Alert archive / Nebraska / Flash Flood Warnings in 2021

Flash Flood Warning 13, NWS Cheyenne, WY

October 12, 2021Cheyenne County, Morrill County, Nebraska

NWS Cheyenne, WY issued this flash flood warning at Oct 12, 2021, 5:43 PM MDT for Cheyenne County, Morrill County, Nebraska. It was in force for 87 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Oct 12, 2021, 5:43 PM MDT (23:43 UTC)
Expired: Oct 12, 2021, 7:10 PM MDT
In force: 87 min
Issued by: NWS Cheyenne, WY
Area: Storm-based polygon
Flood severity: None

Counties Cheyenne County, NE, Morrill County, NE

The radar

The Cheyenne radar (KCYS), 161 km from the middle of the area, began a volume at 23:44 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

Denver, CO (KDNR), launched 12:00Z, 11.7 hours before the alert went out and 158 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1285 m above ground
0-6 km bulk shear: 56 kt
0-1 km storm-relative helicity: 170 m²/s²
0-3 km storm-relative helicity: 335 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

772 
WGUS55 KCYS 122343
FFWCYS
NEC033-123-130245-
/O.NEW.KCYS.FF.W.0013.211012T2343Z-211013T0245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Cheyenne WY
543 PM MDT Tue Oct 12 2021

The National Weather Service in Cheyenne has issued a

* Flash Flood Warning for...
  Eastern Cheyenne County in the panhandle of Nebraska...
  Southern Morrill County in the panhandle of Nebraska...

* Until 845 PM MDT.

* At 543 PM MDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 2 inches of rain 
  have fallen. The expected rainfall rate is 1 to 2 inches in 2 
  hours. Additional rainfall amounts of 1 to 1.5 inches are possible 
  in the warned area. Flash flooding is ongoing or expected to begin 
  shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar.

  IMPACT...Flash flooding of small creeks and streams, urban
           areas, highways, streets and underpasses as well as
           other poor drainage and low-lying areas.

* Some locations that will experience flash flooding include...
  Sidney, Lodgepole, Dalton, Gurley, Colton, Sunol and Sidney 
  Airport.

This includes the following highways...
	Interstate 80 in Nebraska between mile markers 56 and 75.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

Be aware of your surroundings and do not drive on flooded roads.

In hilly terrain there are hundreds of low water crossings which are 
potentially dangerous in heavy rain. Do not attempt to cross flooded 
roads. Find an alternate route.

&&

LAT...LON 4144 10305 4144 10264 4100 10265 4101 10303

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL...1-2 INCHES IN 2 HOURS

$$

Cox

1 follow-up statement

918 
WGUS75 KCYS 130110
FFSCYS

Flash Flood Statement
National Weather Service Cheyenne WY
710 PM MDT Tue Oct 12 2021

NEC033-123-130120-
/O.CAN.KCYS.FF.W.0013.000000T0000Z-211013T0245Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Cheyenne NE-Morrill NE-
710 PM MDT Tue Oct 12 2021

...FLASH FLOOD WARNING IS CANCELLED FOR EASTERN CHEYENNE AND 
SOUTHERN MORRILL COUNTIES...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Please continue to heed remaining road closures.

LAT...LON 4144 10305 4144 10264 4100 10265 4100 10266
      4100 10274 4101 10303

$$

Cox

The office that day

Everything else NWS Cheyenne, WY issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Oct 12, 4:26 AM MDT	High Wind Warning	CYS	Banner, Box Butte, Cheyenne, Dawes, Kimball, Morrill and 2 more	38 hr
Oct 12, 4:27 PM MDT	Special Weather Statement	CYS	Morrill	33 min
Oct 12, 4:37 PM MDT	Special Weather Statement	CYS	Morrill	38 min
Oct 12, 4:53 PM MDT	Special Weather Statement	CYS	Cheyenne	37 min
Oct 12, 5:13 PM MDT	Severe Thunderstorm Warning	CYS	Cheyenne, Morrill	47 min

Nearby

Flash Flood Warnings in Nebraska, 2021 Every flash flood warning in 2021

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.