Alert archive / Iowa / Tornado Warnings in 2018

Tornado Warning 53, NWS Des Moines, IA

September 3, 2018Poweshiek County, Iowa

NWS Des Moines, IA issued this tornado warning at Sep 3, 2018, 6:58 PM CDT for Poweshiek 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: Sep 3, 2018, 6:58 PM CDT (23:58 UTC)
Expired: Sep 3, 2018, 7:30 PM CDT
In force: 32 min
Issued by: NWS Des Moines, IA
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 0.75 in

County Poweshiek County, IA

The radar

The Des Moines radar (KDMX), 107 km from the middle of the area, began a volume at 00:05 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
Sep 3, 6:09 PM CDT	Tornado Watch	SPC	2 hr

The nearest sounding before it

Davenport, (KDVN), launched 12:00Z, 12.0 hours before the alert went out and 163 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: 1178 J/kg
Mixed-layer CIN: -30 J/kg
Mixed-layer LCL: 851 m above ground
0-6 km bulk shear: 26 kt
0-1 km storm-relative helicity: 118 m²/s²
0-3 km storm-relative helicity: 107 m²/s²
Significant tornado parameter: 0.4
Supercell composite: 2.5

Open this sounding in Storm Lab

The text

As transmitted.

953 
WFUS53 KDMX 032358
TORDMX
IAC157-040030-
/O.NEW.KDMX.TO.W.0053.180903T2358Z-180904T0030Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Des Moines IA
658 PM CDT MON SEP 3 2018

The National Weather Service in Des Moines  has issued a

* Tornado Warning for...
  Southeastern Poweshiek County in central Iowa...

* Until 730 PM CDT.
    
* At 657 PM CDT, a severe thunderstorm capable of producing a tornado
  was located over Montezuma, moving east at 20 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 tornadic thunderstorm will remain over mainly rural areas of
  southeastern Poweshiek County, including the following locations...
  Deep River, Guernsey and Barnes City.

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 4151 9255 4161 9260 4169 9230 4151 9230
TIME...MOT...LOC 2357Z 255DEG 18KT 4156 9253 

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

$$

Martin

3 follow-up statements

766 
WWUS53 KDMX 040007
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
707 PM CDT MON SEP 3 2018

IAC157-040030-
/O.CON.KDMX.TO.W.0053.000000T0000Z-180904T0030Z/
Poweshiek IA-
707 PM CDT MON SEP 3 2018

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 730 PM CDT FOR
SOUTHEASTERN POWESHIEK COUNTY...
    
At 706 PM CDT, a severe thunderstorm capable of producing a tornado
was located near Montezuma, moving east at 20 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.

Locations impacted include...
Montezuma, Deep River, Barnes City and Guernsey. 

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 4151 9249 4163 9253 4169 9230 4151 9230
TIME...MOT...LOC 0006Z 255DEG 18KT 4157 9247 

TORNADO...RADAR INDICATED
HAIL...0.00IN

$$

Martin

357 
WWUS53 KDMX 040013
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
713 PM CDT MON SEP 3 2018

IAC157-040030-
/O.CON.KDMX.TO.W.0053.000000T0000Z-180904T0030Z/
Poweshiek IA-
713 PM CDT MON SEP 3 2018

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 730 PM CDT FOR
SOUTHEASTERN POWESHIEK COUNTY...
    
At 713 PM CDT, a severe thunderstorm capable of producing a tornado
was located near Montezuma, moving east at 20 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.

Locations impacted include...
Deep River and Guernsey. 

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 4151 9243 4164 9248 4169 9230 4151 9230
TIME...MOT...LOC 0013Z 254DEG 20KT 4159 9241 

TORNADO...RADAR INDICATED
HAIL...0.00IN

$$

Martin

041 
WWUS53 KDMX 040025
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
725 PM CDT MON SEP 3 2018

IAC157-040035-
/O.EXP.KDMX.TO.W.0053.000000T0000Z-180904T0030Z/
Poweshiek IA-
725 PM CDT MON SEP 3 2018

...THE TORNADO WARNING FOR SOUTHEASTERN POWESHIEK COUNTY WILL EXPIRE
AT 730 PM CDT...
                
The storm which prompted the warning has weakened below severe
limits, and no longer appears capable of producing a tornado.
Therefore, the warning will be allowed to expire.

A Tornado Watch remains in effect until 1000 PM CDT for central Iowa.

LAT...LON 4151 9243 4164 9248 4169 9230 4151 9230
TIME...MOT...LOC 0025Z 255DEG 18KT 4160 9234 

$$

Martin

The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 2, 7:32 PM CDT	Areal Flood Warning	DMX	Black Hawk, Bremer, Butler	24 hr
Sep 3, 4:29 PM CDT	Special Weather Statement	DMX	Jasper, Warren	61 min
Sep 3, 5:07 PM CDT	River Flood Warning	DMX	Tama	7 days
Sep 3, 5:07 PM CDT	River Flood Warning	DMX	Black Hawk	6 days
Sep 3, 5:07 PM CDT	River Flood Warning	DMX	Black Hawk	5 days
Sep 3, 6:31 PM CDT	Special Weather Statement	DMX	Poweshiek	44 min

Nearby

Tornado Warnings in Iowa, 2018 Every tornado warning in 2018 Tornadoes in 2018

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.