Alert archive / Nebraska / Tornado Watches in 1998
Tornado Watch 331
The Storm Prediction Center issued this tornado watch at May 11, 1998, 8:00 PM CDT for 25 counties in Iowa; Atchison County, Holt County, Nodaway County, Missouri; 26 counties in Nebraska. It was in force for 6 hr.
The area
The outline as issued.
The facts
- Issued
- May 11, 1998, 8:00 PM CDT (01:00 UTC)
- Expired
- May 12, 1998, 2:00 AM CDT
- In force
- 6 hr
- Issued by
- the Storm Prediction Center
All 54 counties
Adair County, IA, Adams County, IA, Audubon County, IA, Buena Vista County, IA, Calhoun County, IA, Carroll County, IA, Cass County, IA, Cherokee County, IA, Crawford County, IA, Fremont County, IA, Greene County, IA, Guthrie County, IA, Harrison County, IA, Ida County, IA, Mills County, IA, Monona County, IA, Montgomery County, IA, Page County, IA, Plymouth County, IA, Pocahontas County, IA, Pottawattamie County, IA, Sac County, IA, Shelby County, IA, Taylor County, IA, Woodbury County, IA, Atchison County, MO, Holt County, MO, Nodaway County, MO, Burt County, NE, Butler County, NE, Cass County, NE, Cedar County, NE, Colfax County, NE, Cuming County, NE, Dakota County, NE, Dixon County, NE, Dodge County, NE, Douglas County, NE, Gage County, NE, Jefferson County, NE, Johnson County, NE, Lancaster County, NE, Nemaha County, NE, Otoe County, NE, Pawnee County, NE, Richardson County, NE, Saline County, NE, Sarpy County, NE, Saunders County, NE, Seward County, NE, Stanton County, NE, Thurston County, NE, Washington County, NE, Wayne County, NE
The radar
The Omaha radar (KOAX), 21 km from the middle of the area, began a volume at 01:01 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
12 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 11, 8:51 PM CDT | Severe Thunderstorm Warning | OAX | Stanton | 64 min |
| May 11, 9:05 PM CDT | Severe Thunderstorm Warning | OAX | Jefferson, Saline | 60 min |
| May 11, 9:09 PM CDT | Tornado Warning | OAX | Jefferson | 61 min |
| May 11, 9:32 PM CDT | Severe Thunderstorm Warning | OAX | Burt, Cuming | 33 min |
| May 11, 9:43 PM CDT | Severe Thunderstorm Warning | OAX | Lancaster | 47 min |
| May 11, 10:02 PM CDT | Severe Thunderstorm Warning | OAX | Jefferson | 48 min |
| May 11, 10:18 PM CDT | Severe Thunderstorm Warning | FSD | Plymouth, Woodbury | 32 min |
| May 11, 10:20 PM CDT | Severe Thunderstorm Warning | OAX | Monona | 35 min |
| May 11, 10:34 PM CDT | Severe Thunderstorm Warning | FSD | Cherokee, Ida | 46 min |
| May 11, 10:42 PM CDT | Severe Thunderstorm Warning | OAX | Gage | 48 min |
| May 11, 10:47 PM CDT | Severe Thunderstorm Warning | OAX | Mills, Pottawattamie | 48 min |
| May 11, 10:51 PM CDT | Severe Thunderstorm Warning | OAX | Jefferson | 34 min |
The nearest sounding before it
Omaha, NE (KOAX), launched 00:00Z, 1.0 hours before the alert went out and 21 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
- 294 J/kg
- Mixed-layer CIN
- -65 J/kg
- Mixed-layer LCL
- 1842 m above ground
- 0-6 km bulk shear
- 36 kt
- 0-1 km storm-relative helicity
- 89 m²/s²
- 0-3 km storm-relative helicity
- 226 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 1.7
The text
As transmitted, in the capitals the NWS used until 2016.
307 WWUS9 KMKC 120031 SEL1 MKC WW 120031 NEZ000-IAZ000-MOZ000-120700- BULLETIN - IMMEDIATE BROADCAST REQUESTED TORNADO WATCH NUMBER 331 STORM PREDICTION CENTER NORMAN OK 731 PM CDT MON MAY 11 1998 THE STORM PREDICTION CENTER HAS ISSUED A TORNADO WATCH FOR PORTIONS OF EASTERN NEBRASKA WESTERN IOWA EXTREME NORTHWESTERN MISSOURI EFFECTIVE THIS MONDAY NIGHT AND TUESDAY MORNING FROM 800 PM UNTIL 200 AM CDT. TORNADOES...HAIL TO 2 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 20 MILES WEST OF FALLS CITY NEBRASKA TO 40 MILES NORTHEAST OF SIOUX 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. OTHER WATCH INFORMATION... CONTINUE...WW 329...WW 330... DISCUSSION...LINE OF THUNDERSTORMS...WITH A HISTORY OF TORNADOES AND LARGE HAIL...WILL MOVE EASTWARD INTO WATCH AREA ALONG SURFACE FRONT. CAPES FROM 1500 TO 2500 J/KG AND MID LEVEL FLOW INCREASING AHEAD OF UPPER SHORT WAVE INDICATE A CONTINUED THREAT OF A FEW TORNADIC SUPERCELLS. AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 70 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 450. MEAN STORM MOTION VECTOR 24035. ...ROGASH 400,0972 424,0972 424,0941 400,0942
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 12, 4:00 PM CDT | Severe Thunderstorm Watch | SPC | Allamakee, Clayton, Fayette, Winneshiek | 6 hr |
| May 12, 4:15 PM CDT | Severe Thunderstorm Watch | SPC | Appanoose, Benton, Cedar, Clinton, Davis, Des Moines and 16 more | 6 hr |
Nearby
Tornado Watches in Nebraska, 1998Tornado Watches in Iowa, 1998Tornado Watches in Missouri, 1998Every tornado watch in 1998
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.