Alert archive / Wyoming / Flash Flood Warnings in 2018

Flash Flood Warning 7, NWS Cheyenne, WY

May 28, 2018Laramie County, Wyoming

NWS Cheyenne, WY issued this flash flood warning at May 28, 2018, 6:03 PM MDT for Laramie County, Wyoming. It was in force for 3 hr. 3 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: May 28, 2018, 6:03 PM MDT (00:03 UTC)
Expired: May 28, 2018, 9:00 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), 27 km from the middle of the area, began a volume at 00:06 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
May 28, 6:08 PM MDT	FLASH FLOOD	Hillsdale, WY	THREE TO FOUR INCHES OF RAPIDLY RUNNING WATER AT CR 142 SOUTH OF CR 212.
May 28, 6:28 PM MDT	FLASH FLOOD	Hillsdale, WY	RAPIDLY FLOWING WATER SIX TO EIGHT INCHES DEEP ACROSS CR 142 SOUTH OF CR 212. SEVERAL LOW PLACES WATER IS TWO TO THREE INCHES DEEP NEAR CROP FIELDS.
May 28, 8:20 PM MDT	FLASH FLOOD	2 W Burns, WY	NUMEROUS ROADS INUNDATED AND HAVE BEEN BARRICADED BY COUNTY PUBLIC WORKS DEPARTMENT. FLOWING WATER OF 3 TO 6 INCHES OVER MANY ROADWAYS.

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

The nearest sounding before it

N. Platte/Lee Bi, NE (KLBF), launched 00:00Z, 0.1 hours before the alert went out and 326 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: 410 J/kg
Mixed-layer CIN: -333 J/kg
Mixed-layer LCL: 1525 m above ground
0-6 km bulk shear: 32 kt
0-1 km storm-relative helicity: 59 m²/s²
0-3 km storm-relative helicity: 115 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.2

Open this sounding in Storm Lab

The text

As transmitted.

980 
WGUS55 KCYS 290003
FFWCYS
WYC021-290300-
/O.NEW.KCYS.FF.W.0007.180529T0003Z-180529T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Cheyenne WY
603 PM MDT MON MAY 28 2018

The National Weather Service in Cheyenne has issued a

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

* Until 900 PM MDT

At 602 PM MDT, Doppler radar indicated thunderstorms producing heavy 
rain across the warned area. Up to two inches of rain have   already 
fallen and an additional one to two inches will be possible over the 
next two hours. Flash flooding is expected to begin shortly.

* Some locations that will experience flooding include...
  Cheyenne, Pine Bluffs, Burns, Albin, Hillsdale, Meriden Rest Area,
  Gun Barrel, Carpenter and Ranchettes.

This includes Interstate 80 in Wyoming between mile markers 368 and
402.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4100 10469 4101 10470 4131 10470 4156 10456
      4156 10405 4100 10405

$$

Allen

The office that day

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

Issued	Product	Office	Counties	Lasted
May 28, 6:17 PM MDT	Special Weather Statement	CYS	Goshen	43 min
May 28, 6:22 PM MDT	Areal Flood Advisory	CYS	Goshen	3 hr
May 28, 6:26 PM MDT	Severe Thunderstorm Warning	CYS	Goshen, Laramie	49 min
May 28, 6:44 PM MDT	Special Weather Statement	CYS	Platte	46 min
May 28, 8:02 PM MDT	Special Weather Statement	CYS	Niobrara	43 min
May 28, 8:58 PM MDT	Areal Flood Advisory	CYS	Laramie	4 hr

Nearby

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