Alert archive / Iowa / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 113, NWS Omaha, NE

July 30, 2021Montgomery County, Page County, Iowa

NWS Omaha, NE issued this severe thunderstorm warning at Jul 30, 2021, 9:13 PM CDT for Montgomery County, Page County, Iowa. It was in force for 32 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Jul 30, 2021, 9:13 PM CDT (02:13 UTC)
Expired: Jul 30, 2021, 9:45 PM CDT
In force: 32 min
Issued by: NWS Omaha, NE
Area: Storm-based polygon
Hail: 1.0 in
Wind: 65.0 mph

Counties Montgomery County, IA, Page County, IA

The radar

The Omaha radar (KOAX), 110 km from the middle of the area, began a volume at 02:16 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 watch it was issued in

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

Issued	Product	Office	Lasted
Jul 30, 8:47 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 110 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: 2669 J/kg
Mixed-layer CIN: -3 J/kg
Mixed-layer LCL: 967 m above ground
0-6 km bulk shear: 40 kt
0-1 km storm-relative helicity: 52 m²/s²
0-3 km storm-relative helicity: 279 m²/s²
Significant tornado parameter: 3.4
Supercell composite: 19.5

Open this sounding in Storm Lab

The text

As transmitted.

854 
WUUS53 KOAX 310213
SVROAX
IAC137-145-310245-
/O.NEW.KOAX.SV.W.0113.210731T0213Z-210731T0245Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Omaha/Valley Nebraska
913 PM CDT Fri Jul 30 2021

The National Weather Service in Omaha has issued a

* Severe Thunderstorm Warning for...
  Montgomery County in southwestern Iowa...
  Northern Page County in southwestern Iowa...

* Until 945 PM CDT.

* At 912 PM CDT, severe thunderstorms were located along a line
  extending from 7 miles northeast of Stanton to 8 miles southwest of
  Villisca to 5 miles north of Essex, moving south at 35 mph.

  HAZARD...65 mph wind gusts and quarter size hail.

  SOURCE...Radar indicated.

  IMPACT...Hail damage to vehicles is expected. Expect wind damage 
           to roofs, siding, and trees.

* Severe thunderstorms will be near...
  Villisca and Essex around 925 PM CDT.
  Clarinda around 930 PM CDT.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4069 9519 4090 9534 4091 9539 4100 9538
      4116 9504 4116 9493 4073 9493
TIME...MOT...LOC 0212Z 340DEG 30KT 4104 9499 4088 9511 4091 9533 

HAIL...1.00IN
WIND...65MPH
 
$$

Petersen

2 follow-up statements

725 
WWUS53 KOAX 310228
SVSOAX

Severe Weather Statement
National Weather Service Omaha/Valley Nebraska
928 PM CDT Fri Jul 30 2021

IAC137-145-310245-
/O.CON.KOAX.SV.W.0113.000000T0000Z-210731T0245Z/
Montgomery IA-Page IA-
928 PM CDT Fri Jul 30 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 945 PM CDT
FOR SOUTHEASTERN MONTGOMERY AND NORTHERN PAGE COUNTIES...

At 927 PM CDT, severe thunderstorms were located along a line
extending from near Villisca to near Clarinda to near Essex, moving
south at 35 mph.

HAZARD...60 mph wind gusts and quarter size hail.

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees.

Locations impacted include...
  Clarinda.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4069 9519 4090 9534 4104 9493 4073 9493
TIME...MOT...LOC 0227Z 340DEG 30KT 4093 9494 4077 9506 4080 9528 

HAIL...1.00IN
WIND...60MPH
 
$$

Petersen

856 
WWUS53 KOAX 310241
SVSOAX

Severe Weather Statement
National Weather Service Omaha/Valley Nebraska
941 PM CDT Fri Jul 30 2021

IAC137-145-310250-
/O.EXP.KOAX.SV.W.0113.000000T0000Z-210731T0245Z/
Montgomery IA-Page IA-
941 PM CDT Fri Jul 30 2021

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN MONTGOMERY AND
NORTHERN PAGE COUNTIES WILL EXPIRE AT 945 PM CDT...
            
The storms which prompted the warning have weakened below severe
limits, and no longer pose an immediate threat to life or property.
Therefore, the warning will be allowed to expire.

A Severe Thunderstorm Watch remains in effect until 200 AM CDT for
southwestern Iowa.

Remember, a Severe Thunderstorm Warning still remains in effect for
portions of Fremont and Page Counties.

LAT...LON 4069 9519 4090 9534 4104 9493 4073 9493
TIME...MOT...LOC 0240Z 340DEG 30KT 4084 9490 4068 9502 4071 9524 

$$

Petersen

The office that day

Everything else NWS Omaha, NE issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 30, 8:06 PM CDT	Special Weather Statement	OAX	Pottawattamie	24 min
Jul 30, 8:12 PM CDT	Severe Thunderstorm Warning	OAX	Pottawattamie, Shelby	33 min
Jul 30, 8:42 PM CDT	Severe Thunderstorm Warning	OAX	Mills, Montgomery, Page, Pottawattamie	33 min
Jul 30, 9:03 PM CDT	Severe Thunderstorm Warning	OAX	Fremont, Mills, Page	42 min
Jul 30, 9:39 PM CDT	Severe Thunderstorm Warning	OAX	Fremont, Page	51 min
Jul 30, 10:12 PM CDT	Tornado Warning	OAX	Page	18 min
Jul 31, 2:14 AM CDT	Special Weather Statement	OAX	Pottawattamie	76 min

Nearby

Severe Thunderstorm Warnings in Iowa, 2021 Every severe thunderstorm warning in 2021

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.