Alert archive / Wyoming / Flash Flood Warnings in 2011

Flash Flood Warning 14, NWS Cheyenne, WY

July 12, 2011Goshen County, Laramie County, Platte County, Wyoming

NWS Cheyenne, WY issued this flash flood warning at Jul 12, 2011, 10:26 PM MDT for Goshen County, Laramie County, Platte County, Wyoming. It was in force for 4 hr. 1 report 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: Jul 12, 2011, 10:26 PM MDT (04:26 UTC)
Expired: Jul 13, 2011, 2:46 AM MDT
In force: 4 hr
Issued by: NWS Cheyenne, WY
Area: Storm-based polygon
Flood severity: None

Counties Goshen County, WY, Laramie County, WY, Platte County, WY

The radar

The Cheyenne radar (KCYS), 29 km from the middle of the area, began a volume at 04:28 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
Jul 13, 12:15 AM MDT	FLASH FLOOD	Cheyenne, WY	NWS EMPLOYEE REPORTED 6 INCHES OF STANDING WATER AT THE INTERSECTION OF EVANS AND PERSHING.

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, 4.4 hours before the alert went out and 218 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: 596 J/kg
Mixed-layer CIN: -61 J/kg
Mixed-layer LCL: 1449 m above ground
0-6 km bulk shear: 25 kt
0-1 km storm-relative helicity: -12 m²/s²
0-3 km storm-relative helicity: 256 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 2.2

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

357 
WGUS55 KCYS 130426
FFWCYS
WYC015-021-031-131030-
/O.NEW.KCYS.FF.W.0014.110713T0426Z-110713T1030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE CHEYENNE WY
1026 PM MDT TUE JUL 12 2011

THE NATIONAL WEATHER SERVICE IN CHEYENNE HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  EXTREME SOUTHERN PLATTE COUNTY IN SOUTHEAST WYOMING...
  SOUTHWESTERN GOSHEN COUNTY IN SOUTHEAST WYOMING...
  WESTERN LARAMIE COUNTY IN SOUTHEAST WYOMING...

* UNTIL 430 AM MDT WEDNESDAY

* AT 1023 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
  SLOW MOVING THUNDERSTORMS WITH VERY HEAVY RAINFALL ACROSS THE      
  WARNED AREA. RAINFALL REPORTS OF TWO TO TWO AND A HALF INCHES HAVE 
  ALREADY FALLEN ACROSS THE AREA EARLIER THIS EVENING. SOILS ARE     
  SATURATED AND STREAMS ARE RUNNING HIGH.

* RUNOFF FROM THIS EXCESSIVE RAINFALL WILL CAUSE FLASH FLOODING TO
  OCCUR. SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE...
  CHEYENNE...CRYSTAL LAKE RESERVOIR...FEDERAL...GRANITE SPRINGS
  RESERVOIR...HORSE CREEK...IRON MOUNTAIN...NORTH CHEYENNE...WARREN
  AF BASE AND WHITAKER.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

SLOW MOVING STORMS ARE MOVING INTO CENTRAL AND WESTERN LARAMIE 
COUNTY FROM NORTHERN COLORADO LATE THIS EVENING. ADDITIONAL RAINFALL 
AMOUNTS OF 1 TO 2 INCHES ARE ARE POSSIBLE IN THE WARNED AREA.

BE ESPECIALLY CAUTIOUS AT NIGHT WHEN IT IS HARDER TO RECOGNIZE THE
DANGERS OF FLOODING. IF FLASH FLOODING IS OBSERVED ACT QUICKLY. DO
NOT ENTER THE WATER. TURN AROUND AND MOVE UP TO HIGHER GROUND TO
ESCAPE FLOOD WATERS. DO NOT STAY IN AREAS SUBJECT TO FLOODING WHEN
WATER BEGINS RISING.

TO REPORT FLOODING...HAVE THE NEAREST LAW ENFORCEMENT AGENCY RELAY
YOUR REPORT TO THE NATIONAL WEATHER SERVICE FORECAST OFFICE IN
CHEYENNE.

&&

LAT...LON 4167 10455 4102 10450 4103 10523 4166 10528

$$

CLAYCOMB

1 follow-up statement

836 
WGUS75 KCYS 130846
FFSCYS

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE CHEYENNE WY
246 AM MDT WED JUL 13 2011

WYC015-021-031-130900-
/O.CAN.KCYS.FF.W.0014.000000T0000Z-110713T1030Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
GOSHEN WY-LARAMIE WY-PLATTE WY-
246 AM MDT WED JUL 13 2011

...THE FLASH FLOOD WARNING THAT WAS IN EFFECT FOR EXTREME
SOUTHEASTERN PLATTE...WESTERN LARAMIE AND SOUTHWESTERN GOSHEN
COUNTIES IS CANCELLED...

EXCESS RUNOFF FROM HEAVY RAIN HAS ENDED OVER THE WARNED AREA. STREAMS
AND CREEKS IN THE WARNED AREA WERE BEGINNING TO RECEDE...BUT WILL 
LIKELY REMAIN BANKFULL THROUGH EARLY THIS MORNING. IF ANY ADDITIONAL 
FLOODING IS OBSERVED...PLEASE REPORT IT TO YOUR LOCAL LAW 
ENFORCEMENT AGENCY.

LAT...LON 4167 10455 4102 10450 4103 10523 4166 10528

$$

TJT

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 12, 6:03 PM MDT	Tornado Warning	CYS	Goshen, Laramie, Platte	30 min
Jul 12, 6:03 PM MDT	Tornado Warning	CYS	Laramie	27 min
Jul 12, 6:56 PM MDT	Severe Thunderstorm Warning	CYS	Laramie	45 min
Jul 12, 7:09 PM MDT	Flash Flood Warning	CYS	Goshen, Laramie	8 hr
Jul 12, 7:46 PM MDT	Severe Thunderstorm Warning	CYS	Laramie	32 min

Nearby

Flash Flood Warnings in Wyoming, 2011 Every flash flood warning in 2011

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.