Alert archive / South Dakota / Flash Flood Warnings in 2011

Flash Flood Warning 19, NWS Rapid City, SD

July 4, 2011Custer County, South Dakota

NWS Rapid City, SD issued this flash flood warning at Jul 4, 2011, 3:58 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
Jul 4, 2011, 3:58 PM MDT (21:58 UTC)
Expired
Jul 4, 2011, 9:09 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 22:00 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

Rapid City, SD (KUNR), launched 12:00Z, 10.0 hours before the alert went out and 63 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 12:00Z on 2011-07-04Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1069 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 12:00Z on 2011-07-04The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -18 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
1069 J/kg
Mixed-layer CIN
-380 J/kg
Mixed-layer LCL
1605 m above ground
0-6 km bulk shear
21 kt
0-1 km storm-relative helicity
-18 m²/s²
0-3 km storm-relative helicity
252 m²/s²
Significant tornado parameter
0.0
Supercell composite
-0.1

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 Jul 4, 12:49 PM MDT, 3 hours 9 minutes earlier.

Area forecast discussion, Jul 4, 12:49 PM MDT, 3 hours 9 minutes before
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
1249 PM MDT MON JUL 4 2011

.DISCUSSION...WATER VAPOR IMAGES REVEALED A MONSOONAL MOISTURE FLOW
TOWARD THE CWA AS A MIDLEVEL SHORT-WAVE TROUGH WAS EXITING THE
EASTERN DAKOTAS. A WEAK SURFACE COLD FRONT HAS PUSHED THROUGH ALL
BUT FAR SOUTHERN SD WITH A MOIST NORTHERLY FLOW IN ITS WAKE. MLCIN
WAS STILL 100-250 J/KG WHICH WAS KEEPING A LID ON CONVECTION. A
SHORT-WAVE TROUGH APPEARED TO BE OVER WESTERN/CENTRAL WY.

FOR THE REST OF THIS AFTERNOON AND TONIGHT...EXPECT CONVECTION TO
INITIATE OVER THE BLKHLS BY 200-300 PM AND THEN GRADUALLY BUILD
ALONG THE SURFACE BOUNDARY BETWEEN 400-600 PM. A FEW CONVECTIVE
COMPLEXES LIKELY WILL ENSUE AS THE APPROACHING SHORT-WAVE TROUGH
INTERACTS WITH THE ABUNDANT LOW-LEVEL MOISTURE...SURFACE BOUNDARY...
AND MLCAPE OF 1000-3500 J/KG. IN ADDITION...DECENT Q-G FORCING IS
PROGGED AS A 70-KT UPPER JET PASSES TO OUR NORTH...PLACING MUCH OF
THE CWA IN UPPER-LEVEL DIVERGENCE. THE 0-6KM SHEAR IS SOMEWHAT
MARGINAL SO DO NOT EXPECT MANY SUPERCELLS. HAIL WILL BE THE MAIN
THREAT GIVEN THE LARGE CAPE...ALONG WITH LOCALLY HEAVY RAINFALL AS A
WEAK LOW-LEVEL JET FOCUSES MOISTURE AND MASS CONVERGENCE ACROSS
SOUTH-CENTRAL SD LATER TONIGHT.

ON TUESDAY THE UPPER TROUGH MOVES EAST BUT CONVECTION WILL LINGER
THROUGH MUCH OF THE MORNING. DRYING WILL WORK IN FROM THE NORTH AS A
SURFACE RIDGE SETTLES ACROSS THE DAKOTAS AND THE MONSOONAL MOISTURE
PLUMES SHIFTS SOUTH. THIS WILL LEAVE A THETA-E RIDGE ACROSS EASTERN
WY...BUT WITH MINIMAL FORCING DO NOT EXPECT MUCH MORE THAN ISOLATED
AFTERNOON STORMS ACROSS SD...WITH SCATTERED COVERAGE AT BEST IN
EASTERN WY. IT WILL BE SEVERAL DEGREES COOLER THAN TODAY DUE TO COLD
AIR ADVECTION IN THE LOW LEVELS.

ON TUESDAY NIGHT THERE WILL BE SOME RIDGING ALOFT WITH NORTHWEST
FLOW. A SUBTLE WAVE MAY MOVE ACROSS WY AND SUPPORT EVENING STORMS
OVER MAINLY EASTERN WY...CLOSER TO THE MONSOONAL MOISTURE PLUME.
OTHERWISE THIS WILL BE A RELATIVE LULL IN CONVECTIVE ACTIVITY.

THERE WILL BE A BETTER CHANCE FOR STORMS WEDNESDAY AFTERNOON AND
ESPECIALLY WEDNESDAY NIGHT AS ANOTHER WAVE MOVES THROUGH THE RIDGE
AND THE MONSOONAL MOISTURE PLUME SHIFTS BACK TO THE NORTH. A 50-KT
JET IS PROGGED TO PASS TO OUR NORTH WITH UPPER-LEVEL DIVERGENCE OVER
THE CWA. IT DOES NOT LOOK TO BE AS ACTIVE AS TONIGHT WILL BE GIVEN
THE WEAKER UPPER-LEVEL JET AND MARGINAL DEEP-LAYER SHEAR...BUT SOME
LOCALLY HEAVY RAINFALL WILL AGAIN BE POSSIBLE AS PRECIPITABLE WATER
IS 140-160 PERCENT OF AVERAGE AND A LOW-LEVEL JET DEVELOPS ACROSS
WESTERN SD.

EXTENDED...AN UNSETTLED WEATHER PATTERN WILL CONTINUE AS A VARIETY
OF WEAK SHORT-WAVE TROUGHS PROGRESS THROUGH A LOW AMPLITUDE RIDGE...
BRINGING DAILY CHANCES FOR THUNDERSTORMS. TEMPERATURES WILL REMAIN
NEAR TO SLIGHTLY ABOVE AVERAGE.

&&

.AVIATION...THUNDERSTORMS WILL DEVELOP OVER THE AREA LATE THIS
AFTERNOON INTO THIS EVENING...BRINGING AREAS OF MVFR AND LCL IFR VIS
IN HEAVIER PRECIP. SOME STORMS MAY BECOME SEVERE. SHOWERS AND STORMS
WILL PERSIST ACROSS MUCH OF WESTERN SOUTH DAKOTA OVERNIGHT WITH SOME
MVFR CIGS POSSIBLE LATE TONIGHT THROUGH 15Z TUESDAY MORNING.

&&

.HYDROLOGY...FLASH FLOOD GUIDANCE ACROSS SOUTH-CENTRAL SD IS FROM
1-3 INCHES OVER A FEW HOURS. THE POTENTIAL FOR SLOW-MOVING STORMS
EXISTS AS THE 0-6KM MEAN WIND IS ONLY 5-10 KTS. MOISTURE TRANSPORT
VECTORS ARE PROGGED TO CONVERGE IN THIS AREA OVERNIGHT...HELPING
BOOST PRECIPITABLE WATER TO 140-160 PERCENT OF AVERAGE. THE SURFACE
BOUNDARY SHOULD PROVIDE A FOCUS FOR STORM INITIATION AND POSSIBLE
TRAINING OF ECHOES. THE FLASH FLOOD WATCH FOR SOUTH-CENTRAL SD LOOKS
REASONABLE GIVEN THIS SETUP.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...FLASH FLOOD WATCH FROM THIS EVENING THROUGH LATE TONIGHT FOR
     BENNETT-HAAKON-JACKSON-MELLETTE-TODD-TRIPP.

WY...NONE.

&&

BUNKERS/RUDGE
Hazardous weather outlook, Jul 4, 4:49 AM MDT, 11 hours 9 minutes before
HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE RAPID CITY SD
449 AM MDT MON JUL 4 2011

SDZ001-002-012>014-024>032-041>044-046-047-049-072>074-WYZ054>058-
071-051300-
BENNETT-BUTTE-CENTRAL BLACK HILLS-CUSTER CO PLAINS-FALL RIVER-HAAKON-
HARDING-HERMOSA FOOT HILLS-JACKSON-MELLETTE-NORTHEASTERN CROOK-
NORTHERN BLACK HILLS-NORTHERN CAMPBELL-NORTHERN FOOT HILLS-
NORTHERN MEADE CO PLAINS-PENNINGTON CO PLAINS-PERKINS-RAPID CITY-
SHANNON-SOUTHERN BLACK HILLS-SOUTHERN CAMPBELL-SOUTHERN FOOT HILLS-
SOUTHERN MEADE CO PLAINS-STURGIS/PIEDMONT FOOT HILLS-TODD-TRIPP-
WESTERN CROOK-WESTON-WYOMING BLACK HILLS-ZIEBACH-
449 AM MDT (549 AM CDT) MON JUL 4 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN SOUTH DAKOTA AND
NORTHEASTERN WYOMING.

.DAY ONE...TODAY AND TONIGHT

THERE IS A CHANCE OF THUNDERSTORMS THIS AFTERNOON AND TONIGHT. THERE
IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS ALL OF NORTHEAST
WYOMING AND WESTERN SOUTH DAKOTA...WITH LARGE HAIL AND DAMAGING
WIND GUSTS THE MAIN THREATS. IN ADDITION...HEAVY RAINS ARE
POSSIBLE...ESPECIALLY TONIGHT ACROSS SOUTH CENTRAL SOUTH DAKOTA.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

THERE IS A CHANCE OF THUNDERSTORMS ON TUESDAY. SOME OF THESE STORMS
COULD BE SEVERE MAINLY ACROSS NORTHEAST WYOMING AND FAR WESTERN
SOUTH DAKOTA...WITH LARGE HAIL AND DAMAGING WIND GUSTS THE MAIN
THREATS. THERE ARE ADDITIONAL CHANCES FOR THUNDERSTORMS EACH DAY THE
REST OF THE WEEK.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY.

In the hours before

Special weather statement, Jul 4, 2:11 PM MDT, 1 hour 47 minutes before
<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>
Special weather statement, Jul 4, 2:52 PM MDT, 1 hour 6 minutes before
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE RAPID CITY SD
252 PM MDT MON JUL 4 2011

SDZ029-074-042130-
HERMOSA FOOT HILLS SD-SOUTHERN BLACK HILLS SD-
252 PM MDT MON JUL 4 2011

...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL CUSTER COUNTY UNTIL 330
PM MDT...

AT 247 PM MDT...ALONG A LINE EXTENDING FROM 7 MILES SOUTHEAST OF
JEWEL CAVE TO ARGYLE...AND MOVING SOUTH AT 5 MPH.

HAIL UP TO THE SIZE OF PENNIES IS EXPECTED WITH THESE STORMS...ALONG
WITH HEAVY RAIN.

LOCATIONS NEAR THE PATH OF INCLUDE...
  WIND CAVE VISITORS CENTER...
  ARGYLE...

TORRENTIAL RAIN...WHICH MAY FLOOD LOW LYING AREAS SUCH AS DITCHES AND
UNDERPASSES...IS ALSO LIKELY. DO NOT DRIVE YOUR VEHICLE ON A FLOODED
ROADWAY.

BUNKERS
Special weather statement, Jul 4, 3:46 PM MDT, 12 minutes before
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE RAPID CITY SD
346 PM MDT MON JUL 4 2011

SDZ029-042230-
SOUTHERN BLACK HILLS SD-
346 PM MDT MON JUL 4 2011

...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL CUSTER COUNTY UNTIL 430
PM MDT...

AT 343 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A
STRONG THUNDERSTORM NEAR SANATOR...OR 6 MILES SOUTHWEST OF DOWNTOWN
CUSTER...MOVING SOUTHEAST AT 5 MPH.

HAIL UP TO ONE-HALF INCH IN DIAMETER IS EXPECTED WITH THIS STORM...
ALONG WITH HEAVY RAIN.

LOCATIONS NEAR THE PATH OF THIS STORM INCLUDE...
  SANATOR...

IF THREATENING WEATHER APPROACHES YOUR AREA...TAKE SHELTER IN A
STURDY BUILDING.

TORRENTIAL RAIN...WHICH MAY FLOOD LOW LYING AREAS SUCH AS DITCHES AND
UNDERPASSES...IS ALSO LIKELY. DO NOT DRIVE YOUR VEHICLE ON A FLOODED
ROADWAY.

TRIMARCHI

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 4, 3:25 AM MDTFlash Flood WatchUNRBennett, Haakon, Jackson, Mellette, Todd, Tripp24 hr

Nearby

Flash Flood Warnings in South Dakota, 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.