Alert archive / Wyoming / Flash Flood Warnings in 1993

Flash Flood Warning 4, NWS Cheyenne, WY

August 20, 1993Goshen County, Wyoming

NWS Cheyenne, WY issued this flash flood warning at Aug 20, 1993, 3:34 AM MDT for Goshen County, Wyoming. It was in force for 86 min.

The area

The counties it named.

The facts

Issued
Aug 20, 1993, 3:34 AM MDT (09:34 UTC)
Expired
Aug 20, 1993, 5:00 AM MDT
In force
86 min
Issued by
NWS Cheyenne, WY
Area
Whole counties

County Goshen County, WY

The nearest sounding before it

Rapid City, SD (KRAP), launched 00:00Z, 9.6 hours before the alert went out and 251 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, Rapid City, SD at 00:00Z on 1993-08-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 774 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Rapid City, SD at 00:00Z on 1993-08-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 8 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
774 J/kg
Mixed-layer CIN
-36 J/kg
Mixed-layer LCL
1714 m above ground
0-6 km bulk shear
25 kt
0-1 km storm-relative helicity
8 m²/s²
0-3 km storm-relative helicity
39 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.6

Open this sounding in Storm Lab

The text

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

000 
TTAA00 KCYS 200938 COR
FFWCYS
WYC015-201230-

BULLETIN - EBS ACTIVATION REQUESTED
FLASH FLOOD WARNING...CORRECTED
NATIONAL WEATHER SERVICE CHEYENNE WY
334 AM MDT FRI AUG 20 1993

THE NATIONAL WEATHER SERVICE IN CHEYENNE HAS ISSUED A
FLASH FLOOD WARNING EFFECTIVE UNTIL  630 AM MDT
FOR PEOPLE IN THE FOLLOWING LOCATION...

IN SOUTHEAST WYOMING

   ...CENTRAL GOSHEN COUNTY

...THIS WARNING INCLUDES THE TOWNS OF TORRINGTON..LINGLE..AND VETERAN...

AT 315 AM MDT...MORE THUNDERSTORMS WERE DEVELOPING IN CENTRAL GOSHEN
COUNTY AT 315 AM MDT. THIS AREA RECEIVED HEAVY RAIN EARLIER WHICH
RESULTED IN FLASH FLOODING. ANY NEW RAIN WILL PRODUCE MORE FLOODING.
THUNDERSTORMS WILL CONTINUE IN CENTRAL GOSHEN COUNTY THROUGH 7 AM MDT.
THIS HAS PROMPTED THE NATIONAL WEATHER SERVICE TO EXTEND THE FLASH FLOOD
WARNING UNTIL 7 AM MDT.

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

A FLASH FLOOD WARNING MEANS THAT FLOODING IS OCCURRING OR IS
IMMINENT.  MOST FLASH FLOOD DEATHS OCCUR IN AUTOMOBILES.  DO NOT
ATTEMPT TO CROSS BRIDGES...DIPS...OR LOW SPOTS IF WATER COVERS
THE ROADWAY.  NEVER TRY TO CROSS A FLOWING STREAM...EVEN A SMALL
ONE...ON FOOT.  TO ESCAPE RISING WATER MOVE UP TO HIGHER GROUND.

...CORRECTED TO ADD SPECIAL CODING...



WCJIN-WYSE
CAS

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, Aug 20, 12:27 AM MDT, 3 hours 7 minutes before
WYZ068-069-070-200830-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHEYENNE WY
1227 AM MDT FRI AUG 20 1993

...STRONG THUNDERSTORMS WERE NEAR WHEATLAND IN SOUTHEAST WYOMING...

AT 1215 AM MDT...RADAR INDICATED THAT STRONG THUNDERSTORMS HAD
REDEVELOPED ABOUT 10 MILES SOUTHEAST OF WHEATLAND. ANOTHER STORM
WAS 8 MILES NORTHEAST OF SLATER. THIS AREA IS RIGHT ALONG THE PLATTE AND
GOSHEN COUNTY LINE. THE THUNDERSTORMS WERE MOVING NORTHEAST AT 15 MILES
AN HOUR.

NO REPORTS HAD BEEN RECEIVED FROM OBSERVERS IN THE AREAS. SMALL HAIL IS
ALSO LIKELY. STORMS IN THIS AREA EARLIER IN THE EVENING PRODUCED HEAVY
RAIN. MORE RAIN OVER THE WET GROUND COULD CAUSE RAPID RUNOFF AND
LOCALIZED FLASH FLOODING IN SOME AREAS.

PEOPLE TRAVELING IN PLATTE AND GOSHEN COUNTIES SHOULD PAY CLOSE
ATTENTION AND WATCH FOR FLOODING IN LOW LYING AREAS. DO NOT ATTEMPT TO
DRIVE OR WADE THROUGH FLOODED AREAS. THE CURRENT COULD BE STRONGER THAN
EXPECTED AND OTHER HAZARDS COULD BE HIDDEN BENEATH THE WATER.

WCJIN-WYSE
CAS
Special weather statement, Aug 20, 12:31 AM MDT, 3 hours 3 minutes before
WYZ068-069-070-200830-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHEYENNE WY
1227 AM MDT FRI AUG 20 1993

...STRONG THUNDERSTORMS WERE NEAR WHEATLAND IN SOUTHEAST WYOMING...

AT 1215 AM MDT...RADAR INDICATED THAT STRONG THUNDERSTORMS HAD
REDEVELOPED ABOUT 10 MILES SOUTHEAST OF WHEATLAND. ANOTHER STORM
WAS 8 MILES NORTHEAST OF SLATER. THIS AREA IS RIGHT ALONG THE PLATTE AND
GOSHEN COUNTY LINE. THE THUNDERSTORMS WERE MOVING NORTHEAST AT 15 MILES
AN HOUR.

NO REPORTS HAD BEEN RECEIVED FROM OBSERVERS IN THE AREAS. SMALL HAIL IS
ALSO LIKELY. STORMS IN THIS AREA EARLIER IN THE EVENING PRODUCED HEAVY
RAIN. MORE RAIN OVER THE WET GROUND COULD CAUSE RAPID RUNOFF AND
LOCALIZED FLASH FLOODING IN SOME AREAS.

PEOPLE TRAVELING IN PLATTE AND GOSHEN COUNTIES SHOULD PAY CLOSE
ATTENTION AND WATCH FOR FLOODING IN LOW LYING AREAS. DO NOT ATTEMPT TO
DRIVE OR WADE THROUGH FLOODED AREAS. THE CURRENT COULD BE STRONGER THAN
EXPECTED AND OTHER HAZARDS COULD BE HIDDEN BENEATH THE WATER.

WCJIN-WYSE
CAS

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 19, 6:19 PM MDTSevere Thunderstorm WarningCYSGoshen56 min
Aug 20, 1:21 AM MDTFlash Flood WarningCYSGoshen2 hr
Aug 20, 2:22 AM MDTSevere Thunderstorm WarningCYSGoshen34 min

Nearby

Flash Flood Warnings in Wyoming, 1993Every flash flood warning in 1993

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.