On August 25th, heavy rains from thunderstorms rains produced flash flooding in northeast Wayne County. The storms formed along a weak warm front as it slowly moved eastward across northeast Nebraska.
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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 OAX wrote it up.
On August 25th, heavy rains from thunderstorms rains produced flash flooding in northeast Wayne County. The storms formed along a weak warm front as it slowly moved eastward across northeast Nebraska.
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 Omaha, NE wrote its last area forecast discussion before the first event at Aug 25, 5:38 AM CST, 5 hours 17 minutes earlier.
Area Forecast Discussion National Weather Service Omaha/Valley NE 638 AM CDT Fri Aug 25 2017 .SHORT TERM...(Today through Sunday) Issued at 310 AM CDT Fri Aug 25 2017 Main forecast concerns are convective coverage today and then thunderstorm chances into Sunday. The primary things of note from the 00Z upper air charts included the following. At 300 mb, winds were generally less than 50 kts from the northern and central parts of the Plains westward to the west coast of the CONUS. Weak 12 hour height falls and weak cold air advection at 500 mb were spreading east across NE, but the strongest height falls were over British Columbia and Alberta. Thermal ridge at 700 mb was to our west, with temperatures only around +8C over eastern NE. Highest mid level moisture was along the Gulf coast. Modest moisture extended from TX northward across the western parts of KS and NE into central SD. Surface analysis showed low pressure centered over WY with a trough extending south toward the TX panhandle. A couple of weak convergence zones were in the region, one extending from the NE panhandle into the central part of the state and another from WY into SD. Heaviest rain from storms early this morning has been mostly east of KOFK and north of KOMA. Recent runs of the high resolution convection allowing models have NOT done a good job of handling the storms early this morning. At least some of this activity seems to be related to a low level jet around 925 mb, in combination with a weak surface boundary. This may keep isolated to scattered storms (with potential for localized heavy rain) over the forecast area through mid morning, before they lift northeast into northwest IA. With at least some clearing this afternoon, expect most highs in the lower 80s. Storms should develop again either over northeast or central NE and then expand east over the area mainly north of Interstate 80. Activity may continue to bubble up into the afternoon and increase for the southern parts of the forecast area Saturday night into Sunday morning. Confidence on this is not overly high, but the pattern would support at least a slight chance. If cloud cover decreases as expected Sunday, we should see highs in the lower and mid 80s. .LONG TERM...(Sunday night through Thursday) Issued at 310 AM CDT Fri Aug 25 2017 In general, this period looks mainly dry. Longer range models are in pretty good agreement that a mid tropospheric high with a center of about 595 decameters should be located over UT, with a weak closed low over WI. That puts our area in northwest flow, which is not always dry, but it is difficult to time shortwave troughs. Through Wednesday, the high to the west weakens slightly while the closed low tracks to the OH valley. The mid level flow across the central Plains becomes weak, and overall forcing for ascent is weak. Toward Thursday, the flow does flatten a bit and become more zonal. High temperatures during this period should be in the upper 70s to mid 80s, with lows mainly in the mid 50s to lower 60s. && .AVIATION...(For the 12Z TAFS through 12Z Saturday morning) Issued at 630 AM CDT Fri Aug 25 2017 Slow-moving thunderstorms affecting KOMA/KLNK this morning. Some MVFR/IFR/LIFR conditions possible with the heavier thunderstorms. The short range models are doing a better job with the more southward area of storms and holding on to them into the morning...where previous runs were mostly void of storms KOMA southward. Early on...GFS heavy rain recognition procedure picked up on pooled high rh south of where the precip was and this area shifts to the MO River at 15Z...then lifts northeast through 18Z. Some back- building still occuring in Cuming Co. Held on to shra/tsra the longest at KOMA through 15Z. South/variable winds 5 to 12kts increase to 15 to 25kts later this morning and continue tonight until the cold front approaches. Left winds up at KOFK in the evening...so did not include LLWS at this time. TSRA return the the KOFK forecast after 06Z. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && SHORT TERM...Miller LONG TERM...Miller AVIATION...Zapotocny
Hazardous Weather Outlook National Weather Service Omaha/Valley NE 1104 AM CDT Fri Aug 25 2017 IAZ043-055-056-069-079-080-090-091-NEZ011-012-015>018-030>034- 042>045-050>053-065>068-078-088>093-260615- Monona-Harrison-Shelby-Pottawattamie-Mills-Montgomery-Fremont- Page-Knox-Cedar-Thurston-Antelope-Pierce-Wayne-Boone-Madison- Stanton-Cuming-Burt-Platte-Colfax-Dodge-Washington-Butler- Saunders-Douglas-Sarpy-Seward-Lancaster-Cass-Otoe-Saline- Jefferson-Gage-Johnson-Nemaha-Pawnee-Richardson- 1104 AM CDT Fri Aug 25 2017 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHWEST IOWA...WEST CENTRAL IOWA...EAST CENTRAL NEBRASKA...NORTHEAST NEBRASKA AND SOUTHEAST NEBRASKA. .DAY ONE...THIS AFTERNOON AND TONIGHT Scattered thunderstorms are expected to redevelop tonight for parts of eastern Nebraska and southwest Iowa. A few storms may approach severe...mainly over northeast Nebraska...with large hail, damaging winds and locally heavy rain the main hazards. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY Thunderstorm chances will continue for at least parts of the area from Saturday into Sunday. ..SPOTTER INFORMATION STATEMENT... Spotter activation will not be needed this or tonight.
Special Weather Statement National Weather Service Omaha/Valley Nebraska 944 AM CDT FRI AUG 25 2017 NEZ012-018-251515- Cedar NE-Wayne NE- 944 AM CDT FRI AUG 25 2017 ...Significant Weather Advisory for NORTH CENTRAL WAYNE AND SOUTHEASTERN CEDAR COUNTIES UNTIL 1015 AM CDT... At 943 AM CDT, trained weather spotters reported a strong thunderstorm 5 miles west of Concord, or 23 miles southwest of Ponca, moving east at 10 mph. Dime size hail and wind gusts up to 50 mph were reported 4 miles north of Wayne. Heavy rain was also occurring. Locations impacted include... Laurel. This includes Highway 20 in Nebraska between mile markers 388 and 398. 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 4227 9702 4225 9711 4241 9720 4250 9702 TIME...MOT...LOC 1443Z 249DEG 11KT 4236 9709 Dergan
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE OMAHA/VALLEY NEBRASKA
1101 AM CDT FRI AUG 25 2017
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1058 AM HEAVY RAIN ASHLAND 41.04N 96.37W
08/25/2017 M2.18 INCH SAUNDERS NE CO-OP OBSERVER
OVERNIGHT AMOUNT
&&
DEEThe Omaha radar (KOAX), 122 km away, was scanning. The volume nearest the first event began at 17:08 UTC.
1 flash flood. Local standard time, as filed.
Emergency management reports water was running over roads near the Wayne/Dixon County border. The flash flooding occurred with water over the roads generally between Wayne County County Roads 572 to 575 Avenue and between 860 to 864 Roads.
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: 721074.