Alert archive / Iowa / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 164, NWS Des Moines, IA

September 6, 20204 counties in Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at Sep 6, 2020, 3:14 AM CDT for 4 counties in Iowa. It was in force for 46 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued
Sep 6, 2020, 3:14 AM CDT (08:14 UTC)
Expired
Sep 6, 2020, 4:00 AM CDT
In force
46 min
Issued by
NWS Des Moines, IA
Area
Storm-based polygon
Hail
1.25 in
Wind
60.0 mph

Counties Cerro Gordo County, IA, Hancock County, IA, Kossuth County, IA, Wright County, IA

The radar

The Des Moines radar (KDMX), 144 km from the middle of the area, began a volume at 08:17 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.

IssuedProductOfficeLasted
Sep 5, 9:34 PM CDTSevere Thunderstorm WatchSPC7 hr
Sep 6, 2:53 AM CDTSevere Thunderstorm WatchSPC6 hr

The nearest sounding before it

Minneapolis, MN (KMPX), launched 00:00Z, 8.2 hours before the alert went out and 203 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-pSkew-T log-p diagram, Minneapolis, MN at 00:00Z on 2020-09-06Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Minneapolis, MN at 00:00Z on 2020-09-06The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 84 square meters per square second.1939587897Sfc1 km3 km6 km9 kmRMLM
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
2083 m above ground
0-6 km bulk shear
54 kt
0-1 km storm-relative helicity
84 m²/s²
0-3 km storm-relative helicity
170 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Des Moines, IA wrote its last area forecast discussion before this severe thunderstorm warning went out at Sep 6, 3:02 AM CDT, 12 minutes earlier.

Area forecast discussion, Sep 6, 3:02 AM CDT, 12 minutes before
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Hazardous weather outlook, Sep 5, 9:51 PM CDT, 5 hours 23 minutes before
Hazardous Weather Outlook
National Weather Service Des Moines IA
951 PM CDT Sat Sep 5 2020

IAZ004>007-015>017-023>028-034>039-047>050-060>062-075-070300-
Emmet-Kossuth-Winnebago-Worth-Palo Alto-Hancock-Cerro Gordo-
Pocahontas-Humboldt-Wright-Franklin-Butler-Bremer-Calhoun-Webster-
Hamilton-Hardin-Grundy-Black Hawk-Boone-Story-Marshall-Tama-Polk-
Jasper-Poweshiek-Mahaska-
951 PM CDT Sat Sep 5 2020

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...Tonight

Thunderstorms are expected to move into the outlook area late
evening and overnight. Severe storms are possible with large hail
and damaging wind gusts the main threats. Locally heavy rainfall
is also possible.

.DAYS TWO THROUGH SEVEN...Sunday through Friday

Thunderstorms are possible mainly Sunday morning. Stronger storms
may produce very strong wind gusts. Heavy rainfall is also
possible.

Multiple rounds of showers and thunderstorms forecast this week.
The severe threat will be better determined in the coming days.

.SPOTTER INFORMATION STATEMENT...

Spotter may be needed tonight.

IAZ033-044>046-057>059-070>074-081>086-092>097-070300-
Sac-Crawford-Carroll-Greene-Audubon-Guthrie-Dallas-Cass-Adair-
Madison-Warren-Marion-Adams-Union-Clarke-Lucas-Monroe-Wapello-
Taylor-Ringgold-Decatur-Wayne-Appanoose-Davis-
951 PM CDT Sat Sep 5 2020

This Hazardous Weather Outlook is for portions of central Iowa.

.DAY ONE...Tonight

Isolated thunderstorms are possible overnight. Strong wind is
possible with the more intense storms. Locally heavy rainfall is
also possible.

.DAYS TWO THROUGH SEVEN...Sunday through Friday

Thunderstorms are possible across eastern portions of the outlook
area Sunday morning and again later in the afternoon. Stronger
storms may produce very strong wind gusts. Heavy rainfall is also
possible.

Multiple rounds of showers and thunderstorms forecast this week.
The severe threat will be better determined in the coming days.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

FAB

In the hours before

Local storm report, Sep 6, 1:20 AM CDT, 1 hour 54 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
120 AM CDT SUN SEP 6 2020

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1246 AM     HAIL             READLYN                 42.70N 92.23W
09/06/2020  E1.75 INCH       BREMER             IA   PUBLIC

            REPORTED ON SOCIAL MEDIA VIA KWWL.

&&

CAH
Local storm report, Sep 6, 1:46 AM CDT, 1 hour 28 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
146 AM CDT SUN SEP 6 2020

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1250 AM     HAIL             2 N DUNKERTON           42.60N 92.16W
09/06/2020  E1.75 INCH       BLACK HAWK         IA   PUBLIC

            REPORTED ON SOCIAL MEDIA VIA KGAN.

&&

CAH
Local storm report, Sep 6, 2:54 AM CDT, 20 minutes before
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The office that day

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

IssuedProductOfficeCountiesLasted
Sep 6, 12:39 AM CDTSevere Thunderstorm WarningDMXBlack Hawk, Bremer36 min
Sep 6, 1:32 AM CDTSevere Thunderstorm WarningDMXEmmet, Hancock, Kossuth, Winnebago43 min
Sep 6, 2:14 AM CDTSevere Thunderstorm WarningDMXEmmet, Hancock, Kossuth, Winnebago46 min
Sep 6, 2:21 AM CDTSevere Thunderstorm WarningDMXBremer19 min
Sep 6, 2:57 AM CDTSevere Thunderstorm WarningDMXCerro Gordo, Hancock, Kossuth, Winnebago, Worth48 min
Sep 6, 3:40 AM CDTSevere Thunderstorm WarningDMXButler, Cerro Gordo, Franklin, Hancock, Hardin, Wright50 min

Nearby

Severe Thunderstorm Warnings in Iowa, 2020Every severe thunderstorm warning 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.