Alert archive / Iowa / Severe Thunderstorm Warnings in 1998
Severe Thunderstorm Warning 18, NWS Omaha, NE
NWS Omaha, NE issued this severe thunderstorm warning at Apr 6, 1998, 5:57 PM CDT for Sarpy County, Nebraska; Mills County, Pottawattamie County, Iowa. It was in force for 63 min. 3 reports came from inside the area while it was in force.
The area
The counties it named, with what was reported inside it.
The facts
- Issued
- Apr 6, 1998, 5:57 PM CDT (22:57 UTC)
- Expired
- Apr 6, 1998, 7:00 PM CDT
- In force
- 63 min
- Issued by
- NWS Omaha, NE
- Area
- Whole counties
Counties Mills County, IA, Pottawattamie County, IA, Sarpy County, NE
The radar
The Omaha radar (KOAX), 54 km from the middle of the area, began a volume at 22:59 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
| Time | Report | Where | Remark |
|---|---|---|---|
| Apr 6, 6:00 PM CDT | Hail 0.75 | Offutt Afb, NE | |
| Apr 6, 6:00 PM CDT | Hail 2 | Bellevue, NE | |
| Apr 6, 6:05 PM CDT | Hail 1.25 | Offutt Afb, NE |
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.
The nearest sounding before it
Omaha, NE (KOAX), launched 12:00Z, 11.0 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.
- Mixed-layer CAPE
- 2 J/kg
- Mixed-layer CIN
- -340 J/kg
- Mixed-layer LCL
- 961 m above ground
- 0-6 km bulk shear
- 48 kt
- 0-1 km storm-relative helicity
- 34 m²/s²
- 0-3 km storm-relative helicity
- 66 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.2
The text
The text of this product is not in the archive. The NWS text archive before 2002 is incomplete.
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.
In the hours before
Special weather statement, Apr 6, 11:58 AM CDT, 5 hours 59 minutes before
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</html>Special weather statement, Apr 6, 11:58 AM CDT, 5 hours 59 minutes before
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<div class="status" id="status">Temporary Notice</div>
<h1 id="headline">This service is currently unavailable.</h1>
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The site you requested is temporarily down for maintenance or an unexpected outage.
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</html>Local storm report, Apr 6, 3:38 PM CDT, 2 hours 19 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
338 PM CDT MON APR 06 1998
TIME(CDT) .....CITY LOCATION..... STATE ...EVENT/REMARKS...
....COUNTY LOCATION....
105 PM 3 NW WEEPING WATER NE .75 INCH HAIL
04/06/98 CASS
300 PM MAGNOLIA IA 1.5 INCH HAIL
04/06/98 HARRISONLocal storm report, Apr 6, 3:38 PM CDT, 2 hours 19 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
338 PM CDT MON APR 06 1998
TIME(CDT) .....CITY LOCATION..... STATE ...EVENT/REMARKS...
....COUNTY LOCATION....
105 PM 3 NW WEEPING WATER NE .75 INCH HAIL
04/06/98 CASS
300 PM MAGNOLIA IA 1.5 INCH HAIL
04/06/98 HARRISONSpecial weather statement, Apr 6, 5:10 PM CDT, 47 minutes before
NEZ011-012-015>018-030>034-042>045-050>053-065>068-078-088>093- IAZ043-055-056-069-079-080-090-091-080000- SEVERE WEATHER OUTLOOK NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 510 PM CDT MON APR 6 1998 ...SEVERE WEATHER OUTLOOK FOR EASTERN NEBRASKA AND SOUTHWEST IOWA... SPOTTER ACTION... STORM SPOTTER ACTIVATION MAY BE NEEDED THIS EVENING IN SOUTHEAST NEBRASKA AND SOUTHWEST IOWA. DISCUSSION... A WARM FRONT FROM WEST OF BEATRICE TO JUST SOUTH OF OMAHA INTO CENTRAL KANSAS WILL BE THE FOCUSING MECHANISM FOR THUNDERSTORM DEVELOPMENT INTO THE EVENING HOURS. WARM...MOIST UNSTABLE AIR WITH FAVORABLE INFLOW AND A FAVORABLE UPPER JET WILL BE CONDUCIVE TO SEVERE THUNDERSTORM DEVELOPMENT. THUNDERSTORMS FIRING INTO NORTHERN KANSAS WILL LIKELY SPREAD INTO SOUTHEAST NEBRASKA. IN ADDITION...STRONG TO SEVERE THUNDERSTORMS ARE ARE POSSIBLE NORTH OF THE WARM FRONT WHERE FAVORABLE WAIR AIR ADVECTION AND CONVERGENCE IS ALSO TAKING PLACE. THE PRIMARY THREAT WILL BE LARGE HAIL...TORNADOES ARE ALSO A RISK DUE TO THE FAVORABLE WIND SHEAR. ZAPOTOCNY
Special weather statement, Apr 6, 5:10 PM CDT, 47 minutes before
NEZ011-012-015>018-030>034-042>045-050>053-065>068-078-088>093- IAZ043-055-056-069-079-080-090-091-080000- SEVERE WEATHER OUTLOOK NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 510 PM CDT MON APR 6 1998 ...SEVERE WEATHER OUTLOOK FOR EASTERN NEBRASKA AND SOUTHWEST IOWA... SPOTTER ACTION... STORM SPOTTER ACTIVATION MAY BE NEEDED THIS EVENING IN SOUTHEAST NEBRASKA AND SOUTHWEST IOWA. DISCUSSION... A WARM FRONT FROM WEST OF BEATRICE TO JUST SOUTH OF OMAHA INTO CENTRAL KANSAS WILL BE THE FOCUSING MECHANISM FOR THUNDERSTORM DEVELOPMENT INTO THE EVENING HOURS. WARM...MOIST UNSTABLE AIR WITH FAVORABLE INFLOW AND A FAVORABLE UPPER JET WILL BE CONDUCIVE TO SEVERE THUNDERSTORM DEVELOPMENT. THUNDERSTORMS FIRING INTO NORTHERN KANSAS WILL LIKELY SPREAD INTO SOUTHEAST NEBRASKA. IN ADDITION...STRONG TO SEVERE THUNDERSTORMS ARE ARE POSSIBLE NORTH OF THE WARM FRONT WHERE FAVORABLE WAIR AIR ADVECTION AND CONVERGENCE IS ALSO TAKING PLACE. THE PRIMARY THREAT WILL BE LARGE HAIL...TORNADOES ARE ALSO A RISK DUE TO THE FAVORABLE WIND SHEAR. ZAPOTOCNY
The office that day
Everything else NWS Omaha, NE issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 6, 1:26 PM CDT | Severe Thunderstorm Warning | OAX | Douglas, Saunders | 34 min |
| Apr 6, 2:29 PM CDT | Severe Thunderstorm Warning | OAX | Washington | 46 min |
| Apr 6, 2:22 PM CDT | Severe Thunderstorm Warning | OAX | Pottawattamie | 48 min |
| Apr 6, 5:31 PM CDT | Severe Thunderstorm Warning | OAX | Monona | 34 min |
Nearby
Severe Thunderstorm Warnings in Iowa, 1998Severe Thunderstorm Warnings in Nebraska, 1998Every severe thunderstorm warning 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; verification from NCEI's Storm Data; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.