Alert archive / Iowa / Severe Thunderstorm Warnings in 2012

Severe Thunderstorm Warning 155, NWS Des Moines, IA

August 8, 2012Dallas County, Polk County, Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at Aug 8, 2012, 3:54 PM CDT for Dallas County, Polk County, Iowa. It was in force for 38 min. 12 reports 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
Aug 8, 2012, 3:54 PM CDT (20:54 UTC)
Expired
Aug 8, 2012, 4:32 PM CDT
In force
38 min
Issued by
NWS Des Moines, IA
Area
Storm-based polygon
Hail
1.0 in
Wind
60.0 mph

Counties Dallas County, IA, Polk County, IA

The radar

The Des Moines radar (KDMX), 12 km from the middle of the area, began a volume at 20:54 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

TimeReportWhereRemark
Aug 8, 3:54 PM CDTTSTM WND DMG2 Ene Waukee, IA12 INCH DIAMETER TREES SNAPPED AT BASE SOUTH OF THE INTERSECTION OF HICKMAN AND 156TH.
Aug 8, 3:55 PM CDTTSTM WND GST 65Ssw Clive, IA
Aug 8, 3:57 PM CDTTSTM WND GST 60West Des Moines, IAAT INTERSECTION OF 68TH AND DOUGLAS...NUMEROUS 2 INCH DIAMETER LIMBS DOWN WITH WINDS ESTIMATED IN EXCESS OF 60 MPH.
Aug 8, 3:59 PM CDTHAIL 13 Ne Des Moines, IATRAINED SPOTTER REPORTS HAIL RANGING UP TO QUARTER SIZED ALONG WITH STRONG WIND GUSTS. MULTIPLE BRANCHES DOWN UP TO 6-8 INCHES IN DIAMETER. MINOR HAIL DAMAGE TO VEHICLES. ALSO LOW LYING INTERSECTIONS IMPASSIBLE DUE TO STANDING WATER FROM HEAVY RAINS.
Aug 8, 4:02 PM CDTTSTM WND GST 651 Nnw Des Moines, IAAT KCCI STUDIO
Aug 8, 4:02 PM CDTTSTM WND GST 70West Des Moines, IAWINDS ESTIMATED IN EXCESS OF 70 MPH. EXTREME RAINFALL RATES AS WELL.
Aug 8, 4:04 PM CDTHAIL 1Grimes, IAAMATEUR RADIO OPERATOR REPORTED QUARTER SIZED HAIL IN GRIMES.
Aug 8, 4:04 PM CDTHAIL 1Urbandale, IA
Aug 8, 4:06 PM CDTTSTM WND GST 666 Nw Des Moines, IA
Aug 8, 4:09 PM CDTTSTM WND GST 702 E Urbandale, IAWIND ACCOMPANIED BY QUARTER HAIL
Aug 8, 4:11 PM CDTTSTM WND GST 654 Ene Des Moines, IA65 MPH WINDS ESTIMATED AT THE STATE FAIR GROUNDS.
Aug 8, 4:17 PM CDTTSTM WND GST 502 Nw Clive, IA

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

IssuedProductOfficeLasted
Aug 8, 2:21 PM CDTSevere Thunderstorm WatchSPC6 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 8.9 hours before the alert went out and 220 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-pSkew-T log-p diagram, Omaha, NE at 12:00Z on 2012-08-08Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 994 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Omaha, NE at 12:00Z on 2012-08-08The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 103 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
994 J/kg
Mixed-layer CIN
-254 J/kg
Mixed-layer LCL
1661 m above ground
0-6 km bulk shear
22 kt
0-1 km storm-relative helicity
103 m²/s²
0-3 km storm-relative helicity
78 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.4

Open this sounding in Storm Lab

The text

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

519 
WUUS53 KDMX 082054
SVRDMX
IAC049-153-082145-
/O.NEW.KDMX.SV.W.0155.120808T2054Z-120808T2145Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE DES MOINES IA
354 PM CDT WED AUG 8 2012

THE NATIONAL WEATHER SERVICE IN DES MOINES HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  SOUTHEASTERN DALLAS COUNTY IN CENTRAL IOWA...
  SOUTHERN POLK COUNTY IN CENTRAL IOWA...

* UNTIL 445 PM CDT

* AT 350 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM CAPABLE OF PRODUCING QUARTER SIZE HAIL...AND
  DAMAGING WINDS IN EXCESS OF 60 MPH.  THIS STORM WAS LOCATED NEAR
  WAUKEE...OR 13 MILES WEST OF DES MOINES...AND MOVING EAST AT 25
  MPH.

* LOCATIONS IMPACTED INCLUDE...
  DES MOINES...GRIMES...CLIVE...WEST DES MOINES...URBANDALE...WINDSOR
  HEIGHTS...JOHNSTON...ANKENY...PLEASANT HILL...ALTOONA...DES MOINES
  INT AIRPORT...SAYLORVILLE AND ANKENY AIRPORT.

THIS INCLUDES INTERSTATE 80 BETWEEN MILE MARKERS 114 AND 143.

THIS INCLUDES INTERSTATE 35 BETWEEN MILE MARKERS 68 AND 93.

THIS INCLUDES INTERSTATE 235 BETWEEN MILE MARKERS 1 AND 14.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

MOVE TO AN INTERIOR ROOM AND STAY AWAY FROM WINDOWS. IF YOU ARE IN A
MOBILE HOME...GET OUT NOW...AND SEEK SHELTER IN A REINFORCED
BUILDING.

&&

LAT...LON 4167 9398 4177 9348 4152 9342 4150 9393
TIME...MOT...LOC 2054Z 259DEG 20KT 4160 9383
WIND...HAIL 60MPH 1.00IN

$$
3 follow-up statements
161 
WWUS53 KDMX 082101
SVSDMX

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE DES MOINES IA
401 PM CDT WED AUG 8 2012

IAC049-153-082145-
/O.CON.KDMX.SV.W.0155.000000T0000Z-120808T2145Z/
POLK IA-DALLAS IA-
401 PM CDT WED AUG 8 2012

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT FOR SOUTHEASTERN
DALLAS AND SOUTHERN POLK COUNTIES UNTIL 445 PM CDT...

AT 358 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING QUARTER SIZE HAIL...AND
DESTRUCTIVE WINDS IN EXCESS OF 70 MPH.  THIS STORM WAS LOCATED NEAR
CLIVE...OR 10 MILES WEST OF DES MOINES...MOVING EAST AT 25 MPH.

IN ADDITION...FROM 350 TO 400 PM NUMEROUS REPORTS OF 60 TO 70 MPH 
WINDS HAVE BEEN REPORTED OVER THE THE WEST SIDE OF THE DES MOINES 
METROPOLITAN AREA WITH THIS STORM.

LOCATIONS IMPACTED INCLUDE...
  DES MOINES...GRIMES...CLIVE...WEST DES MOINES...URBANDALE...WINDSOR
  HEIGHTS...JOHNSTON...ANKENY...PLEASANT HILL...ALTOONA...DES MOINES
  INT AIRPORT...SAYLORVILLE AND ANKENY AIRPORT.

THIS INCLUDES INTERSTATE 80 BETWEEN MILE MARKERS 114 AND 143.

THIS INCLUDES INTERSTATE 35 BETWEEN MILE MARKERS 68 AND 94.

THIS INCLUDES INTERSTATE 235 BETWEEN MILE MARKERS 1 AND 14.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

PREPARE FOR DAMAGING WINDS...FALLING TREES AND FLYING DEBRIS. MOVE
INDOORS AND STAY AWAY FROM WINDOWS. IF YOU ARE IN A MOBILE HOME...GET
OUT NOW...AND SEEK SHELTER IN A REINFORCED BUILDING.

&&

LAT...LON 4167 9398 4177 9348 4152 9342 4150 9393
TIME...MOT...LOC 2100Z 259DEG 20KT 4161 9379
WIND...HAIL 70MPH 1.00IN

$$
511 
WWUS53 KDMX 082109
SVSDMX

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE DES MOINES IA
409 PM CDT WED AUG 8 2012

IAC049-082119-
/O.CAN.KDMX.SV.W.0155.000000T0000Z-120808T2145Z/
DALLAS IA-
409 PM CDT WED AUG 8 2012

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN DALLAS COUNTY IS
CANCELLED...

THE STORM WHICH PROMPTED THE WARNING HAS MOVED EAST OF THE WARNED 
AREA.

LAT...LON 4159 9379 4171 9378 4177 9348 4152 9342
      4151 9379
TIME...MOT...LOC 2109Z 259DEG 20KT 4162 9372

$$

IAC153-082145-
/O.CON.KDMX.SV.W.0155.000000T0000Z-120808T2145Z/
POLK IA-
409 PM CDT WED AUG 8 2012

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT FOR SOUTHERN POLK
COUNTY UNTIL 445 PM CDT...

AT 407 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING QUARTER SIZE HAIL...AND
DESTRUCTIVE WINDS IN EXCESS OF 70 MPH.  THIS STORM WAS LOCATED NEAR
URBANDALE...OR 7 MILES NORTHWEST OF DES MOINES...MOVING EAST AT 25
MPH.

LOCATIONS IMPACTED INCLUDE...
  DES MOINES...WINDSOR HEIGHTS...JOHNSTON...ANKENY...PLEASANT HILL...
  ALTOONA...DES MOINES INT AIRPORT...SAYLORVILLE AND ANKENY AIRPORT.

THIS INCLUDES INTERSTATE 80 BETWEEN MILE MARKERS 122 AND 143.

THIS INCLUDES INTERSTATE 35 BETWEEN MILE MARKERS 68 AND 94.

THIS INCLUDES INTERSTATE 235 BETWEEN MILE MARKERS 1 AND 14.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

PREPARE FOR DAMAGING WINDS...FALLING TREES AND FLYING DEBRIS. MOVE
INDOORS AND STAY AWAY FROM WINDOWS. IF YOU ARE IN A MOBILE HOME...GET
OUT NOW...AND SEEK SHELTER IN A REINFORCED BUILDING.

&&

LAT...LON 4159 9379 4171 9378 4177 9348 4152 9342
      4151 9379
TIME...MOT...LOC 2109Z 259DEG 20KT 4162 9372
WIND...HAIL 70MPH 1.00IN

$$
137 
WWUS53 KDMX 082132
SVSDMX

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE DES MOINES IA
432 PM CDT WED AUG 8 2012

IAC153-082142-
/O.CAN.KDMX.SV.W.0155.000000T0000Z-120808T2145Z/
POLK IA-
432 PM CDT WED AUG 8 2012

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHERN POLK COUNTY IS
CANCELLED...

THE STORM WHICH PROMPTED THE WARNING HAS WEAKENED BELOW SEVERE
LIMITS...AND NO LONGER POSES AN IMMEDIATE THREAT TO LIFE OR PROPERTY.
HOWEVER HEAVY RAIN AND LOCAL FLOODING ARE STILL LIKELY WITH THIS 
THUNDERSTORM.

LAT...LON 4159 9379 4171 9378 4177 9348 4152 9342
      4151 9379
TIME...MOT...LOC 2132Z 259DEG 20KT 4164 9355

$$

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 7, 7:45 PM CDTSevere Thunderstorm WarningDMXAdair, Cass45 min
Aug 8, 2:00 PM CDTSevere Thunderstorm WarningDMXCalhoun, Carroll, Greene45 min
Aug 8, 2:37 PM CDTSevere Thunderstorm WarningDMXGreene53 min
Aug 8, 3:01 PM CDTSevere Thunderstorm WarningDMXBoone, Dallas, Greene, Guthrie43 min
Aug 8, 3:09 PM CDTSevere Thunderstorm WarningDMXAdair, Madison51 min
Aug 8, 3:30 PM CDTSevere Thunderstorm WarningDMXBoone, Story30 min
Aug 8, 4:16 PM CDTSevere Thunderstorm WarningDMXJasper, Marion, Polk, Warren29 min
Aug 8, 4:45 PM CDTSevere Thunderstorm WarningDMXHancock, Winnebago36 min
Aug 8, 4:48 PM CDTSevere Thunderstorm WarningDMXWorth27 min
Aug 8, 6:05 PM CDTSevere Thunderstorm WarningDMXButler, Cerro Gordo, Franklin25 min
Aug 8, 6:29 PM CDTSevere Thunderstorm WarningDMXButler, Franklin46 min

Nearby

Severe Thunderstorm Warnings in Iowa, 2012Every severe thunderstorm warning in 2012

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.