Des Moines, IA

Weather Forecast Office

June 28, 2017 Tornado Summaries - Updated July 4th

Overview

Supercell thunderstorms developed during the afternoon hours on June 28 across portions of Iowa. Several confirmed tornado touchdowns were reported across the state including seven in the Des Moines forecast area. In addition, reports of golf ball to baseball sized hail were also received.

Tornado
Storm Reports
Environment

Tornadoes:

Tornado #1 - Near Stuart
Adair County

Date	June 28, 2017
Time (Local)	3:57pm - 4:30pm
EF Rating	EF-0
Est. Peak Winds	75 mph
Path Length	14.98 miles
Max Width	80 yards
Injuries/Deaths	0/0
Summary: Path was intermittent at first with condensation funnel not always visibile. However, the funnel eventually formed and was well documented as it moved across northern Adair county. It remained in rural areas with only minor damage to a few outbuildings and trees.

Track Map


Photograph from Dan O'Banion (via Robert Kempf)	Photograph from Dan O'Banion (via Robert Kempf)	Photograph from Katt Hrubetz (via Robert Kempf)	Radar reflectivity data from the Des Moines WSR-88D radar.

Tornado #2 - 3.0 NW of Carbon
Adams County

Date	June 28, 2017
Time (Local)	4:21pm - 4:30pm
EF Rating	EF-1
Est. Peak Winds	90 mph
Path Length	3.85 miles
Max Width	100 yards
Injuries/Deaths	0/0
Summary: Tornado tracked across rural areas northwest of Carbon. Some minor damage occurred to outbuildings with most of the damage occurring to trees along the path.

Track Map


Radar reflectivity (left) and storm relative velocity (right) near the start of the tornado. A hook echo is evident, along with some rotation	Reflectivity and storm relative velocity at 4:43pm. The area of rotation was strongest at this time.

Tornado #3 - 5.5 ESE of Greenfield
Adair and Madison Counties

Date	June 28, 2017
Time (Local)	4:45pm - 5:00pm
EF Rating	EF-1
Est. Peak Winds	93 mph
Path Length	7.71 miles
Max Width	100 yards
Injuries/Deaths	0/0
Summary: Tornado developed in eastern Adair county and travelled east through rural areas before entering Madison county. There was minor damage to one property and impressive tree damage along the Adair/Madison county line.

Track Map


Reflectivity image during the tornado from the Des Moines WSR-88D radar, showing a weak hook echo	Storm-relative velocity radar data shows the tornadic circulation, located between Arbor Hill and Macksburg	Reflectivity (left) and Correlation Coefficient (right). The low CC values at the same location of the hook echo indicate a tornadic debris signature

Tornado #4 - 5.0 South of Bedford
Taylor County

Date	June 28, 2017
Time (Local)	5:05pm - 5:35pm
EF Rating	EF-1
Est. Peak Winds	110 mph
Path Length	8.05 miles
Max Width	500 yards
Injuries/Deaths	0/0
Summary: Tornado initially touched down south of Bedford. The most severe damage occurred to several homes and outbuildings where peak wind speeds were estimated to be near 110 mph.

Track Map


Reflectivity from the Des Moines WSR-88D	Storm relative velocity data shows an area of rotation south-southwest of Bedford	Four panel radar imagery showing a strong circulation (top right). A tornadic debris signature is evident at this time (circled)

Tornado #5 - 4.0 SW of Pleasantville
Warren and Marion Counties

Date	June 28, 2017
Time (Local)	5:55pm - 6:26pm
EF Rating	EF-1
Est. Peak Winds	100 mph
Path Length	18.32 miles
Max Width	700 yards
Injuries/Deaths	0/0
Summary: The tornado initially touched down about 4 miles southwest of Pleasantville. Some trees were topped and uprooted, and several structures sustained damage. Multiple power poles were snapped. The worst damage occurred to several homes and outbuildings where peak wind speeds were estimated to be near 100 mph. The tornado may have lifted or cycled several times along it's damage path.

Track Map


Reflectivity data from the Des Moines WSR-88D radar at 6:00pm. A well defined hook echo is evident at this time.	Reflectivity (left) and storm-relative velocity (right) show a strong circulation just south of Pleasantville.	Reflectivity (left) and correlation coefficient (right). A tornadic debris signature is indicated by the low values of correlation coefficient.

Tornado #6 - 4.5 NNW of Prescott
Adams County

Date	June 28, 2017
Time (Local)	4:43pm - 4:46pm
EF Rating	EF-0
Est. Peak Winds	70 mph
Path Length	1.94 miles
Max Width	30 yards
Injuries/Deaths	0/0
Summary: A weak tornado passed through rural areas of Adams county north of Prescott. Very minor tree damage was observed at one rural house.

Track Map

Caption

Tornado #7 - 2.2 E of New Virginia
Warren County

Date	June 28, 2017
Time (Local)	6:18pm - 6:19pm
EF Rating	EF-0
Est. Peak Winds	65
Path Length	0.51 miles
Max Width	25 yards
Injuries/Deaths	0/0
Summary: A brief tornado east of New Vriginia. Moved across an open field east of town with no damage noted.

Track Map

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

EF0 Weak 65-85 mph	EF1 Moderate 86-110 mph	EF2 Significant 111-135 mph	EF3 Severe 136-165 mph	EF4 Extreme 166-200 mph	EF5 Catastrophic 200+ mph

Storm Reports

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

0834 PM     HAIL             3 ESE BEDFORD           40.65N 94.68W
06/28/2017  M1.75 INCH       TAYLOR             IA   TRAINED SPOTTER



0710 PM     HAIL             LA PORTE CITY           42.32N 92.19W
06/28/2017  E1.00 INCH       BLACK HAWK         IA   PUBLIC

            REPORT VIA SOCIAL MEDIA.

0708 PM     FUNNEL CLOUD     PLEASANTVILLE           41.39N 93.27W
06/28/2017                   MARION             IA   TRAINED SPOTTER



0655 PM     TSTM WND GST     3 S IOWA FALLS          42.47N 93.27W
06/28/2017  M58 MPH          HARDIN             IA   ASOS

            58 MPH/50 KNOT WIND GUST MEASURED AT IOWA
            FALLS AIRPORT (KIFA).

0625 PM     FUNNEL CLOUD     2 SE KNOXVILLE          41.30N 93.08W
06/28/2017                   MARION             IA   TRAINED SPOTTER



0624 PM     TORNADO          4 ENE NEW VIRGINIA      41.20N 93.67W
06/28/2017                   WARREN             IA   EMERGENCY MNGR



0622 PM     FUNNEL CLOUD     1 W NEW VIRGINIA        41.18N 93.75W
06/28/2017                   WARREN             IA   TRAINED SPOTTER



0619 PM     HAIL             GLADBROOK               42.19N 92.71W
06/28/2017  U1.00 INCH       TAMA               IA   AMATEUR RADIO



0607 PM     HAIL             GLADBROOK               42.19N 92.72W
06/28/2017  E1.25 INCH       TAMA               IA   BROADCAST MEDIA

            REPORT VIA SOCIAL MEDIA.

0603 PM     TORNADO          4 S PLEASANTVILLE       41.33N 93.26W
06/28/2017                   MARION             IA   TRAINED SPOTTER

            REPORTED A FEW MILES SOUTH OF HWY 5 IN
            PLEASANTVILLE.

0550 PM     HAIL             2 WNW MARSHALLTOWN      42.05N 92.95W
06/28/2017  M0.50 INCH       MARSHALL           IA   TRAINED SPOTTER



0548 PM     HAIL             1 NNW MARSHALLTOWN      42.05N 92.92W
06/28/2017  E0.88 INCH       MARSHALL           IA   PUBLIC



0536 PM     FUNNEL CLOUD     LORIMOR                 41.13N 94.06W
06/28/2017                   UNION              IA   PUBLIC



0530 PM     TSTM WND DMG     2 ENE URBANDALE         41.65N 93.71W
06/28/2017                   POLK               IA   TRAINED SPOTTER

            SIX INCH TREE BRANCHES DOWN.

0530 PM     FUNNEL CLOUD     5 E CRESTON             41.07N 94.27W
06/28/2017                   UNION              IA   TRAINED SPOTTER



0530 PM     HAIL             CLIVE                   41.61N 93.77W
06/28/2017  M1.00 INCH       POLK               IA   PUBLIC



0523 PM     HAIL             1 NNE WINDSOR HEIGHTS   41.62N 93.71W
06/28/2017  E1.25 INCH       POLK               IA   NWS EMPLOYEE



0522 PM     HAIL             1 SW WINDSOR HEIGHTS    41.59N 93.73W
06/28/2017  E1.00 INCH       POLK               IA   PUBLIC

            REPORT VIA SOCIAL MEDIA.

0521 PM     HAIL             1 WSW WAUKEE            41.60N 93.89W
06/28/2017  E1.00 INCH       DALLAS             IA   PUBLIC

            REPORT VIA SOCIAL MEDIA.

0518 PM     HAIL             WAUKEE                  41.61N 93.86W
06/28/2017  E0.88 INCH       DALLAS             IA   PUBLIC

            REPORT VIA SOCIAL MEDIA.

0516 PM     HAIL             1 SW WAUKEE             41.59N 93.87W
06/28/2017  E1.00 INCH       DALLAS             IA   AMATEUR RADIO



0510 PM     HAIL             3 ESE BEDFORD           40.65N 94.68W
06/28/2017  E2.75 INCH       TAYLOR             IA   TRAINED SPOTTER

            DELAYED REPORT.

0509 PM     HAIL             CAMBRIDGE               41.90N 93.53W
06/28/2017  E1.75 INCH       STORY              IA   LAW ENFORCEMENT



0508 PM     HAIL             BEDFORD                 40.67N 94.72W
06/28/2017  E2.75 INCH       TAYLOR             IA   BROADCAST MEDIA

            REPORT VIA SOCIAL MEDIA.

0508 PM     TORNADO          7 SW BEDFORD            40.59N 94.82W
06/28/2017                   TAYLOR             IA   TRAINED SPOTTER

            REPORT FROM EAX.

0508 PM     HAIL             BEDFORD                 40.67N 94.72W
06/28/2017  E2.50 INCH       TAYLOR             IA   CO-OP OBSERVER



0505 PM     HAIL             2 S DE SOTO             41.51N 94.00W
06/28/2017  E1.75 INCH       DALLAS             IA   TRAINED SPOTTER



0450 PM     HAIL             4 SE NEW MARKET         40.70N 94.85W
06/28/2017  E1.00 INCH       TAYLOR             IA   TRAINED SPOTTER



0446 PM     HAIL             VAN METER               41.53N 93.96W
06/28/2017  E2.75 INCH       DALLAS             IA   BROADCAST MEDIA

            DELAYED REPORT VIA SOCIAL MEDIA.

0445 PM     HAIL             ELKHART                 41.79N 93.51W
06/28/2017  M0.25 INCH       POLK               IA   TRAINED SPOTTER



0428 PM     TORNADO          3 SW DEXTER             41.48N 94.26W
06/28/2017                   ADAIR              IA   AMATEUR RADIO

            3 MILES SOUTH OF I80, 4 MILES EAST OF P26.

0422 PM     FUNNEL CLOUD     3 S FONTANELLE          41.25N 94.56W
06/28/2017                   ADAIR              IA   TRAINED SPOTTER



0417 PM     TORNADO          4 S EARLHAM             41.43N 94.11W
06/28/2017                   MADISON            IA   AMATEUR RADIO



0414 PM     TORNADO          4 S EARLHAM             41.43N 94.13W
06/28/2017                   MADISON            IA   AMATEUR RADIO



0412 PM     TORNADO          3 SSW STUART            41.46N 94.34W
06/28/2017                   ADAIR              IA   EMERGENCY MNGR

            TORNADO REPORTED.

0340 PM     HAIL             FORT DODGE              42.51N 94.18W
06/28/2017  M0.88 INCH       WEBSTER            IA   TRAINED SPOTTER



0335 PM     TSTM WND GST     4 NNW FORT DODGE        42.56N 94.19W
06/28/2017  M59 MPH          WEBSTER            IA   ASOS

            59 MPH/51 KNOT WIND GUST MEASURED AT THE
            FORT DODGE AIRPORT (KFOD).

0326 PM     HAIL             FORT DODGE              42.51N 94.18W
06/28/2017  E1.00 INCH       WEBSTER            IA   TRAINED SPOTTER

            MOSTLY DIME, BUT SOME QUARTER SIZED HAIL
            MIXED IN.

0326 PM     HAIL             FORT DODGE              42.50N 94.18W
06/28/2017  M1.75 INCH       WEBSTER            IA   PUBLIC



0324 PM     HAIL             1 NNW FORT DODGE        42.52N 94.18W
06/28/2017  M0.50 INCH       WEBSTER            IA   AMATEUR RADIO



0850 PM     HAIL             5 WNW MALOY             40.71N 94.50W
06/28/2017  E1.25 INCH       TAYLOR             IA   TRAINED SPOTTER



0329 AM     HAIL             5 N WOODWARD            41.92N 93.92W
06/28/2017  E1.00 INCH       BOONE              IA   EMERGENCY MNGR

            ESTIMATED NICKEL TO QUARTER SIZED HAIL. IN
            ADDITION ESTIMATED 40-45 MPH WINDS.


&&

$$

Environment

Full summary of the event will be updated soon.


Figure 1: Surface observations at 4:00pm show a low pressure system in Minnesota, with warm, moist air ahead of a front extending into southwest Iowa	Figure 2: 500mb analysis at 4:00pm depicting a broad area of 40-50kt flow across Iowa	Figure 3: 850mb analysis at 4:00pm showing moist southwesterly flow into Iowa during the afternoon

A large area of moderate to strong instability, characterized by MLCAPE values in excess of 2000-2500 J/kg, was located across much of Iowa. Strong speed shear combined with veering winds aloft contributed to significant low level wind shear, and effective storm relative helicity values during the afternoon exceeded 200m2/s2. Lifted condensation levels (LCLs) were also low, which kept cloud bases close to the ground.


Figure 4: MLCAPE plot at 4:00pm, showing moderate to strong instability across most of Iowa during the afternoon	Figure 5: Effective SRH plot, with values of over 200 m2/s2 located in the southeastern half of Iowa	Figure 6: LCL values at 4:00pm, indicating very low cloud bases less than 1000m

Additional environmental data.


Figure 7: Visible satellite showing multiple thunderstorms developing near 4:00pm, shortly after thunderstorms began to develop	Figure 8: Deep moisture convergence along the frontal boundary as storms began to develop during the afternoon	Figure 9: Effective bulk wind shear values during the afternoon were generally greater than 40kts

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