Alert archive / Iowa / Severe Thunderstorm Warnings in 2023

Severe Thunderstorm Warning 101, NWS Omaha, NE

May 7, 2023Harrison County, Shelby County, Iowa

NWS Omaha, NE issued this severe thunderstorm warning at May 7, 2023, 10:38 PM CDT for Harrison County, Shelby County, Iowa. It was in force for 48 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: May 7, 2023, 10:38 PM CDT (03:38 UTC)
Expired: May 7, 2023, 11:26 PM CDT
In force: 48 min
Issued by: NWS Omaha, NE
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties Harrison County, IA, Shelby County, IA

The radar

The Omaha radar (KOAX), 78 km from the middle of the area, began a volume at 03:42 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
May 7, 6:45 PM CDT	Severe Thunderstorm Watch	SPC	6 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 3.6 hours before the alert went out and 78 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: 2189 J/kg
Mixed-layer CIN: -62 J/kg
Mixed-layer LCL: 1443 m above ground
0-6 km bulk shear: 55 kt
0-1 km storm-relative helicity: 67 m²/s²
0-3 km storm-relative helicity: 282 m²/s²
Significant tornado parameter: 1.8
Supercell composite: 18.2

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 Omaha, NE wrote its last area forecast discussion before this severe thunderstorm warning went out at May 7, 6:26 PM CDT, 4 hours 12 minutes earlier.

Area forecast discussion, May 7, 6:26 PM CDT, 4 hours 12 minutes before

Area Forecast Discussion
National Weather Service Omaha/Valley NE
626 PM CDT Sun May 7 2023

...Updated Aviation Forecast Discussion...

.DISCUSSION...
Issued at 200 PM CDT Sun May 7 2023

Key Messages:

 - Enhanced risk for severe storms tonight

 - Thunderstorm chances continue through next weekend

Regional obs were showing an area of low pressure situated over
north-central KS with attendant warm front extending into southeast
NE/s-central IA. Meanwhile, leading edge of cold front extended from
about the NE panhandle to southeast SD.

Diurnal heating has allowed for decent destabilization so far across
the CWA where MLCAPES were 1500-2500 J/kg.

Near term issue to contend with is possible severe storms later this
evening. Short term models continue to show post-frontal convection
developing just west of the CWA within the next few hours before
advancing eastward late this afternoon. By early evening, expect
discrete storm formation over the CWA with quick intensification
along axis of steep low level lapse rates/increasing boundary layer
moisture convergence. With deep layer shear progged over 50kt, the
environment will be quite capable of supporting rotating cells with
large hail the initial severe threat. As the evening progresses,
expect storm mode transition to MCS with wind threat becoming the
primary hazard. And given shear on hand, cannot rule out the
potential for a tornadic storm.

Otherwise, thunder chances are in play Monday into next weekend in
part to several passing upper impulses before the approach of a
strong upper system on Thursday.

Highs:
Mon - upper 70s/low 80s
Tue - mid 70s/low 80s
Wed - mid/upper 70s
Thu - mid/upper 70s
Fri - low 80S
Sat - low 80s
Sun - mid 70s

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 626 PM CDT Sun May 7 2023

Main concern remains thunderstorm potential this evening. Storms
could develop in both the KOMA and KLNK anywhere in the 00 to 02Z
timeframe, but guidance suggests the highest chances would be 01
to 04Z, so included TEMPO mention at both sites. Storms could be
strong to severe, with hail, winds over 50 kts, and a possible
tornado, but confidence in a severe storm hitting any TAF site is
low. For KOFK, storms currently in central Nebraska will be the
concern. Guidance suggests they may slide just south, but included
TEMPO group there as well from 02 to 04Z. Storms should exit
shortly after midnight with VFR conditions and northerly winds
near 10 kts thereafter.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&

DISCUSSION...DEE
AVIATION...CA

Hazardous weather outlook, May 7, 3:15 PM CDT, 7 hours 23 minutes before

Hazardous Weather Outlook
National Weather Service Omaha/Valley NE
315 PM CDT Sun May 7 2023

IAZ043-055-056-069-079-080-090-091-NEZ011-012-015>018-030>034-
042>045-050>053-065>068-078-088>093-081015-
Monona-Harrison-Shelby-Pottawattamie-Mills-Montgomery-Fremont-
Page-Knox-Cedar-Thurston-Antelope-Pierce-Wayne-Boone-Madison-
Stanton-Cuming-Burt-Platte-Colfax-Dodge-Washington-Butler-
Saunders-Douglas-Sarpy-Seward-Lancaster-Cass-Otoe-Saline-
Jefferson-Gage-Johnson-Nemaha-Pawnee-Richardson-
315 PM CDT Sun May 7 2023

This Hazardous Weather Outlook is for portions of southwest
Iowa...west central Iowa...east central Nebraska...northeast
Nebraska and southeast Nebraska.

.DAY ONE...Tonight and Monday

Severe thunderstorms will be possible this evening, mainly along
and south of the I-80 corridor. The primary hazards will be large
hail and damaging winds. A few storms may even be accompanied by
a tornado.

.DAYS TWO THROUGH SEVEN...Monday night through Sunday

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed tonight..

In the hours before

Local storm report, May 7, 9:52 PM CDT, 46 minutes before

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Local storm report, May 7, 10:05 PM CDT, 33 minutes before

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Local storm report, May 7, 10:16 PM CDT, 22 minutes before

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Local storm report, May 7, 10:27 PM CDT, 11 minutes before

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Local storm report, May 7, 10:30 PM CDT, 8 minutes before

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Local storm report, May 7, 10:32 PM CDT, 6 minutes before

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The office that day

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

Issued	Product	Office	Counties	Lasted
May 7, 7:06 PM CDT	Severe Thunderstorm Warning	OAX	Cass, Otoe	54 min
May 7, 7:17 PM CDT	Severe Thunderstorm Warning	OAX	Gage, Johnson, Lancaster, Otoe	43 min
May 7, 7:20 PM CDT	Severe Thunderstorm Warning	OAX	Saline	29 min
May 7, 7:21 PM CDT	Severe Thunderstorm Warning	OAX	Cass, Sarpy	54 min
May 7, 7:27 PM CDT	Severe Thunderstorm Warning	OAX	Gage, Jefferson, Lancaster, Saline	48 min
May 7, 7:33 PM CDT	Severe Thunderstorm Warning	OAX	Cass	42 min
May 7, 7:36 PM CDT	Severe Thunderstorm Warning	OAX	Gage, Jefferson	28 min
May 7, 7:48 PM CDT	Severe Thunderstorm Warning	OAX	Johnson, Nemaha, Otoe	42 min
May 7, 7:56 PM CDT	Severe Thunderstorm Warning	OAX	Gage, Jefferson, Saline	34 min
May 7, 7:56 PM CDT	Severe Thunderstorm Warning Considerable damage threat	OAX	Cass, Otoe	64 min
May 7, 8:16 PM CDT	Severe Thunderstorm Warning	OAX	Gage, Jefferson, Johnson, Pawnee	44 min
May 7, 8:16 PM CDT	Severe Thunderstorm Warning	OAX	Cass	44 min
May 7, 8:21 PM CDT	Severe Thunderstorm Warning	OAX	Lancaster, Sarpy, Saunders	39 min
May 7, 8:26 PM CDT	Severe Thunderstorm Warning	OAX	Butler, Lancaster, Saunders, Seward	34 min
May 7, 8:29 PM CDT	Severe Thunderstorm Warning	OAX	Nemaha, Otoe	31 min
May 7, 8:56 PM CDT	Severe Thunderstorm Warning	OAX	Lancaster, Saunders	34 min
May 7, 8:56 PM CDT	Severe Thunderstorm Warning	OAX	Nemaha, Otoe	19 min
May 7, 8:58 PM CDT	Severe Thunderstorm Warning	OAX	Gage, Johnson, Pawnee	47 min
May 7, 9:21 PM CDT	Severe Thunderstorm Warning	OAX	Cass, Otoe	39 min
May 7, 9:44 PM CDT	Severe Thunderstorm Warning	OAX	Nemaha, Pawnee, Richardson	61 min
May 7, 10:04 PM CDT	Severe Thunderstorm Warning	OAX	Gage, Jefferson, Saline	56 min
May 7, 10:54 PM CDT	Severe Thunderstorm Warning Considerable damage threat	OAX	Gage, Jefferson, Johnson, Lancaster, Otoe, Pawnee and 1 more	51 min
May 7, 11:10 PM CDT	Severe Thunderstorm Warning Considerable damage threat	OAX	Cass, Gage, Johnson, Lancaster, Nemaha, Otoe and 2 more	40 min
May 7, 7:39 PM CDT	Severe Thunderstorm Warning	OAX	Montgomery, Pottawattamie	96 min
May 7, 8:11 PM CDT	Tornado Warning	OAX	Fremont	22 min
May 7, 8:13 PM CDT	Tornado Warning	OAX	Mills, Montgomery, Page	19 min
May 7, 8:29 PM CDT	Severe Thunderstorm Warning Considerable damage threat	OAX	Fremont, Mills, Montgomery, Page	61 min
May 7, 8:54 PM CDT	Severe Thunderstorm Warning Considerable damage threat	OAX	Montgomery, Page	66 min
May 7, 8:57 PM CDT	Severe Thunderstorm Warning	OAX	Mills, Pottawattamie	14 min
May 7, 9:17 PM CDT	Severe Thunderstorm Warning	OAX	Shelby	28 min
May 7, 9:36 PM CDT	Severe Thunderstorm Warning	OAX	Pottawattamie	39 min
May 7, 10:06 PM CDT	Severe Thunderstorm Warning	OAX	Pottawattamie	54 min
May 7, 10:15 PM CDT	Severe Thunderstorm Warning	OAX	Pottawattamie	47 min
May 7, 11:04 PM CDT	Severe Thunderstorm Warning	OAX	Shelby	30 min

Nearby

Severe Thunderstorm Warnings in Iowa, 2023 Every severe thunderstorm warning in 2023

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.