Alert archive / Nebraska / Severe Thunderstorm Warnings in 2018

Severe Thunderstorm Warning 285, NWS Omaha, NE

September 20, 20185 counties in Nebraska

NWS Omaha, NE issued this severe thunderstorm warning at Sep 20, 2018, 7:37 PM CDT for 5 counties in Nebraska. 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 counties it named.

The facts

Issued: Sep 20, 2018, 7:37 PM CDT (00:37 UTC)
Expired: Sep 20, 2018, 8:00 PM CDT
In force: 23 min
Issued by: NWS Omaha, NE
Area: Storm-based polygon
Hail: 0.75 in
Wind: 60.0 mph

Counties Gage County, NE, Jefferson County, NE, Lancaster County, NE, Saline County, NE, Seward County, NE

The radar

The Omaha radar (KOAX), 102 km from the middle of the area, began a volume at 00:36 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
Sep 20, 3:11 PM CDT	Severe Thunderstorm Watch	SPC	8 hr

The nearest sounding before it

Topeka, KS (KFOE), launched 00:00Z, 0.6 hours before the alert went out and 204 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: 681 J/kg
Mixed-layer CIN: -52 J/kg
Mixed-layer LCL: 1824 m above ground
0-6 km bulk shear: 31 kt
0-1 km storm-relative helicity: 64 m²/s²
0-3 km storm-relative helicity: 166 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 3.3

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 20, 6:10 PM CDT, 1 hour 27 minutes earlier.

Area forecast discussion, Sep 20, 6:10 PM CDT, 1 hour 27 minutes before

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Hazardous weather outlook, Sep 20, 3:33 PM CDT, 4 hours 4 minutes before

Hazardous Weather Outlook
National Weather Service Omaha/Valley NE
333 PM CDT Thu Sep 20 2018

IAZ043-055-056-069-079-080-090-091-NEZ015-018-032>034-042>045-
050>053-065>068-078-088>093-211045-
Monona-Harrison-Shelby-Pottawattamie-Mills-Montgomery-Fremont-
Page-Thurston-Wayne-Stanton-Cuming-Burt-Platte-Colfax-Dodge-
Washington-Butler-Saunders-Douglas-Sarpy-Seward-Lancaster-Cass-
Otoe-Saline-Jefferson-Gage-Johnson-Nemaha-Pawnee-Richardson-
333 PM CDT Thu Sep 20 2018

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 Friday

A band of strong to severe thunderstorms is expected to spread
east across the area this afternoon through this evening, along
and ahead of a cold front. The primary hazard with these storms is
damaging winds, though some hail is also possible.

Minor flooding will continue along the Missouri River upstream
of Lewis and Clark Lake in Knox County and in the vicinity of
Brownville.

.DAYS TWO THROUGH SEVEN...Friday night through Thursday

Minor flooding will continue along the Missouri River upstream of
Lewis and Clark Lake in Knox County. Minor flooding along the
Missouri River in the vicinity of Brownville should subside by
Friday.

.SPOTTER INFORMATION STATEMENT...

Storm spotter activation may be needed on a localized basis late
this afternoon and this evening.

NEZ011-012-016-017-030-031-211045-
Knox-Cedar-Antelope-Pierce-Boone-Madison-
333 PM CDT Thu Sep 20 2018

This Hazardous Weather Outlook is for portions of northeast
Nebraska.

.DAY ONE...Tonight and Friday

Isolated strong storms are possible this afternoon into early
evening. Gusty winds and some small hail are possible.

Minor flooding will continue along the Missouri River upstream
of Lewis and Clark Lake in Knox County and in the vicinity of
Brownville.

.DAYS TWO THROUGH SEVEN...Friday night through Thursday

Minor flooding will continue along the Missouri River upstream of
Lewis and Clark Lake in Knox County.

.SPOTTER INFORMATION STATEMENT...

Storm spotter activation will not be required through Friday.

In the hours before

Local storm report, Sep 20, 5:56 PM CDT, 1 hour 41 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
556 PM CDT THU SEP 20 2018

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

0521 PM     TSTM WND GST     BLAIR                   41.54N 96.14W
09/20/2018  E65 MPH          WASHINGTON         NE   TRAINED SPOTTER

            ESTIMATED 60-65MPH WIND.

&&

Special weather statement, Sep 20, 5:58 PM CDT, 1 hour 39 minutes before

Special Weather Statement
National Weather Service Omaha/Valley Nebraska
558 PM CDT THU SEP 20 2018

NEZ065-202330-
Seward NE-
558 PM CDT THU SEP 20 2018

...SIGNIFICANT WEATHER ADVISORY FOR SEWARD COUNTY UNTIL 630 PM CDT...

At 558 PM CDT, Doppler radar was tracking a strong thunderstorm near
Beaver Crossing, or 15 miles southeast of York, moving northeast at
40 mph.

Nickel size hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Seward, Milford, Beaver Crossing, Goehner, Cordova and Tamora.

A Severe Thunderstorm Watch remains in effect until 1100 PM CDT for
southeastern Nebraska.

LAT...LON 4086 9737 4100 9711 4077 9692 4070 9726
      4070 9737
TIME...MOT...LOC 2258Z 236DEG 36KT 4076 9734

MEAD

Local storm report, Sep 20, 6:07 PM CDT, 1 hour 30 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
607 PM CDT THU SEP 20 2018

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

0605 PM     HAIL             4 W BEAVER CROSSING     40.79N 97.35W
09/20/2018  M1.25 INCH       SEWARD             NE   TRAINED SPOTTER

&&

Local storm report, Sep 20, 6:08 PM CDT, 1 hour 29 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
608 PM CDT THU SEP 20 2018

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

0605 PM     TSTM WND GST     4 W BEAVER CROSSING     40.79N 97.35W
09/20/2018  E65 MPH          SEWARD             NE   TRAINED SPOTTER

            SMALL TREE LIMBS DOWN AND 65 MPH WIND
            ESTIMATED.

&&

Special weather statement, Sep 20, 6:19 PM CDT, 1 hour 18 minutes before

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Local storm report, Sep 20, 6:33 PM CDT, 1 hour 4 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 20, 7:10 PM CDT	Severe Thunderstorm Warning	OAX	Jefferson, Saline	35 min
Sep 20, 8:02 PM CDT	Severe Thunderstorm Warning	OAX	Cass, Gage, Johnson, Lancaster, Nemaha, Otoe and 1 more	28 min
Sep 20, 8:24 PM CDT	Severe Thunderstorm Warning	OAX	Cass, Johnson, Nemaha, Otoe, Pawnee, Richardson and 2 more	36 min
Sep 20, 9:41 PM CDT	Special Weather Statement	OAX	Richardson	34 min
Sep 21, 10:06 AM CDT	River Flood Warning	OAX	Washington	7 days
Sep 21, 10:06 AM CDT	River Flood Warning	OAX	Cass	13 days
Sep 21, 10:06 AM CDT	River Flood Warning	OAX	Otoe	40 days
Sep 21, 10:06 AM CDT	River Flood Warning	OAX	Richardson	51 days
Sep 21, 10:25 AM CDT	River Flood Advisory	OAX	Douglas, Sarpy	8 days
Sep 20, 7:14 PM CDT	Severe Thunderstorm Warning	OAX	Harrison, Pottawattamie, Shelby	31 min
Sep 20, 7:56 PM CDT	Special Weather Statement	OAX	Shelby	34 min
Sep 20, 8:49 PM CDT	Severe Thunderstorm Warning	OAX	Fremont, Mills, Montgomery, Page	26 min

Nearby

Severe Thunderstorm Warnings in Nebraska, 2018 Every severe thunderstorm warning in 2018

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.