A series of Bering Sea storms will impact western Alaska this week, with elevated water levels, isolated coastal flooding, high surf, erosion, and strong winds. Heavy rain and snow are also expected along the West Coast into Interior Alaska. Showers and thunderstorms will produce a multi-day flash flooding threat across parts of the southern High Plains and Southwest through the weekend. Read More >
Overview
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Severe thunderstorms with large hail and strong winds moved across northeastern Wyoming and western South Dakota Wednesday evening (June 26, 2019). By late evening, the storms began to move rapidly to the northeast around 40 mph across northwestern South Dakota, producing damaging winds and causing power outages. As the main part of the rain was concentrated over northwestern South Dakota, an outflow boundary from the storms moved rapidly to the south. As the boundary approached the Black Hills, the winds rapidly increased from the north and northwest. Wind gusts of 55 mph to 65 mph were reported shortly before midnight across the foothills and plains on the eastern side of the Black Hills around Rapid City. It is fairly unusual to get winds this strong this far ahead of thunderstorms. A heat burst also occurred across south-central South Dakota. |
Radar & Lightning
Radar animation from 7:45 pm MDT to 1:03 am MDT (KUDX)
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| Radar reflectivity (R) and velocity (L) at midnight showing outflow that produced 55-65 mph gusts along the eastern slopes of the Black Hills. |
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Storm Reports
Here are the preliminary severe thunderstorm storm reports for June 26, 2019.
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| Preliminary storm reports for June 26, 2019 (green H's represent hail; blue W's represent wind gusts) |
The storm reports listed below are in descending order and may not necessarily be the final storm reports. Hail reports listed by size (inches) SIZE LOCATION ST COUNTY TIME ------ ----------------------- -- -------------- ------- 1.75 14 NNE RECLUSE WY CAMPBELL 0820 PM 1.25 3 ENE DOWNTOWN GILLETTE WY CAMPBELL 0930 PM 1.00 1 N ROCKYFORD SD OGLALA LAKOTA 0850 PM 1.00 SMITHWICK SD FALL RIVER 0807 PM 1.00 15 NNW RECLUSE WY CAMPBELL 0755 PM 0.88 QUINN SD PENNINGTON 0950 PM 0.75 4 NW DOWNTOWN BELLE FOU SD BUTTE 1024 PM 0.70 8 NW ROCKYPOINT WY CAMPBELL 0854 PM 0.70 11 SSE WESTON WY CAMPBELL 0847 PM 0.50 1 SSW DOWNTOWN BELLE FO SD BUTTE 1045 PM Tstm wind reports listed by speed (mph) SPEED LOCATION ST COUNTY TIME ------ ----------------------- -- -------------- ------- 70.00 HOOVER SD BUTTE 1106 PM 70.00 15 NNW RECLUSE WY CAMPBELL 0756 PM 66.00 7 SSE MEADOW SD PERKINS 1224 AM 65.00 6 ESE ROSEBUD SD TODD 1230 AM HEAT BURST WITH A DECAYING THUNDERSTORM. 64.00 BOX ELDER SD PENNINGTON 1155 PM CONVECTIVE WIND GUSTS ALONG OUTFLOW BOUNDARY 30 MILES FROM THUNDERSTORMS. 63.00 5 WNW NEW UNDERWOOD SD PENNINGTON 1155 PM CONVECTIVE WIND GUSTS ALONG OUTFLOW BOUNDARY 30 MILES FROM THUNDERSTORMS. 62.00 1 WSW RED ELM SD ZIEBACH 0118 AM OCCURRED WITH DECAYING THUNDERSTORMS 61.00 1 NNE FAITH SD MEADE 1256 AM OCCURRED WITH DECAYING THUNDERSTORMS 61.00 RAPID CITY AIRPORT SD PENNINGTON 1155 PM CONVECTIVE WIND GUST ALONG OUTFLOW BOUNDARY 30 MILES FROM THUNDERSTORMS. 61.00 ELLSWORTH AFB SD MEADE 1144 PM CONVECTIVE WIND GUSTS ALONG OUTFLOW BOUNDARY 30 MILES FROM THUNDERSTORMS. 60.00 7 SSW MISSION SD TODD 1233 AM WIND GUST ASSOCIATED WITH A HEAT BURST WITH A COLLAPSING THUNDERSTORM. 60.00 CHERRY CREEK SD ZIEBACH 1223 AM CONVECTIVE WIND GUST ALONG OUTFLOW BOUNDRY FROM THUNDERSTORMS 30 MILES NORTH 60.00 1 WSW RED ELM SD ZIEBACH 1219 AM 60.00 RAPID CITY AIRPORT SD PENNINGTON 1146 PM CONVECTIVE WIND GUSTS ALONG OUTFLOW BOUNDARY 30 MILES FROM THUNDERSTORMS. 60.00 1 SSW DOWNTOWN BELLE FO SD BUTTE 1045 PM 60.00 12 WSW CASTLE ROCK SD BUTTE 1045 PM 60.00 COLONY WY CROOK 1010 PM 60.00 6 ENE CARLILE WY CROOK 0940 PM 60.00 14 NNE RECLUSE WY CAMPBELL 0820 PM 59.00 1 E DOWNTOWN RAPID CITY SD PENNINGTON 1147 PM CONVECTIVE WIND GUSTS ALONG OUTFLOW BOUNDARY 30 MILES FROM THUNDERSTORMS. 56.00 3 NW WASTA SD PENNINGTON 1229 AM CONVECTIVE WIND GUST ON OUTFLOW BOUNDARY 30 MILES FROM THUNDERSTORMS. 55.00 REDIG SD HARDING 1119 PM 54.00 3 W UNION CENTER SD MEADE 1200 AM CONVECTIVE WIND GUSTS ALONG OUTFLOW BOUNDARY 5 TO 10 MILES FROM THUNDERSTORMS. 53.00 SLIM BUTTES SD OGLALA LAKOTA 1114 PM 52.00 3 SW OPAL SD MEADE 1158 PM 51.00 1 N BUFFALO SD HARDING 1053 PM 50.00 8 NW ROCKYPOINT WY CAMPBELL 0854 PM 50.00 15 NNW RECLUSE WY CAMPBELL 0751 PM 49.00 2 ENE WESTON WY CAMPBELL 0852 PM Tstm wind damage reports LOCATION ST COUNTY TIME ----------------------- -- -------------- ------- 8 WNW USTA SD PERKINS 1200 AM ROOF TORN OFF BUILDINGS, HUGE TREES SNAPPED AND SPLIT. TRAILER HOUSE DAMAGED. MISSION SD TODD 1233 AM TREES DOWN IN MISSION. APPEARS TO BE A HEAT BURST WITH A COLLAPSING THUNDERSTORM. 9 WSW RED ELM SD ZIEBACH 0100 AM POWER POLE YARD LIGHT KNOCKED DOWN FROM POST THUNDERSTORM OUTFLOW WIND. WIND ESTIMATED 60 TO 80 MPH. Rain amounts (inches) AMOUNT LOCATION ST COUNTY TIME ------ ----------------------- -- -------------- ------- 1.84 1 SW SHADEHILL SD PERKINS 0644 AM STORM TOTAL RAINFALL 1.75 6 NW SHADEHILL RESERVOI SD PERKINS 0643 AM STORM TOTAL RAINFALL 1.50 8 WNW USTA SD PERKINS 1200 AM ROOF TORN OFF BUILDINGS, HUGE TREES SNAPPED AND SPLIT. TRAILER HOUSE DAMAGED. 1.10 11 WNW DOWNTOWN BELLE F SD BUTTE 0647 AM STORM TOTAL RAINFALL 1.05 2 ENE WESTON WY CAMPBELL 0852 PM 0.90 1 ESE DOWNTOWN BELLE FO SD BUTTE 0647 AM STORM TOTAL RAINFALL
Environment
The near-storm environment was rather unstable (left image) and strongly sheared (right image) based upon the data gathered from the 6 pm MDT balloon launch.
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| Sounding based off the 6 pm balloon release at NWS Rapid City | Hodograph based off the 6 pm balloon release at NWS Rapid City |
The mesoscale analysis from the Storm Prediction Center (SPC) showed modest buoyancy (left image) over northeastern Wyoming into northwestern South Dakota (strongest over central South Dakota). The vertical wind shear from the surface to about 18,000 feet above ground (middle image) was sufficient for rotating thunderstorms and subsequent severe weather across the area. While large hail was observed, especially early in the evening's evolution, the primary hazard was strong wind gusts. The atmosphere was primed for strong thunderstorm downdraft potential across much of northeastern Wyoming and western South Dakota (right image).
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| Most-unstable CAPE (a measure of buoyancy in the atmosphere) valid at 9 pm MDT | 0-6 km wind difference (a measure of storm rotation potential) valid at 9 pm MDT | Downdraft CAPE (a measure of severe wind gust potential) valid at 9 pm MDT |
Heat Burst
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| Winds gusted to 65mph at Rosebud at 1:30am CDT (image courtesy of SDSU) | Temperature at Rosebud jumped from mid-70s to 85F while the dewpoint dropped to 42F (image courtesy of SDSU) | Radar reflectivity around 1:30am CDT shows collapsing thunderstorm near in Todd county. |
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