Alert archive / Iowa / Severe Thunderstorm Warnings in 1998
Severe Thunderstorm Warning 64, NWS Omaha, NE
NWS Omaha, NE issued this severe thunderstorm warning at May 11, 1998, 10:47 PM CDT for Mills County, Pottawattamie County, Iowa. It was in force for 48 min. No storm report in the archive falls inside the area while it was in force.
The area
The counties it named.
The facts
- Issued
- May 11, 1998, 10:47 PM CDT (03:47 UTC)
- Expired
- May 11, 1998, 11:35 PM CDT
- In force
- 48 min
- Issued by
- NWS Omaha, NE
- Area
- Whole counties
Counties Mills County, IA, Pottawattamie County, IA
The radar
The Omaha radar (KOAX), 67 km from the middle of the area, began a volume at 03:47 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.
The watch it was issued in
The SPC watch in force over the same counties when this warning went out.
| Issued | Product | Office | Lasted |
|---|---|---|---|
| May 11, 8:00 PM CDT | Tornado Watch | SPC | 6 hr |
The nearest sounding before it
Omaha, NE (KOAX), launched 00:00Z, 3.8 hours before the alert went out and 68 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
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, May 11, 5:25 PM CDT, 5 hours 22 minutes before
NEZ011-012-015>018-030>034-042>045-050>053-065>068-078-088>093- IAZ043-055-056-069-079-080-090-091-121200- SEVERE WEATHER OUTLOOK NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 525 PM CDT MON MAY 11 1998 ...SEVERE WEATHER OUTLOOK FOR EASTERN NEBRASKA AND SOUTHWEST IOWA... SPOTTER ACTION... STORM SPOTTER GROUPS IN EASTERN NEBRAKA AND SOUTHWEST IOWA SHOULD MAINTAIN A STATE OF READINESS THIS EVENING AND TONIGHT. THERE IS A GOOD PROBABILITY SPOTTER ACTIVATION WILL BE REQUIRED. DISCUSSION... THUNDERSTORMS DEVELOPING OVER CENTRAL NEBRASKA WILL LIKELY BECOME SEVERE WITH TORNADOES POSSIBLE AS THEY MOVE INTO EASTERN NEBRASKA THIS EVENING. INITIALLY THE SEVERE THREAT IN EASTERN NEBRASKA WILL BE POINTS SOUTHWEST THROUGH NORTHWEST OF DAVID CITY. HOWEVER...LATER THIS EVENING THE SEVERE THREAT COULD SHIFT INTO THE REST OF EASTERN NEBRASKA AND WESTERN IOWA. TORNADOES AND LARGE HAIL WILL BE THE INITIAL SEVERE THREAT...WITH LARGE HAIL AND DAMAGING WINDS BECOMING THE MAIN THREAT LATER THIS EVENING AND OVERNIGHT. THE THUNDERSTORMS WERE FORMING ALONG A SLOW MOVING COLD FRONT EXTENDING ACROSS CENTRAL NEBRASKA. IN ADDITION...A STRONG DISTURBANCE IN THE UPPER ATMOSPHERE WILL BE MOVING ACROSS THE STATE TONIGHT. GUSTY SOUTH WINDS AHEAD OF THE FRONT WILL CONTINUE TO BRING WARM AND MOIST AIR INTO THE REGION WHILE THE UPPER SYSTEM WILL PROVIDE STRENGTHENING WINDS ALOFT FAVORABLE FOR SEVERE THUNDERSTORMS. CHERMOK
Special weather statement, May 11, 5:25 PM CDT, 5 hours 22 minutes before
NEZ011-012-015>018-030>034-042>045-050>053-065>068-078-088>093- IAZ043-055-056-069-079-080-090-091-121200- SEVERE WEATHER OUTLOOK NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 525 PM CDT MON MAY 11 1998 ...SEVERE WEATHER OUTLOOK FOR EASTERN NEBRASKA AND SOUTHWEST IOWA... SPOTTER ACTION... STORM SPOTTER GROUPS IN EASTERN NEBRAKA AND SOUTHWEST IOWA SHOULD MAINTAIN A STATE OF READINESS THIS EVENING AND TONIGHT. THERE IS A GOOD PROBABILITY SPOTTER ACTIVATION WILL BE REQUIRED. DISCUSSION... THUNDERSTORMS DEVELOPING OVER CENTRAL NEBRASKA WILL LIKELY BECOME SEVERE WITH TORNADOES POSSIBLE AS THEY MOVE INTO EASTERN NEBRASKA THIS EVENING. INITIALLY THE SEVERE THREAT IN EASTERN NEBRASKA WILL BE POINTS SOUTHWEST THROUGH NORTHWEST OF DAVID CITY. HOWEVER...LATER THIS EVENING THE SEVERE THREAT COULD SHIFT INTO THE REST OF EASTERN NEBRASKA AND WESTERN IOWA. TORNADOES AND LARGE HAIL WILL BE THE INITIAL SEVERE THREAT...WITH LARGE HAIL AND DAMAGING WINDS BECOMING THE MAIN THREAT LATER THIS EVENING AND OVERNIGHT. THE THUNDERSTORMS WERE FORMING ALONG A SLOW MOVING COLD FRONT EXTENDING ACROSS CENTRAL NEBRASKA. IN ADDITION...A STRONG DISTURBANCE IN THE UPPER ATMOSPHERE WILL BE MOVING ACROSS THE STATE TONIGHT. GUSTY SOUTH WINDS AHEAD OF THE FRONT WILL CONTINUE TO BRING WARM AND MOIST AIR INTO THE REGION WHILE THE UPPER SYSTEM WILL PROVIDE STRENGTHENING WINDS ALOFT FAVORABLE FOR SEVERE THUNDERSTORMS. CHERMOK
The office that day
Everything else NWS Omaha, NE issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 11, 7:26 PM CDT | Severe Thunderstorm Warning | OAX | Knox | 44 min |
| May 11, 8:02 PM CDT | Severe Thunderstorm Warning | OAX | Antelope, Pierce | 48 min |
| May 11, 8:27 PM CDT | Severe Thunderstorm Warning | OAX | Boone | 48 min |
| 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, 10:42 PM CDT | Severe Thunderstorm Warning | OAX | Gage | 48 min |
| May 11, 10:51 PM CDT | Severe Thunderstorm Warning | OAX | Jefferson | 34 min |
| May 11, 10:20 PM CDT | Severe Thunderstorm Warning | OAX | Monona | 35 min |
Nearby
Severe Thunderstorm Warnings in Iowa, 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.