Alert archive / Iowa / Severe Thunderstorm Warnings in 1998

Severe Thunderstorm Warning 20, NWS Des Moines, IA

April 12, 1998Carroll County, Crawford County, Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at Apr 12, 1998, 8:22 PM CDT for Carroll County, Crawford County, Iowa. It was in force for 48 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 12, 1998, 8:22 PM CDT (01:22 UTC)
Expired: Apr 12, 1998, 9:10 PM CDT
In force: 48 min
Issued by: NWS Des Moines, IA
Area: Whole counties

Counties Carroll County, IA, Crawford County, IA

What was reported inside it

Time	Report	Where
Apr 12, 8:40 PM CDT	Hail 1	Halbur, IA
Apr 12, 9:10 PM CDT	Hail 0.75	Glidden, IA
Apr 12, 9:15 PM CDT	Hail 1	Glidden, 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
Apr 12, 3:30 PM CDT	Severe Thunderstorm Watch	SPC	6 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 1.4 hours before the alert went out and 131 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.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 390 J/kg
Mixed-layer CIN: -83 J/kg
Mixed-layer LCL: 1826 m above ground
0-6 km bulk shear: 51 kt
0-1 km storm-relative helicity: 210 m²/s²
0-3 km storm-relative helicity: 324 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 1.3

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

000 
TTAA00 KDSM 130122 RRA
SVRDSM
IAC027-047-130210-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE DES MOINES IA
822 PM CDT SUN APR 12 1998

* SEVERE THUNDERSTORM WARNING FOR
  WESTERN CARROLL COUNTY - WEST CENTRAL IOWA
  SOUTHEASTERN CRAWFORD COUNTY - WEST CENTRAL IOWA

* UNTIL 910 PM CDT
 
* SOME AREAS AFFECTED
    MANILLA
    ASPINWALL
    HALBUR
    CARROLL

* AT 820 PM CDT RADAR INDICATED A SEVERE THUNDERSTORM 60 MILES
  NORTHEAST OF COUNCIL BLUFFS OR NEAR MANILLA MOVING EAST NORTHEAST AT
  35 MPH.

* THE STORM WILL CROSS INTO CARROLL COUNTY AT 850 PM AND BE NEAR
  THE CITY OF CARROLL AT 910 PM.

LARGE HAIL AND INTENSE RAINFALL IS LIKELY WITH THIS STORM.

STARK

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 12, 3:33 PM CDT, 4 hours 49 minutes before

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086-
092>097-130230-

CENTRAL IOWA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
333 PM CDT SUN APR 12 1998

HAZARD--ISOLATED SEVERE THUNDERSTORMS WITH WIND GUSTS TO 65 MPH AND
HAIL UP TO GOLFBALL SIZE.

AREA OF CONCERN--WEST OF INTERSTATE 35.

TIMING DETAILS--BETWEEN 600 AND 1100 PM.

METEOROLOGICAL COMMENTS--A LINE OF THUNDERSTORMS HAS BEGUN TO DEVELOP
ALONG A DRY LINE IN EASTERN NEBRASKA...ONE OF WHICH HAS BECOME SEVERE
ALREADY. THE ATMOSPHERE OVER IOWA CONTINUES TO DESTABILIZE WITH STRONG
WINDS AS HIGH AS 70 MPH AT 5000 FEET. ANY THUNDERSTORMS WILL BE ABLE
TO BRING THESE WINDS DOWN TO THE SURFACE AND CAUSE DAMAGE. MOISTURE
REMAINS SOMEWHAT LIMITED...SO TORNADOES STILL APPEAR UNLIKELY.
HOWEVER...RAPID COOLING ALOFT WILL BE ENOUGH TO SUPPORT ISOLATED LARGE
HAIL. BY LATE EVENING AS THE DRY LINE MOVES TO AROUND I-35 AND THE LOW
LEVELS COOL OFF...THE STORMS SHOULD BEGIN TO WEAKEN.

PRECAUTIONS--A SEVERE THUNDERSTORM WATCH HAS BEEN ISSUED WEST OF AN
ESTHERVILLE-SHENANDOAH LINE UNTIL 900 PM. SPOTTER ACTIVATION SHOULD BE
UNDERWAY IN THIS AREA. SPOTTER GROUPS FURTHER EAST SHOULD BE PREPARED
FOR ACTIVATION LATER THIS EVENING. ANY SEVERE STORMS SHOULD BE RATHER
ISOLATED.

PYTLAK

The office that day

Everything else NWS Des Moines, IA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 12, 7:06 PM CDT	Severe Thunderstorm Warning	DMX	Emmet	34 min
Apr 12, 7:47 PM CDT	Severe Thunderstorm Warning	DMX	Crawford	33 min
Apr 12, 8:53 PM CDT	Severe Thunderstorm Warning	DMX	Carroll	32 min

Nearby

Severe Thunderstorm Warnings in Iowa, 1998 Every 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.