Alert archive / Nebraska / Severe Thunderstorm Warnings in 2015

Severe Thunderstorm Warning 221, NWS Omaha, NE

September 7, 2015Cass County, Otoe County, Nebraska

NWS Omaha, NE issued this severe thunderstorm warning at Sep 7, 2015, 11:51 PM CDT for Cass County, Otoe County, Nebraska. It was in force for 24 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 7, 2015, 11:51 PM CDT (04:51 UTC)
Expired: Sep 8, 2015, 12:15 AM CDT
In force: 24 min
Issued by: NWS Omaha, NE
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties Cass County, NE, Otoe County, NE

The radar

The Omaha radar (KOAX), 63 km from the middle of the area, began a volume at 04:50 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, 4.9 hours before the alert went out and 63 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: 1737 J/kg
Mixed-layer CIN: -55 J/kg
Mixed-layer LCL: 792 m above ground
0-6 km bulk shear: 46 kt
0-1 km storm-relative helicity: 94 m²/s²
0-3 km storm-relative helicity: 95 m²/s²
Significant tornado parameter: 1.3
Supercell composite: 6.9

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 Sep 7, 11:46 PM CDT, 5 minutes earlier.

Area forecast discussion, Sep 7, 11:46 PM CDT, 5 minutes before

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Hazardous weather outlook, Sep 7, 3:58 PM CDT, 7 hours 53 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
358 PM CDT MON SEP 7 2015

IAZ043-055-056-069-NEZ011-012-015>018-030>034-042>045-050>052-
081100-
MONONA-HARRISON-SHELBY-POTTAWATTAMIE-KNOX-CEDAR-THURSTON-ANTELOPE-
PIERCE-WAYNE-BOONE-MADISON-STANTON-CUMING-BURT-PLATTE-COLFAX-
DODGE-WASHINGTON-BUTLER-SAUNDERS-DOUGLAS-
358 PM CDT MON SEP 7 2015

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHWEST
IOWA...WEST CENTRAL IOWA...EAST CENTRAL NEBRASKA AND NORTHEAST
NEBRASKA.

.DAY ONE...TONIGHT AND TUESDAY

THERE IS A MARGINAL RISK FOR SEVERE THUNDERSTORM DEVELOPMENT OVER
THE OUTLOOK AREA TONIGHT...ALTHOUGH THE BEST SEVERE RISK APPEARS
TO BE SETTING UP SOUTH OF THE REGION. IF STORMS DEVELOP...THE
PRIMARY HAZARDS WOULD BE LARGE HAIL AND DAMAGING WINDS.

.DAYS TWO THROUGH SEVEN...TUESDAY NIGHT THROUGH MONDAY

THUNDERSTORMS WILL BE POSSIBLE AGAIN ON WEDNESDAY NIGHT AS AN
UPPER LEVEL LOW PRESSURE SYSTEM MOVES THROUGH THE AREA.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT LIKELY TONIGHT.

IAZ079-080-090-091-NEZ053-065>068-078-091-081100-
MILLS-MONTGOMERY-FREMONT-PAGE-SARPY-SEWARD-LANCASTER-CASS-OTOE-
SALINE-NEMAHA-
358 PM CDT MON SEP 7 2015

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHWEST
IOWA...EAST CENTRAL NEBRASKA AND SOUTHEAST NEBRASKA.

.DAY ONE...TONIGHT AND TUESDAY

FLASH FLOOD WATCH REMAINS IN EFFECT FROM 7 PM CDT THIS EVENING
THROUGH TUESDAY MORNING.

THUNDERSTORM ACTIVITY WILL REDEVELOP TONIGHT WITH PROLONGED
PERIODS OF HEAVY RAINFALL BECOMING MOST PREVALENT SOUTH OF THE
I-80 CORRIDOR TONIGHT. AS OF NOW...IT APPEARS TOTAL ACCUMULATIONS
OF 2 INCHES OR SO IS LIKELY TO OCCUR IN THE VICINITY OF AREAS THAT
RECEIVED HEAVY RAINFALL SUNDAY NIGHT WHICH WILL HEIGHTEN THE
THREAT OF FLASH FLOODING.

.DAYS TWO THROUGH SEVEN...TUESDAY NIGHT THROUGH MONDAY

THERE IS A CHANCE OF THUNDERSTORMS TUESDAY NIGHT AS WELL AS THURSDAY
AND THURSDAY NIGHT.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED THROUGH TUESDAY.

NEZ088>090-092-093-081100-
JEFFERSON-GAGE-JOHNSON-PAWNEE-RICHARDSON-
358 PM CDT MON SEP 7 2015

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHEAST
NEBRASKA.

.DAY ONE...TONIGHT AND TUESDAY

SEVERE THUNDERSTORM WATCH 505 IN EFFECT UNTIL 9 PM.

FLASH FLOOD WATCH REMAINS IN EFFECT FROM 7 PM CDT THIS EVENING
THROUGH TUESDAY MORNING.

SEVERE THUNDERSTORMS PRODUCING LARGE HAIL AND DAMAGING WINDS ARE
POSSIBLE THROUGH THIS EVENING OVER EXTREME SOUTHEAST NEBRASKA. AN
ISOLATED TORNADO COULD ALSO OCCUR IN THIS AREA AS WELL.

MEANWHILE...PROLONGED PERIODS OF HEAVY RAINFALL WILL BE MOST
PREVALENT SOUTH OF THE I-80 CORRIDOR TONIGHT. AS OF NOW...IT
APPEARS TOTAL ACCUMULATIONS OF 2 INCHES OR SO IS LIKELY TO OCCUR
IN THE VICINITY OF AREAS THAT RECEIVED HEAVY RAINFALL SUNDAY NIGHT
WHICH WILL HEIGHTEN THE THREAT OF FLASH FLOODING.

.DAYS TWO THROUGH SEVEN...TUESDAY NIGHT THROUGH MONDAY

THERE IS A CHANCE OF THUNDERSTORMS TUESDAY NIGHT AS WELL AS THURSDAY
AND THURSDAY NIGHT.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED THIS EVENING.

In the hours before

Local storm report, Sep 7, 9:17 PM CDT, 2 hours 34 minutes before

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Local storm report, Sep 7, 9:33 PM CDT, 2 hours 18 minutes before

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Local storm report, Sep 7, 9:36 PM CDT, 2 hours 15 minutes before

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Special weather statement, Sep 7, 11:02 PM CDT, 49 minutes before

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Local storm report, Sep 7, 11:24 PM CDT, 27 minutes before

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Special weather statement, Sep 7, 11:37 PM CDT, 14 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
Sep 7, 7:12 PM CDT	Special Weather Statement	OAX	Saline	48 min
Sep 7, 7:45 PM CDT	Severe Thunderstorm Warning	OAX	Gage, Lancaster, Saline	45 min
Sep 7, 8:22 PM CDT	Severe Thunderstorm Warning	OAX	Gage	53 min
Sep 7, 8:45 PM CDT	Special Weather Statement	OAX	Seward	45 min
Sep 7, 9:00 PM CDT	Severe Thunderstorm Warning	OAX	Gage, Johnson, Pawnee	45 min
Sep 7, 9:34 PM CDT	Severe Thunderstorm Warning	OAX	Johnson, Nemaha, Pawnee, Richardson	41 min
Sep 7, 9:50 PM CDT	Areal Flood Advisory	OAX	Johnson	4 hr
Sep 7, 10:09 PM CDT	Severe Thunderstorm Warning	OAX	Johnson, Nemaha	51 min
Sep 7, 10:14 PM CDT	Tornado Warning	OAX	Nemaha	15 min
Sep 7, 10:42 PM CDT	Areal Flood Advisory	OAX	Nemaha	4 hr
Sep 7, 10:45 PM CDT	Severe Thunderstorm Warning	OAX	Nemaha	30 min
Sep 7, 11:02 PM CDT	Special Weather Statement	OAX	Lancaster	43 min
Sep 7, 11:37 PM CDT	Special Weather Statement	OAX	Lancaster	38 min
Sep 8, 12:22 AM CDT	Special Weather Statement	OAX	Cass, Lancaster, Otoe	38 min
Sep 8, 3:06 AM CDT	Severe Thunderstorm Warning	OAX	Nemaha, Otoe	24 min
Sep 8, 3:33 AM CDT	Special Weather Statement	OAX	Burt, Colfax, Cuming, Dodge, Thurston	42 min
Sep 8, 7:51 AM CDT	River Flood Warning	OAX	Cass	18 hr

Nearby

Severe Thunderstorm Warnings in Nebraska, 2015 Every severe thunderstorm warning in 2015

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.