Alert archive / Nebraska / Severe Thunderstorm Warnings in 2018

Severe Thunderstorm Warning 248, NWS Omaha, NE

August 6, 2018Cass County, Otoe County, Nebraska; Fremont County, Iowa

NWS Omaha, NE issued this severe thunderstorm warning at Aug 6, 2018, 6:10 PM CDT for Cass County, Otoe County, Nebraska; Fremont County, Iowa. It was in force for 35 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
Aug 6, 2018, 6:10 PM CDT (23:10 UTC)
Expired
Aug 6, 2018, 6:45 PM CDT
In force
35 min
Issued by
NWS Omaha, NE
Area
Storm-based polygon
Hail
0.75 in
Wind
60.0 mph

Counties Fremont County, IA, Cass County, NE, Otoe County, NE

The radar

The Omaha radar (KOAX), 70 km from the middle of the area, began a volume at 23:09 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 nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 11.2 hours before the alert went out and 70 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-pSkew-T log-p diagram, Omaha, NE at 12:00Z on 2018-08-06Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 94 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Omaha, NE at 12:00Z on 2018-08-06The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -49 square meters per square second.19395878Sfc1 km3 km6 km9 kmRMLM
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
94 J/kg
Mixed-layer CIN
-247 J/kg
Mixed-layer LCL
731 m above ground
0-6 km bulk shear
26 kt
0-1 km storm-relative helicity
-49 m²/s²
0-3 km storm-relative helicity
-183 m²/s²
Significant tornado parameter
0.0
Supercell composite
-0.0

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 Aug 6, 3:53 PM CDT, 2 hours 17 minutes earlier.

Area forecast discussion, Aug 6, 3:53 PM CDT, 2 hours 17 minutes before
<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>
Hazardous weather outlook, Aug 6, 4:32 PM CDT, 1 hour 38 minutes before
Hazardous Weather Outlook
National Weather Service Omaha/Valley NE
432 PM CDT Mon Aug 6 2018

IAZ043-055-056-069-079-080-090-091-NEZ011-012-015>018-030>034-
042>045-050>053-065>068-078-088>093-071145-
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-
432 PM CDT Mon Aug 6 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

There is a slight risk for severe thunderstorms tonight in
southeast Nebraska and southwest Iowa, with damaging winds and
large hail the primary hazards. Areas of heavy rain are also
possible, which could lead to localized flooding. The area most
vulnerable for severe storms and heavy rain will be along and
south of a line from Columbus to Omaha and Oakland Iowa.

Two rounds of thunderstorms are expected tonight. The first will
mainly occur in the evening as storms in central Nebraska expand
east through southeast Nebraska and southwest Iowa in an area of
higher instability and shear. Large hail and damaging winds may
result. Also, these storms will track along similar paths, with
some areas seeing multiple rounds of moderate rainfall. An inch or
two of rain could fall, with more than that in localized spots.

The second round of thunderstorms is expected after midnight as an
upper level system swings into the region. Damaging winds will be
the most likely severe threat with these storms, but more heavy
rain could fall across areas that will see rain during the
evening. Again, localized flooding could occur.

Other more general thunderstorm activity is forecast north of a
Columbus to Omaha and Oakland line through the night. Severe
storms are not expected here.

Most of the thunderstorm should be moving east of southwest Iowa
by late Tuesday morning. Then an isolated thunderstorm may bubble
up during the afternoon just about anywhere across eastern
Nebraska and southwest Iowa. However severe storms are not
expected with this activity.

Minor flooding will continue along the Missouri River above Lewis
and Clark Lake through tonight.

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

Flooding will continue along the Missouri River above Lewis and
Clark Lake.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated tonight or Tuesday.

In the hours before

Special weather statement, Aug 6, 5:50 PM CDT, 20 minutes before
Special Weather Statement
National Weather Service Omaha/Valley Nebraska
550 PM CDT MON AUG 6 2018

NEZ068-062315-
Otoe NE-
550 PM CDT MON AUG 6 2018

...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL OTOE COUNTY UNTIL 615 PM
CDT...

At 550 PM CDT, Doppler radar was tracking a strong thunderstorm near
Unadilla, or 25 miles southeast of Lincoln, moving east at 20 mph.

Half inch hail and wind gusts up to 50 mph will be possible with this
storm.

Locations impacted include...
Syracuse, Unadilla, Talmage, Lorton, Dunbar, Otoe and Burr.

LAT...LON 4053 9635 4071 9636 4077 9593 4053 9592
TIME...MOT...LOC 2250Z 268DEG 19KT 4063 9627

DEWALD

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 5, 9:01 PM CDTSpecial Weather StatementOAXDodge29 min
Aug 5, 9:10 PM CDTSevere Thunderstorm WarningOAXDodge35 min
Aug 5, 10:04 PM CDTSevere Thunderstorm WarningOAXButler, Dodge, Saunders26 min
Aug 5, 11:27 PM CDTSpecial Weather StatementOAXCuming33 min
Aug 5, 11:46 PM CDTSpecial Weather StatementOAXPlatte29 min
Aug 6, 5:50 PM CDTSpecial Weather StatementOAXOtoe25 min
Aug 6, 6:32 PM CDTSpecial Weather StatementOAXRichardson28 min
Aug 6, 12:18 AM CDTSpecial Weather StatementOAXMonona27 min
Aug 6, 2:21 AM CDTSpecial Weather StatementOAXHarrison24 min
Aug 6, 6:40 PM CDTSevere Thunderstorm WarningOAXFremont, Page50 min

Nearby

Severe Thunderstorm Warnings in Nebraska, 2018Severe Thunderstorm Warnings in Iowa, 2018Every 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.