Alert archive / Iowa / Tornado Warnings in 2020

Tornado Warning 16, NWS Des Moines, IA

July 14, 2020Polk County, Iowa

NWS Des Moines, IA issued this tornado warning at Jul 14, 2020, 7:22 PM CDT for Polk County, Iowa. It was in force for 23 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 14, 2020, 7:22 PM CDT (00:22 UTC)
Expired: Jul 14, 2020, 7:45 PM CDT
In force: 23 min
Issued by: NWS Des Moines, IA
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 1.0 in

County Polk County, IA

The radar

The Des Moines radar (KDMX), 2 km from the middle of the area, began a volume at 00:27 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 14, 4:11 PM CDT	Severe Thunderstorm Watch	SPC	7 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 0.4 hours before the alert went out and 226 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: 499 J/kg
Mixed-layer CIN: -286 J/kg
Mixed-layer LCL: 1133 m above ground
0-6 km bulk shear: 31 kt
0-1 km storm-relative helicity: 174 m²/s²
0-3 km storm-relative helicity: 226 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.3

Open this sounding in Storm Lab

The text

As transmitted.

820 
WFUS53 KDMX 150022
TORDMX
IAC153-150045-
/O.NEW.KDMX.TO.W.0016.200715T0022Z-200715T0045Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Des Moines IA
722 PM CDT Tue Jul 14 2020

The National Weather Service in Des Moines  has issued a

* Tornado Warning for...
  West central Polk County in central Iowa...

* Until 745 PM CDT.
    
* At 722 PM CDT, a severe thunderstorm capable of producing a tornado
  was located over Saylorville Lake, or near Johnston, moving
  southeast at 15 mph.

  HAZARD...Tornado and quarter size hail.

  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...
  Johnston and Saylorville around 740 PM CDT.
  Ankeny around 745 PM CDT.

This includes Interstate 80 between mile markers 132 and 133.
 
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 4173 9377 4176 9374 4172 9359 4164 9367
TIME...MOT...LOC 0022Z 309DEG 15KT 4174 9374 

TORNADO...RADAR INDICATED
HAIL...1.00IN

$$

Curtis

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 14, 7:16 PM CDT	Severe Thunderstorm Warning	DMX	Dallas, Polk	44 min
Jul 14, 7:55 PM CDT	Severe Thunderstorm Warning	DMX	Dallas, Polk, Warren	50 min
Jul 14, 7:56 PM CDT	Flash Flood Warning	DMX	Dallas, Jasper, Polk	3 hr
Jul 14, 8:36 PM CDT	Severe Thunderstorm Warning	DMX	Jasper, Mahaska, Marion	24 min
Jul 14, 8:40 PM CDT	Severe Thunderstorm Warning	DMX	Jasper, Marion, Warren	35 min
Jul 14, 8:56 PM CDT	Severe Thunderstorm Warning	DMX	Jasper, Marion	34 min
Jul 14, 9:09 PM CDT	Severe Thunderstorm Warning	DMX	Marion, Warren	51 min
Jul 14, 9:20 PM CDT	Severe Thunderstorm Warning	DMX	Mahaska, Marion	40 min
Jul 14, 9:35 PM CDT	Severe Thunderstorm Warning	DMX	Lucas, Marion, Monroe	40 min
Jul 14, 10:17 PM CDT	Special Weather Statement	DMX	Lucas, Monroe, Wayne	58 min
Jul 14, 11:00 PM CDT	Severe Thunderstorm Warning	DMX	Ringgold, Union	30 min

Nearby

Tornado Warnings in Iowa, 2020 Every tornado warning in 2020 Tornadoes in 2020

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.