Alert archive / South Dakota / Flash Flood Warnings in 2011

Flash Flood Warning 5, NWS Rapid City, SD

May 23, 2011Custer County, South Dakota

NWS Rapid City, SD issued this flash flood warning at May 23, 2011, 5:23 PM MDT for Custer County, South Dakota. It was in force for 5 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: May 23, 2011, 5:23 PM MDT (23:23 UTC)
Expired: May 23, 2011, 9:55 PM MDT
In force: 5 hr
Issued by: NWS Rapid City, SD
Area: Storm-based polygon
Flood severity: None

County Custer County, SD

The radar

The Rapid City radar (KUDX), 70 km from the middle of the area, began a volume at 23:25 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

N. Platte/Lee Bi, NE (KLBF), launched 12:00Z, 11.4 hours before the alert went out and 367 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: 3 J/kg
Mixed-layer CIN: -284 J/kg
Mixed-layer LCL: 930 m above ground
0-6 km bulk shear: 24 kt
0-1 km storm-relative helicity: -34 m²/s²
0-3 km storm-relative helicity: -7 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.0

Open this sounding in Storm Lab

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.

NWS Rapid City, SD wrote its last area forecast discussion before this flash flood warning went out at May 23, 2:59 PM MDT, 2 hours 24 minutes earlier.

Area forecast discussion, May 23, 2:59 PM MDT, 2 hours 24 minutes before

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
259 PM MDT MON MAY 23 2011

.DISCUSSION...CURRENT SURFACE MAP SHOWS TROF ACROSS
MONTANA/WYOMING. SCATTERED SHOWERS/ISOLATED THUNDERSTORMS
DEVELOPING ACROSS THE AREA THIS AFTERNOON.

12Z MODELS IN DECENT AGREEMENT WITH UPPER TROF CROSSING THE
ROCKIES TONIGHT AND CLOSING OFF AN UPPER LOW OVER NE CO/NW KS TUESDAY
EVENING. LEAD SHORTWAVE LIFTING THROUGH CO/WY IS WILL RESULT IN AN
INCREASE OF SHOWERS/THUNDERSTORMS OVERNIGHT...MAINLY ACROSS NE
WY/WRN SD. LOCALLY HEAVY RAIN POSSIBLE FROM THE
THUNDERERSTORMS...WITH FLOOD THREAT OVER SW SD.

DIFFLUENT FLOW SETS UP OVER THE AREA ON TUESDAY...WITH LOW LEVEL
FLOW BECOMING MORE UPSLOPE INTO THE BLACK HILLS. FORECAST
SOUNDINGS GIVE 100-400J/KG MUCAPE WITH MOIST ADIABATIC
THERMAL/SATURATED RH PROFILE THROUGH 400MB. NOT MUCH LIFT WILL BE
NEED TO GENERATE PRECIPITATION. MODEL QPF AMOUNTS RANGE FROM 1-3+
INCHES...WIT THE HEAVIEST ACROSS SW SD. SOME CONVECTIVE FEEDBACK
ISSUES ARE RESPONSIBLE FOR THE HIGHEST QPF AMOUNTS. 15Z SREF QPF
LOOKS LIKE REASONABLE COMPROMISE. AVERAGE AMOUNTS ACROSS SOUTHWEST
SOUTH DAKOTA WILL BE IN THE ONE INCH RANGE...WITH LOCALLY HIGHER
AMOUNTS ACROSS THE BLACK HILLS IN UPSLOPE ENHANCEMENT OR WITH ANY
SLOW MOVING CONVECTION.

DRY SURFACE HIGH BUILDS IN FROM THE NORTH ON WEDNESDAY AS A
SURFACE LOW CROSSES NEBRASKA. THIS WILL KEEP ANY PRECIPITATION
CONFINED TO THE SOUTHWESTERN PARTS OF THE FORECAST AREA ON
WEDNESDAY...WITH DRY WEATHER EXPECTED ON WEDNESDAY NIGHT.

EXTENDED...UNSETTLED WEATHER IS EXPECTED TO CONTINUE THROUGH MUCH OF
THE LONG TERM AS A SERIES OF UPPER LEVEL DISTURBANCES CROSS THE
REGION. THE BEST CHANCES FOR SHOWERS AND A FEW STORMS LOOK TO BE
THURSDAY NIGHT INTO FRIDAY...AND SATURDAY NIGHT THROUGH SUNDAY
NIGHT. TEMPERATURES WILL GENERALLY BE NEAR AVERAGE THROUGH THE
PERIOD...WITH HIGHS MAINLY IN THE 60S AND LOWER 70S.

&&

.AVIATION...RAIN SHOWERS...AND ISOLATED THUNDERSTORMS THIS
EVENING...WILL INCREASE ACROSS THE AREA TONIGHT AS THE NEXT SYSTEM
APPROACHES. CIGS WILL LOWER TO MVFR TONIGHT...AND POSSIBLY IFR
ACROSS SOME LOCATIONS LATE TONIGHT. MVFR/IFR VSBY WILL BE POSSIBLE
IN THE HEAVIER SHOWERS...AND IF PATCHY FOG DEVELOPS.

&&

.HYDROLOGY...FLOODING CONTINUES ACROSS MANY RIVERS AND CREEKS FROM
FAR NORTHEASTERN WY INTO NORTHWESTERN AND PARTS OF WEST CENTRAL SD.
THE MOST SIGNIFICANT FLOODING CONTINUES TO BE ALONG THE LITTLE
MISSOURI...BELLE FOURCHE...AND CHEYENNE RIVERS...AND ITS
TRIBUTARIES. SEE SPECIFIC FLOOD PRODUCTS FOR FURTHER DETAILS.

SHOWERS WILL CONTINUE TO INCREASE IN COVERAGE AND INTENSITY INTO
TONIGHT AS NEXT UPPER LEVEL SYSTEM APPROACHES THE AREA. THE HEAVIEST
RAINFALL LOOKS TO BE TONIGHT AND TUESDAY FROM THE BLACK HILLS AREA
INTO THE SOUTHWESTERN SD PLAINS...WHERE 1 TO 2 INCHES OF RAINFALL IS
POSSIBLE BY WEDNESDAY MORNING. A FLOOD WATCH REMAINS IN EFFECT FOR
SOUTHWESTERN SD.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...FLOOD WATCH FROM 6 PM MDT THIS EVENING THROUGH LATE TUESDAY
     NIGHT FOR BENNETT-CENTRAL BLACK HILLS-CUSTER CO PLAINS-FALL
     RIVER-HERMOSA FOOT HILLS-JACKSON-NORTHERN BLACK HILLS-
     PENNINGTON CO PLAINS-RAPID CITY-SHANNON-SOUTHERN BLACK
     HILLS-SOUTHERN FOOT HILLS-SOUTHERN MEADE CO PLAINS-
     STURGIS/PIEDMONT FOOT HILLS.

WY...NONE.
&&

Hazardous weather outlook, May 23, 4:30 AM MDT, 12 hours 53 minutes before

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The office that day

Everything else NWS Rapid City, SD issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 23, 3:25 PM MDT	River Flood Warning	UNR	Meade	53 hr

Nearby

Flash Flood Warnings in South Dakota, 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.