Alert archive / Nebraska / Special Weather Statements in 2017

Special Weather Statement, NWS Omaha, NE

August 21, 2017Knox County, Nebraska

NWS Omaha, NE issued this special weather statement at Aug 21, 2017, 1:49 PM CDT for Knox County, Nebraska. It was in force for 56 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 21, 2017, 1:49 PM CDT (18:49 UTC)
Expired: Aug 21, 2017, 2:45 PM CDT
In force: 56 min
Issued by: NWS Omaha, NE

County Knox County, NE

The radar

The Sioux Falls radar (KFSD), 152 km from the middle of the area, began a volume at 18:52 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 text

As transmitted.

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What forecasters said that day

The local office's own words before this special weather statement 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 special weather statement went out at Aug 21, 6:02 AM CDT, 7 hours 47 minutes earlier.

Area forecast discussion, Aug 21, 6:02 AM CDT, 7 hours 47 minutes before

Area Forecast Discussion
National Weather Service Omaha/Valley NE
602 AM CDT Mon Aug 21 2017

.SHORT TERM...(Today through Wednesday)
Issued at 225 AM CDT Mon Aug 21 2017

Rapid MCS formation has occurred early this morning over western
IA near the intersection of a synoptic surface front and residual
outflow boundary, per mesoanalysis. The presence of a 40-45 kt
southwesterly LLJ will aid in back-building storms across our IA
counties through 12z with a net south or southeast displacement of
the MCS through that time frame. Elsewhere, IR satellite data
indicate a plume of mid to high-level moisture (and associated
clouds) advancing northeast through the High Plains in association
with a subtropical-branch shortwave trough over NM.

--Eclipse forecast--

While it appears that the ongoing storms across IA will shift
east of the area by mid morning, model guidance remains consistent
in showing the High Plains cloud shield steadily advancing
northeast into the mid-MO Valley today. Model cross sections of
relative humidity along the path of totality indicate the
potential for considerable cloudiness at 1 PM CDT at or above the
18-20 kft level. At present, we remain uncertain of the opacity of
these clouds, and this is something visible satellite should
clarify in the hours leading up to the event. High temperatures
will be generally in the lower to mid 80s with afternoon heat
index values rising into the lower 90s across southeast NE and
southwest IA. Precipitation chances will remain low through early
afternoon.

By mid afternoon into this evening, height falls associated with
an amplifying polar-branch trough over the ND-MN Red River Valley
coupled with the influence of the subtropical-branch system
tracking into the central Plains will yield an uptick in
convective activity across the forecast area. The most intense
storms will likely form along a cold front moving south into
northeast NE and west-central Iowa where forecast soundings
indicate ample instability and vertical shear for organized severe
weather. Damaging winds, hail and heavy rain will be the primary
hazards with these storms as they advance southeast across the
area this evening and tonight. An isolated tornado is possible,
especially with any storm that can favorably interact with an
outflow boundary remnant from the MCS currently ongoing across IA.

A cooler and drier Canadian air mass will reside across the mid-MO
Valley on Tue and Wed with dry conditions expected.

.LONG TERM...(Wednesday night through Sunday)
Issued at 225 AM CDT Mon Aug 21 2017

A longwave trough will persist across eastern North America from
the middle to latter part of this work week before a more
substantial upstream trough and lower-latitude perturbations move
into the Canadian Prairies and Great Plains this weekend. This
large-scale pattern will yield continued mild and dry weather
through Friday, before precipitation chances increase this
weekend.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 602 AM CDT Mon Aug 21 2017

A back-building MCS is in progress as of 1045z across western IA
with more recent storm development along the western edge of the
associated cold pool between KOMA and KLNK. Expect storms to
persist for the next two to three hours before dissipating with
the cessation of the nocturnal LLJ. We will mention prevailing VCTS
at KOMA and KLNK with a TEMPO group for MVFR TSRA at KOMA between
12 and 14z. From mid morning through early afternoon, we expect
prevailing VFR conditions across eastern NE with increasing high-
level cloudiness. Thunderstorm potential will increase by mid to
late afternoon at KOFK and early evening at KOMA and KLNK as a
cold front moves south through the area.

&&

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

SHORT TERM...Mead
LONG TERM...Mead
AVIATION...Mead

Hazardous weather outlook, Aug 21, 4:16 AM CDT, 9 hours 33 minutes before

Hazardous Weather Outlook
National Weather Service Omaha/Valley NE
416 AM CDT Mon Aug 21 2017

IAZ043-055-056-069-079-080-090-091-NEZ011-012-015>018-030>034-
042>045-050>053-065>068-078-088>093-212330-
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-
416 AM CDT Mon Aug 21 2017

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

.DAY ONE...TODAY AND TONIGHT

River flooding will continue today along the Big Blue River and
Lincoln Creek, mainly in Butler, Seward and Saline counties. River
and stream levels will likely rise today across portions of
western Iowa in response to heavy rainfall overnight.

Thunderstorm chances will increase later this afternoon into
tonight along and ahead of a cold front moving through the area. A
few severe storms appear possible with a risk for damaging winds,
large hail and flooding rainfall.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

Some flooding remains possible along the Big Blue River into
Tuesday.

Thunderstorm chances return on Friday night and continue
for at least parts of the area through Sunday.

..SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed this afternoon or evening.

In the hours before

Local storm report, Aug 21, 10:24 AM CDT, 3 hours 25 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
1024 AM CDT MON AUG 21 2017

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

0800 AM     HEAVY RAIN       SHENANDOAH              40.76N 95.37W
08/21/2017  M1.66 INCH       PAGE               IA   CO-OP OBSERVER

            RAINFALL 24 HOUR

0800 AM     HEAVY RAIN       MAPLETON                42.17N 95.79W
08/21/2017  M2.94 INCH       MONONA             IA   CO-OP OBSERVER

            RAINFALL 24 HOUR

0800 AM     HEAVY RAIN       GLENWOOD                41.05N 95.74W
08/21/2017  M2.21 INCH       MILLS              IA   CO-OP OBSERVER

            RAINFALL 24 HOUR

0800 AM     HEAVY RAIN       SIDNEY                  40.75N 95.64W
08/21/2017  M1.08 INCH       FREMONT            IA   CO-OP OBSERVER

            RAINFALL 24 HOUR

0800 AM     HEAVY RAIN       HARLAN                  41.65N 95.33W
08/21/2017  M2.51 INCH       SHELBY             IA   AWOS

            RAINFALL 24 HOUR

0800 AM     HEAVY RAIN       1 SE PANAMA             41.72N 95.46W
08/21/2017  M1.58 INCH       SHELBY             IA   COCORAHS

            RAINFALL 24 HOUR

&&

JJ-E.KLISH

Local storm report, Aug 21, 10:47 AM CDT, 3 hours 2 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
1047 AM CDT MON AUG 21 2017

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

0800 AM     HEAVY RAIN       PAPILLION               41.16N 96.04W
08/21/2017  M1.13 INCH       SARPY              NE   COCORAHS

            RAINFALL 24 HOUR

0800 AM     HEAVY RAIN       ELK HORN                41.59N 95.06W
08/21/2017  M2.22 INCH       SHELBY             IA   COCORAHS

            RAINFALL 24 HOUR

0800 AM     HEAVY RAIN       COLLEGE SPRINGS         40.62N 95.12W
08/21/2017  M1.85 INCH       PAGE               IA   COCORAHS

            RAINFALL 24 HOUR

0800 AM     HEAVY RAIN       4 NNE EMERSON           41.07N 95.37W
08/21/2017  M1.02 INCH       MONTGOMERY         IA   COCORAHS

            RAINFALL 24 HOUR

0800 AM     HEAVY RAIN       1 WSW PAPILLION         41.15N 96.06W
08/21/2017  M1.12 INCH       SARPY              NE   COCORAHS

            RAINFALL 24 HOUR

&&

JJ-E.KLISH

Local storm report, Aug 21, 10:52 AM CDT, 2 hours 57 minutes before

PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
1052 AM CDT MON AUG 21 2017

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

0800 AM     HEAVY RAIN       N PANAMA                40.60N 96.51W
08/21/2017  M1.58 INCH       LANCASTER          NE   COCORAHS

            RAINFALL 24 HOUR

&&

J-E.KLISH

Local storm report, Aug 21, 10:53 AM CDT, 2 hours 56 minutes before

PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
1053 AM CDT MON AUG 21 2017

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

0800 AM     HEAVY RAIN       2 SSW PAPILLION         41.13N 96.06W
08/21/2017  M1.13 INCH       SARPY              NE   COCORAHS

            RAINFALL 24 HOUR

&&

J-E.KLISH

Special weather statement, Aug 21, 1:23 PM CDT, 26 minutes before

Special Weather Statement
National Weather Service Omaha/Valley Nebraska
123 PM CDT MON AUG 21 2017

NEZ011-211915-
Knox NE-
123 PM CDT MON AUG 21 2017

...Significant Weather Advisory for WEST CENTRAL KNOX COUNTY UNTIL
215 PM CDT...

At 123 PM CDT, Doppler radar was tracking a strong thunderstorm 10
miles west of Verdigre, or 23 miles northeast of O'Neill, moving
northeast at 40 mph.

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

Locations impacted include...
Verdigre, Niobrara and Santee Reservation.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

A severe thunderstorm watch remains in effect until 700 PM CDT for
northeastern Nebraska.

LAT...LON 4268 9830 4277 9804 4276 9800 4261 9792
      4249 9830
TIME...MOT...LOC 1823Z 239DEG 34KT 4262 9824

PEARSON

Special weather statement, Aug 21, 1:49 PM CDT, 0 minutes before

Special Weather Statement
National Weather Service Omaha/Valley Nebraska
149 PM CDT MON AUG 21 2017

NEZ011-012-016-017-211945-
Cedar NE-Pierce NE-Knox NE-Antelope NE-
149 PM CDT MON AUG 21 2017

...Significant Weather Advisory for NORTHWESTERN PIERCE...NORTHERN
ANTELOPE...SOUTHERN KNOX AND WEST CENTRAL CEDAR COUNTIES UNTIL 245 PM
CDT...

At 149 PM CDT, Doppler radar was tracking a strong thunderstorm 9
miles northeast of Orchard, or 26 miles east of O'neill, moving
southeast at 15 mph.

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

Locations impacted include...
Creighton, Bloomfield, Wausa, Verdigre, Orchard, Brunswick, Center,
Winnetoon, Royal, Bazile Mills, Ashfall Fossil Beds State Historical
Park, The Highway 14 And 59 Junction and Santee Reservation.

This includes Highway 20 in Nebraska between mile markers 329 and
344.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

&&

A severe thunderstorm watch remains in effect until 700 PM CDT for
northeastern Nebraska.

LAT...LON 4261 9798 4271 9756 4250 9744 4240 9768
      4227 9830 4249 9830
TIME...MOT...LOC 1849Z 238DEG 11KT 4245 9813

PEARSON

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 21, 9:17 AM CDT	Special Weather Statement	OAX	Pawnee	43 min
Aug 21, 1:02 PM CDT	Severe Thunderstorm Warning	OAX	Cedar, Knox	43 min
Aug 21, 1:23 PM CDT	Special Weather Statement	OAX	Knox	52 min
Aug 21, 1:43 PM CDT	Severe Thunderstorm Warning	OAX	Cedar	47 min
Aug 21, 3:16 PM CDT	Special Weather Statement	OAX	Cedar	44 min
Aug 21, 4:22 PM CDT	Special Weather Statement	OAX	Burt, Colfax, Dodge	53 min
Aug 21, 5:12 PM CDT	Special Weather Statement	OAX	Cedar	33 min
Aug 21, 6:35 PM CDT	River Flood Warning	OAX	Butler	36 hr
Aug 21, 1:47 AM CDT	Special Weather Statement	OAX	Pottawattamie, Shelby	43 min
Aug 21, 2:11 AM CDT	Special Weather Statement	OAX	Montgomery	49 min

Nearby

Special Weather Statements in Nebraska, 2017 Every special weather statement 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; radar from the NEXRAD Level II archive.