Alert archive / Iowa / Severe Thunderstorm Warnings in 1998

Severe Thunderstorm Warning 18, NWS Des Moines, IA

April 12, 1998Emmet County, Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at Apr 12, 1998, 7:06 PM CDT for Emmet County, Iowa. It was in force for 34 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: Apr 12, 1998, 7:06 PM CDT (00:06 UTC)
Expired: Apr 12, 1998, 7:40 PM CDT
In force: 34 min
Issued by: NWS Des Moines, IA
Area: Whole counties

County Emmet County, IA

The radar

The Sioux Falls radar (KFSD), 167 km from the middle of the area, began a volume at 00:07 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 nearest sounding before it

Minneapolis, MN (KMPX), launched 00:00Z, 0.1 hours before the alert went out and 185 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1693 m above ground
0-6 km bulk shear: 34 kt
0-1 km storm-relative helicity: 491 m²/s²
0-3 km storm-relative helicity: 712 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

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

000 
TTAA00 KDSM 130006 RRA
SVRDSM
IAC063-130040-

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

* SEVERE THUNDERSTORM WARNING FOR
  EMMET COUNTY - NORTHWESTERN IOWA

* UNTIL 740 PM CDT
 
* SOME AREAS AFFECTED
    ESTHERVILLE
    ARMSTRONG
    DOLLIVER
    WALLINGFORD

* AT 705 PM CDT RADAR INDICATED A SEVERE THUNDERSTORM 20 MILES NORTH
  NORTHEAST OF SPENCER OR NEAR SUPERIOR MOVING NORTHEAST AT 40 MPH.

* THE STORM WILL BE NEAR ESTHERVILLE AT 720 PM.

 WINDS OVER 60 MPH ARE LIKELY WITH THIS STORM.

MYERS

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, 3 hours 33 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, 7:47 PM CDT	Severe Thunderstorm Warning	DMX	Crawford	33 min
Apr 12, 8:22 PM CDT	Severe Thunderstorm Warning	DMX	Carroll, Crawford	48 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.