Alert archive / Nebraska / Flash Flood Warnings in 2011

Flash Flood Warning 23, NWS Cheyenne, WY

August 4, 2011Cheyenne County, Nebraska

NWS Cheyenne, WY issued this flash flood warning at Aug 4, 2011, 7:55 PM MDT for Cheyenne County, Nebraska. It was in force for 4 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
Aug 4, 2011, 7:55 PM MDT (01:55 UTC)
Expired
Aug 5, 2011, 12:19 AM MDT
In force
4 hr
Issued by
NWS Cheyenne, WY
Area
Storm-based polygon
Flood severity
None

County Cheyenne County, NE

The radar

The Cheyenne radar (KCYS), 175 km from the middle of the area, began a volume at 01:57 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 00:00Z, 1.9 hours before the alert went out and 169 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-pSkew-T log-p diagram, Denver, CO at 00:00Z on 2011-08-05Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Denver, CO at 00:00Z on 2011-08-05The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -97 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
2478 m above ground
0-6 km bulk shear
27 kt
0-1 km storm-relative helicity
-97 m²/s²
0-3 km storm-relative helicity
-114 m²/s²
Significant tornado parameter
0.0
Supercell composite
-0.0

Open this sounding in Storm Lab

The text

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

637 
WGUS55 KCYS 050155
FFWCYS
NEC033-050800-
/O.NEW.KCYS.FF.W.0023.110805T0155Z-110805T0800Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE CHEYENNE WY
755 PM MDT THU AUG 4 2011

THE NATIONAL WEATHER SERVICE IN CHEYENNE HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  NORTHEASTERN CHEYENNE COUNTY IN THE PANHANDLE OF NEBRASKA...

* UNTIL 200 AM MDT FRIDAY

* AT 752 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED   
SLOW MOVING THUNDERSTORMS WITH VERY HEAVY RAINFALL MOVING ACROSS THE 
WARNED AREA. DOPPLER RADAR ESTIMATED NEARLY 2 INCHES OF RAIN HAD 
OCCURRED DURING THE LAST HOUR. THE BACK EDGE OF THE THUNDERSTORMS 
WERE BEGINNING TO MOVE INTO EASTERN KIMBALL COUNTY...SO THE HEAVY 
RAINFALL MAY CONTINUE ACROSS THIS AREA DURING THE NEXT COUPLE OF 
HOURS BEFORE ENDING. UNTIL THEN...ANOTHER ONE TO TWO INCHES OF 
RAINFALL WILL BE POSSIBLE. 

* RUNOFF FROM THIS EXCESSIVE RAINFALL WILL CAUSE FLASH FLOODING TO
  OCCUR. SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE...
  GURLEY.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE
ROADWAY. THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS
SAFELY.

&&

LAT...LON 4123 10261 4122 10298 4144 10297 4143 10264
      4140 10264 4140 10260

$$

COX
2 follow-up statements
644 
WGUS75 KCYS 050444
FFSCYS

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE CHEYENNE WY
1044 PM MDT THU AUG 4 2011

NEC033-050800-
/O.CON.KCYS.FF.W.0023.000000T0000Z-110805T0800Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
CHEYENNE NE-
1044 PM MDT THU AUG 4 2011

...FLASH FLOOD WARNING REMAINS IN EFFECT FOR NORTHEASTERN CHEYENNE
COUNTY UNTIL 200 AM MDT...

AT 1043 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A 
FEW LIGHT RAIN SHOWERS ACROSS EASTERN CHEYENNE COUNTY PRODUCING 
RAINFALL AMOUNTS UNDER ONE TENTH OF AN INCH.

AT 1030 PM MDT...THE CHEYENNE COUNTY SHERIFFS OFFICE HAD NO REPORTS 
OF FLOODING FROM THE FLASH FLOOD WARNING AREA.

DOPPLER RADAR ESTIMATES THAT 2 TO 3 INCHES OF RAIN FELL FROM EARLIER 
THUNDERSTORMS IN A SMALL AREA 13 MILES NORTHEAST OF SIDNEY...OR 9 
MILES NORTH OF SUNOL.

THE FLASH FLOOD WARNING MAY BE CANCELLED EARLY IF THERE ARE NO 
FLOODING REPORTS...ESPECIALLY SINCE HEAVIER RAINFALL HAS ENDED 
ACROSS THE FLASH FLOOD WARNING AREA.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE
ROADWAY. THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS
SAFELY.

REPORT FLOODING TO THE NEAREST LAW ENFORCEMENT AGENCY SO THAT THEY
MAY TAKE APPROPRIATE ACTION TO CLOSE FLOODED ROADWAYS. THEY WILL
RELAY YOUR REPORT TO THE NATIONAL WEATHER SERVICE IN CHEYENNE.

&&

LAT...LON 4123 10261 4122 10298 4144 10297 4143 10264
      4140 10264 4140 10260

$$

RUBIN
896 
WGUS75 KCYS 050619
FFSCYS

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE CHEYENNE WY
1219 AM MDT FRI AUG 5 2011

NEC033-050634-
/O.CAN.KCYS.FF.W.0023.000000T0000Z-110805T0800Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
CHEYENNE NE-
1219 AM MDT FRI AUG 5 2011

...THE FLASH FLOOD WARNING THAT WAS IN EFFECT FOR NORTHEASTERN
CHEYENNE COUNTY IS CANCELLED...

EXCESS RUNOFF FROM HEAVY RAIN HAS ENDED OVER THE WARNED AREA. STREAMS
AND CREEKS IN THE WARNED AREA HAVE RECEDED OR WERE BEGINNING TO
RECEDE...ENDING THE FLOOD THREAT. IF FLOODING HAS BEEN OBSERVED...
PLEASE REPORT IT TO YOUR LOCAL LAW ENFORCEMENT AGENCY.

LAT...LON 4123 10261 4122 10298 4144 10297 4143 10264
      4140 10264 4140 10260

$$

HAHN

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 4, 6:02 PM MDTSevere Thunderstorm WarningCYSMorrill58 min
Aug 4, 6:38 PM MDTSevere Thunderstorm WarningCYSBox Butte, Morrill28 min
Aug 4, 6:58 PM MDTSevere Thunderstorm WarningCYSMorrill43 min
Aug 4, 7:13 PM MDTSevere Thunderstorm WarningCYSCheyenne15 min
Aug 4, 7:33 PM MDTAreal Flood AdvisoryCYSCheyenne26 min
Aug 5, 3:48 PM MDTSpecial Weather StatementCYSKimball57 min
Aug 5, 4:04 PM MDTSpecial Weather StatementCYSKimball56 min
Aug 5, 4:42 PM MDTSpecial Weather StatementCYSKimball63 min
Aug 5, 4:51 PM MDTSpecial Weather StatementCYSBox Butte39 min
Aug 5, 5:17 PM MDTSpecial Weather StatementCYSDawes43 min
Aug 5, 5:39 PM MDTSpecial Weather StatementCYSBox Butte51 min
Aug 5, 5:53 PM MDTSevere Thunderstorm WarningCYSBox Butte42 min

Nearby

Flash Flood Warnings in Nebraska, 2011Every 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.