Tornadoes:

A National Weather Service Storm Damage Assessment Team has reviewed damage from two tornadoes which occurred across portions of southeast Grand Forks County and one tornado across eastern Traill County. These tornadoes resulted from storms in the afternoon and early evening of August 27, 2016. There were no injuries or fatalities from these tornadoes.

Based on video and photographic evidence, plus multiple eyewitness accounts, it is clear that two separate and distinct tornadoes occurred from the same parent supercell thunderstorm in southeast Grand Forks County. The first was a brief touchdown in far southeast Arvilla township and the second was a much larger and longer tracking tornado across northern Pleasant View township.

A third tornado occurred nearly an hour and a half later in east central Traill County. This tornado crossed the Interstate 29 corridor and produced severe damage at two farmsteads and at the Taft elevator complex.

Tornado #1 - SSW Arvilla Grand Forks County Date August 27, 2016 Time (Local) 4:12 - 4:14 pm CDT EF Rating EF-0 Est. Peak Winds 70 mph Path Length 0.5 miles Max Width 100 yards Injuries/Deaths 0 Summary: This tornado touched down for 1-2 minutes and tracked for less than one-half mile over a largely open field west of CR 2. Track Map (Click to Enlarge)

Tornado #2 - S Arvilla/Emerado Grand Forks County Date August 27, 2016 Time (Local) 4:18 - 4:32 pm CDT EF Rating EF-1 Est. Peak Winds 110 mph Path Length 4.0 miles Max Width 600 yards Injuries/Deaths 0 Summary: This large tornado snapped/uprooted numerous trees along its path. It demolished a small barn and spread barn materials, ranch debris, and small trailers over a broad area. Track Map (Click to Enlarge)

A small barn was destroyed five miles SSE of Arvilla near the intersection of CR 2 and CR 6. (NWS Storm Survey)

Tornado #3 - Cummings/Hillsboro Traill County Date August 27, 2016 Time (Local) 6:02 - 6:10 pm CDT EF Rating EF-3 Est. Peak Winds 140 mph Path Length 3.0 miles Max Width 300 yards Injuries/Deaths 0 Summary: This tornado destroyed a two car garage and snapped/uprooted numerous trees at a farmstead west of Interstate 29. It then crossed the I-29 corridor and tore down filled grain bins and toppled elevator legs at the Taft elevator complex. Further east, it demolished half of an engineered metal building and then tore the roof off of a well constructed home and caved in sections of the main floor exterior walls. The tornado appears to have ended within a half mile to the east of this farmstead. Track Map (Click to Enlarge)

The tops were blown off of full metal grain brains while smaller bins were knocked over at the Taft elevator complex approximately four miles north of
Hillsboro along Interstate 29. (NWS Storm Survey)

Many of the exterior walls caved in on a house one-quarter mile southeast of the Taft elevator complex as the roof was blown off. (NWS Storm Survey)

Please note that this information is preliminary and subject to change pending final review of the events and publication in NWS Storm Data.

The Enhanced Fujita (EF) Scale classifies tornadoes into the following categories:

Radar:

Click to Enlarge

Radar Screenshots

At 4:18 p.m., a tornado was touching down 5 miles southeast of Arvilla, ND. The image on the left is radar reflectivity and shows the classic hook echo pattern that is associated with tornadoes. On the right, the red and green pixels beside each other show strong rotation in the Doppler velocity data.

By 6:05 p.m., the storm had moved further south into Traill county. Another tornado (eventually rated EF-3) had developed and was causing damage north of Hillsboro. Again, reflectivity is on the left and Doppler velocity is on the right.

Storm Reports:

Below is a map of large hail reports (>1" in diameter) and preliminary tornado reports from across the area on Saturday, August 27, 2016.

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND
400 PM CDT SUN AUG 28 2016

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0108 PM     HAIL             2 WSW PRAIRIE ROSE      46.81N 96.87W
08/27/2016  M0.75 INCH       CASS               ND   TRAINED SPOTTER

            PEA TO PENNY SIZE HAIL.

0110 PM     HAIL             WNW COLFAX              46.47N 96.87W
08/27/2016  M0.88 INCH       RICHLAND           ND   PUBLIC

            GUSTY WINDS AND HAIL UP TO NICKEL SIZE.

0110 PM     HAIL             WEST FARGO              46.87N 96.90W
08/27/2016  E0.88 INCH       CASS               ND   TRAINED SPOTTER

0113 PM     HAIL             WEST FARGO              46.87N 96.90W
08/27/2016  M1.25 INCH       CASS               ND   TRAINED SPOTTER

            MOSTLY NICKEL TO QUARTER SIZE HAIL...FEW TO HALF DOLLAR
            SIZE. WINDS ESTIMATED 40 MPH.

0114 PM     HAIL             FARGO                   46.88N 96.82W
08/27/2016  M1.00 INCH       CASS               ND   TRAINED SPOTTER

0119 PM     HAIL             FARGO                   46.88N 96.82W
08/27/2016  E0.75 INCH       CASS               ND   TRAINED SPOTTER

            DIME SIZE HAIL BEGINNING TO TURN THE GROUND WHITE.

0119 PM     HAIL             FARGO                   46.88N 96.82W
08/27/2016  E1.00 INCH       CASS               ND   BROADCAST MEDIA

            SLIGHTLY LARGER THAN QUARTER HAIL AT NDSU.

0120 PM     HAIL             FARGO                   46.88N 96.82W
08/27/2016  E0.88 INCH       CASS               ND   TRAINED SPOTTER

            MINOR STREET FLOODING WITH HAIL UP TO NICKEL SIZE.

0120 PM     HAIL             MOORHEAD                46.86N 96.76W
08/27/2016  M1.00 INCH       CLAY               MN   TRAINED SPOTTER

            PEA TO QUARTER SIZE HAIL IN NORTH MOORHEAD.

0124 PM     HAIL             FARGO                   46.88N 96.82W
08/27/2016  M2.00 INCH       CASS               ND   PUBLIC

            PHOTO VIA SOCIAL MEDIA FROM NORTH FARGO. TIME ESTIMATED.


0155 PM     HAIL             3 ESE KENT              46.42N 96.63W
08/27/2016  E1.00 INCH       WILKIN             MN   BROADCAST MEDIA

            REPORT POSTED VIA SOCIAL MEDIA. TIME ESTIMATED BASED ON
            RADAR.

0229 PM     HEAVY RAIN       1 N ADA                 47.31N 96.51W
08/27/2016  M3.18 INCH       NORMAN             MN   MESONET

            RAINFALL FROM NDAWN STATION 1N ADA TODAY SO FAR.

0253 PM     HAIL             8 N EVERDELL            46.38N 96.41W
08/27/2016  M1.00 INCH       WILKIN             MN   TRAINED SPOTTER

0257 PM     HAIL             8 N EVERDELL            46.38N 96.41W
08/27/2016  M1.75 INCH       WILKIN             MN   TRAINED SPOTTER

            HAIL COVERING THE GROUND.

0305 PM     HAIL             8 N EVERDELL            46.38N 96.41W
08/27/2016  M1.75 INCH       WILKIN             MN   TRAINED SPOTTER

            HAIL UP TO GOLFBALL SIZE AT COUNTY ROAD 16 AND 270TH
            AVENUE. DRIFTS OF HAIL UP TO 1 FT ON EDGE OF ROAD WITH
            HAIL COVERING ROAD. CROP DAMAGE DUE TO HAIL.

0306 PM     HAIL             2 SW HONEYFORD          48.01N 97.50W
08/27/2016  E0.75 INCH       GRAND FORKS        ND   PUBLIC

            DIME SIZE HAIL JUST SOUTHWEST OF HONEYFORD.

0323 PM     HAIL             10 ESE CRYSTAL          48.54N 97.47W
08/27/2016  M1.00 INCH       PEMBINA            ND   LAW ENFORCEMENT

            PEA TO QUARTER SIZE HAIL ON HWY 81 AT PEMBINA/WALSH
            COUNTY LINE.

0337 PM     HAIL             10 ESE CRYSTAL          48.54N 97.47W
08/27/2016  E1.25 INCH       PEMBINA            ND   LAW ENFORCEMENT

            WALNUT SIZED HAIL REPORTED AT US 81 AT WALSH/PEMBINA
            COUNTY LINE.

0341 PM     HAIL             ARVILLA                 47.92N 97.49W
08/27/2016  E1.75 INCH       GRAND FORKS        ND   PUBLIC

            VIA SOCIAL MEDIA.

0341 PM     HAIL             ARVILLA                 47.92N 97.49W
08/27/2016  E2.50 INCH       GRAND FORKS        ND   PUBLIC

            RELAYED VIA SOCIAL MEDIA. SIZE ESTIMATED FROM PHOTO.

0350 PM     HAIL             GRAND FORKS AFB         47.96N 97.38W
08/27/2016  E0.75 INCH       GRAND FORKS        ND   PUBLIC

            PEA TO DIME SIZE HAIL VIA SOCIAL MEDIA.

0352 PM     HAIL             2 W NASH                48.47N 97.56W
08/27/2016  E1.00 INCH       WALSH              ND   PUBLIC

0412 PM     TORNADO          4 S ARVILLA             47.86N 97.49W
08/27/2016  F0               GRAND FORKS        ND   STORM CHASER

            TORNADO TOUCHDOWN FOR 1-2 MINUTES...TRACKED MAYBE A HALF
            MILE ACROSS AND OPEN FIELD UNTIL 414 PM CDT. PEAK WINDS
            ESTIMATED TO 70 MPH. MAXIMUM WITH TO 100 YARDS.

0418 PM     TORNADO          5 S ARVILLA             47.85N 97.48W
08/27/2016  F1               GRAND FORKS        ND   NWS STORM SURVEY

            A LARGE TORNADO TRACKED TO THE SOUTHEAST FOR ROUGHLY 4
            MILES TO AROUND 8 SSW OF EMERADO BY 432 PM. THIS TORNADO
            SNAPPED OR UPROOTED NUMEROUS TREES ALONG ITS PATH...IT
            DEMOLISHED A SMALL BARN AND SPREAD BARN AND RANCH DEBRIS
            OVER A BROAD AREA. PEAK WINDS ESTIMATED TO 110 MPH.
            MAXIMUM WIDTH TO 600 YARDS.

0429 PM     HAIL             GRAFTON                 48.42N 97.40W
08/27/2016  M1.00 INCH       WALSH              ND   LAW ENFORCEMENT

0430 PM     HAIL             5 S EMERADO             47.85N 97.36W
08/27/2016  E1.75 INCH       GRAND FORKS        ND   TRAINED SPOTTER

            LARGE HAIL FELL ACROSS SOUTHERN OAKVILLE AND CHESTER
            TOWNSHIPS.

0442 PM     HAIL             LAPORTE                 47.21N 94.76W
08/27/2016  E0.75 INCH       HUBBARD            MN   TRAINED SPOTTER

0456 PM     HAIL             1 NW FOXHOME            46.29N 96.32W
08/27/2016  M1.00 INCH       WILKIN             MN   CO-OP OBSERVER

0518 PM     HAIL             HOLMES                  47.72N 97.30W
08/27/2016  E2.50 INCH       GRAND FORKS        ND   PUBLIC

            VIA PHOTO ON SOCIAL MEDIA. TIME ESTIMATED FROM RADAR.

0529 PM     HAIL             5 SE FERGUS FALLS       46.23N 95.99W
08/27/2016  E0.75 INCH       OTTER TAIL         MN   TRAINED SPOTTER

            DIME SIZE HAIL AND ESTIMATED 25 MPH WINDS.

0540 PM     HAIL             BUXTON                  47.60N 97.10W
08/27/2016  M1.50 INCH       TRAILL             ND   TRAINED SPOTTER

0601 PM     TSTM WND GST     2 N CUMMINGS            47.54N 97.08W
08/27/2016  M66.00 MPH       TRAILL             ND   MESONET

            MEASURED BY BUXTON RWIS STATION NEAR MM 114 ON I-29.

0602 PM     TORNADO          2 SSW CUMMINGS          47.49N 97.10W
08/27/2016  F3               TRAILL             ND   NWS STORM SURVEY

            A TORNADO TOUCHED DOWN AND TRACKED TO THE SOUTHEAST FOR
            NEARLY 3 MILES TO ABOUT 2.5 NNE OF HILLSBORO BY 610 PM
            CDT. THIS TORNADO DESTROYED A TWO CAR GARAGE AND SNAPPED
            OR UPROOTED NUMEROUS TREES NORTHWEST OF THE TAFT
            ELEVATOR. IT CROSSED I-29 NEAR TAFT AND TORE DOWN FILLED
            GRAIN BINS...ELEVATOR LEGS...AND TORE THE ROOFING OFF THE
            OFFICE. IT THEN TORE THE ROOF OFF AND CAVED IN WALLS OF A
            WELL BUILT HOME EAST OF THE ELEVATOR COMPLEX. PEAK WINDS
            ESTIMATED TO 140 MPH. MAXIMUM WIDTH TO 300 YARDS.

0727 PM     HAIL             1 SE PERLEY             47.17N 96.79W
08/27/2016  E1.50 INCH       NORMAN             MN   PUBLIC

0818 PM     HAIL             2 E AVERILL             46.97N 96.50W
08/27/2016  M1.50 INCH       CLAY               MN   NWS EMPLOYEE

            MEASURED HAIL WELL AFTER IT HAD FALLEN.

Golf ball to Tennis ball sized hail caused large amounts of damage in Arvilla. Photo courtesy of Stacy Marto.

Rain Reports:

Below is a 48-hour radar rainfall estimate of the event ending at 7 AM on Sunday August, 28th. This graphic is followed by actual rain gauge reports from across the area in text format.

Public Information Statement
National Weather Service Grand Forks ND
1013 AM CDT Sun Aug 28 2016

...Rainfall Reports...

Location                     Amount    Time/Date       Lat/Lon              
Ada MN                       3.49 in   0705 AM 08/28   47.30N/96.52W        
Twin Valley MN               2.32 in   0800 AM 08/28   47.26N/96.26W        
Fertile MN 3 WSW  (Sandhill  2.20 in   0945 AM 08/28   47.51N/96.34W        
Perley MN (NDAWN)            2.01 in   0705 AM 08/28   47.17N/96.80W        
Red Lake Falls MN            1.28 in   0700 AM 08/28   47.88N/96.28W        
Rothsay MN                   1.24 in   0835 AM 08/28   46.48N/96.27W        
Grand Forks ND (AFB)         1.07 in   0658 AM 08/28   47.97N/97.40W        
Mayville ND (NDAWN)          1.04 in   0705 AM 08/28   47.50N/97.22W        
Maple Bay MN 5 ESE           1.02 in   0700 AM 08/28   47.59N/96.13W        
Eldred MN (NDAWN)            1.00 in   0705 AM 08/28   47.73N/96.78W        
Baudette MN (AP)             0.92 in   0653 AM 08/28   48.72N/94.61W        
Thief R Falls MN (AP)        0.92 in   0656 AM 08/28   48.06N/96.18W        
Thief River Falls MN         0.90 in   0700 AM 08/28   48.12N/96.18W        
Red Lake Falls MN (Red Lake  0.90 in   0930 AM 08/28   47.90N/96.27W        
Mavie MN 2 S (NDAWN)         0.83 in   0705 AM 08/28   48.12N/95.95W        
Holt MN 6 E (Thief River)    0.82 in   0830 AM 08/28   48.30N/96.07W        
Gatzke MN 9 SW (DNR)         0.80 in   0920 AM 08/28   48.30N/95.87W        
Brooks MN 3 WNW (Lost R)     0.78 in   0945 AM 08/28   47.83N/96.05W        
Abercrombie ND               0.75 in   0600 AM 08/28   46.45N/96.73W        
Thief River Falls MN 5 N (Th 0.75 in   0945 AM 08/28   48.19N/96.17W        
Mahnomen MN 1 SE (Wild Rice  0.72 in   0945 AM 08/28   47.31N/95.95W        

Observations are collected from a variety of sources with varying
equipment and exposures. Not all data listed are considered official.