Alert archive / Iowa / Tornado Warnings in 1998
Tornado Warning 18, NWS Omaha, NE
NWS Omaha, NE issued this tornado warning at May 21, 1998, 7:50 PM CDT for Harrison County, Monona County, Iowa. It was in force for 50 min. 7 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
- May 21, 1998, 7:50 PM CDT (00:50 UTC)
- Expired
- May 21, 1998, 8:40 PM CDT
- In force
- 50 min
- Issued by
- NWS Omaha, NE
- Area
- Whole counties
Counties Harrison County, IA, Monona County, IA
What was reported inside it
| Time | Report | Where | Remark |
|---|---|---|---|
| May 21, 7:54 PM CDT | Hail 0.75 | Blencoe, IA | |
| May 21, 8:01 PM CDT | Thunderstorm Wind 56 | Magnolia, IA | Trees downed. |
| May 21, 8:06 PM CDT | Hail 0.75 | Woodbine, IA | |
| May 21, 8:10 PM CDT | Hail 0.75 | Logan, IA | |
| May 21, 8:10 PM CDT | Thunderstorm Wind 61 | Woodbine, IA | Many tree limbs downed. |
| May 21, 8:20 PM CDT | Thunderstorm Wind 70 | Magnolia, IA | Trees uprooted and power lines downed. |
| May 21, 8:30 PM CDT | Tornado F0 | Castana, IA |
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 00:00Z, 0.8 hours before the alert went out and 73 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
- 66 J/kg
- Mixed-layer CIN
- -295 J/kg
- Mixed-layer LCL
- 905 m above ground
- 0-6 km bulk shear
- 59 kt
- 0-1 km storm-relative helicity
- 300 m²/s²
- 0-3 km storm-relative helicity
- 484 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 7.6
The text
As transmitted, in the capitals the NWS used until 2016.
102 WFUS1 KOMA 220054 RRA TOROMA IAC085-133-220140- BULLETIN - EAS ACTIVATION REQUESTED TORNADO WARNING NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 750 PM CDT THU MAY 21 1998 THE NATIONAL WEATHER SERVICE IN OMAHA HAS ISSUED A * TORNADO WARNING FOR... MONONA COUNTY IN WEST CENTRAL IOWA HARRISON COUNTY IN SOUTHWESTERN IOWA * UNTIL 840 PM CDT * AT 748 PM CDT... DOPPLER RADAR AND SPOTTERS INDICATED A DEVELOPING TORNADO 38 MILES NORTH OF DOWNTOWN OMAHA OR IN THE VICINITY OF LITTLE SIOUX MOVING EAST AT 30 MPH. A FUNNEL CLOUD HAS BEEN REPORTED IN THE LITTLE SIOUX AREA. * THE TORNADO IS EXPECTED TO BE NEAR... LITTLE SIOUX AT 748 PM CDT CALIFORNIA JUNCTION AT 752 PM CDT PISGAH AT 755 PM CDT PREPARATION CANYON ST. PARK AT 755 PM CDT THIS REPLACES THE SEVERE THUNDERSTORM WARNING FOR MONONA AND HARRISON COUNTIES. TORNADOES MAY OCCUR NEAR THE LEADING EDGE OF THIS STORM AND COULD BE DIFFICULT TO SEE BECAUSE OF THE VERY HEAVY RAIN. TAKE SHELTER ON THE LOWEST LEVEL OF YOUR HOME OR BUSINESS BEFORE THE STORM REACHES YOUR AREA. MILLER
What forecasters said that day
The local office's own words before this tornado 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 21, 5:05 PM CDT, 2 hours 45 minutes before
NEZ011-012-015>018-030>034-042>045-050>053-065>068-078-088>093- IAZ043-055-056-069-079-080-090-091-221200- SEVERE WEATHER OUTLOOK NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 505 PM CDT THU MAY 21 1998 ...SEVERE WEATHER OUTLOOK FOR EASTERN NEBRASKA AND SOUTHWEST IOWA... SPOTTER ACTION... STORM SPOTTER ACTIVATION MAY BE NEEDED TONIGHT IN EASTERN NEBRASKA AND SOUTHWEST IOWA. DISCUSSION... THUNDERSTORMS WILL BE SCATTERED ACROSS MUCH OF EASTERN NEBRASKA AND SOUTHWEST IOWA THROUGH TONIGHT. THE CHANCE OF SEVERE STORMS IS SLIGHTLY HIGHER SOUTH OF A LINE FROM NELIGH TO TEKAMAH AND HARLAN IOWA WHERE THE ATMOSPHERE IS MORE UNSTABLE. THUNDERSTORMS WILL HAVE POTENTIAL TO PRODUCE DAMAGING WINDS AND HAIL. SIGNIFICANT RAINFALL IS ALSO POSSIBLE. > A NEARLY STATIONARY FRONT EXTENDS FROM SOUTHERN MISSOURI TO NORTHERN KANSAS AND EASTERN WYOMING. VERY MOIST AND UNSTABLE AIR SOUTH OF THE FRONT WILL CONTINUE TO BE LIFTED NORTH ACROSS NEBRASKA AND SOUTHWEST IOWA...WHILE UPPER LEVEL DISTURBANCES TRACK OVER THE AREA. MILLER
Special weather statement, May 21, 5:05 PM CDT, 2 hours 45 minutes before
NEZ011-012-015>018-030>034-042>045-050>053-065>068-078-088>093- IAZ043-055-056-069-079-080-090-091-221200- SEVERE WEATHER OUTLOOK NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 505 PM CDT THU MAY 21 1998 ...SEVERE WEATHER OUTLOOK FOR EASTERN NEBRASKA AND SOUTHWEST IOWA... SPOTTER ACTION... STORM SPOTTER ACTIVATION MAY BE NEEDED TONIGHT IN EASTERN NEBRASKA AND SOUTHWEST IOWA. DISCUSSION... THUNDERSTORMS WILL BE SCATTERED ACROSS MUCH OF EASTERN NEBRASKA AND SOUTHWEST IOWA THROUGH TONIGHT. THE CHANCE OF SEVERE STORMS IS SLIGHTLY HIGHER SOUTH OF A LINE FROM NELIGH TO TEKAMAH AND HARLAN IOWA WHERE THE ATMOSPHERE IS MORE UNSTABLE. THUNDERSTORMS WILL HAVE POTENTIAL TO PRODUCE DAMAGING WINDS AND HAIL. SIGNIFICANT RAINFALL IS ALSO POSSIBLE. > A NEARLY STATIONARY FRONT EXTENDS FROM SOUTHERN MISSOURI TO NORTHERN KANSAS AND EASTERN WYOMING. VERY MOIST AND UNSTABLE AIR SOUTH OF THE FRONT WILL CONTINUE TO BE LIFTED NORTH ACROSS NEBRASKA AND SOUTHWEST IOWA...WHILE UPPER LEVEL DISTURBANCES TRACK OVER THE AREA. MILLER
The office that day
Everything else NWS Omaha, NE issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 21, 7:29 PM CDT | Severe Thunderstorm Warning | OAX | Harrison, Monona | 61 min |
| May 21, 8:47 PM CDT | Tornado Warning | OAX | Pottawattamie | 33 min |
| May 22, 2:36 AM CDT | Severe Thunderstorm Warning | OAX | Page | 64 min |
Nearby
Tornado Warnings in Iowa, 1998Every tornado warning in 1998Tornadoes 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.