Alert archive / Iowa / Severe Thunderstorm Warnings in 1998
Severe Thunderstorm Warning 255, NWS Des Moines, IA
NWS Des Moines, IA issued this severe thunderstorm warning at Jul 6, 1998, 9:29 PM CDT for Jasper County, Polk County, Iowa. It was in force for 46 min. 4 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
- Jul 6, 1998, 9:29 PM CDT (02:29 UTC)
- Expired
- Jul 6, 1998, 10:15 PM CDT
- In force
- 46 min
- Issued by
- NWS Des Moines, IA
- Area
- Whole counties
Counties Jasper County, IA, Polk County, IA
The radar
The Des Moines radar (KDMX), 34 km from the middle of the area, began a volume at 02:30 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 |
|---|---|---|---|
| Jul 6, 9:36 PM CDT | Thunderstorm Wind 55 | Ankeny, IA | |
| Jul 6, 9:54 PM CDT | Thunderstorm Wind 55 | Ankeny, IA | |
| Jul 6, 10:05 PM CDT | Thunderstorm Wind 52 | Des Moines, IA | |
| Jul 6, 10:18 PM CDT | Thunderstorm Wind 52 | Colfax, 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 watch it was issued in
The SPC watch in force over the same counties when this warning went out.
| Issued | Product | Office | Lasted |
|---|---|---|---|
| Jul 6, 7:30 PM CDT | Severe Thunderstorm Watch | SPC | 6 hr |
The nearest sounding before it
Davenport, (KDVN), launched 00:00Z, 2.5 hours before the alert went out and 234 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
- 1624 J/kg
- Mixed-layer CIN
- -12 J/kg
- Mixed-layer LCL
- 1080 m above ground
- 0-6 km bulk shear
- 28 kt
- 0-1 km storm-relative helicity
- 23 m²/s²
- 0-3 km storm-relative helicity
- 30 m²/s²
- Significant tornado parameter
- 0.2
- Supercell composite
- 2.1
The text
As transmitted, in the capitals the NWS used until 2016.
000 TTAA00 KDSM 070229 RRA SVRDSM IAC099-153-070315- BULLETIN - IMMEDIATE BROADCAST REQUESTED SEVERE THUNDERSTORM WARNING NATIONAL WEATHER SERVICE DES MOINES IA 929 PM CDT MON JUL 6 1998 THE NATIONAL WEATHER SERVICE IN DES MOINES HAS ISSUED A * SEVERE THUNDERSTORM WARNING FOR... JASPER COUNTY IN CENTRAL IOWA EASTERN POLK COUNTY IN CENTRAL IOWA * UNTIL 1015 PM CDT * AT 926 PM CDT... DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM 12 MILES NORTHEAST OF DES MOINES OR 6 MILES SOUTHWEST OF FARRAR MOVING EAST AT 30 MPH. * THIS STORM CAN BE EXPECTED NEAR... DES MOINES NOW PLEASANT HIIL NOW COLFAX BY 937 PM CDT PRAIRE CITY BY 938 PM CDT BAXTER BY 947 PM TCDT NEWTON BY 950 PM CDT DAMAGING WINDS AND HEAVY RAIN ARE LIKELY. GO INSIDE A STURDY BUILDING AND STAY AWAY FROM WINDOWS! JOHNSON/SMALL
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, Jul 6, 4:42 PM CDT, 4 hours 47 minutes before
IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086- 092>097-071100- CENTRAL IOWA THUNDERSTORM OUTLOOK NATIONAL WEATHER SERVICE DES MOINES IA 442 PM CDT MON JUL 6 1998 HAZARD--WIDESPREAD HEAVY RAIN OF 1 TO 3 INCHES AND ISOLATED AMOUNTS UP TO 5. A FEW STORMS COULD ALSO PRODUCE WIND GUSTS TO 80 MPH AND HAIL UP TO GOLFBALL SIZE. AREA OF CONCERN--ALL OF CENTRAL IOWA. TIMING DETAILS--THE HEAVY RAIN THREAT WILL LAST ALL NIGHT AND INTO TUESDAY MORNING. THE SEVERE WEATHER THREAT WILL BE HIGHEST BETWEEN 800 PM AND 300 AM. METEOROLOGICAL COMMENTS--A THUNDERSTORM COMPLEX HAS ALREADY DEVELOPED OVER NORTHEAST NEBRASKA AND SOUTHEAST SOUTH DAKOTA THIS AFTERNOON WITH NUMEROUS SEVERE THUNDERSTORM WARNINGS IN EFFECT. WIND GUSTS UP TO 70 MPH AND 1 INCH DIAMETER HAIL HAVE ALREADY BEEN REPORTED. THIS COMPLEX WILL MOVE INTO IOWA AFTER DARK AS IT FEEDS ON EXTREMELY HIGH MOISTURE VALUES THROUGHOUT THE ATMOSPHERE. PRECIPITABLE WATERS WERE APPROACHING 2 INCHES THIS AFTERNOON WITH SURFACE DEWPOINTS APPROACHING 80 DEGREES. AS THE NIGHT WEARS ON THE THUNDERSTORMS SHOULD BECOME WEAKER...BUT THEY WILL ALSO BEGIN TO TRAIN ALONG AN EAST-WEST STATIONARY FRONT STUCK RIGHT OVER THE HEART OF IOWA. PRECAUTIONS--A FLASH FLOOD WATCH IS ALREADY IN EFFECT FOR THE ENTIRE STATE...AND SEVERE THUNDERSTORM WATCHES MAY BE REQUIRED LATER THIS EVENING. SPOTTER ACTIVATION IS A NEAR CERTAINTY TONIGHT...ESPECIALLY IN THE NORTHWEST HALF OF THE STATE WHERE THE STORMS WILL LIKELY BE AT THEIR STRONGEST LATE THIS EVENING. PYTLAK
Special weather statement, Jul 6, 4:58 PM CDT, 4 hours 31 minutes before
IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086- 092>097-071100- CENTRAL IOWA THUNDERSTORM OUTLOOK...UPDATED NATIONAL WEATHER SERVICE DES MOINES IA 458 PM CDT MON JUL 6 1998 HAZARD--WIDESPREAD HEAVY RAIN OF 1 TO 3 INCHES AND ISOLATED AMOUNTS UP TO 5. A FEW STORMS COULD ALSO PRODUCE WIND GUSTS TO 80 MPH AND HAIL UP TO GOLFBALL SIZE. AREA OF CONCERN--ALL OF CENTRAL IOWA. TIMING DETAILS--THE HEAVY RAIN THREAT WILL LAST ALL NIGHT AND INTO TUESDAY MORNING. THE SEVERE WEATHER THREAT WILL BE HIGHEST BETWEEN 800 PM AND 300 AM. METEOROLOGICAL COMMENTS--A THUNDERSTORM COMPLEX HAS ALREADY DEVELOPED OVER NORTHEAST NEBRASKA AND SOUTHEAST SOUTH DAKOTA THIS AFTERNOON WITH NUMEROUS SEVERE THUNDERSTORM WARNINGS IN EFFECT. WIND GUSTS UP TO 70 MPH AND 1 INCH DIAMETER HAIL HAVE ALREADY BEEN REPORTED. THIS COMPLEX WILL MOVE INTO IOWA AFTER DARK AS IT FEEDS ON EXTREMELY HIGH MOISTURE VALUES THROUGHOUT THE ATMOSPHERE. PRECIPITABLE WATERS WERE APPROACHING 2 INCHES THIS AFTERNOON WITH SURFACE DEWPOINTS APPROACHING 80 DEGREES. AS THE NIGHT WEARS ON THE THUNDERSTORMS SHOULD BECOME WEAKER...BUT THEY WILL ALSO BEGIN TO TRAIN ALONG AN EAST-WEST STATIONARY FRONT STUCK RIGHT OVER THE HEART OF IOWA. PRECAUTIONS--A FLASH FLOOD WATCH IS ALREADY IN EFFECT FOR THE ENTIRE STATE...AND A TORNADO WATCH WILL BE ISSUED FOR NORTHWEST IOWA SHORTLY. SPOTTER ACTIVATION IS A NEAR CERTAINTY TONIGHT...ESPECIALLY IN THE NORTHWEST HALF OF THE STATE WHERE THE STORMS WILL LIKELY BE AT THEIR STRONGEST LATE THIS EVENING. PYTLAK UPDATED TO MENTION IMPENDING TORNADO WATCH IN NORTHWEST IOWA
Special weather statement, Jul 6, 8:44 PM CDT, 45 minutes before
IAZ004-005-015-023-024-033-034-044-045-070340- SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE DES MOINES IA 844 PM CDT MON JUL 6 1998 ...TORNADO WATCH HAS BEEN CANCELLED FOR PARTS OF WEST CENTRAL AND NORTHWEST IOWA... THE TORNADO WATCH THAT WAS IN EFFECT FOR PARTS OF WEST CENTRAL AND NORTHWEST IOWA IS NO LONGER IN EFFECT. THE STRONGEST THUNDERSTORMS HAVE SHIFTED SOUTHEAST OF THE AREA AN NO LONGER POSE A THREAT TO THE AREA. THUNDERSTORMS WILL CONTINUE INTERMITTANTLY DURING THE NIGHT BUT THE THREAT OF WIDESPREAD SEVERE WEATHER HAS ENDED. SMITH
Special weather statement, Jul 6, 8:44 PM CDT, 45 minutes before
IAZ004-005-015-023-024-033-034-044-045-070340- SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE DES MOINES IA 844 PM CDT MON JUL 6 1998 ...TORNADO WATCH HAS BEEN CANCELLED FOR PARTS OF WEST CENTRAL AND NORTHWEST IOWA... THE TORNADO WATCH THAT WAS IN EFFECT FOR PARTS OF WEST CENTRAL AND NORTHWEST IOWA IS NO LONGER IN EFFECT. THE STRONGEST THUNDERSTORMS HAVE SHIFTED SOUTHEAST OF THE AREA AN NO LONGER POSE A THREAT TO THE AREA. THUNDERSTORMS WILL CONTINUE INTERMITTANTLY DURING THE NIGHT BUT THE THREAT OF WIDESPREAD SEVERE WEATHER HAS ENDED. SMITH
The office that day
Everything else NWS Des Moines, IA issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 6, 7:22 PM CDT | Tornado Warning | DMX | Carroll | 33 min |
| Jul 6, 8:15 PM CDT | Severe Thunderstorm Warning | DMX | Dallas, Guthrie | 35 min |
| Jul 6, 8:46 PM CDT | Flash Flood Warning | DMX | Dallas | 3 hr |
| Jul 6, 8:54 PM CDT | Severe Thunderstorm Warning | DMX | Dallas, Polk | 36 min |
| Jul 6, 9:14 PM CDT | Flash Flood Warning | DMX | Guthrie | 6 hr |
| Jul 6, 9:20 PM CDT | Severe Thunderstorm Warning | DMX | Story | 35 min |
| Jul 6, 9:21 PM CDT | Flash Flood Warning | DMX | Polk | 6 hr |
| Jul 6, 9:35 PM CDT | Tornado Warning | DMX | Polk | 35 min |
| Jul 6, 9:45 PM CDT | Severe Thunderstorm Warning | DMX | Marion, Warren | 45 min |
| Jul 6, 10:00 PM CDT | Tornado Warning | DMX | Marion | 35 min |
| Jul 6, 10:15 PM CDT | Severe Thunderstorm Warning | DMX | Jasper | 35 min |
| Jul 6, 10:37 PM CDT | Severe Thunderstorm Warning | DMX | Marion | 33 min |
| Jul 6, 11:41 PM CDT | Flash Flood Warning | DMX | Dallas | 3 hr |
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; verification from NCEI's Storm Data; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.