Flood and Hail in South Dakota, July 27, 2015

Name: Flood and Hail in South Dakota, July 27, 2015
Start: 2015-07-27T15:35
End: 2015-07-27T20:00
Location: South Dakota

July 27, 2015 · NWS UNR · 14 events in 3 counties and zones

A severe thunderstorm moved northeastward from Wyoming across the Black Hills. The storm initially produced very large hail over the central Black Hills and then strong wind gusts as it began to weaken over the Rapid City area.

Where it happened

Every event with a place to put it. Tap one for its entry below.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

Open the live radar over this ground

The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 14

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What happened

The episode as NWS UNR wrote it up.

What forecasters said that day

The local office's own words before the first event, 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 the first event at Jul 27, 1:06 PM MST, 2 hours 29 minutes earlier.

Area forecast discussion, Jul 27, 1:06 PM MST, 2 hours 29 minutes before

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
206 PM MDT MON JUL 27 2015

.SHORT TERM...THIS EVENING THROUGH TUESDAY NIGHT
ISSUED AT 144 PM MDT MON JUL 27 2015

WATER VAPOR SHOWS INTENSE UPPER LOW OVER NRN ID WITH STRONG SHORT
WAVE EJECTING NEWD THRU WY. AT THE SFC...LOW CENTER IS OVER SERN
MT WITH TROF EXTENDING SWD THROUGH ERN WY...AND CDFNT LAGGING
BEHIND ABOUT 100NM. ELEVATED CONVECTION HAS BEEN ONGOING ACRS ERN
WY AND IS BEGINNING TO ROOT IN THE BL EARLY THIS AFTN.

THIS AFTN/TONIGHT...EXPECT CONVECTION TO CONTINUE FIRING ALONG SFC
TROF AS IT ADVANCES FROM ERN WY INTO WRN SD. CAP IS STILL IN PLACE
ACRS THE WRN SD PLAINS...BUT WILL ERODE AS THE AFTN PROGRESSES WHERE
MLCAPE IN THE 1000-2000J/KG IS EXPECTED AND EFFECTIVE BULK SHEAR
RANGES FROM 30-50KTS. WHILE A FEW STRONG TO SVR STORMS ARE
POSSIBLE IN NERN WY...THE BEST CONVECTIVE PARAMETERS RESIDE OVER
WRN SD AND ESPECIALLY INTO NWRN SD. ACTIVITY WILL QUICKLY
PROGRESS THROUGH THE CWFA THIS EVENING AND END IN MOST PLACES BY
MIDNIGHT. AS THE CDFNT SURGES INTO THE CWFA LATE THIS
AFTN/EVE...EXPECT A PERIOD OF GUSTY NW WINDS GIVEN 4-8MB/3HR PRES
RISES. WINDS MAY BRIEFLY RISE INTO THE ADVISORY CATEGORY WHEN THE
CDFNT FIRST PUSHES THROUGH...BUT ARE NOT EXPECTED TO LAST VERY
LONG SO WILL NOT ISSUE A WIND ADVISORY AT THIS TIME.

TUESDAY...DRY AND MUCH COOLER AIR WILL WORK ACRS THE CWFA WITH
STACKED UPPER LOW TRACKING EWD ALONG THE CNDN/ND BORDER. 850MB
WINDS WILL INCREASE INTO THE 40-50KT RANGE ACRS NWRN SD...WITH
GOOD MIXING RESULTING IN ADVISORY/WARNING TYPE WINDS AND WILL KEEP
THE HIGH WIND WATCH IN PLACE. HIGH TEMPS IN THE 70S TO LOWER
80S...GENERALLY 60S IN THE BLKHLS.

.LONG TERM...WEDNESDAY THROUGH MONDAY
ISSUED AT 144 PM MDT MON JUL 27 2015

REGION WILL REMAIN UNDER NORTHWEST FLOW FOR THE REST OF
THE WEEK AS UPPER RIDGE BUILDS OVER THE WESTERN CONUS...RESULTING IN
MAINLY DRY WEATHER AND A GRADUAL WARMING TREND. A COUPLE WEAK
DISTURBANCES MAY RESULT IN SOME ISOLATED SHOWERS AND STORMS OVER THE
SOUTHERN CWA THROUGH THE WEEKEND. HIGHS WILL BE NEAR TO SLIGHTLY
ABOVE SEASONAL AVERAGES FOR THIS TIME OF YEAR.

&&

.AVIATION...FOR THE 18Z TAFS THROUGH 18Z TUESDAY
ISSUED AT 144 PM MDT MON JUL 27 2015

THUNDERSTORMS WILL REDEVELOP THIS AFTERNOON AS A STRONG
SYSTEM CROSSES THE REGION. MVFR CONDS WILL BE POSSIBLE WITH TS AS
WELL AS LARGE HAIL AND GUSTY WINDS. A STRONG COLD FRONT WILL PUSH
THROUGH THE REGION TONIGHT WITH GUSTY NW WINDS DEVELOPING TONIGHT.

&&

.FIRE WEATHER...
ISSUED AT 144 PM MDT MON JUL 27 2015

A DEEP UPPER LOW WILL MOVE ACROSS MT/ND TNGT AND TUES. AHEAD OF
THE LOW...VERY WARM SOUTHERLY FLOW WILL CONTINUE TO BRING DRIER
AIR INTO NERN WY. GUSTY SOUTH WINDS...HIGH TEMPERATURES...AND LOW
HUMIDITIES WILL CONTINUE RED FLAG CONDITIONS INTO THE EVNG. ISOLD-
SCT TSRA ALSO WILL CROSS THE AERA...AND COULD RESULT IN DRY
LIGHTNING BEFORE THEY MOVE INTO WRN SD. A COLD FRONT WILL SWEEP
ACROSS THE REGION TONIGHT BRINGING GUSTY NORTHWEST WINDS.

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...HIGH WIND WATCH FROM TUESDAY MORNING THROUGH TUESDAY EVENING
     FOR SDZ001-002-012>014-073.
WY...RED FLAG WARNING UNTIL MIDNIGHT MDT TONIGHT FOR
     WYZ259-297-298.

&&

SHORT TERM...JOHNSON
LONG TERM...13
AVIATION...13
FIRE WEATHER...13

Hazardous weather outlook, Jul 27, 2:12 AM MST, 13 hours 23 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>

In the hours before

Local storm report, Jul 27, 2:26 PM MST, 1 hour 9 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>

Local storm report, Jul 27, 2:37 PM MST, 58 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE RAPID CITY SD
337 PM MDT MON JUL 27 2015

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0245 PM     HAIL             5 NE GALENA             44.39N 103.59W
07/27/2015  E1.75 INCH       LAWRENCE           SD   PUBLIC

            SHAVE REPORT

&&

JC

Local storm report, Jul 27, 2:41 PM MST, 54 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>

Local storm report, Jul 27, 2:56 PM MST, 39 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>

Local storm report, Jul 27, 3:03 PM MST, 32 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>

Local storm report, Jul 27, 3:27 PM MST, 8 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>

The radar

The Rapid City radar (KUDX), 78 km away, was scanning. The volume nearest the first event began at 22:33 UTC.

Open the radar archive at this moment

Event by event

7 hail, 6 thunderstorm wind, 1 flood. Local standard time, as filed.

Thunderstorm Wind, Pennington

When: July 27, 3:35 PM MST
Where: Pennington County, 8.98 mi WSW of Hill City
Measured: 56 kt (64 mph) measured gust
Reported by: Park/Forest Service
Coordinates: 43.870, -103.740

Hail, Pennington

When: July 27, 4:00 PM MST
Where: Pennington County, 3.57 mi ESE of Hill City
Measured: 3.5 in hail
Reported by: NWS Employee
Coordinates: 43.917, -103.510

Hail, Pennington

When: July 27, 4:00 PM MST to 4:15 PM MST
Where: Pennington County, 2.6 mi NW of Mt Rushmore
Measured: 1.75 in hail
Reported by: SHAVE Project
Coordinates: 43.908, -103.485

Hail, Pennington

When: July 27, 4:15 PM MST
Where: Pennington County, Keystone
Measured: 1 in hail
Reported by: Trained Spotter
Coordinates: 43.900, -103.420

Hail, Custer

When: July 27, 4:15 PM MST
Where: Custer County, 5.43 mi NNE of Custer
Measured: 1.5 in hail
Reported by: Park/Forest Service
Coordinates: 43.844, -103.563

Ping pong ball sized hail was reported at Sylvan Lake.

Hail, Pennington

When: July 27, 4:15 PM MST
Where: Pennington County, 1.69 mi ESE of Keystone
Measured: 1.5 in hail
Reported by: SHAVE Project
Coordinates: 43.892, -103.388

Hail, Pennington

When: July 27, 4:23 PM MST
Where: Pennington County, Rockerville
Measured: 1 in hail
Reported by: Law Enforcement
Coordinates: 43.960, -103.360

Thunderstorm Wind, Pennington

When: July 27, 4:27 PM MST
Where: Pennington County, 2.04 mi NE of Hayward
Measured: 52 kt (60 mph) estimated gust
Reported by: Public
Coordinates: 43.890, -103.300

Wind gusts were estimated at 60 mph.

Thunderstorm Wind, Pennington

When: July 27, 4:42 PM MST
Where: Pennington County, 2 mi WSW of Rapid City
Measured: 52 kt (60 mph) estimated gust
Reported by: NWS Employee
Coordinates: 44.069, -103.257

Wind gusts were estimated at 60 mph.

Hail, Pennington

When: July 27, 4:45 PM MST
Where: Pennington County, 4.27 mi SSW of Rapid City
Measured: 1.25 in hail
Reported by: Trained Spotter
Coordinates: 44.020, -103.240

Thunderstorm Wind, Pennington

When: July 27, 4:48 PM MST
Where: Pennington County, 4.29 mi SSW of Rapid City
Measured: 60 kt (69 mph) measured gust
Reported by: NWS Employee
Coordinates: 44.020, -103.241

Thunderstorm Wind, Pennington

When: July 27, 4:55 PM MST to 5:05 PM MST
Where: Pennington County, (Rap)rapid City Arpt
Measured: 63 kt (72 mph) measured gust
Reported by: ASOS
Coordinates: 44.050, -103.050

Thunderstorm Wind, Meade

When: July 27, 4:58 PM MST
Where: Meade County, 6.5 mi NNE of Ellsworth Afb
Measured: 52 kt (60 mph) estimated gust
Reported by: Public
Coordinates: 44.233, -103.039

Wind gusts were estimated at 60 mph.

Flood, Pennington

When: July 27, 6:00 PM MST to 8:00 PM MST
Where: Pennington County, 2.64 mi ESE of Rapid City to 2.73 mi ESE of Rapid City
Cause: Heavy Rain
Reported by: NWS Employee
Coordinates: 44.072, -103.168

Runoff from heavy rainfall covered streets and parking lots between Elk Vale Road and Concourse Drive.

What these are

Thunderstorm Wind: Winds from a thunderstorm of 50 knots (58 mph) or more, or lower winds that caused damage or casualties. Measured gusts are marked MG, estimated EG.
Hail: Hail three-quarters of an inch or larger, or smaller hail that caused damage, filed with the largest stone measured.
Flood: Flooding that develops more slowly than a flash flood: rivers leaving their banks, or water standing over land for an extended time.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in South Dakota in 2015 Every state in 2015 This day in weather history Warnings in South Dakota, July 2015

Sources

NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-10-01. Each event’s entry at NCEI: 593540, 593529, 593530, 593531, 593532, 593533, 593534, 593535, 593536, 593537, 593538, 593539, 593541, 593576.