Alert archive / Nebraska / Flash Flood Warnings in 2018

Flash Flood Warning 2, NWS Cheyenne, WY

May 18, 2018Dawes County, Sioux County, Nebraska

NWS Cheyenne, WY issued this flash flood warning at May 18, 2018, 10:50 PM MDT for Dawes County, Sioux 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: May 18, 2018, 10:50 PM MDT (04:50 UTC)
Expired: May 19, 2018, 1:45 AM MDT
In force: 3 hr
Issued by: NWS Cheyenne, WY
Area: Storm-based polygon
Flood severity: None

Counties Dawes County, NE, Sioux County, NE

The radar

The Rapid City radar (KUDX), 152 km from the middle of the area, began a volume at 04:52 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

Rapid City, SD (KRAP), launched 00:00Z, 4.8 hours before the alert went out and 145 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: 229 J/kg
Mixed-layer CIN: -9 J/kg
Mixed-layer LCL: 1207 m above ground
0-6 km bulk shear: 25 kt
0-1 km storm-relative helicity: -22 m²/s²
0-3 km storm-relative helicity: -19 m²/s²
Significant tornado parameter: -0.0
Supercell composite: -0.6

Open this sounding in Storm Lab

The text

As transmitted.

923 
WGUS55 KCYS 190450
FFWCYS
NEC045-165-190745-
/O.NEW.KCYS.FF.W.0002.180519T0450Z-180519T0745Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Cheyenne WY
1050 PM MDT FRI MAY 18 2018

The National Weather Service in Cheyenne has issued a

* Flash Flood Warning for...
  Central Dawes County in the Panhandle of Nebraska...
  Northeastern Sioux County in the Panhandle of Nebraska...

* Until 145 AM MDT

* At 1049 PM MDT, local law enforcement officials reported
  thunderstorms producing heavy rain across the warned area. Up to
  two inches of rain have already fallen. Flash flooding is expected 
  to begin shortly. Law enforcement reports four feet of water in 
  Crawford.

* Some locations that will experience flooding include...
  Chadron, Crawford, Fort Robinson Campground, Chadron Campground,
  Whitney Lake, Red Cloud Campground, Chadron Airport, Whitney, Fort
  Robinson and Chadron St Park.

Additional rainfall amounts of 1 to 2 inches are possible in the 
warned area.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be especially cautious at night when it is harder to recognize the
dangers of flooding.

&&

LAT...LON 4265 10278 4258 10363 4283 10366 4289 10359
      4300 10279 4282 10280 4278 10278

$$

Rubin

1 follow-up statement

180 
WGUS75 KCYS 190742
FFSCYS

Flash Flood Statement
National Weather Service Cheyenne WY
142 AM MDT SAT MAY 19 2018

NEC045-165-190752-
/O.EXP.KCYS.FF.W.0002.000000T0000Z-180519T0745Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Dawes NE-
142 AM MDT SAT MAY 19 2018

...THE FLASH FLOOD WARNING FOR CENTRAL DAWES COUNTY WILL EXPIRE AT
145 AM MDT...

Flood waters have receded. Flooding is no longer expected to pose a
threat. Please continue to heed any remaining road closures.

LAT...LON 4265 10278 4258 10363 4283 10366 4289 10359
      4300 10279 4282 10280 4278 10278

$$

Hahn

The office that day

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

Issued	Product	Office	Counties	Lasted
May 18, 6:12 PM MDT	Special Weather Statement	CYS	Sioux	63 min
May 18, 10:00 PM MDT	Special Weather Statement	CYS	Dawes	45 min
May 18, 11:26 PM MDT	Areal Flood Advisory	CYS	Scotts Bluff	4 hr
May 19, 12:38 AM MDT	Flash Flood Warning	CYS	Banner, Kimball, Scotts Bluff	7 hr
May 19, 7:43 AM MDT	Areal Flood Advisory	CYS	Banner, Kimball, Scotts Bluff	5 hr
May 19, 8:01 AM MDT	Flash Flood Warning	CYS	Kimball	3 hr
May 19, 10:01 AM MDT	Areal Flood Warning	CYS	Banner, Kimball, Scotts Bluff, Sioux	6 hr
May 19, 11:34 AM MDT	Areal Flood Advisory	CYS	Box Butte, Cheyenne, Dawes, Morrill	4 hr
May 19, 3:18 PM MDT	Areal Flood Warning	CYS	Banner, Box Butte, Dawes, Kimball, Scotts Bluff, Sioux	6 hr
May 19, 3:29 PM MDT	Areal Flood Advisory	CYS	Box Butte, Cheyenne, Dawes, Morrill	6 hr

Nearby

Flash Flood Warnings in Nebraska, 2018 Every 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.