Alert archive / Iowa / Tornado Warnings in 2021

Tornado Warning 26, NWS Omaha, NE

December 15, 2021Harrison County, Monona County, Shelby County, Iowa

NWS Omaha, NE issued this tornado warning at Dec 15, 2021, 4:31 PM CST for Harrison County, Monona County, Shelby County, Iowa. It was in force for 13 min. 2 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: Dec 15, 2021, 4:31 PM CST (22:31 UTC)
Expired: Dec 15, 2021, 4:44 PM CST
In force: 13 min
Issued by: NWS Omaha, NE
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 0.75 in

Counties Harrison County, IA, Monona County, IA, Shelby County, IA

The radar

The Omaha radar (KOAX), 78 km from the middle of the area, began a volume at 22:36 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
Dec 15, 4:34 PM CST	TSTM WND DMG	4 Ne Logan, IA	DELAYED REPORT, TIME ESTIMATED FROM RADAR. REPORT FROM MPING: TREES UPROOTED OR SNAPPED; ROOF BLOWN OFF.
Dec 15, 4:53 PM CST	TSTM WND DMG	2 S Woodbine, IA	TREES UPROOTED OR SNAPPED; ROOF BLOWN OFF.

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.

Issued	Product	Office	Lasted
Dec 15, 1:23 PM CST	Tornado Watch	SPC	7 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 10.5 hours before the alert went out and 79 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: 2165 m above ground
0-6 km bulk shear: 42 kt
0-1 km storm-relative helicity: 346 m²/s²
0-3 km storm-relative helicity: 384 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

946 
WFUS53 KOAX 152231
TOROAX
IAC085-133-165-152300-
/O.NEW.KOAX.TO.W.0026.211215T2231Z-211215T2300Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Omaha/Valley Nebraska
431 PM CST Wed Dec 15 2021

The National Weather Service in Omaha has issued a

* Tornado Warning for...
  Southeastern Monona County in west central Iowa...
  Northeastern Harrison County in southwestern Iowa...
  Northwestern Shelby County in southwestern Iowa...

* Until 500 PM CST.
    
* At 431 PM CST, a severe thunderstorm capable of producing a tornado
  was located 7 miles southeast of Pisgah, or 29 miles southwest of
  Denison, moving northeast at 75 mph.

  HAZARD...Tornado.

  SOURCE...Radar indicated rotation.

  IMPACT...Flying debris will be dangerous to those caught without 
           shelter. Mobile homes will be damaged or destroyed. 
           Damage to roofs, windows, and vehicles will occur.  Tree 
           damage is likely.

* This dangerous storm will be near...
  Dunlap around 440 PM CST.
  Ute around 450 PM CST.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

&&

LAT...LON 4161 9567 4172 9596 4214 9567 4187 9567
      4186 9544
TIME...MOT...LOC 2231Z 206DEG 64KT 4176 9581 

TORNADO...RADAR INDICATED
MAX HAIL SIZE...<.75 IN

$$

Kern

1 follow-up statement

928 
WWUS53 KOAX 152244
SVSOAX

Severe Weather Statement
National Weather Service Omaha/Valley Nebraska
444 PM CST Wed Dec 15 2021

IAC085-133-165-152253-
/O.CAN.KOAX.TO.W.0026.000000T0000Z-211215T2300Z/
Monona IA-Harrison IA-Shelby IA-
444 PM CST Wed Dec 15 2021

...THE TORNADO WARNING FOR SOUTHEASTERN MONONA...NORTHEASTERN
HARRISON AND NORTHWESTERN SHELBY COUNTIES IS CANCELLED...
        
The storm which prompted the warning has moved out of the area.
Therefore, the warning has been cancelled.

A Tornado Watch remains in effect until 800 PM CST for southwestern
and west central Iowa.

LAT...LON 4161 9567 4172 9596 4214 9567 4187 9567
      4186 9544
TIME...MOT...LOC 2243Z 206DEG 64KT 4197 9568 

$$

Kern

The office that day

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

Issued	Product	Office	Counties	Lasted
Dec 15, 3:35 PM CST	Severe Thunderstorm Warning Destructive damage threat	OAX	Fremont, Harrison, Mills, Pottawattamie	70 min
Dec 15, 3:41 PM CST	Severe Thunderstorm Warning Destructive damage threat	OAX	Harrison, Monona	64 min
Dec 15, 3:55 PM CST	Severe Thunderstorm Warning Destructive damage threat	OAX	Fremont, Harrison, Mills, Montgomery, Page, Pottawattamie and 1 more	80 min
Dec 15, 4:01 PM CST	Tornado Warning	OAX	Fremont, Mills	14 min
Dec 15, 4:12 PM CST	Tornado Warning	OAX	Fremont, Mills	33 min
Dec 15, 4:16 PM CST	Tornado Warning	OAX	Harrison, Pottawattamie	17 min
Dec 15, 4:21 PM CST	Tornado Warning	OAX	Pottawattamie	24 min
Dec 15, 4:30 PM CST	Tornado Warning	OAX	Mills, Montgomery, Pottawattamie	30 min
Dec 15, 4:37 PM CST	Tornado Warning Tornado observed	OAX	Harrison, Shelby	23 min
Dec 15, 4:46 PM CST	Tornado Warning	OAX	Pottawattamie, Shelby	20 min
Dec 15, 4:54 PM CST	Tornado Warning	OAX	Montgomery, Page	15 min
Dec 15, 4:55 PM CST	Tornado Warning	OAX	Shelby	14 min

Nearby

Tornado Warnings in Iowa, 2021 Every tornado warning in 2021 Tornadoes 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.