Alert archive / Nebraska / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 131, NWS Omaha, NE

August 7, 2021Cass County, Lancaster County, Saunders County, Nebraska

NWS Omaha, NE issued this severe thunderstorm warning at Aug 7, 2021, 9:54 PM CDT for Cass County, Lancaster County, Saunders County, Nebraska. It was in force for 17 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Aug 7, 2021, 9:54 PM CDT (02:54 UTC)
Expired: Aug 7, 2021, 10:11 PM CDT
In force: 17 min
Issued by: NWS Omaha, NE
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties Cass County, NE, Lancaster County, NE, Saunders County, NE

The radar

The Omaha radar (KOAX), 33 km from the middle of the area, began a volume at 02:57 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.

Did it verify

Not verified. The Iowa Environmental Mesonet's Cow found no qualifying storm report inside this severe thunderstorm warning while it was in force. That is not proof nothing happened: reports are thin where few people live.

Cow counts a report within 15 km of the polygon while the warning was in force: a tornado for a tornado warning; hail of 1 inch or more, a gust of 58 mph or more or wind damage for a severe thunderstorm warning; a flash flood report for a flash flood warning.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Aug 7, 6:35 PM CDT	Severe Thunderstorm Watch	SPC	6 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 2.9 hours before the alert went out and 33 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: 2933 J/kg
Mixed-layer CIN: -124 J/kg
Mixed-layer LCL: 1327 m above ground
0-6 km bulk shear: 32 kt
0-1 km storm-relative helicity: 149 m²/s²
0-3 km storm-relative helicity: 195 m²/s²
Significant tornado parameter: 0.4
Supercell composite: 3.3

Open this sounding in Storm Lab

The text

As transmitted.

057 
WUUS53 KOAX 080254
SVROAX
NEC025-109-155-080330-
/O.NEW.KOAX.SV.W.0131.210808T0254Z-210808T0330Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Omaha/Valley Nebraska
954 PM CDT Sat Aug 7 2021

The National Weather Service in Omaha has issued a

* Severe Thunderstorm Warning for...
  Northeastern Lancaster County in southeastern Nebraska...
  Southeastern Saunders County in east central Nebraska...
  Northwestern Cass County in southeastern Nebraska...

* Until 1030 PM CDT.

* At 953 PM CDT, a severe thunderstorm was located over Greenwood, or
  17 miles northeast of Lincoln, moving northeast at 40 mph.

  HAZARD...60 mph wind gusts and quarter size hail.

  SOURCE...Radar indicated.

  IMPACT...Hail damage to vehicles is expected. Expect wind damage 
           to roofs, siding, and trees.

* This severe thunderstorm will be near...
  Ashland around 1005 PM CDT.

This includes Interstate 80 in Nebraska between mile markers 409 and
426.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4093 9666 4117 9645 4113 9632 4112 9631
      4109 9634 4104 9632 4102 9629 4101 9624
      4100 9624 4082 9645
TIME...MOT...LOC 0253Z 230DEG 33KT 4099 9646 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

BLB

1 follow-up statement

104 
WWUS53 KOAX 080311 RRA
SVSOAX

Severe Weather Statement
National Weather Service Omaha/Valley Nebraska
1011 PM CDT Sat Aug 7 2021

NEC025-109-155-080321-
/O.CAN.KOAX.SV.W.0131.000000T0000Z-210808T0330Z/
Lancaster NE-Saunders NE-Cass NE-
1011 PM CDT Sat Aug 7 2021

...THE SEVERE THUNDERSTORM WARNING FOR NORTHEASTERN LANCASTER...
SOUTHEASTERN SAUNDERS AND NORTHWESTERN CASS COUNTIES IS CANCELLED...
                
The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore, the warning has been cancelled.  However gusty winds and
very heavy rain are still possible with this thunderstorm.

A Severe Thunderstorm Watch remains in effect until 100 AM CDT for
southeastern and east central Nebraska.

LAT...LON 4093 9666 4117 9645 4113 9632 4112 9631
      4109 9634 4104 9632 4102 9629 4101 9624
      4100 9624 4082 9645
TIME...MOT...LOC 0310Z 230DEG 33KT 4110 9629 

$$

BLB

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 Aug 7, 6:29 PM CDT, 3 hours 25 minutes earlier.

Area forecast discussion, Aug 7, 6:29 PM CDT, 3 hours 25 minutes before

Area Forecast Discussion
National Weather Service Omaha/Valley NE
629 PM CDT Sat Aug 7 2021

...Updated Aviation Forecast Discussion...

.DISCUSSION...
Issued at 243 PM CDT Sat Aug 7 2021

A complex severe weather scenario has been unfolding this morning,
largely due to the plentiful cloud cover and the convection that
occurred earlier this morning. As we go further into the
afternoon, ML CAPE values are expected to increase to around 3500
J/kg, with effective bulk shear values ranging from 20 to 30 kts
by the time convection gets to eastern Nebraska and southwestern
Iowa. Visible satellite shows developing cumulus in south-central
Nebraska into Kansas, and this area will serve as the starting
point for convection this evening. These storms are expected to
begin after 5 PM in a discrete mode with hail being the primary
threat. Veering low-level wind profiles, and enhanced 0-3 km
shear suggest that there is also a limited tornado threat
associated with the initial cells in that same area. These cells
are then expected to evolve into a larger complex that is
expected to begin pushing ENE into eastern Nebraska after 7 PM. As
this larger complex forms, the main threat evolves into damaging
winds as the storm complex becomes cold-pool dominant. These
storms are expected to move eastward towards the Omaha and Lincoln
metro areas, with the best timing for each being 10 and 11 PM
respectively. These storms will continue east and gradually fizzle
out into the middle of the night in central and eastern Iowa. A
few light rain showers and rumbles of thunder could last until
sunrise Sunday as the back end of the mid-level wave advects
through the area.

Tomorrow morning, those spotty showers are expected to give way to
dry weather and southwesterly winds look to settle in. A return to
mostly sunny skies will aid in the return of some warm
temperatures, with highs in the upper 80's to low 90's are
expected along with heat indices approaching 100 degrees. Monday
is expected to hold even warmer temperatures, with areas near the
South Dakota border reaching over 100 degrees. Heat indices of 100
to 110 are currently slated for that day, and could necessitate a
Heat Advisory if the forecast remains on track. Tuesday a mid-
level shortwave trough is expected to pass through the northern
CONUS and may be the next chance at severe weather for the area,
as it drags a cold front eastward. How far south this frontal zone
extends is still in flux, and the location will likely dictate
what kind of hazards we expect.

Wednesday into the weekend, highs in the 90's on Wed/Thu will give
way to cooler weather Fri/Sat as the mid-level flow transitions
to northwesterly flow. Several shortwave impulses are depicted by
the global deterministic models, and may drive low-end shower and
storm chances in the extended forecast. While nothing looks like a
soaker, some kind of rainfall will be greatly appreciated.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 615 PM CDT Sat Aug 7 2021

Mostly VFR conditions are expected however through 07z there is a
good chance of variable conditions in and around thunderstorms
with gusty strong winds. Intermittent MVFR cigs are possible
through 07z.

&&

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

DISCUSSION...Petersen
AVIATION...Kern

Hazardous weather outlook, Aug 7, 3:45 PM CDT, 6 hours 9 minutes before

Hazardous Weather Outlook
National Weather Service Omaha/Valley NE
345 PM CDT Sat Aug 7 2021

IAZ043-055-056-069-079-080-090-091-NEZ011-012-015>018-030>034-
042>045-050>053-065>068-078-088>093-081045-
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-
345 PM CDT Sat Aug 7 2021

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 Sunday

There is a slight risk of severe thunderstorms this afternoon and
continuing overnight. Large hail is the primary hazard with the
initial storm development this afternoon, with damaging winds the
more likely severe hazard during the evening and overnight.

Storms are forecast to develop in central Nebraska early this
evening where instability and shear are maximized along an
approaching cold front. These storms are expected to congeal into
a larger cluster, then sweep east across eastern Nebraska and
western Iowa through the late evening and overnight.

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

There is a marginal risk of severe thunderstorms Sunday afternoon
in parts of far southeast Nebraska and southwest Iowa.

Severe thunderstorms are also possible Monday night and Tuesday as
a cold front moves into the Plains.

Otherwise hot and muggy weather will return to the region this
Sunday and Monday. Heat index values are currently expected to
reach or exceed 105 on Monday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated.

In the hours before

Local storm report, Aug 7, 9:43 PM CDT, 11 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
943 PM CDT SAT AUG 7 2021

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

0940 PM     FLASH FLOOD      2 WNW OFFUTT AFB        41.13N 95.95W
08/07/2021                   SARPY              NE   PUBLIC

            REPORT FROM MPING: STREET/ROAD FLOODING;
            STREET/ROAD CLOSED; VEHICLES STRANDED.

&&

Local storm report, Aug 7, 9:47 PM CDT, 7 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
947 PM CDT SAT AUG 7 2021

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

0946 PM     FLASH FLOOD      3 SE OMAHA              41.23N 95.96W
08/07/2021                   DOUGLAS            NE   PUBLIC

            FLOODING OVER THE CURBS. ESTIMATED 6 INCHES
            OF RAIN.

&&

DEWALD

Local storm report, Aug 7, 9:48 PM CDT, 6 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
948 PM CDT SAT AUG 7 2021

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

0943 PM     FLASH FLOOD      3 WSW BELLEVUE          41.14N 95.96W
08/07/2021                   SARPY              NE   PUBLIC

            REPORT FROM MPING: STREET/ROAD FLOODING;
            STREET/ROAD CLOSED; VEHICLES STRANDED.

&&

DEWALD

Local storm report, Aug 7, 9:49 PM CDT, 5 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
949 PM CDT SAT AUG 7 2021

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

0949 PM     FLASH FLOOD      2 N MILLARD             41.23N 96.16W
08/07/2021                   DOUGLAS            NE   PUBLIC

            CAR STRANDED IN FLOOD WATERS.

&&

DEWALD

Local storm report, Aug 7, 9:50 PM CDT, 4 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
950 PM CDT SAT AUG 7 2021

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

0946 PM     HAIL             OFFUTT AFB              41.11N 95.92W
08/07/2021  E1.00 INCH       SARPY              NE   PUBLIC

&&

DEWALD

Local storm report, Aug 7, 9:51 PM CDT, 3 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
951 PM CDT SAT AUG 7 2021

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

0947 PM     HAIL             BELLEVUE                41.16N 95.92W
08/07/2021  M1.00 INCH       SARPY              NE   EMERGENCY MNGR

            NEAR BELLEVUE UNIVERSITY - QUARTER TO
            HALF-DOLLAR SIZE HAIL.

&&

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 7, 7:23 PM CDT	Special Weather Statement	OAX	Platte	52 min
Aug 7, 7:29 PM CDT	Severe Thunderstorm Warning	OAX	Butler, Saunders	46 min
Aug 7, 7:56 PM CDT	Severe Thunderstorm Warning Considerable damage threat	OAX	Cass, Douglas, Sarpy, Saunders	49 min
Aug 7, 8:10 PM CDT	Severe Thunderstorm Warning	OAX	Butler	50 min
Aug 7, 8:23 PM CDT	Severe Thunderstorm Warning Considerable damage threat	OAX	Cass, Sarpy, Saunders	22 min
Aug 7, 8:29 PM CDT	Severe Thunderstorm Warning	OAX	Saunders	31 min
Aug 7, 8:33 PM CDT	Areal Flood Advisory	OAX	Butler, Colfax, Lancaster, Platte, Saunders, Seward	4 hr
Aug 7, 8:39 PM CDT	Areal Flood Advisory	OAX	Douglas, Sarpy	3 hr
Aug 7, 8:41 PM CDT	Severe Thunderstorm Warning Considerable damage threat	OAX	Cass, Douglas, Lancaster, Sarpy, Saunders	49 min
Aug 7, 8:50 PM CDT	Areal Flood Advisory	OAX	Douglas, Sarpy, Saunders	3 hr
Aug 7, 8:50 PM CDT	Severe Thunderstorm Warning Considerable damage threat	OAX	Douglas	40 min
Aug 7, 8:55 PM CDT	Severe Thunderstorm Warning	OAX	Butler, Saunders	35 min
Aug 7, 9:05 PM CDT	Flash Flood Warning	OAX	Butler, Colfax, Douglas, Sarpy, Saunders	4 hr
Aug 7, 9:09 PM CDT	Severe Thunderstorm Warning	OAX	Gage, Jefferson, Saline	51 min
Aug 7, 9:24 PM CDT	Severe Thunderstorm Warning	OAX	Douglas, Sarpy, Washington	51 min
Aug 7, 9:35 PM CDT	Flash Flood Warning Considerable damage threat	OAX	Douglas, Sarpy	3 hr
Aug 7, 9:37 PM CDT	Severe Thunderstorm Warning	OAX	Butler, Lancaster, Saunders, Seward	22 min
Aug 7, 9:49 PM CDT	Severe Thunderstorm Warning	OAX	Gage, Jefferson, Johnson, Pawnee	41 min
Aug 7, 9:59 PM CDT	Severe Thunderstorm Warning	OAX	Butler	27 min
Aug 7, 10:25 PM CDT	Flash Flood Warning	OAX	Cass, Lancaster, Otoe, Sarpy, Saunders, Seward	2 hr
Aug 7, 10:30 PM CDT	Flash Flood Warning Emergency	OAX	Douglas	89 min
Aug 7, 10:38 PM CDT	Severe Thunderstorm Warning	OAX	Johnson, Nemaha, Otoe	52 min
Aug 7, 11:10 PM CDT	River Flood Warning	OAX	Saunders	13 hr
Aug 8, 12:41 AM CDT	Areal Flood Warning	OAX	Butler, Cass, Colfax, Douglas, Lancaster, Otoe and 4 more	12 hr
Aug 8, 2:37 PM CDT	Heat Advisory	OAX	Butler, Cass, Colfax, Dodge, Douglas, Gage and 13 more	54 hr

Nearby

Severe Thunderstorm Warnings in Nebraska, 2021 Every severe thunderstorm warning in 2021

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.