Strong outflow winds from dying thunderstorms produced wind gusts around 65 mph across portions of Meade County and eastern Pennington County.
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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.
The episode as NWS UNR wrote it up.
Strong outflow winds from dying thunderstorms produced wind gusts around 65 mph across portions of Meade County and eastern Pennington County.
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 Aug 18, 1:58 PM MST, 22 minutes earlier.
Area Forecast Discussion For Western SD and Northeastern WY National Weather Service Rapid City SD 258 PM MDT Sat Aug 18 2018 .DISCUSSION...(This Evening Through Saturday) Issued at 258 PM MDT Sat Aug 18 2018 Current surface analysis shows lee trough over far western SD, with weak low pressure over southwest ND. Upper level analysis shows strong trough over MT, starting to close off as it moves over the high plains. Skies are mainly cloudy over northeast WY and far western SD, with increasing clouds to the east. KUDX radar shows showers and storms from northeast WY into the Black HIlls, with the strongest activity over the northern Black Hills area. Temps range from the 60s and lower 70s over northeast WY and the Black Hills to near 90 over south central SD. Winds are generally west- northwest behind the surface trough, southerly to the east of it. Unsettled and wet weather can be expected through the weekend as the trough moves across the region. The rainfall will generally come in two phases. The first will be with the passing surface trough and shortwave energy through early this evening. Another batch of rainfall is then expected later tonight through much of Sunday with the passing upper level system. Many areas will receive beneficial rainfall over the weekend, a half inch or more, with some areas from the northern Black Hills and northwest SD to central SD seeing 1 to 2 inches or more. For late this afternoon and early evening, showers and thunderstorms will continue to expand eastward across western SD, with some decrease in coverage likely over northeast WY. Plenty of instability around for at least isolated strong to marginally severe storms over western and central SD, MUCAPE values of 1000 to over 2000 j/kg. However, shear and winds aloft are relatively weak and will likely result in most of the stronger storms not sustaining themselves for very long. With precipitable water values above average, locally heavy rainfall can be expected. Any stronger storms will generally move east of the area mid to late evening, with lingering showers and a few storms overnight. Lows tonight will be in the 50s and lower 60s. Sunday will be cool, cloudy, blustery, and showery for most areas as the upper level system passes over the region. A few thunderstorms are likely, especially to the south and east of the Black Hills, with some heavier rainfall expected. Highs will only be in the 60s to mid 70s. Showers will end and skies will gradually clear from northwest to southeast Sunday afternoon and night as the system moves away. Cooler conditions will linger into at least the first part of the week, with highs mostly in the upper 60s and 70s on Monday and Tuesday. A ridge is forecast to build over the western US during the first half of the week. As it does, a weak disturbance could bring isolated to widely scattered showers and thunderstorms Monday night into Tuesday, especially to northeast WY and southwest SD. At this point, the rest of the week looks mostly dry and at least seasonably warm. The ridge to the west will likely weaken some as is moves toward the plains late in the week. && .AVIATION...(For the 18Z TAFS Through 18Z Sunday) Issued At 1120 AM MDT Sat Aug 18 2018 Showers and thunderstorms will continue to develop from west to east across the area today, with widespread coverage later this afternoon and evening. MVFR/local IFR conditions expected with the thunderstorms. After the initial wave of showers/thunderstorms cross the area, a brief dry period may be possible before widespread showers develop again this evening/overnight. MVFR/IFR ceilings will increase in coverage tonight, around 03Z across northeast Wyoming and after 06Z across western South Dakota. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...None. WY...None. && DISCUSSION...26 AVIATION...15
Hazardous Weather Outlook National Weather Service Rapid City SD 205 AM MDT Sat Aug 18 2018 SDZ001-002-012>014-024>032-041>044-046-047-049-072>074-WYZ054>058- 071-191300- Harding-Perkins-Butte-Northern Meade Co Plains-Ziebach- Northern Black Hills-Northern Foot Hills-Rapid City- Southern Foot Hills-Central Black Hills-Southern Black Hills- Custer Co Plains-Pennington Co Plains-Haakon-Fall River- Oglala Lakota-Jackson-Bennett-Mellette-Todd-Tripp- Sturgis/Piedmont Foot Hills-Southern Meade Co Plains- Hermosa Foot Hills-Northern Campbell-Southern Campbell- Western Crook-Wyoming Black Hills-Weston-Northeastern Crook- 205 AM MDT Sat Aug 18 2018 /305 AM CDT Sat Aug 18 2018/ This Hazardous Weather Outlook is for western South Dakota and northeastern Wyoming. .DAY ONE...Today and Tonight Widespread thunderstorms are expected today and tonight. There is a marginal risk of severe thunderstorms this afternoon and evening with hail and strong winds. Locally heavy rainfall is also possible. .DAYS TWO THROUGH SEVEN...Sunday through Friday Scattered thunderstorms are possible Sunday, Severe thunderstorms are not expected at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed today. && Stay tuned to NOAA weather radio for further updates...or check our web site at weather.gov/rapidcity
Special Weather Statement
National Weather Service Rapid City SD
141 PM MDT SAT AUG 18 2018
SDZ024-025-182030-
Northern Black Hills SD-Northern Foot Hills SD-
141 PM MDT SAT AUG 18 2018
...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN LAWRENCE COUNTY
UNTIL 230 PM MDT...
At 141 PM MDT, Doppler radar was tracking a strong thunderstorm near
Brownsville, or 6 miles south of Lead, moving northeast at 10 mph.
Nickel size hail will be possible with this storm.
Locations impacted include...
Deadwood, Brownsville, Galena and Roubaix Lake.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.
&&
LAT...LON 4417 10377 4430 10384 4438 10368 4437 10357
4422 10358
TIME...MOT...LOC 1941Z 245DEG 7KT 4426 10374
RudgePRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE RAPID CITY SD
225 PM MDT SAT AUG 18 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0220 PM HAIL 3 ESE GALENA 44.32N 103.59W
08/18/2018 E1.00 INCH LAWRENCE SD PUBLIC
&&
MEPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE RAPID CITY SD
232 PM MDT SAT AUG 18 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0232 PM HAIL 5 SSE WHITEWOOD 44.40N 103.59W
08/18/2018 E1.00 INCH LAWRENCE SD PUBLIC
&&
MEPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE RAPID CITY SD
242 PM MDT SAT AUG 18 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0241 PM HAIL 4 NNW TILFORD 44.35N 103.46W
08/18/2018 E1.00 INCH MEADE SD TRAINED SPOTTER
&&
MESpecial Weather Statement National Weather Service Rapid City SD 251 PM MDT SAT AUG 18 2018 SDZ024-026-028-072-182115- Northern Black Hills SD-Central Black Hills SD- Sturgis/Piedmont Foot Hills SD-Rapid City SD- 251 PM MDT SAT AUG 18 2018 ...STRONG THUNDERSTORM OVER SOUTHWESTERN MEADE...SOUTHEASTERN LAWRENCE AND CENTRAL PENNINGTON COUNTIES... At 250 PM MDT, Doppler radar was tracking a strong thunderstorm near Piedmont, or 11 miles northwest of Rapid City, moving northeast at 15 mph. Dime size hail will be possible with this storm. Locations impacted include... Black Hawk, Summerset, Nemo, Piedmont and Dalton Lake. This Includes Interstate 90 in South Dakota between Mile Markers 42 and 53. PRECAUTIONARY/PREPAREDNESS ACTIONS... Very heavy rainfall is also occurring with this storm, and may lead to localized flooding. Do not drive your vehicle through flooded roadways. && LAT...LON 4409 10347 4423 10355 4432 10336 4415 10322 TIME...MOT...LOC 2050Z 243DEG 14KT 4421 10342 JC
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE RAPID CITY SD
302 PM MDT SAT AUG 18 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0302 PM HAIL 1 NNW PIEDMONT 44.24N 103.40W
08/18/2018 M1.00 INCH MEADE SD NWS EMPLOYEE
&&
METhe national radar mosaic for the moment the first event began.
3 high wind. Local standard time, as filed.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in South Dakota in 2018Every state in 2018This day in weather historyWarnings in South Dakota, August 2018
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 2026-09-24. Each event’s entry at NCEI: 775742, 775740, 775743.