Alert archive / Nebraska / Severe Thunderstorm Warnings in 2017

Severe Thunderstorm Warning 23, NWS Omaha, NE

April 9, 2017Cass County, Otoe County, Nebraska; Fremont County, Mills County, Iowa

NWS Omaha, NE issued this severe thunderstorm warning at Apr 9, 2017, 9:47 PM CDT for Cass County, Otoe County, Nebraska; Fremont County, Mills County, Iowa. It was in force for 43 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
Apr 9, 2017, 9:47 PM CDT (02:47 UTC)
Expired
Apr 9, 2017, 10:30 PM CDT
In force
43 min
Issued by
NWS Omaha, NE
Area
Storm-based polygon
Hail
1.0 in
Wind
50.0 mph

Counties Fremont County, IA, Mills County, IA, Cass County, NE, Otoe County, NE

The radar

The Omaha radar (KOAX), 68 km from the middle of the area, began a volume at 02:50 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 nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 2.8 hours before the alert went out and 68 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, Omaha, NE at 00:00Z on 2017-04-10Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 863 joules per kilogram.LCLLFCEL10008507005003002001001 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, Omaha, NE at 00:00Z on 2017-04-10The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 133 square meters per square second.19395878Sfc1 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
863 J/kg
Mixed-layer CIN
-169 J/kg
Mixed-layer LCL
1606 m above ground
0-6 km bulk shear
55 kt
0-1 km storm-relative helicity
133 m²/s²
0-3 km storm-relative helicity
265 m²/s²
Significant tornado parameter
0.1
Supercell composite
5.0

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 Omaha, NE wrote its last area forecast discussion before this severe thunderstorm warning went out at Apr 9, 6:29 PM CDT, 3 hours 18 minutes earlier.

Area forecast discussion, Apr 9, 6:29 PM CDT, 3 hours 18 minutes before
Area Forecast Discussion
National Weather Service Omaha/Valley NE
629 PM CDT Sun Apr 9 2017

.SHORT TERM...(Tonight through Wednesday)
Issued at 341 PM CDT Sun Apr 9 2017

Large scale flow via WV imagery this aftn was depicting a
shortwave trof situated over the nrn high plains beginning to push
into the wrn Dakotas. Meanwhile...88D regional mosaic was showing
a narrow line of convection forming in the panhandle along a
dryline/20deg sfc dew point depressions.

At this point...HIRES models indicate the environment will become
less supportive for severe storm early this evening.  Deep layer
shear will remain relatively strong...but CAPE drop off dramatically.
Cannot totally rule out the possibility for one or two severe/near
severe storms though with hail possible over the nrn CWA.  Toward
mid/late evening...the RAP13 advertises a narrow line convection
forming along increasing bndry lyr threat-E convergence
along/south of the I-80 corridor associated with a cold front
dropping into the cntrl Plains. With DCAPES around 1200J/kg
coupled with increasing lyr Theta-E diff...seems possible a few
storms may produce severe/near-severe winds gusts over the srn
CWA.

Monday aftn...NAM12/GFS20/CMC all prog secondary shot of cold air
advection into the CWA with another round of pcpn activity mainly
over the nrn CWA being driven by rather strong 305-310k isentropic
upglide. More pcpn possible on Wednesday with the passage of a
shortwave trof coupled with warm front lifting thru the region.

.LONG TERM...(Wednesday night through Sunday)
Issued at 341 PM CDT Sun Apr 9 2017

GFS20/ECM/CMC all advertise a progressive pattern during the
extended pds with pcpn chances from Thursday night into Saturday
evening.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 627 PM CDT Sun Apr 9 2017

Thunderstorms across central NE appear to have enough support to
possibly hold together to affect the TAF sites within a few hours,
by 01-02z at KOFK/KLNK and 02-03z at KOMA. Have put in about 2-3
hour window of thunder at all TAF sites. Otherwise, VFR initially,
but becoming MVFR at KOFK through the night. Gusty northwest winds
developing tomorrow morning, with a few showers in the vicinity of
KOFK.

&&

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

SHORT TERM...DEE
LONG TERM...DEE
AVIATION...
Hazardous weather outlook, Apr 9, 4:52 PM CDT, 4 hours 55 minutes before
Hazardous Weather Outlook
National Weather Service Omaha/Valley NE
452 PM CDT Sun Apr 9 2017

IAZ043-055-056-069-079-080-090-091-NEZ011-012-015>018-030>034-
042>045-050>053-065>068-078-088>093-101200-
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-
452 PM CDT Sun Apr 9 2017

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

Scattered thunderstorms are possible this evening. A few of these
storms may become strong to severe, with large hail and damaging
winds the main threats. The potential is highest from
southeasternmost Nebraska into southwest Iowa.

.DAYS TWO THROUGH SEVEN...MONDAY NIGHT THROUGH SUNDAY

There will be a chance for thunderstorms Wednesday and Wednesday
night, and again from Friday into Saturday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated tonight or Monday.

In the hours before

Local storm report, Apr 9, 8:59 PM CDT, 48 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
859 PM CDT SUN APR 09 2017

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

0859 PM     HAIL             WILBER                  40.48N 96.96W
04/09/2017  M1.00 INCH       SALINE             NE   TRAINED SPOTTER

&&

VDEWALD
Local storm report, Apr 9, 9:09 PM CDT, 38 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
909 PM CDT SUN APR 09 2017

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

0900 PM     HAIL             FIRTH                   40.53N 96.60W
04/09/2017  M1.00 INCH       LANCASTER          NE   TRAINED SPOTTER

&&

VDEWALD
Local storm report, Apr 9, 9:15 PM CDT, 32 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
915 PM CDT SUN APR 09 2017

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

0910 PM     HAIL             1 S PANAMA              40.59N 96.51W
04/09/2017  M1.00 INCH       LANCASTER          NE   TRAINED SPOTTER

&&

VDEWALD
Local storm report, Apr 9, 9:17 PM CDT, 30 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
917 PM CDT SUN APR 09 2017

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

0904 PM     HAIL             DE WITT                 40.40N 96.92W
04/09/2017  M1.00 INCH       SALINE             NE   EMERGENCY MNGR

&&

VDEWALD
Local storm report, Apr 9, 9:27 PM CDT, 20 minutes before
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The office that day

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

IssuedProductOfficeCountiesLasted
Apr 9, 8:14 PM CDTSevere Thunderstorm WarningOAXJefferson, Saline46 min
Apr 9, 8:26 PM CDTSpecial Weather StatementOAXButler, Saunders34 min
Apr 9, 8:44 PM CDTSpecial Weather StatementOAXLancaster46 min
Apr 9, 8:52 PM CDTSevere Thunderstorm WarningOAXGage, Jefferson, Lancaster, Saline38 min
Apr 9, 9:11 PM CDTSevere Thunderstorm WarningOAXGage, Johnson, Lancaster, Nemaha, Otoe49 min
Apr 9, 9:24 PM CDTSevere Thunderstorm WarningOAXGage, Johnson, Otoe, Pawnee33 min
Apr 9, 10:02 PM CDTSpecial Weather StatementOAXPawnee43 min
Apr 9, 10:18 PM CDTSevere Thunderstorm WarningOAXJohnson, Nemaha, Pawnee, Richardson42 min
Apr 9, 10:26 PM CDTSpecial Weather StatementOAXPawnee49 min
Apr 9, 10:30 PM CDTSevere Thunderstorm WarningOAXGage, Johnson, Nemaha, Pawnee, Richardson45 min
Apr 9, 11:01 PM CDTSpecial Weather StatementOAXNemaha29 min
Apr 9, 11:17 PM CDTSpecial Weather StatementOAXNemaha43 min
Apr 9, 11:36 PM CDTSpecial Weather StatementOAXNemaha, Richardson24 min
Apr 9, 11:39 PM CDTSevere Thunderstorm WarningOAXNemaha, Richardson36 min
Apr 10, 12:16 AM CDTSevere Thunderstorm WarningOAXRichardson29 min
Apr 10, 3:28 PM CDTFreeze WarningOAXButler, Gage, Jefferson, Lancaster, Saline, Seward17 hr
Apr 9, 10:05 PM CDTSpecial Weather StatementOAXFremont40 min

Nearby

Severe Thunderstorm Warnings in Nebraska, 2017Severe Thunderstorm Warnings in Iowa, 2017Every severe thunderstorm warning in 2017

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.