Only 12-24 hours after significant rainfall drenched eastern sections of South Central Nebraska resulting in considerable lowland flooding and closure of several county roads, another round of heavy rain-producing storms flared up mainly between 2 PM and 9 PM CDT on Friday the 20th. This time around, the highest rainfall amounts focused a bit farther west, and especially near the Highway 281 corridor from Hall to Greeley Counties. For the 24-hour period ending on the morning of the 21st, one of the highest measured rain totals was 3.74 inches, southwest of Spalding in Greeley County. Also, for the calendar day of the 20th, Central Nebraska Regional Airport in Grand Island established a new daily rainfall record of 2.46 inches. The concentrated heavy rain just north of Grand Island resulted in flooded roadways near the intersections of Hall, Howard and Merrick Counties.
Although the mesoscale environment was supportive of severe weather given surface-based CAPE around 1000 J/kg and deep-layer vertical wind shear around 40 knots, the storm mode was predominantly multicell, fostering the heavy rain threat as storms trained from south to north over many of the same areas. That being said, the combination of low cloud bases and sufficient low level vorticity in the vicinity of a weak cold front resulted in a few reports of funnel clouds within South Central Nebraska, including near Grand Island. However, there were no confirmed tornado touchdowns. Looking at the large scale synoptic weather pattern, this was the second of three consecutive days of widespread thunderstorm activity within the area, thanks to an expansive, strong mid-level low pressure system centered near the Wyoming-Montana border on the afternoon of the 20th.

Flood in HOWARD, NEBRASKA
From 20-MAY-11 18:00:00 to 21-MAY-11 14:00:00 (CST-6)
Location: ST LIBORY
Flood cause: Heavy Rain
Property damage: 25.00K
Crop damage: 500.00K
Reported by: Law Enforcement

Heavy rainfall across the area resulted in numerous county roads and intersections being closed in the southeastern part of the county.  A few remained closed well into the day of the 21st.

Heavy Rain in GREELEY, NEBRASKA
From 20-MAY-11 06:00:00 to 21-MAY-11 06:00:00 (CST-6)
Location: SPALDING
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Storm total rainfall of 3.74 inches was reported by a NeRAIN observer.

Heavy Rain in GREELEY, NEBRASKA
From 20-MAY-11 06:00:00 to 21-MAY-11 06:00:00 (CST-6)
Location: SPALDING
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Storm total rainfall of 3.01 inches was reported by a NeRAIN observer.

Flood in HALL, NEBRASKA
From 20-MAY-11 17:00:00 to 21-MAY-11 16:00:00 (CST-6)
Location: (GRI)GRAND IS RGNL A
Flood cause: Heavy Rain
Property damage: 25.00K
Crop damage: 500.00K
Reported by: Law Enforcement

Heavy rainfall across the area resulted in numerous county roads and intersections being closed in the northeastern part of the county.  A number remained closed well into the day of the 21st.  Brief street flooding was reported in Grand Island.

Flood in MERRICK, NEBRASKA
From 20-MAY-11 18:00:00 to 21-MAY-11 14:00:00 (CST-6)
Location: WORMS
Flood cause: Heavy Rain
Property damage: 25.00K
Crop damage: 500.00K
Reported by: Law Enforcement

Heavy rainfall across the area resulted in numerous county roads and intersections being closed in the western part of the county.  A few remained closed well into the day of the 21st.