Alert archive / Wyoming / Flash Flood Warnings in 1999
Flash Flood Warning 1, NWS Cheyenne, WY
NWS Cheyenne, WY issued this flash flood warning at Apr 30, 1999, 4:10 PM MDT for Laramie County, Wyoming. It was in force for 6 hr. No storm report in the archive falls inside the area while it was in force.
The area
The counties it named.
The facts
- Issued
- Apr 30, 1999, 4:10 PM MDT (22:10 UTC)
- Expired
- Apr 30, 1999, 10:15 PM MDT
- In force
- 6 hr
- Issued by
- NWS Cheyenne, WY
- Area
- Whole counties
County Laramie County, WY
The radar
The Cheyenne radar (KCYS), 20 km from the middle of the area, began a volume at 22:13 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 12:00Z, 10.2 hours before the alert went out and 202 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.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 511 m above ground
- 0-6 km bulk shear
- 25 kt
- 0-1 km storm-relative helicity
- 113 m²/s²
- 0-3 km storm-relative helicity
- 141 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
000 TTAA00 KCYS 302242 COR FFWCYS WYC021-010415- BULLETIN-IMMEDIATE BROADCAST REQUESTED...CORRECTION FOR DAM NAME FLASH FLOOD WARNING NATIONAL WEATHER SERVICE CHEYENNE WY 440 PM MDT FRI APR 30 1999 THE NATIONAL WEATHER SERVICE IN CHEYENNE HAS ISSUED A * FLASH FLOOD WARNING FOR A DAM FAILURE IN... SOUTHWESTERN AND SOUTH CENTRAL LARAMIE COUNTY IN SOUTHEASTERN WYOMING * UNTIL 1015 PM MDT * AT 400 PM MDT...EMERGENCY MANAGEMENT OFFICIALS REPORTED THE STRONG POSSIBILITY THAT THE NORTH FORK CROW CREEK DIVERSIONARY RESERVOIR WILL FAIL. * BECAUSE OF HEAVY RAIN...WATER IS OVERTOPPING THE NORTH FORK CROW CREEK DIVERSIONARY RESERVOIR. IT IS LIKELY THAT THE DAM WILL FAIL WITHIN THE NEXT TWO HOURS. FLOODING COULD OCCUR ALONG CROW CREEK THROUGH SILVER CROWN...15 MILES WEST OF CHEYENNE...F.E. WARREN AIR FORCE BASE...AND THE SOUTHEAST AND WEST PORTIONS OF THE CITY OF CHEYENNE. THE NORTH FORK CROW CREEK DIVERSIONARY RESERVOIR IS MUCH SMALLER THAN THE NORTH CROW CREEK RESERVIOR THAT WAS EARLIER WARNED FOR. THUS...THE IMPACT OF ANY DAM BREAK WILL BE MUCH LESS SIGNIFICANT ALONG CROW CREEK THAN EARLIER EXPECTED. IF THE DAM FAILS...IT WILL TAKE APPROXIMATELY 5 HOURS FOR THE FLOODING TO REACH THE CITY OF CHEYENNE. RESIDENTS ALONG CROW CREEK SHOULD BE PREPARED TO EVACUATE. STAY TUNED FOR LATER DEVELOPMENTS CONCERNING THIS SITUATION. DO NOT DRIVE THROUGH FLOODED AREAS. SHALLOW... SWIFTLY FLOWING WATER CAN WASH A CAR FROZM A ROADWAY. ALSO...THE ROADBED MAY NOT BE INTACT UNDER THE WATER. WCJIN-WYSE COX
What forecasters said that day
The local office's own words before this flash flood warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
In the hours before
Special weather statement, Apr 30, 10:20 AM MDT, 5 hours 50 minutes before
WYZ059>070-NEZ001>003-019>021-054-055-302300- SEVERE WEATHER OUTLOOK NATIONAL WEATHER SERVICE CHEYENNE WY 1020 AM MDT FRI APR 30 1999 THE SEVERE WEATHER POTENTIAL IN THE NWS CHEYENNE WARNING AREA IS LOW FOR TODAY. SOUTHEAST WYOMING AND THE WESTERN NEBRASKA PANHANDLE WILL REMAIN UNDER A COOL AND MOIST WEATHER PATTERN TODAY. THE THREAT FOR THUNDERSTORMS WILL MAINLY BE CONFINED TO CARBON COUNTY OF SOUTH-CENTRAL WYOMING. RAINFALL AMOUNTS OF 2 TO 3 INCHES ARE POSSIBLE OVER THE SOUTHERN LARAMIE RANGE...JUST EAST OF LARAMIE...TODAY AND TONIGHT. THIS WILL KEEP CREEKS AND STREAMS FULL AND FLOWING RAPIDLY THERE. AN INCH TO AN INCH AND A HALF OF RAIN IS POSSIBLE AS FAR EAST AS CHEYENNE THROUGH TONIGHT. AN URBAN AND SMALL STREAM FLOOD ADVISORY REMAINS IN EFFECT FOR THE LARAMIE MOUNTAIN RANGE...PLATTE COUNTY AND WESTERN LARAMIE COUNTY FOR TODAY. CONVERSE COUNTY...NORTH AND EAST OF INTERSTATE 25...HAS BEEN DROPPED FROM THE FLOOD ADVISORY. SPOTTER ACTIVATION WILL NOT BE NECESSARY THIS AFTERNOON. WCJIN-WYSE-WYNE COX
Special weather statement, Apr 30, 10:20 AM MDT, 5 hours 50 minutes before
WYZ059>070-NEZ001>003-019>021-054-055-302300- SEVERE WEATHER OUTLOOK NATIONAL WEATHER SERVICE CHEYENNE WY 1020 AM MDT FRI APR 30 1999 THE SEVERE WEATHER POTENTIAL IN THE NWS CHEYENNE WARNING AREA IS LOW FOR TODAY. SOUTHEAST WYOMING AND THE WESTERN NEBRASKA PANHANDLE WILL REMAIN UNDER A COOL AND MOIST WEATHER PATTERN TODAY. THE THREAT FOR THUNDERSTORMS WILL MAINLY BE CONFINED TO CARBON COUNTY OF SOUTH-CENTRAL WYOMING. RAINFALL AMOUNTS OF 2 TO 3 INCHES ARE POSSIBLE OVER THE SOUTHERN LARAMIE RANGE...JUST EAST OF LARAMIE...TODAY AND TONIGHT. THIS WILL KEEP CREEKS AND STREAMS FULL AND FLOWING RAPIDLY THERE. AN INCH TO AN INCH AND A HALF OF RAIN IS POSSIBLE AS FAR EAST AS CHEYENNE THROUGH TONIGHT. AN URBAN AND SMALL STREAM FLOOD ADVISORY REMAINS IN EFFECT FOR THE LARAMIE MOUNTAIN RANGE...PLATTE COUNTY AND WESTERN LARAMIE COUNTY FOR TODAY. CONVERSE COUNTY...NORTH AND EAST OF INTERSTATE 25...HAS BEEN DROPPED FROM THE FLOOD ADVISORY. SPOTTER ACTIVATION WILL NOT BE NECESSARY THIS AFTERNOON. WCJIN-WYSE-WYNE COX
Nearby
Flash Flood Warnings in Wyoming, 1999Every flash flood warning in 1999
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.