The pre-dawn hours of this Sunday featured a surprisingly-potent, southward-surging complex of severe thunderstorms that provoked considerable wind damage primarily within Sherman, Buffalo, Howard and Hall counties, and likely isolated wind damage in several nearby counties as well. Some of the worst impacts occurred in and near Ravenna, where estimated gusts to around 85 MPH downed numerous…
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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 GID wrote it up.
The pre-dawn hours of this Sunday featured a surprisingly-potent, southward-surging complex of severe thunderstorms that provoked considerable wind damage primarily within Sherman, Buffalo, Howard and Hall counties, and likely isolated wind damage in several nearby counties as well. Some of the worst impacts occurred in and near Ravenna, where estimated gusts to around 85 MPH downed numerous trees, some as large as 4-6 feet in diameter. Portions of the community were without power for several hours, and a few homes and vehicles also sustained damage. In Kearney, while damage was not widespread, three large trees crashed down on a trailer home causing substantial roof damage. Other communities that suffered wind damage (mainly to trees) included: Loup City, Pleasanton, Cairo, Boelus and Grand Island (although impacts were quite minimal on the grounds of the ongoing Nebraska State Fair). Once storms pushed south of the Interstate 80 corridor, most peak gusts checked in around or below 50 MPH, although a mesonet station near Nelson clocked a 60 MPH gust shortly before the strongest part of the complex departed southward into Kansas. As for rainfall, the majority of South Central Nebraska received at least 0.50-1.00, but localized pockets of mainly Valley, Sherman and Howard counties tallied 2+.
Breaking down event timing and evolution, the late evening featured a smattering of fairly weak storms here and there. However, the main event did not get even get underway until 2-3 a.m. CDT, as the beginning stages of a developing squall line took shape in far northern portions of South Central Nebraska, evolving from earlier activity that initiated in northern Nebraska. Over the next few hours, this linear complex surged south, wreaking the aforementioned wind damage and eventually assuming the form of a mature bow echo before departing into north central Kansas mainly between 5:30-6:30 a.m. CDT.
Although the severity of this late-night severe event was not well-anticipated, a chance of thunderstorms was in the forecast as the mid-upper levels featured a fairly compact shortwave trough diving out of SD into Nebraska in a north-northwest flow regime. Closer to the surface at 850 millibars, modest south-southwesterly flow resulted in decent low-level moisture convergence into central Nebraska, and at the surface, a weak cold front sagged southward across the state as the night wore on (eventually augmented by storm outflow). Once storms established a surging cold pool, the moisture-rich surface environment proved favorable to fostering severe wind gusts, with dewpoints averaging in the mid-60s to around 70 F. Around the time the damaging wind event ramped up, mesoscale analysis indicated most-unstable CAPE up to around 2000 j/kg and effective deep-layer wind shear around 40 knots.
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 Hastings, NE wrote its last area forecast discussion before the first event at Aug 27, 12:39 AM CST, 1 hour 45 minutes earlier.
Area Forecast Discussion National Weather Service Hastings NE 139 AM CDT Sun Aug 27 2017 .SHORT TERM...(Today and tonight) Issued at 138 AM CDT Sun Aug 27 2017 Aloft: NW flow will become almost due N tonight as a ridge and large subtropical high lodges over the Wrn USA with a trof over the E. WV imagery shows a shortwave trof over the Dakota's. The tail end of this trof will cross the CWA today. Surface: A very subtle cool front was dropping S thru Neb. It should be into Nrn KS by midday and to near I-70 by sunset. High pres will then build over the rgn tonight. At 06Z a couple strong-svr tstms were in progress over the Sandhills and rgnl 88D mosaic and IR satellite shows tstms have been increasing over the last 3 hrs. Models are in excellent agreement that these storms will cont SSE into the CWA thru the rest of the overnight hrs and into Sun AM. RAP mesoanalysis indicates 2000-3000 J/kg of MUCAPE. With low-lvl easterlies...deep layer shear is very strong (exceeding 40 kts). We have already seen an elevated supercell. SPC is monitoring the rgn for a possible svr tstm watch. The main question is will these storms maintain their potency as they drop SSE overnight. Given impending tstms...plan to keep this product short. Tstms exit the CWA probably by midday. Late afternoon redevelopment is unlikely as the front will be S into KS. Main fcst concerns for today is how much debris cloudiness will linger behind the tstms? Also concerned about patchy fog potential late Sun night into Mon AM. .LONG TERM...(Monday through Saturday) Issued at 138 AM CDT Sun Aug 27 2017 Dry and quiet wx in NNW or NW flow as a ridge dominates over the Wrn USA with a trof in the E. Slightly cooler than normal temps Mon-Tue...then near normal Wed-Fri. Possibly a little above normal Sat. This week will cont the incredibly comfortable pattern that has dominates since late July. && .AVIATION...(For the 06Z KGRI/KEAR TAFS through 06Z Monday) Issued at 1230 AM CDT Sun Aug 27 2017 Significant Wx: Brief IFR TSRAs possible until 15Z. Overnight: VFR multi-layered clds as sct shwrs/tstms are developing and/or moving in. There could be a period of IFR VSBYs in +TSRA but there isn't enough certainty to include in the TAFs yet. Winds will be lgt from the E-SE except near TSRAs which could produce G40KT. Confidence: Low Sun: TSRAs could linger into the AM hrs...then probably with decreasing clouds. However...it is very uncertain how much cloudiness will remain in the wake of any storms...but a period of MVFR CIGs is possible. NE-ENE winds around 10 kts. Confidence: Low Sun Eve: VFR with a few altocu possible around 9K ft. Winds becoming lgt/vrbl. There may be some fog issues after 06Z. Further assessment will be necessary for the 12Z TAFs. Confidence: Medium && .GID WATCHES/WARNINGS/ADVISORIES... NE...None. KS...None. && SHORT TERM...Kelley LONG TERM...Kelley AVIATION...Kelley
Hazardous Weather Outlook...UPDATED National Weather Service Hastings NE 200 AM CDT Sun Aug 27 2017 KSZ005>007-017>019-NEZ039>041-046>049-060>064-072>077-082>087- 280700- Phillips-Smith-Jewell-Rooks-Osborne-Mitchell-Valley-Greeley-Nance- Sherman-Howard-Merrick-Polk-Dawson-Buffalo-Hall-Hamilton-York- Gosper-Phelps-Kearney-Adams-Clay-Fillmore-Furnas-Harlan-Franklin- Webster-Nuckolls-Thayer- 200 AM CDT Sun Aug 27 2017 This Hazardous Weather Outlook is for south central Nebraska and portions of north central Kansas. .DAY ONE...Rest of Tonight. Scattered thunderstorms are likely and some storms could be severe. The main threat will be hail up to 2 inches in diameter... but isolated pockets of damaging winds could also occur. .DAYS TWO THROUGH SEVEN...Sunday through Friday. Scattered thunderstorms will continue into Sunday morning but should exit the area by early afternoon. Some of these storms could be severe...with hail up to the size of golf balls the main threat. .SPOTTER INFORMATION STATEMENT... Spotters...please relay reports of hail and wind damage to the National Weather Service. && More information may be obtained at the following web page: https://www.weather.gov/hastings Kelley
Special Weather Statement National Weather Service Hastings NE 300 AM CDT SUN AUG 27 2017 NEZ039-046-270845- Valley NE-Sherman NE- 300 AM CDT SUN AUG 27 2017 ...STRONG THUNDERSTORMS WILL AFFECT SOUTHERN VALLEY AND SHERMAN COUNTIES THROUGH 345 AM CDT... At 259 AM CDT, National Weather Service meteorologists were tracking strong thunderstorms along a line extending from North Loup to near Ansley. Movement was southeast at 30 mph. Penny size hail and wind gusts up to 50 mph will be possible with these storms. Strong thunderstorms will be near... North Loup around 305 AM CDT. Litchfield around 340 AM CDT. Hazard around 345 AM CDT. PRECAUTIONARY/PREPAREDNESS ACTIONS... Frequent cloud to ground lightning is occurring with these storms. Lightning can strike 10 miles away from a thunderstorm. Seek a safe shelter inside a building or vehicle. These storms may intensify, so be certain to monitor local radio stations and available television stations for additional information and possible warnings from the National Weather Service. && LAT...LON 4154 9875 4105 9875 4105 9921 4153 9921 TIME...MOT...LOC 0759Z 306DEG 25KT 4147 9878 4135 9940 Kelley
The Grand Island radar (KUEX), 116 km away, was scanning. The volume nearest the first event began at 08:22 UTC.
6 thunderstorm wind. Local standard time, as filed.
Wind gusts estimated to be near 70 MPH resulted in some large trees being downed in Loup City, blocking a few streets.
Wind gusts in the area were estimated to be near 85 MPH, based on damage reports. There was widespread tree damage reported, especially in the Ravenna area. Several large trees were downed, some 4 to 6 feet in diameter, and heavy equipment was needed to clear some roads. Power lines were also downed in the area and a few homes and vehicles were damaged.
Wind gusts estimated to be near 70 MPH resulted in tree damage across the area. Large tree limbs were downed along Highway 58 near Dannebrog. A large pine tree in Boelus had its top snapped off, with a large branch impaling the roof of a nearby house.
Wind gusts along this path were estimated to be between 60 and 70 MPH, with the strongest wind being in the Cairo area and generally a bit weaker in Grand Island. There were several reports of large tree limbs being downed in the area, some as large as 8-9 inches in diameter.
Wind gusts were estimated to be near 70 MPH. A trailer home was damaged when 3 trees were downed. Part of a tree knocked a hole through the roof, allowing water to get inside the home.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Nebraska in 2017Every state in 2017This day in weather historyWarnings in Nebraska, August 2017
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: 714466, 714478, 714463, 714474, 714468, 714467.