Alert archive / Iowa / Severe Thunderstorm Warnings in 2017

Severe Thunderstorm Warning 75, NWS Omaha, NE

May 16, 20174 counties in Iowa; Burt County, Washington County, Nebraska

NWS Omaha, NE issued this severe thunderstorm warning at May 16, 2017, 6:37 PM CDT for 4 counties in Iowa; Burt County, Washington County, Nebraska. It was in force for 38 min. 4 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: May 16, 2017, 6:37 PM CDT (23:37 UTC)
Expired: May 16, 2017, 7:15 PM CDT
In force: 38 min
Issued by: NWS Omaha, NE
Area: Storm-based polygon
Tornado: Possible
Hail: 1.25 in
Wind: 80.0 mph

Counties Harrison County, IA, Monona County, IA, Pottawattamie County, IA, Shelby County, IA, Burt County, NE, Washington County, NE

The radar

The Omaha radar (KOAX), 65 km from the middle of the area, began a volume at 23:39 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.

What was reported inside it

Time	Report	Where	Remark
May 16, 6:50 PM CDT	TSTM WND DMG	Missouri Valley, IA	SEVERAL LARGE BRANCHES DOWN
May 16, 7:02 PM CDT	TSTM WND GST 65	Tekamah, NE
May 16, 7:20 PM CDT	TSTM WND DMG	Shelby, IA	OUTBUILDINGS DAMAGED
May 16, 7:25 PM CDT	TSTM WND DMG	4 W Shelby, IA	LARGE TREE UPROOTED

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

Did it verify

Verified. The Iowa Environmental Mesonet's Cow matched 2 storm reports to this severe thunderstorm warning; the first came 13 minutes after it went out.

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
May 16, 4:57 PM CDT	Severe Thunderstorm Watch	SPC	7 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 11.6 hours before the alert went out and 65 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: 356 J/kg
Mixed-layer CIN: -358 J/kg
Mixed-layer LCL: 1160 m above ground
0-6 km bulk shear: 37 kt
0-1 km storm-relative helicity: 228 m²/s²
0-3 km storm-relative helicity: 192 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

688 
WUUS53 KOAX 162337
SVROAX
IAC085-133-155-165-NEC021-177-170015-
/O.NEW.KOAX.SV.W.0075.170516T2337Z-170517T0015Z/

BULLETIN - EAS ACTIVATION REQUESTED
Severe Thunderstorm Warning
National Weather Service Omaha/Valley Nebraska
637 PM CDT TUE MAY 16 2017

The National Weather Service in Omaha has issued a

* Severe Thunderstorm Warning for...
  Southeastern Monona County in west central Iowa...
  Northwestern Pottawattamie County in southwestern Iowa...
  Harrison County in southwestern Iowa...
  Southwestern Shelby County in southwestern Iowa...
  Southeastern Burt County in east central Nebraska...
  Northeastern Washington County in east central Nebraska...

* Until 715 PM CDT

* At 636 PM CDT, a severe thunderstorm was located 4 miles south of
  Modale, or 19 miles north of Omaha, moving east at 45 mph.

  This is a very dangerous storm. 

  HAZARD...80 mph wind gusts and half dollar size hail. 

  SOURCE...Radar indicated. 

  IMPACT...Flying debris will be dangerous to those caught without 
           shelter. Mobile homes will be heavily damaged. Expect 
           considerable damage to roofs, windows, and vehicles. 
           Extensive tree damage and power outages are likely. 

* Locations impacted include...
  Missouri Valley, Tekamah, Logan, Avoca, Shelby, Minden, Mondamin,
  Persia, Modale, Pisgah, Moorhead, Woodbine, Dunlap, Panama,
  Portsmouth, Magnolia, Little Sioux, Tennant, Preparation Canyon
  State Park and Willow Lake Recreation Area.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

This is a DANGEROUS SITUATION. This storm is producing widespread 
wind damage. SEEK SHELTER NOW inside a sturdy structure and stay 
away from windows!

&&

LAT...LON 4145 9600 4181 9626 4201 9567 4187 9567
      4186 9554 4148 9531
TIME...MOT...LOC 2336Z 251DEG 40KT 4155 9601 

TORNADO...POSSIBLE
HAIL...1.25IN
WIND...80MPH
 
$$

MILLER

1 follow-up statement

396 
WWUS53 KOAX 162350
SVSOAX

Severe Weather Statement
National Weather Service Omaha/Valley Nebraska
650 PM CDT TUE MAY 16 2017

IAC085-133-155-165-NEC021-177-170015-
/O.CON.KOAX.SV.W.0075.000000T0000Z-170517T0015Z/
Monona IA-Pottawattamie IA-Harrison IA-Shelby IA-Burt NE-
Washington NE-
650 PM CDT TUE MAY 16 2017

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 715 PM CDT
FOR SOUTHEASTERN MONONA...NORTHWESTERN POTTAWATTAMIE...HARRISON...
SOUTHWESTERN SHELBY...SOUTHEASTERN BURT AND NORTHEASTERN WASHINGTON
COUNTIES...

At 649 PM CDT, a severe thunderstorm was located over Logan, or 27
miles north of Omaha, moving northeast at 50 mph.

This is a very dangerous storm.

HAZARD...80 mph wind gusts and quarter size hail. 

SOURCE...Radar indicated. 

IMPACT...Flying debris will be dangerous to those caught without 
         shelter. Mobile homes will be heavily damaged. Expect 
         considerable damage to roofs, windows, and vehicles. 
         Extensive tree damage and power outages are likely. 

Locations impacted include...
Missouri Valley, Tekamah, Logan, Avoca, Shelby, Minden, Mondamin,
Persia, Modale, Pisgah, Moorhead, Woodbine, Dunlap, Panama,
Portsmouth, Magnolia, Little Sioux, Tennant, Preparation Canyon State
Park and Willow Lake Recreation Area.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

This is a DANGEROUS SITUATION. This storm is producing widespread 
wind damage across parts of Harrison and Pottawattamie counties.
Seek shelter now inside a sturdy structure and stay away from 
windows.

&&

LAT...LON 4145 9600 4181 9626 4201 9567 4187 9567
      4186 9554 4148 9531
TIME...MOT...LOC 2349Z 246DEG 41KT 4163 9582 

HAIL...1.00IN
WIND...80MPH
 
$$

MILLER

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 May 16, 3:17 PM CDT, 3 hours 20 minutes earlier.

Area forecast discussion, May 16, 3:17 PM CDT, 3 hours 20 minutes before

Area Forecast Discussion
National Weather Service Omaha/Valley NE
317 PM CDT Tue May 16 2017

.SHORT TERM...(Tonight through Friday)
Issued at 315 PM CDT Tue May 16 2017

WV imagery this afternoon showing a deep longwave trof cutting
through the western CONUS with potent southern tier vort max
currently over southern CA/western AZ. At the surface...relatively
weak low pressure was centered in eastern CO with a stagnant
thermal boundary extending into eastern Neb then northern IA. A
second boundary/cold front was situated from central MN to
southwest SD. Daytime heating/influx of moisture has pushed
instability parameters to the extreme with MLCAPES 2500-3500J/kg
over the region.

A highly unstable environment will be in place to allow for
convective development in western KS this afternoon...which will
eventually reach the CWA early this evening. Expect updraft
initiation on nose of 8-9C/km low level lapse rates protruding into
moisture rich environment...promoting rapid storm development. All
this coincident to boundary layer theta-E convergence.

HRRR and RAP13 have been pretty consistent the last several runs
showing the cluster of western KS storms will cross into 0-3km bulk
shear of 40kt or so...forming into a QLCS. Complex is progged then
to quickly race along the Neb/KS border during the early evening
hours before crossing into southeastern Neb/extreme southwest IA.
Along with probable severe wind gusts(increasing layer differential
max theta-E)...an isolated tornado forming along the bowing line
segment cannot be ruled out.

Meanwhile farther north...narrow line of convection is progged to
fire later the afternoon along a stagnant surface boundary extending
from south-central Neb into west-central IA. Activity will expand
then in areal coverage mainly over northeast Neb/west-central IA
toward mid evening. Steep mid-level lapse rates topping moisture
rich boundary layer suggest severe hail producers are quite
probable.

In addition...a heavy rain threat will be in place as well tonight.
The last several runs of both NAM/GFS show continuity advertising a
high degree of precipitation efficiency consisting of deep warm
cloud layer/strong moist low level inflow...and 30-40 microbars of
omega coincident to PWS approaching 2"

Wednesday/Wednesday evening...core of southwest shortwave trof will
lift right over the CWA and bring wrap around precip mainly over the
northern CWA.

Precip chances continue Thursday afternoon through Friday associated
with a large and relatively slow moving upper low/several impulses
exiting the Rockies.

.LONG TERM...(Friday night through Tuesday)
Issued at 315 PM CDT Tue May 16 2017

Precip chances continue into the early part of next weekend
accompanied by a noticeable cooling trend into early next week.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1207 PM CDT Tue May 16 2017

Gusty south winds will continue this afternoon across eastern
Nebraska with scattered-broken clouds at around FL040.
Thunderstorms are expected to form to the west this afternoon
before moving into the area this evening. Short-term model
guidance remains in good agreement in suggesting that a bowing
line of storms will affect the Lincoln and Omaha areas between
about 01 and 04z. As such, a mention of strong wind gusts have
been included in the TAFs during that time frame. Otherwise,
expect episodic showers and thunderstorms overnight into Wednesday
morning with the potential for more widespread MVFR ceilings
developing late tonight.

&&

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

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

Hazardous weather outlook, May 16, 4:22 PM CDT, 2 hours 15 minutes before

Hazardous Weather Outlook
National Weather Service Omaha/Valley NE
422 PM CDT Tue May 16 2017

IAZ043-055-056-069-079-080-090-091-NEZ011-012-015>018-030>034-
042>045-050>053-065>068-078-088>093-171130-
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-
422 PM CDT Tue May 16 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 WEDNESDAY

A highly unstable and moist environment will be in place to
promote severe thunderstorm development late this afternoon
before increasing in areal coverage through the evening. The
primary severe weather threat along and south of I-80 will be
damaging wind gusts with the potential for an isolated tornado.
For areas north of I-80...the main threat will be large hail and
damaging winds.

In addition...the possibility for heavy rainfall and localized
flooding is quite high in association with more intense
thunderstorms.

Even though the severe weather will likely come to a close around
midnight, the threat for flooding will continue with showers and
thunderstorms across the region later tonight.

Thunderstorms will also be possible again on Wednesday.

.DAYS TWO THROUGH SEVEN...WEDNESDAY NIGHT THROUGH TUESDAY

The chance of thunderstorms will extend into Wednesday evening and
again Thursday night through Saturday morning. Additional
thunderstorms are possible Monday into Tuesday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will liklely be needed late this afternoon and
tonight.

Fobert

In the hours before

Local storm report, May 16, 6:19 PM CDT, 18 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
619 PM CDT TUE MAY 16 2017

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

0605 PM     HAIL             WAVERLY                 40.91N 96.53W
05/16/2017  E1.75 INCH       LANCASTER          NE   PUBLIC

            GOLF BALLS AND 50MPH WINDS

&&

KGROSS

Local storm report, May 16, 6:24 PM CDT, 13 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
624 PM CDT TUE MAY 16 2017

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

0620 PM     HAIL             6 S GRETNA              41.05N 96.24W
05/16/2017  E1.00 INCH       SARPY              NE   TRAINED SPOTTER

            FLYING J TRUCK STOP

&&

DFOBERT

Local storm report, May 16, 6:25 PM CDT, 12 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
625 PM CDT TUE MAY 16 2017

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

0610 PM     TSTM WND DMG     2 S YUTAN               41.21N 96.40W
05/16/2017                   SAUNDERS           NE   BROADCAST MEDIA

            MULTIPLE TREE BRANCHES DOWN AND TREE SPLIT IN HALF

&&

KGROSS

Local storm report, May 16, 6:29 PM CDT, 8 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
629 PM CDT TUE MAY 16 2017

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

0615 PM     HAIL             LINCOLN                 40.82N 96.69W
05/16/2017  E1.00 INCH       LANCASTER          NE   PUBLIC

            40TH AND OLD CHENEY

&&

KGROSS

Local storm report, May 16, 6:33 PM CDT, 4 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
633 PM CDT TUE MAY 16 2017

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

0620 PM     HAIL             15 W OMAHA              41.26N 96.30W
05/16/2017  E1.00 INCH       DOUGLAS            NE   TRAINED SPOTTER

            LAKE ZORINSKY AREA

&&

DFOBERT

Local storm report, May 16, 6:36 PM CDT, 1 minute before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
636 PM CDT TUE MAY 16 2017

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

0630 PM     HAIL             OMAHA                   41.26N 96.01W
05/16/2017  E1.00 INCH       DOUGLAS            NE   PUBLIC

            178TH AND HARRISON

&&

KGROSS

The office that day

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

Issued	Product	Office	Counties	Lasted
May 16, 6:15 PM CDT	Severe Thunderstorm Warning	OAX	Harrison	45 min
May 16, 6:18 PM CDT	Severe Thunderstorm Warning	OAX	Harrison, Mills, Pottawattamie	42 min
May 16, 6:43 PM CDT	Severe Thunderstorm Warning	OAX	Mills, Montgomery, Pottawattamie	47 min
May 15, 10:12 PM CDT	Special Weather Statement	OAX	Butler, Seward	18 min
May 15, 10:25 PM CDT	Special Weather Statement	OAX	Antelope	35 min
May 15, 10:41 PM CDT	Severe Thunderstorm Warning	OAX	Antelope, Knox	34 min
May 15, 10:43 PM CDT	Special Weather Statement	OAX	Madison	32 min
May 15, 10:58 PM CDT	Special Weather Statement	OAX	Madison	32 min
May 15, 11:04 PM CDT	Special Weather Statement	OAX	Platte	41 min
May 15, 11:11 PM CDT	Severe Thunderstorm Warning	OAX	Madison, Stanton, Wayne	34 min
May 15, 11:16 PM CDT	Severe Thunderstorm Warning	OAX	Knox	44 min
May 15, 11:27 PM CDT	Special Weather Statement	OAX	Antelope, Boone, Madison, Pierce, Platte	48 min
May 15, 11:30 PM CDT	Special Weather Statement	OAX	Cuming	30 min
May 15, 11:40 PM CDT	Special Weather Statement	OAX	Wayne	50 min
May 15, 11:47 PM CDT	Special Weather Statement	OAX	Butler, Saline, Seward	43 min
May 16, 12:05 AM CDT	Special Weather Statement	OAX	Thurston	40 min
May 16, 4:46 PM CDT	Special Weather Statement	OAX	Seward	14 min
May 16, 4:52 PM CDT	Severe Thunderstorm Warning	OAX	Butler, Lancaster, Saline, Saunders, Seward	38 min
May 16, 5:19 PM CDT	Severe Thunderstorm Warning	OAX	Saunders	41 min
May 16, 5:26 PM CDT	Severe Thunderstorm Warning	OAX	Lancaster, Seward	34 min
May 16, 5:35 PM CDT	Severe Thunderstorm Warning	OAX	Dodge, Douglas, Saunders, Washington	40 min
May 16, 5:53 PM CDT	Severe Thunderstorm Warning	OAX	Cass, Dodge, Douglas, Lancaster, Sarpy, Saunders and 1 more	52 min
May 16, 6:54 PM CDT	Severe Thunderstorm Warning	OAX	Cass, Otoe	36 min

Nearby

Severe Thunderstorm Warnings in Iowa, 2017 Severe Thunderstorm Warnings in Nebraska, 2017 Every 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.