A complex of thunderstorms developed during the evening across western South Dakota, moving east and becoming more organized as the low-level jet increased focus into south central and southeast South Dakota late at night. Deep-layer effective shear reached 35 to 45 knots with MUCAPE to 2000J/kg.
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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 FSD wrote it up.
A complex of thunderstorms developed during the evening across western South Dakota, moving east and becoming more organized as the low-level jet increased focus into south central and southeast South Dakota late at night. Deep-layer effective shear reached 35 to 45 knots with MUCAPE to 2000J/kg. 0-3km shear was 25 to 35 knots, largely normal to the orientation of the convective line. A large-scale bowing segment evolved quickly with a long track of damaging wind across southeast South Dakota into northwest Iowa. Several mesovortices developed along the line and produced swaths of enhanced wind damage, many with winds from 80 to 90 mph, and as high as 115 mph. Three people were injured as the strong winds went through a campground, tearing up trees and tents, and rolling campers.
A rare, but short-lived, late night tornado was spawned near one of the stronger mesovortices.
Areas of high rainfall rates resulted in spotty urban flash flooding.
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 Sioux Falls, SD wrote its last area forecast discussion before the first event at Jul 16, 9:29 PM CST, 5 hours 43 minutes earlier.
AREA FORECAST DISCUSSION
National Weather Service Sioux Falls SD
1029 PM CDT Tue Jul 16 2019
.SHORT TERM...(This Evening through Wednesday)
Issued at 326 PM CDT Tue Jul 16 2019
Scattered strong to severe thunderstorms are possible tonight into
early Wednesday morning.
Scattered thunderstorms from an exiting MCV will continue to move
eastward into the Upper MS Valley through early this afternoon.
Residual boundaries, instability and moisture could result in
isolated thunderstorms late this afternoon and evening. However,
better convective chances increase late this evening into early
Wednesday morning as a strong shortwave rolls across the High
Plains.
As this main shortwave moves east over western SD this evening, an
increasing south-north moving low level jet from 30 to 40 knots will
develop. This will also enhance theta-e advection across the area and
hence, expand and intensify convection across south central SD.
MUCAPE will exceed 2500 J/kg this evening, and with an increasingly
deep layer shear profile from 30 to 45+ knots, organized supercells
are likely. A few rotating storms at the initial stage are possible;
however, the primary mode during the overnight hours looks to be
multi-cell clusters of bowing segments as storms move through the
forecast area. Soundings show an inverted V-profile and DCAPE values
over 1000 J/kg and 0-3 km shear from 25-30 knots. Thus, large hail
will be possible in the early stages, but the main threat will be
damaging winds with the potential for 70 mph+.
Confidence level in terms of precipitation chances is moderate to
high. Uncertainty arises with timing as models are not in good
agreement; therefore have followed the 700 mb boundary as reference
for PoPs. As of now, severe thunderstorms will be possible as early
as 1AM CDT or as late as 4AM CDT into Wednesday morning.
Convection re-develops Wednesday afternoon, mainly along and east
of I-29 as instability increases and the low-level jet re-
intensifies. SPC highlights well this risk on its Day 2 severe
weather outlook.
Cloud cover from the exiting MCS could impact temperatures on
Wednesday, mainly for areas along and north of I-90 with highs in
the upper 80s. An Excessive Heat Watch remains in effect for areas
along and south of I-90 where highs are expected to be from the
upper 80s to low 90s.
.LONG TERM...(Wednesday Night through Tuesday)
Issued at 326 PM CDT Tue Jul 16 2019
The main concern in the long term is the continued heat, especially
south of I-90.
As the ongoing MCS moves/weakens east of the forecast area,
lingering showers and thunderstorms will be possible Wednesday night
into Thursday. Better focus for precipitation will be along and east
of I-29. Next precipitation chances are expected Friday night and
again Saturday into Sunday as several vort max/disturbances move
along the westerly flow aloft.
In terms of temperatures, Thursday and Friday look like the warmest
days of the extended with highs ranging from the upper 80s to upper
90s. Afternoon temperatures are expected to reach the low to mid 70s
through the end of the week. As mentioned in the short-term, an
Excessive Heat Watch has been issued for portions of the forecast
area through Friday evening as heat index values are expected to be
up to 105 degrees Fahrenheit.
&&
.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1028 PM CDT Tue Jul 16 2019
Scattered thunderstorms are expected to develop and push across
the area after 08Z tonight, affecting mainly KHON and KFSD into
Wednesday morning. A few additional thunderstorms may develop on
Wednesday afternoon.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...Excessive Heat Watch from Wednesday afternoon through Friday
evening for SDZ050-063>071.
MN...NONE.
IA...Excessive Heat Watch from Wednesday afternoon through Friday
evening for IAZ001>003-012>014-020>022-031-032.
NE...Excessive Heat Watch from Wednesday afternoon through Friday
evening for NEZ013-014.
&&
SHORT TERM...05
LONG TERM...05
AVIATION...JMThe Sioux Falls radar (KFSD), 194 km away, was scanning. The volume nearest the first event began at 09:11 UTC.
24 thunderstorm wind, 1 tornado, 1 lightning, 1 flash flood. Local standard time, as filed.
Significant tree damage occurred at the Snake Creek Campground. Injuries occurred when tree branches fell on tents. Several campers rolled by high winds.
DOT RWIS measured 115 mph wind gust.
A farm outbuilding was destroyed by strong thunderstorm winds.
Widespread tree damage throughout Armour.
Large picnic table blown over and moved a considerable distance.
Significant tree damage.
Significant tree damage and some damage to buildings in town. Power was knocked out to most of the town through the morning hours.
Two large silos suffered considerable damage with roofs collapsed.
A tornado spun up around two miles north of Tripp, touching down just east of a railroad line east of State Highway 37 and north of 285th Street. The tornado tracked to the southeast, where it impacted a farmstead, causing significant damage to two barns and destroying a small outbuilding. The tornado continued across 411th Ave. where it removed the second story of a poorly constructed residence. Fortunately, the residents were not home at the time. After a mile on the ground, a third farmstead was struck tearing metal roofing from a barn. At this point, the tornado veered a bit more southward, finally lifting just after crossing U.S. Highway 18 near 412th Avenue.
Lumber yard lost part of its roof, with most fences taken out.
Numerous branches and limbs broken from trees.
Several large trees down in town.
Significant tree damage throughout the town of Olivet. A gas line was damaged by falling limbs which required evacuation of residents over a two block area for several hours during the morning.
A lightning strike to a single-family home caused a fire, resulting in total loss of the home. |Four residents were home at the time of the lightning strike, but there were no injuries.
Farm outbuilding destroyed northwest of Wakonda.
Wind damage at farmstead to buildings and trees.
Large tree snapped.
Large tree limb broken off and tossed on top of car.
A tree fell on a power line in Lennox, cutting off service to more than 660 customers for several hours.
Numerous large tree limbs snapped.
Up to 2 feet of water pooling in street. 17 vehicles were reported stranded in high water.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in South Dakota in 2019Every state in 2019This day in weather historyThe tornado archive for South Dakota, 2019Warnings in South Dakota, July 2019
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: 847237, 847262, 847258, 847263, 847265, 847266, 847376, 847242, 847268, 847269, 847243, 847245, 847234, 847246, 847270, 847249, 847250, 847379, 847271, 847647, 847252, 847253, 847386, 847255, 847650, 847391, 847233.