT	Severe Thunderstorm Warning	GID	Howard	39 min
Jun 20, 10:04 PM CDT	Tornado Warning	GID	Howard	41 min
Jun 20, 10:09 PM CDT	Tornado Warning	OAX	Cuming	51 min
Jun 20, 10:13 PM CDT	Severe Thunderstorm Warning	GID	Valley	47 min
Jun 20, 10:15 PM CDT	Severe Thunderstorm Warning	GID	Nance	45 min
Jun 20, 10:26 PM CDT	Severe Thunderstorm Warning	GID	Buffalo, Sherman	49 min
Jun 20, 10:31 PM CDT	Tornado Warning	GID	Dawson	44 min
Jun 20, 10:43 PM CDT	Severe Thunderstorm Warning	GID	Greeley, Howard	32 min
Jun 20, 10:56 PM CDT	Severe Thunderstorm Warning	OAX	Burt	64 min
Jun 20, 11:00 PM CDT	Severe Thunderstorm Warning	GID	Merrick, Nance	45 min
Jun 20, 11:00 PM CDT	Severe Thunderstorm Warning	GID	Hall	45 min
Jun 20, 11:06 PM CDT	Severe Thunderstorm Warning	GID	Adams, Kearney	39 min
Jun 20, 11:10 PM CDT	Severe Thunderstorm Warning	GID	Clay, Hamilton	50 min
Jun 20, 11:10 PM CDT	Severe Thunderstorm Warning	GID	Polk	50 min
Jun 20, 11:22 PM CDT	Tornado Warning	OAX	Dodge	48 min
Jun 20, 11:23 PM CDT	Severe Thunderstorm Warning	GID	Buffalo	37 min
Jun 20, 11:34 PM CDT	Severe Thunderstorm Warning	GID	Fillmore, York	41 min
Jun 20, 11:42 PM CDT	Severe Thunderstorm Warning	OAX	Butler, Seward	58 min
Jun 20, 11:48 PM CDT	Severe Thunderstorm Warning	OAX	Gage, Jefferson, Lancaster, Saline	62 min
Jun 21, 12:08 AM CDT	Flash Flood Warning	OAX	Burt, Cuming, Dodge	6 hr
Jun 21, 12:17 AM CDT	Severe Thunderstorm Warning	OAX	Saunders	63 min
Jun 21, 12:19 AM CDT	Severe Thunderstorm Warning	GID	Clay, Fillmore	41 min
Jun 21, 1:05 AM CDT	Severe Thunderstorm Warning	OAX	Cass, Sarpy	60 min
Jun 21, 1:11 AM CDT	Tornado Warning	OAX	Sarpy	34 min

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 1.0 hours before the alert went out and 108 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: 5994 J/kg
Mixed-layer CIN: -4 J/kg
Mixed-layer LCL: 1151 m above ground
0-6 km bulk shear: 39 kt
0-1 km storm-relative helicity: 89 m²/s²
0-3 km storm-relative helicity: 186 m²/s²
Significant tornado parameter: 4.8
Supercell composite: 25.7

Open this sounding in Storm Lab

The text

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

542 
WWUS9 KMKC 210029
SEL1  
MKC WW 210029
NEZ000-210700-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 491
STORM PREDICTION CENTER NORMAN OK
729 PM CDT FRI JUN 20 1997

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

   CENTRAL AND EASTERN NEBRASKA                           

EFFECTIVE THIS FRIDAY NIGHT AND SATURDAY MORNING FROM 800 PM UNTIL
200 AM CDT.

TORNADOES...HAIL TO 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 105 STATUTE MILES EAST AND WEST
OF A LINE FROM 55 MILES WEST NORTHWEST OF NORFOLK NEBRASKA TO 45
MILES WEST SOUTHWEST OF BEATRICE NEBRASKA.

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...  CONTINUE...WW 489...WW 490...

DISCUSSION...THUNDERSTORMS HAVE RAPIDLY DEVELOPED ALONG LOW LEVEL
BOUNDARY ACROSS PARTS OF EASTERN NEBRASKA.  STORMS ARE FORMING IN
EXTREMELY UNSTABLE AIR MASS WITH LIFTED INDEX TO -13 AND CAPE
VALUES ABV 5000 J/KG.  ACTIVITY IS LIKELY TO INTENSIFY THIS EVENING
AS LOW LEVEL JET STRENGTHENS INTO THE CENTRAL PLAINS ENHANCING
CONVERGENCE AND WARM ADVECTION LIFT.  MODERATE WESTERLY FLOW ALOFT
IS PROVIDING FAVROABLE VERTICAL SHEAR TO SUPPORT POSSIBLE
SUPERCELLS...ESPECIALLY GIVEN EXTREME INSTABILITY OF AIR MASS. 
OTHER STORMS OVER WESTERN PARTS OF CENTRAL NEBRASKA WILL SPREAD
EASTWARD WITH TIME TOWARD EASTERN NEBRASKA.

ADDITIONAL WATCHES...STORMS MAY DEVELOP EASTWARD INTO IOWA AND
ANOTHER WW MAY NEEDED EAST OF THE MISSOURI RIVER THIS EVENING. 


AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 4 INCHES.  EXTREME TURBULENCE AND SURFACE WIND
GUSTS TO 70 KNOTS.  A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 600. 
MEAN STORM MOTION VECTOR 27025.


...WEISS

421,0962 400,0953 400,0993 421,1002

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 20, 10:00 PM CDT	Severe Thunderstorm Watch	SPC	Chase, Dundy, Frontier, Furnas, Gosper, Hayes and 5 more	4 hr
Jun 21, 1:30 AM CDT	Severe Thunderstorm Watch	SPC	Nemaha, Otoe, Richardson, Sarpy	6 hr

Nearby

Tornado Watches in Nebraska, 1997 Every 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.