Alert archive / Wyoming / Flash Flood Warnings in 2021

Flash Flood Warning 2, NWS Cheyenne, WY

June 8, 2021Laramie County, Wyoming

NWS Cheyenne, WY issued this flash flood warning at Jun 8, 2021, 7:30 PM MDT for Laramie County, Wyoming. It was in force for 3 hr. 4 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: Jun 8, 2021, 7:30 PM MDT (01:30 UTC)
Expired: Jun 8, 2021, 10:20 PM MDT
In force: 3 hr
Issued by: NWS Cheyenne, WY
Area: Storm-based polygon
Flood severity: None

County Laramie County, WY

The radar

The Cheyenne radar (KCYS), 6 km from the middle of the area, began a volume at 01:33 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
Jun 8, 7:43 PM MDT	FLASH FLOOD	2 Wsw North Cheyenne, WY	LOCAL FLOODING ON DEL RANGE VIA TWITTER.
Jun 8, 8:14 PM MDT	FLASH FLOOD	8 Ene Cheyenne, WY	LOCAL FLOODING 6 INCHES IN DRAINAGE DITCH.
Jun 8, 8:16 PM MDT	FLASH FLOOD	2 Ene Warren Af Base, WY	FLOODING IN DOWNTOWN CHEYENNE.
Jun 8, 10:12 PM MDT	FLOOD	1 W Cheyenne, WY	2 INCHES OF STANDING WATER.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Denver, CO (KDNR), launched 00:00Z, 1.5 hours before the alert went out and 198 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: 424 J/kg
Mixed-layer CIN: -54 J/kg
Mixed-layer LCL: 3769 m above ground
0-6 km bulk shear: 41 kt
0-1 km storm-relative helicity: 92 m²/s²
0-3 km storm-relative helicity: 155 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.2

Open this sounding in Storm Lab

The text

As transmitted.

705 
WGUS55 KCYS 090130
FFWCYS
WYC021-090430-
/O.NEW.KCYS.FF.W.0002.210609T0130Z-210609T0430Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Cheyenne WY
730 PM MDT Tue Jun 8 2021

The National Weather Service in Cheyenne has issued a

* Flash Flood Warning for...
  Southwestern Laramie County in southeastern Wyoming...

* Until 1030 PM MDT.

* At 730 PM MDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 2 inches of rain 
  have fallen. Flash flooding is ongoing or expected to begin 
  shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Doppler radar.

  IMPACT...Flooding of small creeks and streams, urban areas,
           highways, streets and underpasses as well as other
           drainage and low lying areas.

* Some locations that will experience flash flooding include...
  Cheyenne, Frontier Park, Warren Af Base, Warren AFB, South 
  Greeley, North Cheyenne, Ranchettes, South Greeley High and Fox 
  Farm-College.

This includes the following highways...
	Interstate 80 in Wyoming between mile markers 348 and 372.
	Interstate 25 in Wyoming between mile markers 4 and 18.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4116 10502 4129 10478 4120 10461 4109 10461
      4105 10485 4103 10505 4113 10508

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL...0.5-1 INCH IN 1 HOUR 

$$

Hammer

2 follow-up statements

166 
WGUS75 KCYS 090259
FFSCYS

Flash Flood Statement
National Weather Service Cheyenne WY
859 PM MDT Tue Jun 8 2021

WYC021-090430-
/O.CON.KCYS.FF.W.0002.000000T0000Z-210609T0430Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Laramie WY-
859 PM MDT Tue Jun 8 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1030 PM MDT THIS 
EVENING FOR SOUTHWESTERN LARAMIE COUNTY...

At 859 PM MDT, the public reported thunderstorms producing flash 
flooding from thunderstorms across the warned area. Between 2 and 3 
inches of rain have fallen. Flash flooding is occurring in Cheyenne! 
Avoid local travel!

HAZARD...Flash flooding caused by thunderstorms.

SOURCE...Public.

IMPACT...Flooding of small creeks and streams, urban areas,
         highways, streets and underpasses as well as other
         drainage and low lying areas.

Some locations that will experience flash flooding include...
  Cheyenne, Frontier Park, Warren Af Base, Warren AFB, South 
  Greeley, North Cheyenne, Ranchettes, South Greeley High and Fox 
  Farm-College.

This includes the following highways...
	Interstate 80 in Wyoming between mile markers 348 and 372.
	Interstate 25 in Wyoming between mile markers 4 and 18.

Additional rainfall amounts of 0.5 to 1 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.

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

&&

LAT...LON 4116 10502 4129 10478 4120 10461 4109 10461
      4105 10485 4103 10505 4113 10508

FLASH FLOOD...OBSERVED

$$

Hammer

619 
WGUS75 KCYS 090420
FFSCYS

Flash Flood Statement
National Weather Service Cheyenne WY
1020 PM MDT Tue Jun 8 2021

WYC021-090430-
/O.CAN.KCYS.FF.W.0002.000000T0000Z-210609T0430Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Laramie WY-
1020 PM MDT Tue Jun 8 2021

...FLASH FLOOD WARNING FOR SOUTHWESTERN LARAMIE COUNTY HAS BEEN 
REPLACED WITH A FLOOD ADVISORY...

Flash flooding has ended and no longer poses a significant threat. 
However, several inches of standing water may still exist on area 
roadways. Continue to exercise caution, especially in and around 
Cheyenne.

LAT...LON 4116 10502 4129 10478 4120 10461 4109 10461
      4105 10485 4103 10505 4113 10508

$$

Hammer

The office that day

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

Issued	Product	Office	Counties	Lasted
Jun 8, 6:14 PM MDT	Special Weather Statement	CYS	Laramie	31 min
Jun 8, 6:45 PM MDT	Severe Thunderstorm Warning	CYS	Laramie	45 min
Jun 8, 7:27 PM MDT	Severe Thunderstorm Warning	CYS	Laramie	48 min
Jun 8, 8:21 PM MDT	Special Weather Statement	CYS	Niobrara	54 min
Jun 8, 8:29 PM MDT	Special Weather Statement	CYS	Laramie	46 min
Jun 8, 8:35 PM MDT	Severe Thunderstorm Warning	CYS	Niobrara	55 min
Jun 8, 8:36 PM MDT	Special Weather Statement	CYS	Laramie	39 min
Jun 8, 9:03 PM MDT	Severe Thunderstorm Warning	CYS	Goshen, Laramie	42 min
Jun 8, 9:08 PM MDT	Severe Thunderstorm Warning	CYS	Laramie	52 min
Jun 8, 9:33 PM MDT	Special Weather Statement	CYS	Niobrara	57 min
Jun 8, 10:20 PM MDT	Areal Flood Advisory	CYS	Laramie	3 hr
Jun 8, 10:26 PM MDT	Severe Thunderstorm Warning	CYS	Laramie	49 min
Jun 8, 11:15 PM MDT	Severe Thunderstorm Warning	CYS	Laramie	45 min
Jun 9, 2:11 PM MDT	High Wind Watch	CYS	Albany, Converse, Goshen, Laramie, Niobrara, Platte	12 hr
Jun 9, 2:11 PM MDT	High Wind Warning	CYS	Albany, Carbon, Converse, Goshen, Laramie, Niobrara and 1 more	39 hr

Nearby

Flash Flood Warnings in Wyoming, 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.