Scattered severe thunderstorms developed over eastern Nebraska during the afternoon of May 21 and tracked and developed into western Iowa during the early to mid evening hours.  The storms developed as cold air aloft spread into the region on the south side of a large upper low that was over the Dakotas.  Initially the storms developed in the mid afternoon on a dry-line that was southeast of Columbus and Wayne.  The storms became more widespread from late afternoon into early evening as conditions became a little more unstable and a disturbance rotated around the low.  Most of the storms were multi-cellular in nature, including multiple but relatively small severe storms that tracked across the Omaha metro over a period of 1 to 2 hours.  However, a few storms developed supercell characteristics including one that produced a funnel cloud saw by many, and large hail near Surprise.  In addition, due the cold cyclonic spinning air aloft and weak boundaries in the region, several other funnel clouds were also reported.

Hail in PLATTE, NEBRASKA
From 21-MAY-11 16:52:00 to 21-MAY-11 16:52:00 (CST-6)
Location: (OLU)COLUMBUS ARPT
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail up to quarter-size was reported on the east side of Columbus.

Hail in NEMAHA, NEBRASKA
From 21-MAY-11 17:10:00 to 21-MAY-11 17:10:00 (CST-6)
Location: AUBURN
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail up to quarter-size was reported in the Auburn area.

Funnel Cloud in SARPY, NEBRASKA
From 21-MAY-11 18:18:00 to 21-MAY-11 18:25:00 (CST-6)
Location: GRETNA
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Several weak/small funnel clouds briefly formed on at least one storm that moved across Sarpy county.  No touchdowns were observed, but numerous pictures of the funnels were taken and some made the local news report.

Hail in SARPY, NEBRASKA
From 21-MAY-11 18:21:00 to 21-MAY-11 18:27:00 (CST-6)
Location: SPRINGFIELD
Magnitude: 1.50 
Crop damage: 0.00K
Reported by: Trained Spotter

Hail up to 1.5 inches in diameter fell from near Springfield to near Gretna and then to near 159th and Giles Road.  The hail was from the first of at least 3 storms that crossed the county this evening producing large hail.

Hail in CASS, NEBRASKA
From 21-MAY-11 17:54:00 to 21-MAY-11 17:54:00 (CST-6)
Location: MURDOCK
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Hail in SARPY, NEBRASKA
From 21-MAY-11 18:35:00 to 21-MAY-11 19:15:00 (CST-6)
Location: CHALCO
Magnitude: 1.00 
Crop damage: 0.00K
Reported by: Other Federal Agency

From the 2nd of at least 3 storms that produced severe-size hail in Sarpy county this evening.  This storm dropped quarter-size or perhaps a bit larger hail from near Gretna and the Chalco area east northeast to north of Offutt AFB over a period 45 minutes or so.

Hail in SARPY, NEBRASKA
From 21-MAY-11 19:55:00 to 21-MAY-11 19:55:00 (CST-6)
Location: AVERY
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Near 25th and Fairview Road.

Hail in WAYNE, NEBRASKA
From 21-MAY-11 18:10:00 to 21-MAY-11 18:15:00 (CST-6)
Location: WAYNE
Magnitude: 1.75 
Crop damage: 0.00K
Reported by: Trained Spotter

Hail up to golf ball-size fell from southwest of Wayne into town.

Hail in DOUGLAS, NEBRASKA
From 21-MAY-11 18:30:00 to 21-MAY-11 18:51:00 (CST-6)
Location: OMAHA MILLARD ARPT
Magnitude: 1.25 
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Hail of around quarter to half dollar-size fell from the first of at least 2 hail producing thunderstorms that crossed Douglas county/Omaha this evening.  Hail from this storm in Douglas county was first reported in and just southwest of the Millard area with other reports received near 145th and Blondo Streets, 144th and Fort Streets and 156th and State Streets.

Hail in SARPY, NEBRASKA
From 21-MAY-11 18:44:00 to 21-MAY-11 18:49:00 (CST-6)
Location: OFFUTT WEST
Magnitude: 1.25 
Crop damage: 0.00K
Reported by: Public

Hail of around quarter-size or a bit larger fell around the Bellevue area from the split of the first of at least 3 storms that produced severe-size hail in Sarpy county this evening.

Hail in SARPY, NEBRASKA
From 21-MAY-11 20:05:00 to 21-MAY-11 20:06:00 (CST-6)
Location: AVERY
Magnitude: 1.75 
Crop damage: 0.00K
Reported by: Trained Spotter

Hail up to golf ball-size fell in the Bellevue area from at least the 3rd storm that produced severe-size hail in Sarpy county this evening.  The hail was reported to cause some damage to vehicles near 205th and Industrial Road.

Hail in RICHARDSON, NEBRASKA
From 21-MAY-11 16:17:00 to 21-MAY-11 16:17:00 (CST-6)
Location: HUMBOLDT
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in BUTLER, NEBRASKA
From 21-MAY-11 16:20:00 to 21-MAY-11 16:20:00 (CST-6)
Location: SURPRISE
Magnitude: 1.75 
Crop damage: 0.00K
Reported by: COOP Observer

Golf ball-size hail fell near Surprise from the first of 2 supercell thunderstorms that hit the area within an hour and half or so.  The hail from the storms covered the ground several inches deep that stayed on the ground for a few hours.

Hail in CASS, NEBRASKA
From 21-MAY-11 19:55:00 to 21-MAY-11 19:55:00 (CST-6)
Location: OREAPOLIS
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Other Federal Agency

Mostly 1/2 inch size but a few 3/4 to 1 inch in diameter hailstones fell in the Bay Hills Golf Course area.

Hail in BUTLER, NEBRASKA
From 21-MAY-11 18:20:00 to 21-MAY-11 18:20:00 (CST-6)
Location: BRUNO
Magnitude: 1.25 
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Hail around half dollar-size, or perhaps a bit larger, was reported in the Bruno area.

Hail in CEDAR, NEBRASKA
From 21-MAY-11 18:30:00 to 21-MAY-11 18:30:00 (CST-6)
Location: LAUREL
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Hail in DOUGLAS, NEBRASKA
From 21-MAY-11 19:02:00 to 21-MAY-11 19:02:00 (CST-6)
Location: OMAHA
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Funnel Cloud in COLFAX, NEBRASKA
From 21-MAY-11 13:30:00 to 21-MAY-11 13:30:00 (CST-6)
Location: ROGERS
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

High based towering cumulus or a small developing thunderstorm produced a funnel cloud that prompted numerous calls to the NWS from many directions from north of Columbus to the Fremont area.  The funnel could have possibly touched down according to a public report and still pictures viewed at the NWS.  However, no reports of damage or solid confirmation of a touchdown was received.  The cell that produced the funnel was on the northeast or leading edge of a thunderstorm in Butler county that developed into a relatively short-lived line of strong thunderstorms over the next hour or so.

Hail in BUTLER, NEBRASKA
From 21-MAY-11 16:24:00 to 21-MAY-11 16:25:00 (CST-6)
Location: RISING CITY
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Hail of around an inch in diameter fell in and west of Rising City.

Hail in RICHARDSON, NEBRASKA
From 21-MAY-11 16:33:00 to 21-MAY-11 16:33:00 (CST-6)
Location: SHUBERT
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Hail up to penny-size was reported in the area.

Hail in WASHINGTON, NEBRASKA
From 21-MAY-11 19:04:00 to 21-MAY-11 19:04:00 (CST-6)
Location: FT CALHOUN
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Funnel Cloud in BUTLER, NEBRASKA
From 21-MAY-11 17:35:00 to 21-MAY-11 17:37:00 (CST-6)
Location: ULYSSES
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

A supercell thunderstorm produced a funnel and even a possible tornado touchdown near Surprise.  An off-duty NWS meteorologist confirmed the funnel and there were a few unconfirmed reports of a brief tornado near town, but little or no damage was observed.

Flash Flood in BUTLER, NEBRASKA
From 21-MAY-11 17:50:00 to 21-MAY-11 19:30:00 (CST-6)
Location: SURPRISE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Several slow moving thunderstorms crossed the Surprise area dropping around 2 to 3 inches of rain in a few hours.  This produced flash flooding over at least one road in or near Surprise.  Damage due to flooding was minimal, however.  The storms also dropped large hail in the region and a funnel or possible brief tornado.

Hail in BUTLER, NEBRASKA
From 21-MAY-11 16:49:00 to 21-MAY-11 16:49:00 (CST-6)
Location: DAVID CITY
Magnitude: 1.00 
Crop damage: 0.00K
Reported by: Emergency Manager

Most hail stones in town were 1/2 inch or so in diameter, although some hailstones were around quarter-size or perhaps even a bit larger.

Hail in DOUGLAS, NEBRASKA
From 21-MAY-11 19:10:00 to 21-MAY-11 19:11:00 (CST-6)
Location: OMAHA
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Hail of around quarter-size was reported near 90th and Burt and 108th and Blondo Streets.  This was from the second storm to produce severe-size hail this evening in Douglas county.

Thunderstorm Wind in STANTON, NEBRASKA
From 21-MAY-11 18:00:00 to 21-MAY-11 18:00:00 (CST-6)
Location: STANTON
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorm wind gusts estimated at close to 60 mph knocked over 2 trees north of Stanton.  The winds were accompanied by hail just under 3/4 of an inch in diameter.

Hail in CUMING, NEBRASKA
From 21-MAY-11 16:50:00 to 21-MAY-11 16:50:00 (CST-6)
Location: ALOYS
Magnitude: 1.50 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Hail up to ping pong ball-size was reported.