Alert archive / Iowa / Severe Thunderstorm Warnings in 2018

Severe Thunderstorm Warning 147, NWS Omaha, NE

June 18, 2018Harrison County, Pottawattamie County, Shelby County, Iowa

NWS Omaha, NE issued this severe thunderstorm warning at Jun 18, 2018, 3:56 PM CDT for Harrison County, Pottawattamie County, Shelby County, Iowa. It was in force for 16 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: Jun 18, 2018, 3:56 PM CDT (20:56 UTC)
Expired: Jun 18, 2018, 4:12 PM CDT
In force: 16 min
Issued by: NWS Omaha, NE
Area: Storm-based polygon
Hail: 0.75 in
Wind: 60.0 mph

Counties Harrison County, IA, Pottawattamie County, IA, Shelby County, IA

The radar

The Omaha radar (KOAX), 73 km from the middle of the area, began a volume at 20:58 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
Jun 18, 3:05 PM CDT	Severe Thunderstorm Watch	SPC	6 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 8.9 hours before the alert went out and 73 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: 301 J/kg
Mixed-layer CIN: -106 J/kg
Mixed-layer LCL: 1177 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: 84 m²/s²
0-3 km storm-relative helicity: 66 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.1

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 Jun 18, 3:20 PM CDT, 36 minutes earlier.

Area forecast discussion, Jun 18, 3:20 PM CDT, 36 minutes before

Area Forecast Discussion
National Weather Service Omaha/Valley NE
320 PM CDT Mon Jun 18 2018

.SHORT TERM...(Tonight through Thursday)
Issued at 320 PM CDT Mon Jun 18 2018

Convection already firing across parts of the forecast area at 20Z
in advance of a shortwave trough lifing out of western KS. In
addition, two surface boundaries were also in place. A warm front
stretched from northeast NE across northern IA, while a surface
trough was over western KS. These two boundaries will play a large
role in focusing additional rounds of convection over the area
through much of the short term period as a developing upper level
system moves into the region.

Abundant moisture across the region and the nearly stationary
boundaries will provide the potential of several periods of heavy
rain. A flash flood watch has been issued for parts of the area
for tonight into Tuesday morning due to this heavy rain potential.

Temperatures will be cooler compared to the past few days, but the
humid conditions will continue to make for uncomfortable
conditions.

.LONG TERM...(Thursday night through Monday)
Issued at 320 PM CDT Mon Jun 18 2018

Pattern looks to remain rather active into the weekend as the
upper system mentioned above works its way out of the area and
additional shortwave troughs move through by the weekend.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1226 PM CDT Mon Jun 18 2018

Rather variable conditions forecast to develop over the area
during the period as convection becomes widespread through 06Z
with several boundaries expected over the area to act as a focus.

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...Flash Flood Watch from 7 PM CDT this evening through Tuesday
     afternoon for NEZ015-032>034-043>045-050>053.

IA...Flash Flood Watch from 7 PM CDT this evening through Tuesday
     afternoon for IAZ043-055-056-069.

&&

SHORT TERM...Fobert
LONG TERM...Fobert
AVIATION...Fobert

Hazardous weather outlook, Jun 18, 3:50 PM CDT, 6 minutes before

Hazardous Weather Outlook
National Weather Service Omaha/Valley NE
350 PM CDT Mon Jun 18 2018

IAZ043-055-056-069-079-080-090-091-NEZ011-012-015>018-030>034-
042>045-050>053-065>068-078-088>093-191100-
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-
350 PM CDT Mon Jun 18 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 Tuesday

Scattered strong to severe storms are expected to continue over
portions of eastern Nebraska and southwest Iowa late this
afternoon into this evening, mainly north of I-80. The primary
hazards with these storms will be damaging winds, heavy rain, and
some hail to quarter size. A brief tornado is also possible,
especially west of a Wayne to Columbus line.

Heavy rain is also likely tonight across the area and may result
in local flooding. A Flash Flood Watch is in effect for east
central Nebraska into west central Iowa tonight into Tuesday
morning.

.DAYS TWO THROUGH SEVEN...Tuesday night through Monday

Thunderstorm chances will remain in the forecast through the week
and into next weekend. Periods of heavy rain are possible.

.SPOTTER INFORMATION STATEMENT...

Storm spotter activation may be required into this evening.

Fobert

In the hours before

Special weather statement, Jun 18, 2:19 PM CDT, 1 hour 37 minutes before

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Special weather statement, Jun 18, 2:53 PM CDT, 1 hour 3 minutes before

Special Weather Statement
National Weather Service Omaha/Valley Nebraska
253 PM CDT MON JUN 18 2018

IAZ055-069-NEZ044-045-052-053-182030-
Pottawattamie IA-Harrison IA-Sarpy NE-Washington NE-Douglas NE-
Dodge NE-
253 PM CDT MON JUN 18 2018

...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN POTTAWATTAMIE...
SOUTHWESTERN HARRISON...NORTHWESTERN SARPY...WASHINGTON...
SOUTHEASTERN DODGE AND DOUGLAS COUNTIES UNTIL 330 PM CDT...

At 252 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from 3 miles north of Arlington to 3 miles northeast
of Waterloo to 5 miles northwest of Gretna. Movement was northeast at
25 mph.

Wind gusts up to 50 mph will be possible with these storms.

Locations impacted include...
Omaha, western Council Bluffs, Bellevue, Papillion, La Vista, Blair,
Ralston, Gretna, Missouri Valley, Valley, Arlington, Fort Calhoun,
Waterloo, Mondamin, Kennard, Modale, Elkhorn, Millard, Carter Lake
and Bennington.

LAT...LON 4116 9594 4114 9631 4118 9632 4120 9634
      4130 9633 4154 9644 4170 9610 4170 9608
      4171 9607 4175 9599 4145 9585
TIME...MOT...LOC 1952Z 247DEG 23KT 4150 9634 4133 9626 4118 9632

MEAD

The office that day

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

Issued	Product	Office	Counties	Lasted
Jun 17, 7:05 PM CDT	Severe Thunderstorm Warning	OAX	Knox	40 min
Jun 17, 7:39 PM CDT	Severe Thunderstorm Warning	OAX	Knox	51 min
Jun 17, 7:41 PM CDT	Special Weather Statement	OAX	Cedar	34 min
Jun 17, 8:20 PM CDT	Severe Thunderstorm Warning	OAX	Cedar, Knox	55 min
Jun 17, 8:56 PM CDT	Tornado Warning	OAX	Cedar	19 min
Jun 18, 2:19 PM CDT	Special Weather Statement	OAX	Saunders	26 min
Jun 18, 2:53 PM CDT	Special Weather Statement	OAX	Douglas, Washington	37 min
Jun 18, 3:06 PM CDT	Severe Thunderstorm Warning	OAX	Douglas, Washington	24 min
Jun 18, 3:23 PM CDT	Severe Thunderstorm Warning	OAX	Douglas, Washington	37 min
Jun 18, 3:28 PM CDT	Flash Flood Watch	OAX	Burt, Butler, Colfax, Cuming, Dodge, Douglas and 5 more	13 hr
Jun 18, 3:30 PM CDT	Severe Thunderstorm Warning	OAX	Burt, Cuming, Thurston	13 min
Jun 18, 3:42 PM CDT	Severe Thunderstorm Warning	OAX	Boone, Madison, Platte	33 min
Jun 18, 4:11 PM CDT	Severe Thunderstorm Warning	OAX	Boone, Madison, Platte	13 min
Jun 18, 4:26 PM CDT	Special Weather Statement	OAX	Gage	34 min
Jun 18, 4:54 PM CDT	Special Weather Statement	OAX	Lancaster	36 min
Jun 18, 4:54 PM CDT	Severe Thunderstorm Warning	OAX	Gage, Pawnee	41 min
Jun 18, 5:05 PM CDT	Severe Thunderstorm Warning	OAX	Madison, Stanton	25 min
Jun 18, 5:19 PM CDT	Special Weather Statement	OAX	Saunders	26 min
Jun 18, 5:26 PM CDT	Severe Thunderstorm Warning	OAX	Stanton	34 min
Jun 18, 5:31 PM CDT	Tornado Warning	OAX	Stanton	29 min
Jun 18, 5:41 PM CDT	Special Weather Statement	OAX	Douglas	34 min
Jun 18, 5:44 PM CDT	Severe Thunderstorm Warning	OAX	Cuming, Stanton	31 min
Jun 18, 6:08 PM CDT	Areal Flood Advisory	OAX	Douglas, Washington	3 hr
Jun 18, 6:09 PM CDT	Severe Thunderstorm Warning	OAX	Cuming, Thurston, Wayne	36 min
Jun 18, 6:34 PM CDT	Severe Thunderstorm Warning	OAX	Burt, Thurston	26 min
Jun 18, 6:48 PM CDT	Tornado Warning	OAX	Burt, Thurston	27 min
Jun 18, 5:07 PM CDT	Special Weather Statement	OAX	Mills	23 min
Jun 18, 5:32 PM CDT	Areal Flood Advisory	OAX	Mills, Pottawattamie	3 hr
Jun 18, 5:38 PM CDT	Special Weather Statement	OAX	Pottawattamie	52 min
Jun 18, 6:34 PM CDT	Areal Flood Advisory	OAX	Harrison	3 hr
Jun 18, 6:47 PM CDT	Severe Thunderstorm Warning	OAX	Harrison, Pottawattamie, Shelby	43 min

Nearby

Severe Thunderstorm Warnings in Iowa, 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.