Alert archive / Nebraska / Flash Flood Warnings in 2011

Flash Flood Warning 34, NWS Omaha, NE

August 18, 2011Antelope County, Nebraska

NWS Omaha, NE issued this flash flood warning at Aug 18, 2011, 6:25 PM CDT for Antelope County, Nebraska. It was in force for 3 hr. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Aug 18, 2011, 6:25 PM CDT (23:25 UTC)
Expired: Aug 18, 2011, 9:08 PM CDT
In force: 3 hr
Issued by: NWS Omaha, NE
Area: Storm-based polygon
Flood severity: None

County Antelope County, NE

The radar

The Omaha radar (KOAX), 184 km from the middle of the area, began a volume at 23:28 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.

Did it verify

Not verified. The Iowa Environmental Mesonet's Cow found no qualifying storm report inside this flash flood warning while it was in force. That is not proof nothing happened: reports are thin where few people live.

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 nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 11.4 hours before the alert went out and 183 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: 1181 J/kg
Mixed-layer CIN: -126 J/kg
Mixed-layer LCL: 683 m above ground
0-6 km bulk shear: 47 kt
0-1 km storm-relative helicity: 234 m²/s²
0-3 km storm-relative helicity: 385 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 11.7

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

658 
WGUS53 KOAX 182325
FFWOAX
NEC003-190530-
/O.NEW.KOAX.FF.W.0034.110818T2325Z-110819T0530Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
625 PM CDT THU AUG 18 2011

THE NATIONAL WEATHER SERVICE IN OMAHA HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  CENTRAL ANTELOPE COUNTY IN NORTHEAST NEBRASKA

* UNTIL 1230 AM CDT

* AT 615 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
  SLOW MOVING THUNDERSTORMS WITH VERY HEAVY RAINFALL ACROSS THE      
  WARNED AREA. 

* RUNOFF FROM THIS EXCESSIVE RAINFALL WILL CAUSE FLASH FLOODING TO
  OCCUR. SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE...
  CLEARWATER...NELIGH AND ORCHARD.

THE WARNED AREA INCLUDES HIGHWAY 275 IN NEBRASKA BETWEEN MILE MARKERS
25 AND 39.

THE WARNED AREA INCLUDES HIGHWAY 20 IN NEBRASKA BETWEEN MILE MARKERS
329 AND 335.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

FLOODING IS OCCURRING OR IS IMMINENT. MOST FLOOD RELATED DEATHS OCCUR
IN AUTOMOBILES. DO NOT ATTEMPT TO CROSS WATER COVERED BRIDGES...
DIPS...OR LOW WATER CROSSINGS. NEVER TRY TO CROSS A FLOWING STREAM...
EVEN A SMALL ONE...ON FOOT OR IN A VEHICLE.

&&

LAT...LON 4239 9831 4241 9830 4235 9810 4222 9798
      4207 9786 4214 9831

$$

PEARSON

1 follow-up statement

904 
WGUS73 KOAX 190208
FFSOAX

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
908 PM CDT THU AUG 18 2011

NEC003-190224-
/O.CAN.KOAX.FF.W.0034.000000T0000Z-110819T0530Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
ANTELOPE NE-
908 PM CDT THU AUG 18 2011

...THE FLASH FLOOD WARNING THAT WAS IN EFFECT FOR CENTRAL ANTELOPE
COUNTY IS CANCELLED...

EXCESS RUNOFF FROM HEAVY RAIN HAS ENDED OVER THE WARNED AREA. STREAMS
AND CREEKS IN THE WARNED AREA HAVE RECEDED OR WERE BEGINNING TO
RECEDE...ENDING THE FLOOD THREAT. IF FLOODING HAS BEEN OBSERVED...
PLEASE REPORT IT TO YOUR LOCAL LAW ENFORCEMENT AGENCY.

LAT...LON 4239 9831 4241 9830 4235 9810 4222 9798
      4207 9786 4214 9831

$$

PEARSON

What forecasters said that day

The local office's own words before this flash flood 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 flash flood warning went out at Aug 18, 3:18 PM CDT, 3 hours 7 minutes earlier.

Area forecast discussion, Aug 18, 3:18 PM CDT, 3 hours 7 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
318 PM CDT THU AUG 18 2011

.DISCUSSION...

TONIGHT...
THE MAIN FORECAST CONCERN IS POTENTIAL FOR SEVERE THUNDERSTORMS...
ESPECIALLY PRIOR TO 1 AM CDT. ONGOING MESOSCALE CONVECTIVE SYSTEM
SHOULD CONTINUE TO EXPAND IN COVERAGE...THEN PUSH SOUTHEAST OUT OF
THE AREA. DECENT INSTABILITY WAS NOTED IN 18Z KOAX SOUNDING WITH
CAPE VALUES AROUND 3000 J/KG. PRECIPITABLE WATER VALUE WAS OVER
1.50 INCHES AND HAVE HAD SOME RAINFALL REPORTS OVER 1 INCH SO FAR.
SOUTHERLY WINDS SHOULD TURN MORE TOWARD THE EAST AND NORTHEAST
OVERNIGHT WITH LOWS 60 TO 65 NORTH AND MID TO UPPER 60S SOUTH.

TONIGHT THROUGH MID PART OF NEXT WEEK...
A FRONTAL BOUNDARY WILL SAG SOUTH
THROUGH THE AREA FRIDAY...BUT IT ONLY LOOKS LIKE A SLIGHT CHANCE
OF STORMS. THE 12Z NAM WAS FAIRLY AGGRESSIVE WITH DEVELOPMENT OF
STORMS NORTHEAST OF A LINE FROM KOFK TO KOMA FRIDAY AFTERNOON.
THAT SEEMED A BIT BULLISH BUT WILL MENTION SOME CHANCE OF SHOWERS
AND THUNDERSTORMS IN THE AFTERNOON.

SEVERAL SHORTWAVE TROUGHS WILL MOVE ACROSS THE LOCAL AREA IN THE
NORTHWEST FLOW ALOFT FRIDAY NIGHT THROUGH SATURDAY. KEPT PREVIOUS
FAIRLY HIGH RAIN CHANCES GOING. TEMPERATURES WILL BE BELOW NORMAL
SATURDAY WITH HIGHS 75 TO 80 NORTH AND 80 TO 85 SOUTH. COOL HIGH
PRESSURE AND DRY CONDITIONS ARE EXPECTED TO BUILD IN FOR SATURDAY
NIGHT...WITH LOWS MOSTLY 60 TO 65 BUT SOME UPPER 50S POSSIBLE
(ESPECIALLY NORTH).

THE PATTERN WILL REMAIN SOMEWHAT UNSETTLED SUNDAY NIGHT INTO
MONDAY NIGHT WITH NORTHWEST FLOW CONTINUING. IT DOES APPEAR THAT
THE 500 MB RIDGE WILL EXPAND EAST FROM THE ROCKIES AND INTO THE
PLAINS WHICH COULD PUSH TEMPERATURES (ESPECIALLY HIGHS) TO ABOVE
NORMAL LEVELS NEXT WEEK. THE 12Z ECMWF SHOWED A FAIRLY DECENT
SHORTWAVE DROPPING DOWN INTO IOWA TUESDAY INTO WEDNESDAY. THE
GFS WAS NOT AS AGGRESSIVE SO FOR NOW WILL JUST KEEP AN EYE ON
THAT.

&&

.AVIATION...
FOR TAF SITES KOFK/KOMA/KLNK

18Z TAFS

THUNDERSTORMS ARE MOST LIKELY TO AFFECT KOMA BUT MAY ALSO IMPACT
KLNK AND KOFK...MOSTLY PRIOR TO 05Z. SOME VISIBILITY REDUCTION
IS POSSIBLE TOWARD SUNRISE BUT SHOULD BECOME VFR BY MID MORNING.
MVFR CEILINGS APPEAR POSSIBLE FRIDAY AFTERNOON...MAINLY AT KOFK.

&&

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

MILLER

Hazardous weather outlook, Aug 18, 4:15 PM CDT, 2 hours 10 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
415 PM CDT THU AUG 18 2011

IAZ043-055-056-069-079-080-090-091-NEZ011-012-015>018-030>034-
042>045-050>053-065>068-078-088>093-191100-
ANTELOPE-BOONE-BURT-BUTLER-CASS-CEDAR-COLFAX-CUMING-DODGE-DOUGLAS-
FREMONT IA-GAGE-HARRISON IA-JEFFERSON-JOHNSON-KNOX-LANCASTER-MADISON-
MILLS IA-MONONA IA-MONTGOMERY IA-NEMAHA-OTOE-PAGE IA-PAWNEE-PIERCE-
PLATTE-POTTAWATTAMIE IA-RICHARDSON-SALINE-SARPY-SAUNDERS-SEWARD-
SHELBY IA-STANTON-THURSTON-WASHINGTON-WAYNE-
415 PM CDT THU AUG 18 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR MOST OF EASTERN NEBRASKA AND
PARTS OF SOUTHWEST IOWA.

.DAY ONE...TONIGHT AND FRIDAY.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT THIS EVENING FOR MUCH
OF THE AREA. SCATTERED THUNDERSTORMS SHOULD CONTINUE. SOME STORMS
WILL PRODUCE DAMAGING WINDS AND LARGE HAIL. LOCALLY HEAVY RAIN IS
ALSO EXPECTED...WITH SOME SPOTS POSSIBLY RECEIVING OVER 2 INCHES.

THERE IS A SMALL CHANCE FOR THUNDERSTORMS FOR PORTIONS OF THE AREA
FRIDAY AFTERNOON...BUT SEVERE WEATHER IS NOT LIKELY.

MINOR TO MODERATE FLOODING CONTINUES ALONG THE MISSOURI RIVER.

.DAYS TWO THROUGH SEVEN...FRIDAY NIGHT THROUGH THURSDAY

ANOTHER ROUND OF THUNDERSTORMS IS FORECAST FROM FRIDAY EVENING
THROUGH SATURDAY EVENING. AT THIS TIME...SEVERE THUNDERSTORMS ARE
NOT EXPECTED. ADDITIONAL SMALL CHANCES FOR THUNDERSTORMS ARE
EXPECTED SUNDAY NIGHT INTO MONDAY NIGHT.

MINOR TO MODERATE FLOODING WILL CONTINUE ALONG THE MISSOURI RIVER
FOR THE NEXT SEVERAL WEEKS.

.SPOTTER INFORMATION STATEMENT...

STORM SPOTTERS SHOULD SHOULD PASS ALONG ANY OCCURRENCES OF HAIL...
DAMAGING WINDS OR FLASH FLOODING.

MILLER

In the hours before

Local storm report, Aug 18, 5:50 PM CDT, 35 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
550 PM CDT THU AUG 18 2011

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

0543 PM     HAIL             ST. HELENA              42.81N 97.25W
08/18/2011  M2.00 INCH       CEDAR              NE   PUBLIC

&&

RCHERMOK

Local storm report, Aug 18, 6:00 PM CDT, 25 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
600 PM CDT THU AUG 18 2011

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

0546 PM     TORNADO          3 W CLEARWATER          42.17N 98.25W
08/18/2011                   ANTELOPE           NE   TRAINED SPOTTER

            TORNADO ABOUT 3 MILES WEST OF CLEARWATER ON THE GROUND
            ABOUT ONE MILE. EVENT TIME ESTIMATED 546 PM TO 550 PM.

&&

MILLER

Local storm report, Aug 18, 6:01 PM CDT, 24 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
601 PM CDT THU AUG 18 2011

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

0555 PM     TSTM WND GST     RED OAK                 41.01N 95.22W
08/18/2011  M64 MPH          MONTGOMERY         IA   AWOS

&&

RCHERMOK

Local storm report, Aug 18, 6:06 PM CDT, 19 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
606 PM CDT THU AUG 18 2011

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

0540 PM     FLOOD            WINNEBAGO               42.24N 96.47W
08/18/2011                   THURSTON           NE   EMERGENCY MNGR

            WATER REPORTED OVER HIGHWAY 77 IN WINNEBAGO AND INTO
            WALTHILL.

&&

LANDSVORK

Local storm report, Aug 18, 6:08 PM CDT, 17 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
608 PM CDT THU AUG 18 2011

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

0603 PM     HAIL             4 S STANTON             40.92N 95.10W
08/18/2011  E2.75 INCH       MONTGOMERY         IA   TRAINED SPOTTER

&&

LANDSVORK

Local storm report, Aug 18, 6:13 PM CDT, 12 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
613 PM CDT THU AUG 18 2011

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

0603 PM     HAIL             4 N VILLISCA            40.99N 94.98W
08/18/2011  E1.00 INCH       MONTGOMERY         IA   TRAINED SPOTTER

            WINDS ESTIMATED AT 70 MPH.

&&

LANDSVORK

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 18, 12:32 PM CDT	Severe Thunderstorm Warning	OAX	Knox	43 min
Aug 18, 12:56 PM CDT	Severe Thunderstorm Warning	OAX	Cedar, Knox, Pierce	49 min
Aug 18, 1:22 PM CDT	Severe Thunderstorm Warning	OAX	Cedar, Knox, Wayne	53 min
Aug 18, 3:14 PM CDT	Severe Thunderstorm Warning	OAX	Cedar	46 min
Aug 18, 3:44 PM CDT	Severe Thunderstorm Warning	OAX	Burt, Dodge, Washington	46 min
Aug 18, 3:57 PM CDT	Severe Thunderstorm Warning	OAX	Pierce, Wayne	63 min
Aug 18, 3:59 PM CDT	Severe Thunderstorm Warning	OAX	Cedar	20 min
Aug 18, 4:17 PM CDT	Severe Thunderstorm Warning	OAX	Burt, Washington	43 min
Aug 18, 4:48 PM CDT	Severe Thunderstorm Warning	OAX	Antelope, Knox	57 min
Aug 18, 4:53 PM CDT	Severe Thunderstorm Warning	OAX	Thurston	52 min
Aug 18, 4:56 PM CDT	Severe Thunderstorm Warning	OAX	Douglas, Washington	49 min
Aug 18, 5:20 PM CDT	Severe Thunderstorm Warning	OAX	Cass, Douglas, Sarpy	40 min
Aug 18, 5:25 PM CDT	Tornado Warning	OAX	Antelope	50 min
Aug 18, 5:28 PM CDT	Severe Thunderstorm Warning	OAX	Cedar	47 min
Aug 18, 5:37 PM CDT	Severe Thunderstorm Warning	OAX	Antelope, Knox, Pierce	38 min
Aug 18, 5:41 PM CDT	Flash Flood Warning	OAX	Douglas, Washington	5 hr
Aug 18, 5:43 PM CDT	Severe Thunderstorm Warning	OAX	Burt, Thurston	47 min
Aug 18, 5:50 PM CDT	Flash Flood Warning	OAX	Thurston	6 hr
Aug 18, 6:01 PM CDT	Tornado Warning	OAX	Antelope, Knox	44 min
Aug 18, 6:08 PM CDT	Tornado Warning	OAX	Antelope	52 min
Aug 18, 6:15 PM CDT	Severe Thunderstorm Warning	OAX	Burt, Cuming, Thurston, Wayne	45 min
Aug 18, 6:42 PM CDT	Severe Thunderstorm Warning	OAX	Burt, Washington	48 min
Aug 18, 6:56 PM CDT	Severe Thunderstorm Warning	OAX	Burt, Cuming, Dodge, Thurston	33 min
Aug 18, 6:57 PM CDT	Tornado Warning	OAX	Antelope, Boone, Madison	32 min

Nearby

Flash Flood Warnings in Nebraska, 2011 Every flash flood warning in 2011

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.