Alert archive / Nebraska / Flash Flood Warnings in 2018
Flash Flood Warning 21, NWS Omaha, NE
NWS Omaha, NE issued this flash flood warning at Aug 20, 2018, 10:15 AM CDT for Cass County, Douglas County, Sarpy County, Nebraska; Mills County, Pottawattamie County, Iowa. It was in force for 4 hr. 6 reports came from inside the area while it was in force.
The area
The outline as issued, with what was reported inside it.
The facts
- Issued
- Aug 20, 2018, 10:15 AM CDT (15:15 UTC)
- Expired
- Aug 20, 2018, 2:15 PM CDT
- In force
- 4 hr
- Issued by
- NWS Omaha, NE
- Area
- Storm-based polygon
- Flood severity
- None
Counties Mills County, IA, Pottawattamie County, IA, Cass County, NE, Douglas County, NE, Sarpy County, NE
The radar
The Omaha radar (KOAX), 47 km from the middle of the area, began a volume at 15:18 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.
What was reported inside it
| Time | Report | Where | Remark |
|---|---|---|---|
| Aug 20, 10:39 AM CDT | HEAVY RAIN 4 | 2 S Offutt Afb, NE | |
| Aug 20, 10:57 AM CDT | FLASH FLOOD | 2 Nnw Bellevue, NE | STREET FLOODING, REPORTED AT 22ND AND CHANDLER. |
| Aug 20, 11:00 AM CDT | FLASH FLOOD | 2 Ne Offutt Afb, NE | STANDING WATER UP TO THE SIDE OF HOMES IN GREEN ACRES MOBILE HOME PARK. MULTIPLE PHOTOS ON TWITTER. |
| Aug 20, 11:15 AM CDT | HEAVY RAIN 3.04 | Bellevue, NE | |
| Aug 20, 11:40 AM CDT | FLASH FLOOD | 2 Ne Offutt Afb, NE | PAYNE DRIVE INTO HAWORTH PARK CLOSED DUE TO FLASH FLOODING. |
| Aug 20, 11:58 AM CDT | HEAVY RAIN 4.12 | Offutt Afb, NE |
Local storm reports filed while the alert was in force, from inside its polygon or its counties.
The nearest sounding before it
Omaha, NE (KOAX), launched 12:00Z, 3.3 hours before the alert went out and 47 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.
- Mixed-layer CAPE
- 86 J/kg
- Mixed-layer CIN
- -57 J/kg
- Mixed-layer LCL
- 595 m above ground
- 0-6 km bulk shear
- 26 kt
- 0-1 km storm-relative helicity
- -56 m²/s²
- 0-3 km storm-relative helicity
- 86 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
008
WGUS53 KOAX 201515
FFWOAX
IAC129-155-NEC025-055-153-201915-
/O.NEW.KOAX.FF.W.0021.180820T1515Z-180820T1915Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Omaha/Valley Nebraska
1015 AM CDT MON AUG 20 2018
The National Weather Service in Omaha has issued a
* Flash Flood Warning for...
Northwestern Mills County in southwestern Iowa...
Southwestern Pottawattamie County in southwestern Iowa...
Northeastern Sarpy County in east central Nebraska...
Southern Douglas County in east central Nebraska...
Northeastern Cass County in southeastern Nebraska...
* Until 215 PM CDT.
* At 1013 AM CDT, Doppler radar indicated heavy rain across the
warned area. Flash flooding is expected to begin shortly.
* Some locations that will experience flooding include...
Southern Omaha, southwestern Council Bluffs, Bellevue, Papillion,
La Vista, Plattsmouth, Ralston, Pacific Junction, Offutt AFB, Camp
Maha and Lake Manawa State Park.
Additional rainfall amounts of 2 to 3 inches are possible in the
warned area.
This includes Interstate 29 between mile markers 35 and 45.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Excessive runoff from heavy rainfall will cause flooding of small
creeks and streams, urban areas, highways, streets and underpasses as
well as other drainage areas and low lying spots.
&&
LAT...LON 4120 9581 4118 9570 4103 9578 4100 9588
4104 9607 4121 9607
$$
HB2 follow-up statements
512
WGUS73 KOAX 201642
FFSOAX
Flash Flood Statement
National Weather Service Omaha/Valley Nebraska
1142 AM CDT MON AUG 20 2018
IAC129-155-NEC025-055-153-201915-
/O.CON.KOAX.FF.W.0021.000000T0000Z-180820T1915Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Mills IA-Pottawattamie IA-Sarpy NE-Douglas NE-Cass NE-
1142 AM CDT MON AUG 20 2018
...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 215 PM CDT FOR
NORTHWESTERN MILLS...SOUTHWESTERN POTTAWATTAMIE...NORTHEASTERN
SARPY...SOUTHERN DOUGLAS AND NORTHEASTERN CASS COUNTIES...
At 1136 AM CDT, Doppler radar indicated heavy rain across the warned
area, mainly areas west of the Missouri River. 4 to 6 inches of rain
may have already occurred. Flash flooding has already been reported
in portions of Bellevue, Nebraska.
Some locations that will experience flooding include...
Southern Omaha, southwestern Council Bluffs, Bellevue, Papillion, La
Vista, Plattsmouth, Ralston, Pacific Junction, Offutt AFB, Camp Maha
and Lake Manawa State Park.
Additional rainfall amounts up to an inch are possible in the warned
area.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.
Excessive runoff from heavy rainfall will cause flooding of small
creeks and streams, urban areas, highways, streets and underpasses as
well as other drainage areas and low lying spots.
&&
LAT...LON 4120 9581 4118 9570 4103 9578 4100 9588
4104 9607 4121 9607
$$
DEWALD607
WGUS73 KOAX 201912
FFSOAX
Flash Flood Statement
National Weather Service Omaha/Valley Nebraska
212 PM CDT MON AUG 20 2018
IAC129-155-NEC025-055-153-201921-
/O.EXP.KOAX.FF.W.0021.000000T0000Z-180820T1915Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Mills IA-Pottawattamie IA-Sarpy NE-Douglas NE-Cass NE-
212 PM CDT MON AUG 20 2018
...THE FLASH FLOOD WARNING FOR NORTHWESTERN MILLS...SOUTHWESTERN
POTTAWATTAMIE...NORTHEASTERN SARPY...SOUTHERN DOUGLAS AND
NORTHEASTERN CASS COUNTIES WILL EXPIRE AT 215 PM CDT...
The heavy rain threat has greatly diminished, thus the flash flood
warning that was in effect until 115 pm will be allowed to expire.
However, due to the excessive rainfall of 4 to 6 inches that has
previously fallen over the last several hours, a general, areal
flood threat will continue into the evening. Please continue to heed
any remaining road closures. Do not drive into flooded areas.
LAT...LON 4120 9581 4118 9570 4103 9578 4100 9588
4104 9607 4121 9607
$$
DEWALDThe office that day
Everything else NWS Omaha, NE issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 19, 11:57 PM CDT | River Flood Warning | OAX | Otoe | 4 days |
| Aug 19, 11:57 PM CDT | River Flood Warning | OAX | Nemaha | 5 days |
| Aug 19, 11:57 PM CDT | River Flood Warning | OAX | Richardson | 5 days |
| Aug 20, 5:33 AM CDT | Special Weather Statement | OAX | Douglas, Sarpy | 42 min |
| Aug 20, 8:06 AM CDT | Flash Flood Warning | OAX | Douglas | 6 hr |
| Aug 20, 8:54 AM CDT | Areal Flood Warning | OAX | Burt, Cuming, Dodge, Thurston, Washington | 15 hr |
| Aug 20, 10:28 AM CDT | River Flood Warning | OAX | Cass | 3 days |
| Aug 20, 11:22 AM CDT | River Flood Advisory | OAX | Douglas, Sarpy | 51 hr |
| Aug 20, 1:48 PM CDT | Areal Flood Warning | OAX | Cass, Dodge, Douglas, Sarpy, Saunders, Washington | 9 hr |
| Aug 20, 5:07 AM CDT | Flash Flood Warning | OAX | Harrison, Pottawattamie, Shelby | 6 hr |
| Aug 20, 5:23 PM CDT | River Flood Warning | OAX | Fremont | 28 hr |
Nearby
Flash Flood Warnings in Nebraska, 2018Flash Flood Warnings in Iowa, 2018Every flash flood 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.