Alert archive / Iowa / Tornado Warnings in 2021

Tornado Warning 27, NWS Omaha, NE

December 15, 2021Harrison County, Shelby County, Iowa

NWS Omaha, NE issued this tornado warning at Dec 15, 2021, 4:37 PM CST for Harrison County, Shelby County, Iowa. It was in force for 23 min. 3 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, 4:37 PM CST (22:37 UTC)
Expired: Dec 15, 2021, 5:00 PM CST
In force: 23 min
Issued by: NWS Omaha, NE
Area: Storm-based polygon
Tornado: Observed
Hail: 0.75 in

Counties Harrison County, IA, Shelby County, IA

The radar

The Omaha radar (KOAX), 93 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, 4:41 PM CST	TSTM WND DMG	Tennant, IA	LARGE TREE FELL ON HOME.
Dec 15, 4:55 PM CST	TSTM WND GST 72	Harlan, IA
Dec 15, 4:55 PM CST	NON-TSTM WND GST 72	5 S Harlan, IA	AWOS STATION KHNR HARLAN AIRPORT.

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, 10.6 hours before the alert went out and 93 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.

950 
WFUS53 KOAX 152237
TOROAX
IAC085-165-152300-
/O.NEW.KOAX.TO.W.0027.211215T2237Z-211215T2300Z/

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

The National Weather Service in Omaha has issued a

* Tornado Warning for...
  Southeastern Harrison County in southwestern Iowa...
  Shelby County in southwestern Iowa...

* Until 500 PM CST.
    
* At 437 PM CST, a tornado producing storm was located over Minden,
  or 27 miles northeast of Omaha, moving northeast at 80 mph.

  HAZARD...Damaging tornado.

  SOURCE...Radar confirmed tornado.

  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 tornadic storm will be near...
  Shelby and Persia around 440 PM CST.
  Harlan around 450 PM CST.

Other locations in the path of this tornadic thunderstorm include
Irwin.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

To repeat, a tornado is on the ground. 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 4151 9531 4151 9577 4186 9545 4186 9510
      4165 9510
TIME...MOT...LOC 2237Z 223DEG 68KT 4147 9556 

TORNADO...OBSERVED
MAX HAIL SIZE...<.75 IN

$$

CA

1 follow-up statement

435 
WWUS53 KOAX 152251
SVSOAX

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

IAC085-152301-
/O.CAN.KOAX.TO.W.0027.000000T0000Z-211215T2300Z/
Harrison IA-
451 PM CST Wed Dec 15 2021

...THE TORNADO WARNING FOR SOUTHEASTERN HARRISON COUNTY IS
CANCELLED...
    
The tornadic thunderstorm which prompted the warning has moved out 
of the warned area. Therefore, the warning has been cancelled.

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

LAT...LON 4151 9531 4151 9550 4160 9550 4160 9556
      4174 9556 4186 9545 4186 9510 4165 9510
TIME...MOT...LOC 2251Z 209DEG 50KT 4166 9547 

$$

IAC165-152300-
/O.CON.KOAX.TO.W.0027.000000T0000Z-211215T2300Z/
Shelby IA-
451 PM CST Wed Dec 15 2021

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 500 PM CST FOR SHELBY
COUNTY...
        
At 451 PM CST, a confirmed tornado was located 7 miles northeast of
Persia, or 25 miles south of Denison, moving northeast at 60 mph.

HAZARD...Damaging tornado.

SOURCE...Radar confirmed tornado.

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 tornado will be near...
  Harlan around 455 PM CST.

Other locations in the path of this tornadic thunderstorm include
Earling, Irwin and Defiance.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

To repeat, a tornado is on the ground. 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 4151 9531 4151 9550 4160 9550 4160 9556
      4174 9556 4186 9545 4186 9510 4165 9510
TIME...MOT...LOC 2251Z 209DEG 50KT 4166 9547 

TORNADO...OBSERVED
MAX HAIL SIZE...<.75 IN

$$

CA

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, 4:31 PM CST	Tornado Warning	OAX	Harrison, Monona, Shelby	13 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.