Alert archive / Iowa / Severe Thunderstorm Warnings in 2002

Severe Thunderstorm Warning 70, NWS Des Moines, IA

May 5, 2002Sac County, Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at May 5, 2002, 9:11 PM CDT for Sac County, Iowa. It was in force for 34 min. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: May 5, 2002, 9:11 PM CDT (02:11 UTC)
Expired: May 5, 2002, 9:45 PM CDT
In force: 34 min
Issued by: NWS Des Moines, IA
Area: Counties, with a storm outline in the text

County Sac County, IA

The radar

The Des Moines radar (KDMX), 141 km from the middle of the area, began a volume at 02:14 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
May 5, 9:28 PM CDT	Thunderstorm Wind 52 E	Sac City, 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
May 5, 4:30 PM CDT	Tornado Watch	SPC	7 hr
May 5, 8:00 PM CDT	Severe Thunderstorm Watch	SPC	5 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 2.2 hours before the alert went out and 158 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: 1550 J/kg
Mixed-layer CIN: -10 J/kg
Mixed-layer LCL: 1621 m above ground
0-6 km bulk shear: 37 kt
0-1 km storm-relative helicity: 112 m²/s²
0-3 km storm-relative helicity: 166 m²/s²
Significant tornado parameter: 0.4
Supercell composite: 5.0

Open this sounding in Storm Lab

The text

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

000 
WUUS53 KDMX 060211
SVRDSM
IAC161-060245-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE DES MOINES IA
911 PM CDT SUN MAY 5 2002

THE NATIONAL WEATHER SERVICE IN DES MOINES HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  SAC COUNTY IN WEST CENTRAL IOWA

* UNTIL 945 PM CDT

* AT 909 PM...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM OVER EARLY...OR ABOUT 48 MILES SOUTH OF
  SPENCER...MOVING EAST AT 30 MPH.

* THE SEVERE THUNDERSTORM WILL BE...

  NEAR NEMAHA AROUND 915 PM AND
  NEAR SAC CITY AROUND 925 PM.

DAMAGING WINDS OF 60 TO 70 MILES AN HOUR ARE LIKELY IN THE WARNED
AREA.

STAY AWAY FROM WINDOWS DURING A SEVERE STORM...WIND GUSTS OVER 70 MPH
COULD BLOW THEM OUT.

A TORNADO WATCH REMAINS IN EFFECT UNTIL 1100 PM SUNDAY EVENING FOR
NORTHWESTERN IOWA.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL MIDNIGHT MONDAY
MORNING FOR NORTHWESTERN IOWA. A SEVERE THUNDERSTORM WATCH ALSO
REMAINS IN EFFECT UNTIL 100 AM MONDAY MORNING FOR IOWA.

LAT...LON 4256 9537 4221 9532 4220 9484 4257 9492
JOHNSON

The office that day

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

Issued	Product	Office	Counties	Lasted
May 5, 7:15 PM CDT	Severe Thunderstorm Warning	DMX	Audubon	45 min
May 5, 7:28 PM CDT	Severe Thunderstorm Warning	DMX	Crawford	47 min
May 5, 8:01 PM CDT	Severe Thunderstorm Warning	DMX	Sac	44 min
May 5, 8:06 PM CDT	Severe Thunderstorm Warning	DMX	Emmet	39 min
May 5, 8:07 PM CDT	Severe Thunderstorm Warning	DMX	Palo Alto	38 min
May 5, 8:14 PM CDT	Severe Thunderstorm Warning	DMX	Crawford	46 min
May 5, 8:23 PM CDT	Severe Thunderstorm Warning	DMX	Kossuth	52 min
May 5, 8:36 PM CDT	Severe Thunderstorm Warning	DMX	Greene	54 min
May 5, 8:41 PM CDT	Severe Thunderstorm Warning	DMX	Carroll	64 min
May 5, 8:47 PM CDT	Severe Thunderstorm Warning	DMX	Crawford	28 min
May 5, 9:33 PM CDT	Severe Thunderstorm Warning	DMX	Calhoun, Pocahontas	42 min

Nearby

Severe Thunderstorm Warnings in Iowa, 2002 Every severe thunderstorm warning in 2002

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.