A strong atmospheric river will bring heavy rainfall to California through the holiday week. The heaviest rainfall is expected on Wednesday in the Los Angeles Basin. Flash and urban flooding is possible. A prolonged heavy snowfall is expected in the Sierra Nevada from the atmospheric river, raising concerns for major snow‐load impacts. Travel may be difficult to impossible over the passes. Read More >
Overview
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A major severe weather and flooding event occurred on June 23, 2023 over parts of northeastern Wyoming and western South Dakota. A long-track tornado moved across southern Campbell and Weston Counties, striking the North Antelope Rochelle Coal Mine. Elsewhere, significant flash flooding occurred from Spearfish to Saint Onge, and more widespread flooding occurred across parts of the western South Dakota plains. A few discrete storms produced hail up to 2" in diameter across western South Dakota and northeastern Wyoming. Several strong/damaging wind reports occurred later as the severe thunderstorms moved from western into central South Dakota. As can be seen in the lightning map to the right (click to enlarge), thunderstorms occurred across essentially all of our forecast area from northeastern Wyoming into south-central South Dakota. Positive cloud-to-ground flashes were especially notable with the tornadic storm that affected the North Antelope Rochelle Coal Mine as well as the Spearfish supercell that produced flash flooding and large hail. |
 Here is the 24-hour cloud-to-ground lightning map from 6 am MDT Friday (6/23) to 6 am MDT Saturday (6/24). Red plus signs indicate positive polarity flashes and green dashes indicate negative polarity flashes. Total flash counts in upper right. |
Tornadoes
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Tornado - North Antelope Rochelle Mine
Track Map  
Downloadable KMZ File |
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The Enhanced Fujita (EF) Scale classifies tornadoes into the following categories:
| EF0 Weak 65-85 mph |
EF1 Moderate 86-110 mph |
EF2 Significant 111-135 mph |
EF3 Severe 136-165 mph |
EF4 Extreme 166-200 mph |
EF5 Catastrophic 200+ mph |
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Rainfall & Flooding
Some areas received very heavy rainfall of over 3 inches, and this caused flash flooding, most notably in the Spearfish area.
Hydrographs
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| Hydrograph along Spearfish Creek at Spearfish, showing a rapid increase in levels during and after heavy rainfall, followed by receding water. | Hydrograph along Spearfish Creek below Spearfish, showing a rapid increase in levels during and after heavy rainfall, followed by receding water. | Hydrograph along the Belle Fourche River near Fruitdale, showing a large increase in river levels during and after heavy rainfall. | Hydrograph along the Belle Fourche River near Elm Springs, showing a large increase in river levels during and after heavy rainfall, followed by receding water. |
Rainfall Observations and Radar-Estimated Precipitation
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| Observed 24-hour rainfall reports (inches) from 6 am MDT Friday (6/23) to 6 am MDT Saturday (6/24). | Radar-estimated 24-hour precipitation (inches) from 6 am MDT Friday (6/23) to 6 am MDT Saturday (6/24). |
24-Hour Rainfall Reports (by County) Ending Saturday Morning, June 24, 2023
**********************24 HOUR RAINFALL********************** LOCATION 24 HOUR TIME/DATE COMMENTS RAINFALL MEASURED (inches) SOUTH DAKOTA ...Bennett County... 8 NW Vetal 1.23 600 AM 6/24 CoCoRaHS 8 E Martin 1.15 700 AM 6/24 Co-Op Observer Martin 0.78 720 AM 6/24 Facebook 5 NW Swett 0.42 800 AM 6/23 CoCoRaHS 2 W Swett 0.42 600 AM 6/24 CoCoRaHS ...Butte County... 1 NNW Nisland 2.01 800 AM 6/24 SDSU Mesonet 27 WNW Castle Rock 1.17 800 AM 6/24 RAWS 3 SE Nisland 0.75 800 AM 6/24 CoCoRaHS Newell 0.20 900 AM 6/23 Co-Op Observer ...Campbell County... 25 ESE Wright 0.42 800 AM 6/23 RAWS 5 NNW Dwtn Gillette 0.12 800 AM 6/24 ASOS ...Custer County... 3 SSW Argyle 1.50 700 AM 6/23 CoCoRaHS 7 WSW Folsom 1.26 600 AM 6/24 CoCoRaHS 7 WSW Fairburn 1.15 600 AM 6/23 CoCoRaHS 2 SSW Custer 0.64 800 AM 6/23 ASOS Hermosa 0.63 600 AM 6/23 CoCoRaHS Jewel Cave 0.61 800 AM 6/23 SDSU Mesonet 2 WNW Custer 0.61 800 AM 6/23 RAWS 4 W Custer 0.58 800 AM 6/23 CWOP 5 ENE Custer 0.57 700 AM 6/23 CoCoRaHS 1 WNW Wind Cave Visi 0.55 200 PM 6/23 Co-Op Observer 1 WSW Custer 0.53 800 AM 6/23 CoCoRaHS 1 W Wind Cave Visito 0.51 800 AM 6/23 RAWS 8 WNW Fairburn 0.49 800 AM 6/23 RAWS ...Fall River County... 14 NNW Edgemont 5.87 800 AM 6/23 SDSU Mesonet 9 NNE Edgemont 1.54 800 AM 6/23 RAWS 2 W Hot Springs 1.47 700 AM 6/23 CoCoRaHS 14 NW Edgemont 0.95 800 AM 6/23 CoCoRaHS 2 ENE Edgemont 0.94 700 AM 6/23 CoCoRaHS Hot Springs 0.83 700 AM 6/23 CoCoRaHS 4 W Hot Springs 0.71 700 AM 6/23 CoCoRaHS Edgemont 0.68 700 AM 6/23 CoCoRaHS 1 S Hot Springs 0.64 800 AM 6/23 CoCoRaHS 1 NNE Edgemont 0.63 700 AM 6/23 Co-Op Observer 2 SSW Oral 0.38 800 AM 6/23 SDSU Mesonet Oral 0.37 700 AM 6/23 Co-Op Observer 14 SSW Provo 0.37 600 AM 6/23 CoCoRaHS 7 W Ardmore 0.20 800 AM 6/23 SDSU Mesonet ...Haakon County... 12 SSE Milesville 3.88 600 AM 6/24 CoCoRaHS 12 WNW Philip 1.45 800 AM 6/24 CoCoRaHS 17 SW Milesville 1.33 800 AM 6/24 CoCoRaHS 3 E Midland 1.25 700 AM 6/24 CoCoRaHS 9 N Kirley 1.14 700 AM 6/24 CoCoRaHS 7 N Kirley 1.08 700 AM 6/24 CoCoRaHS 5 NE Milesville 1.00 700 PM 6/23 Co-Op Observer 11 W Milesville 0.71 800 AM 6/24 SDSU Mesonet 3 SE Philip 0.43 631 AM 6/24 CoCoRaHS 2 E Cottonwood 0.36 200 PM 6/23 Co-Op Observer 3 E Philip 0.28 800 AM 6/24 ASOS ...Harding County... 9 S Ludlow 1.51 700 AM 6/24 CoCoRaHS 10 W Reva 1.17 800 AM 6/24 SDSU Mesonet 1 N Buffalo 0.94 800 AM 6/24 ASOS 9 NW Ludlow 0.90 430 AM 6/24 CoCoRaHS 9 SSW Ladner 0.87 700 AM 6/23 CoCoRaHS 5 SSE Ralph 0.80 800 AM 6/24 CWOP 9 WSW Ladner 0.65 800 AM 6/24 CoCoRaHS ...Jackson County... 3 WNW Kadoka 1.58 530 AM 6/24 CoCoRaHS 2 E Cottonwood 0.45 800 AM 6/24 SDSU Mesonet 3 WSW Wanblee 0.20 700 AM 6/23 CoCoRaHS ...Lawrence County... 2 NNW Saint Onge 5.10 800 AM 6/24 Trained Spotter 1 SSE Dwtn Spearfish 3.90 800 AM 6/24 CoCoRaHS 1 NW Dwtn Spearfish 1.71 500 AM 6/24 CoCoRaHS 3 SE Spearfish 1.59 800 AM 6/24 RAWS 2 WNW Dwtn Spearfish 1.32 700 AM 6/24 CoCoRaHS 1 E Lead 1.02 800 AM 6/24 CWOP 5 SSE Dwtn Spearfish 0.95 710 AM 6/24 CoCoRaHS 2 NW Central City 0.87 546 AM 6/24 CoCoRaHS 5 SW Brownsville 0.85 800 AM 6/23 CWOP Nemo 0.81 800 AM 6/24 RAWS 3 SE Saint Onge 0.79 615 AM 6/24 CoCoRaHS 6 NNW Dwtn Spearfish 0.76 700 AM 6/24 CoCoRaHS Lead 0.51 900 AM 6/23 Co-Op Observer 1 NNW Dwtn Spearfish 0.32 1000 AM 6/23 Co-Op Observer ...Meade County... 6 WSW Opal 2.08 800 AM 6/23 CWOP 1 NNE Faith 2.05 800 AM 6/24 ASOS 4 NNW Elm Springs 2.00 600 AM 6/24 CoCoRaHS 5 NNE Stoneville 1.99 850 AM 6/23 CoCoRaHS 8 SE Mud Butte 1.97 700 AM 6/24 CoCoRaHS 7 NNE Ellsworth AFB 1.60 700 AM 6/24 CoCoRaHS 2 SW Howes 1.42 700 AM 6/24 CoCoRaHS 6 WNW Union Center 1.30 700 AM 6/23 CoCoRaHS 6 NE Summerset 1.04 700 AM 6/24 CoCoRaHS 6 SSW Fairpoint 1.01 700 AM 6/24 CoCoRaHS Union Center 0.94 800 AM 6/24 SDSU Mesonet 1 NNW Piedmont 0.90 800 AM 6/23 NWS Employee Tilford 0.77 700 AM 6/23 CoCoRaHS 4 NNW Sturgis 0.72 700 AM 6/24 CoCoRaHS 2 N Summerset 0.70 800 AM 6/23 CWOP 9 NNE Sturgis 0.56 700 AM 6/24 CoCoRaHS 4 NNW Tilford 0.55 800 AM 6/24 CoCoRaHS 4 NNE Summerset 0.55 530 AM 6/24 CoCoRaHS 7 E Sturgis 0.42 800 AM 6/24 SDSU Mesonet 2 E Sturgis 0.34 700 PM 6/23 Co-Op Observer 8 WSW Hereford 0.21 700 AM 6/23 CoCoRaHS ...Mellette County... 4 NE Wood 1.81 700 AM 6/24 CoCoRaHS 7 N Wood 1.41 600 AM 6/24 CoCoRaHS 12 NNW White River 1.35 700 AM 6/24 CoCoRaHS 3 NE Norris 1.30 600 AM 6/24 CoCoRaHS 9 N Cedar Butte 0.97 600 AM 6/24 CoCoRaHS 2 SSW Norris 0.92 700 AM 6/24 CoCoRaHS 5 ESE Norris 0.75 614 AM 6/24 Trained Spotter 1 S White River 0.63 800 AM 6/24 SDSU Mesonet 4 WNW Cedar Butte 0.57 800 AM 6/24 SDSU Mesonet ...Oglala Lakota County... 3 ESE Pine Ridge 0.75 800 AM 6/23 ASOS 3 ENE Kyle 0.61 700 AM 6/23 Co-Op Observer 5 NE Porcupine 0.55 800 AM 6/23 RAWS ...Pennington County... 2 WNW Dwtn Rapid Cit 1.55 700 AM 6/24 CoCoRaHS 1 ESE Pactola Resv 1.28 900 AM 6/23 Co-Op Observer 3 W Scenic 1.19 700 AM 6/24 CoCoRaHS 1 N Johnson Siding 1.16 800 AM 6/23 CoCoRaHS 6 W Rochford 1.09 800 AM 6/23 RAWS 1 SW Dwtn Rapid City 1.07 700 AM 6/24 CoCoRaHS 1 N Hisega 0.99 700 AM 6/23 CoCoRaHS 3 NNE Johnson Siding 0.98 700 AM 6/23 CoCoRaHS 1 NNW Hisega 0.95 600 AM 6/23 CoCoRaHS 8 S Wall 0.92 800 AM 6/24 RAWS 1 NE Dwtn Rapid City 0.86 600 AM 6/24 CoCoRaHS 3 E Wasta 0.84 700 AM 6/23 CoCoRaHS 4 NNE Johnson Siding 0.84 800 AM 6/23 CoCoRaHS Wasta 0.81 800 AM 6/23 CWOP 1 SSE Box Elder 0.81 800 AM 6/24 CWOP 4 W Rapid City 0.81 800 AM 6/23 RAWS 19 NNE Creighton 0.77 700 AM 6/24 CoCoRaHS 4 W Dwtn Rapid City 0.76 700 AM 6/23 CoCoRaHS 4 WNW Dwtn Rapid Cit 0.73 700 AM 6/24 CoCoRaHS 4 ESE Dwtn Rapid Cit 0.73 800 AM 6/23 CoCoRaHS Hill City 0.72 700 AM 6/23 Co-Op Observer 4 WNW Rapid City Arp 0.72 700 AM 6/23 CoCoRaHS 4 S Dwtn Rapid City 0.68 700 AM 6/24 CoCoRaHS 2 SSE Dwtn Rapid Cit 0.68 700 AM 6/24 CoCoRaHS 2 SW Dwtn Rapid City 0.67 800 AM 6/24 NWS Employee 12 S Quinn 0.65 800 AM 6/23 CoCoRaHS 2 ENE Wall 0.63 730 AM 6/23 CoCoRaHS 2 ENE Sheridan Lake 0.61 800 AM 6/23 RAWS 4 NW Dwtn Rapid City 0.60 700 AM 6/23 Co-Op Observer 6 W New Underwood 0.54 700 AM 6/24 CoCoRaHS Rapid City Arpt 0.42 800 AM 6/23 ASOS 1 WNW Caputa 0.42 800 AM 6/23 SDSU Mesonet Mount Rushmore 0.41 1258 AM 6/24 Co-Op Observer ...Perkins County... 8 ESE Prairie City 1.25 700 AM 6/24 CoCoRaHS 7 S Shadehill 1.24 800 AM 6/24 RAWS Bison 1.16 800 AM 6/24 SDSU Mesonet 9 SSE Sorum 1.09 700 AM 6/24 CoCoRaHS 3 ESE Lemmon 0.96 800 AM 6/24 SDSU Mesonet 14 WNW Lodgepole 0.61 800 AM 6/23 SDSU Mesonet ...Todd County... 4 NW Parmelee 1.17 700 AM 6/24 CoCoRaHS 14 S Mission 0.58 700 AM 6/24 Co-Op Observer Parmlee 0.45 800 AM 6/24 RAWS 16 SSE Mission 0.43 600 AM 6/24 CoCoRaHS 7 ESE Rosebud 0.36 800 AM 6/24 SDSU Mesonet 7 SE Saint Francis 0.01 900 AM 6/23 CoCoRaHS ...Tripp County... 6 NNW Wewela 2.50 600 AM 6/24 CoCoRaHS 9 N Wewela 2.35 600 AM 6/24 CoCoRaHS 9 ENE Wewela 1.31 600 AM 6/24 CoCoRaHS 5 WSW Colome 1.26 730 AM 6/24 CoCoRaHS 2 WSW Hamill 0.96 700 AM 6/24 CoCoRaHS 2 SSE Ideal 0.85 600 AM 6/24 CoCoRaHS 11 SSE Hamill 0.69 600 AM 6/24 CoCoRaHS 6 N Hamill 0.67 600 AM 6/24 CoCoRaHS 2 W Hamill 0.62 800 AM 6/24 SDSU Mesonet 1 NE Winner 0.57 800 AM 6/24 ASOS ...Ziebach County... 5 NNW Dupree 3.75 700 AM 6/23 CoCoRaHS 9 WSW Red Elm 2.00 631 AM 6/24 Trained Spotter 1 WSW South Eagle Bu 1.80 800 AM 6/24 SDSU Mesonet WYOMING ...Campbell County... 14 SW Weston 0.30 800 AM 6/24 CoCoRaHS 11 NNE Weston 0.28 700 AM 6/24 CoCoRaHS 3 NNE Rozet 0.26 600 AM 6/24 CoCoRaHS 14 NNW Dwtn Gillette 0.25 700 AM 6/24 CoCoRaHS 1 NE Echeta 0.23 800 AM 6/24 RAWS 3 S Dwtn Gillette 0.23 600 AM 6/24 CoCoRaHS Wright 0.19 700 AM 6/23 CoCoRaHS 3 E Dwtn Gillette 0.17 800 AM 6/24 CWOP 1 SSW Rozet 0.17 800 AM 6/24 CWOP 10 SW Dwtn Gillette 0.16 800 AM 6/24 CWOP 5 SW Dwtn Gillette 0.02 700 AM 6/23 CoCoRaHS 4 SE Gillette 0.01 530 PM 6/23 Co-Op Observer 5 SSE Dwtn Gillette 0.01 700 AM 6/23 CoCoRaHS ...Crook County... 1 S Devils Tower 0.94 800 AM 6/24 RAWS Sundance 0.68 600 AM 6/24 CoCoRaHS 7 SE Moorcroft 0.68 800 AM 6/24 CoCoRaHS 8 ENE Alva 0.56 700 AM 6/24 CoCoRaHS 4 SSE Devils Tower 0.55 730 AM 6/24 CoCoRaHS 1 ESE Moorcroft 0.45 600 AM 6/24 CoCoRaHS 3 NNE Moorcroft 0.41 600 AM 6/24 CoCoRaHS 6 SW Beulah 0.20 800 AM 6/23 CoCoRaHS ...Weston County... 1 WNW Clareton 1.85 700 AM 6/23 CoCoRaHS 19 SW Upton 0.83 800 AM 6/23 CWOP 10 N Osage 0.72 700 AM 6/24 CoCoRaHS 8 NNW Newcastle 0.68 700 AM 6/23 CoCoRaHS 4 SE Upton 0.63 700 AM 6/24 CoCoRaHS 11 NE Morrisey 0.54 700 AM 6/23 CoCoRaHS 1 N Upton 0.53 800 AM 6/24 CoCoRaHS 1 WSW Newcastle 0.41 700 AM 6/23 CoCoRaHS 3 E Newcastle 0.41 600 AM 6/24 CoCoRaHS 5 SW Upton 0.37 700 AM 6/24 CoCoRaHS
Photos & Video
Tornado Damage
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| Tornado damage at North Antelope Rochelle Mine credit: NWS |
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Flooding
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| Flooding at Federal St and 7th St in Spearfish (credit: Lucas Pummel) |
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| Flooding in northern Lawrence County (credit: JD Geigle) |
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Hail
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| Hail in Spearfish (credit: Kylie Braunesreither) |
Hail near Butte/Lawrence County line (credit: Matt Kerney) |
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| Hail in Spearfish (credit: Ashley Marie) |
Hail near Butte/Lawrence County line (credit: Matt Kerney) |
Lightning
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| Lightning north of New Underwood (credit: Jacie Schrempp) |
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Radar Products & Animation
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| Radar-based maximum estimated hail size from 6 am MDT June 23, 2023 to 6 am MDT June 24, 2023. Preliminary hail reports (inches) are shown in green and preliminary wind gust reports (mph) are shown in blue. | Radar-based midlevel storm rotation tracks from 6 am MDT June 23, 2023 to 6 am MDT June 24, 2023. Preliminary tornado reports are shown in red. |
Hourly radar animation from 11 am MDT on Friday, June 23, 2023 to 3 am MDT on Saturday, June 24, 2023.
Storm Reports
Here is a list of the wind and hail reports from the severe weather event on June 23–24, 2023. Below that is a map of the preliminary wind, hail, and tornado reports across our area from 6 am MDT on June 23, 2023 to 6 am MDT on June 24, 2023.
...MAXIMUM OBSERVED WINDS SORTED BY MAGNITUDE... LOCATION MAX WIND COMMENTS MPH 25 ESE WRIGHT WY 83 640 PM 6/23/2023 3 NNW SCENIC SD 72 803 PM 6/23/2023 1 NE MIDLAND SD 70 1108 PM 6/23/2023 6 W PARMELEE SD 67 1145 PM 6/23/2023 2 W HAMILL SD 66 1210 AM 6/24/2023 11 SW PARMELEE SD 65 1129 PM 6/23/2023 4 WNW CEDAR BUTTE SD 65 1125 PM 6/23/2023 7 E WANBLEE SD 64 1055 PM 6/23/2023 9 ENE BELVIDERE SD 63 959 PM 6/23/2023 WEWELA SD 61 111 AM 6/24/2023 8 W JEWEL CAVE SD 60 839 PM 6/23/2023 5 N SCENIC SD 60 800 PM 6/23/2023 4 E CACTUS FLAT SD 60 1044 PM 6/23/2023 7 SW ALADDIN WY 60 644 PM 6/23/2023 2 NW SAINT ONGE SD 60 450 PM 6/23/2023 1 ENE MUD BUTTE SD 58 1218 AM 6/24/2023 3 E PHILIP SD 58 1037 PM 6/23/2023 4 SSE WITTEN SD 56 1226 AM 6/24/2023 1 S WHITE RIVER SD 56 1140 PM 6/23/2023 16 WSW DWTN GILLETTE WY 56 422 PM 6/23/2023 3 NW WASTA SD 56 940 PM 6/23/2023 1 NE WINNER SD 55 1250 AM 6/24/2023 13 SSW REVA SD 54 1158 PM 6/23/2023 15 SSE MISSION SD 54 1216 AM 6/24/2023 8 SSW FOLSOM SD 53 954 PM 6/23/2023 FOUR CORNERS WY 53 836 PM 6/23/2023 1 NNE FAITH SD 53 116 AM 6/24/2023 8 S WALL SD 53 1120 PM 6/23/2023 3 W UNION CENTER SD 51 1218 AM 6/24/2023 2 SW BRIDGER SD 50 1005 PM 6/23/2023 ...MAXIMUM HAIL SIZE SORTED BY MAGNITUDE... LOCATION MAX SIZE COMMENTS IN/S/ 2 SSW OPAL SD 2.00 825 PM 6/23/2023 2 SE DWTN SPEARFISH SD 1.75 350 PM 6/23/2023 9 S MUD BUTTE SD 1.75 715 PM 6/23/2023 7 ENE ROCHELLE WY 1.75 735 PM 6/23/2023 5 SW SHARPS CORNER SD 1.50 700 PM 6/23/2023 2 NE KADOKA SD 1.25 945 PM 6/23/2023 5 W HERMOSA SD 1.00 734 PM 6/23/2023 7 ENE BELVIDERE SD 1.00 933 PM 6/23/2023 1 S DWTN RAPID CITY SD 1.00 741 PM 6/23/2023 2 W BOX ELDER SD 1.00 807 PM 6/23/2023 2 SE FRUITDALE SD 1.00 510 PM 6/23/2023 4 NNE SAINT ONGE SD 1.00 437 PM 6/23/2023 2 NW SAINT ONGE SD 1.00 450 PM 6/23/2023 21 ENE NEWELL SD 0.88 655 PM 6/23/2023 SAINT ONGE SD 0.75 421 PM 6/23/2023 4 S DWTN RAPID CITY SD 0.75 722 PM 6/23/2023 5 WNW HERMOSA SD 0.75 740 PM 6/23/2023 12 S FAITH SD 0.70 915 PM 6/23/2023
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| Preliminary local storm reports from 6 am MDT June 23, 2023 to 6 am MDT June 24, 2023. Hail reports are shown with green Hs, wind reports are shown with a blue Ws, and tornado reports are shown with red Ts. State boundaries are in gray lines, and major interstates and highways are shown in orange/tan colors. |
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| Warnings issued by NWS Rapid City through the afternoon and evening of June 23, 2023. Red polygons indicate Tornado Warnings, yellow polygons indicate Severe Thunderstorm Warnings, and green polygons show Flash Flood Warnings. |
Environmental Analysis
Upper-air analyses on the morning of June 23, 2023 captured a pronounced upper-level low over the Great Basin approaching the northern Rockies and High Plains (left image, click to enlarge). A surface analysis valid at the same time showed a stationary front stretching from far southeastern South Dakota southwestward through central Nebraska and extending westward through northern Colorado (right image, click to enlarge). This front had been pushed southward by overnight showers and thunderstorms, but it was expected to retreat northward as a warm front by the afternoon. North of the front, morning temperatures were in the 50s across much of northeastern Wyoming and western South Dakota, and skies were overcast.
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| 500-mb upper-air analysis valid at 6 am MDT on June 23, 2023. This level represents the midlevels of the troposphere, from around 17,000 to 19,000 feet above ground. | Surface analysis valid at 6 am MDT on June 23, 2023. |
The satellite animation below shows that clouds covered much of the area early Friday morning, with a few sub-severe thunderstorms moving across the area (bare ground is blue; water clouds are cyan to lavender; and high ice clouds are orange). Thunderstorms started to develop early in the afternoon around the Black Hills, with a much larger area of storms approaching from western/northwestern Wyoming. The thunderstorms congealed into a large complex of storms by late afternoon and moved across western South Dakota on Friday evening.
Hourly Day-Cloud-Phase GOES-16 satellite animation from 4:56 am until 11:56 pm MDT (6/23/2023). Animation courtesy of the College of DuPage NEXLAB Satellite and Radar website.
Through the morning, clouds decreased (see above satellite animation), with increasing sunshine allowing temperatures to climb into the 60s and 70s. With time, the front gradually lifted northward as a warm front. Near and south of the front, the atmosphere became unstable by the afternoon (refer to the first three images below). As the upper-level low approached the region, vertical wind shear also increased (per the second row of images below). This combination resulted in favorable conditions for a local severe weather outbreak, with a particularly supportive environment for tornadoes in place near the warm front from southern portions of northeastern Wyoming through central South Dakota (refer to the "significant tornado parameter" in the bottom right image). In addition, plenty of atmospheric water vapor was present to allow for heavy rainfall, with precipitable water values by 6 pm MDT exceeding 150% of normal (refer to the bottom left image).
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| Analyzed MLCAPE valid at noon MDT on June 23, 2023 | Analyzed MLCAPE valid at 3 pm MDT on June 23, 2023 | Analyzed MLCAPE valid at 6 pm MDT on June 23, 2023 |
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| Rapid City upper-air balloon sounding valid at 6 pm MDT on June 23, 2023. | Rapid City upper-air balloon hodograph valid at 6 pm MDT on June 23, 2023. |
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| Precipitable water plot valid at 6 pm MDT on June 23, 2023. | Significant tornado parameter valid at 6 pm MDT on June 23, 2023. |
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