July 27, 2010 - Severe Weather and Ashland/Iron County Tornadoes

Tornadoes

Tornado - Morse, WI Ashland County, WI Date July 27, 2010 Time (Local) 6:21 PM - 6:24 PM EF Rating EF-2 Est. Peak Winds 120 mph Path Length 0.93 miles Max Width 650 yards Injuries/Deaths 0/0 Summary: Limited road options, and the surrounding Chequamegon National Forest initially made the damage assessment for this tornado difficult. Significant tree damage was evident from Dry Lake Road, but the entire tornado path was unable to be viewed from the ground. Aerial photographs from the Wisconsin DNR revealed some substantial swaths where about 90-100% of the trees were uprooted or snapped. The damage was reminiscent of the EF-2 tornado that struck the area near the St. Croix River in Pine and Burnett Counties on June 17, 2010. 6:21PM 0.5 Base Reflectivity near Morse 6:21PM 0.5 Base Velocity near Morse NWS Survey Photo near Morse NWS Survey Photo near Morse NWS Survey Photo near Morse NWS Survey Photo near Morse Track Map Downloadable KMZ File

Tornado - Eastern Ashland County, WI Ashland County, WI Date July 27, 2010 Time (Local) 7:12 PM- 7:14 PM EF Rating EF-0 Est. Peak Winds 75 mph Path Length 1.92 miles Max Width 600 yards Injuries/Deaths 0/0 Summary: Some tree damage was evident from Roddis Line Road north of Highway F. The tree damage was relatively minor in this area, but exhibited characteristics of tornadic damage. Therefore, this tornado was classified as an EF-0 tornado on the Enhanced Fujita Scale.     7:12PM 0.5 Base Reflectivity over far southeastern Ashland County 7:12PM 0.5 Base Velocity over far southeastern Ashland County The tight couplet of red colors against green colors in this image suggests very strong rotation. In these images, the radar beam is intersecting the storm about 10,000 feet above ground level. The "gate-to-gate shear" referenced on the storm relative velocity figure is referring to the maximum difference between a "gate", or pixel, of green velocity data, from a red gate immediately adjacent to itself. In this case, the maximum difference is 130 knots, or 150 mph. Remember, this is what the radar is measuring 10,000 feet above the ground - not necessarily what is happening at the surface. The green velocity data indicates winds that are flowing towards the radar (in this case located off the image to the northwest), and the red velocity data indicates winds that are flowing away from the radar. Track Map Downloadable KMZ File

Tornado - Turtle Flambeau Flowage, WI Iron County, WI Date July 27, 2010 Time (Local) 7:20 PM - 7:26 PM EF Rating EF-1 Est. Peak Winds 100 mph Path Length 4.79 mi Max Width 660 yards Injuries/Deaths 3/0 Summary: This tornado likely began somewhere over the western parts of the Turtle Flambeau Flowage - on the southern tip of Big Island. Aerial photographs taken by the Wisconsin DNR showed evidence of tornado damage on smaller islands over the western part of the flowage between the Turtle Dam and Springstead Landing. These islands had large sections of trees completely destroyed - either snapped or uprooted, and the aerial photographs revealed trees laying across one another in a cross-hatched pattern, in a few cases at 90 degree incidence angles.  Substantial tree damage began occurring near Springstead Landing and east into a small neighborhood near the intersection of Flowage Rd. and Franks Ln. A stand of large trees between Flowage Landing Rd. and Simmons Rd. was completely demolished with similar evidence of tornadic winds. All of the trees were snapped or uprooted. Standing on the Springstead Landing, you can now see ridges on the opposite side of the lake, which according to area residents was previously impossible due to the density of the trees. Impacts to cabins in the area started on the western edge of Simmons Rd. and then continued into the neighborhood near the northern tip of Flowage Rd. Some structures in this area were damaged by falling trees. The tree damage in this neighborhood was still rather significant, with large trees up to 2 feet in diameter uprooted or snapped. The tornado then continued east where uprooted and snapped trees were noted along the edge of the shoreline near campsites D-31, C-2, and D-35 before damage became much more sporadic near the canoe portage. It was at this point where the damage path narrowed and the tornado likely ended. It's important to note that this tornado path was embedded in a swath of rather substantial non-tornadic wind damage caused merely by intense thunderstorm wind gusts. The wind damage swath was about 1-3 miles wide and stretched across the Flowage such that most of the campsites received at least some sort of tree damage. 7:21PM 0.5 Base Reflectivity near Turtle Flambeau Flowage 7:21PM 0.5 Base Velocity near Turtle Flambeau Flowage The tight couplet of red colors against green colors suggests very strong rotation. In these images, the radar beam is intersecting the storm about 11,500 feet above ground level. Photos from NWS Duluth Survey Team around the Flowage - in areas impacted by the tornado ONLY Photos from NWS Duluth Survey Team around the Flowage - in areas impacted by the tornado ONLY Photos from NWS Duluth Survey Team around the Flowage - in areas impacted by the tornado ONLY Photos from NWS Duluth Survey Team around the Flowage - in areas impacted by the tornado ONLY Track Map Downloadable KMZ File

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

Wind & Hail

Grand View, Wisconsin, Area Storm Damage

Hail damage to windows in southeastern Bayfield County near Grand View.	Wind damage in southeastern Bayfield County near Grand View.	Wind damage in southeastern Bayfield County near Grand View.	Wind damage in southeastern Bayfield County near Grand View.

Major Hailstorm In Bayfield and Ashland Counties

The significant supercell that later went on to produce a tornado in the Morse area originally was a significant hail producing storm. The first hail report in the area was received at 5:20 PM from 2 miles southeast of Iron River of quarter size hail (1.00" in diameter). More hail reports were then received between the Iron River and Mason/Grand View areas that reached up to 2.75" in diameter. Some trees were snapped off including red pines and oaks. A police car had its windshield cracked, and three other vehicles were dented, as large amounts of wind-driven golfball sized hail fell in that particular location. There were also reports of wheat and corn fields being destroyed, shingle and siding damage to some houses, and that the Highway Department had to scrape the roads clear of several inches of wet leaves that were stripped off by the hail.

Below is an image from the National Severe Storms Laboratory that basically provides an estimate for the maximum size of the hail in a given area, and integrated over several hours on the afternoon and evening of July 27th. The result is a "hail swath map". You can see that the NSSL algorithm estimated a broad swath of at least golfball sized hail, with some pockets of hail up to 3 to 4 inches in diameter. We didn't have anything quite that large reported to us.

Below is a radar image from 5:31 PM CDT from Bayfield County. The large spike of low reflectivities extending southeast from the storm is what is referred to as a "three body scatter spike". These spikes are commonly indicators of a thunderstorm producing severe hail. We received reports of golfball size hail from these areas in Bayfield County. To the right of the radar image is a graphic explaining briefly how the "three body scatter spike" works.

5:31 PM CDT Radar Image - Bayfield County	Graphic Explaining Three-Body Scatter Spike

Storm Reports

Click the image above for Storm Reports from around the country.

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

0420 PM     TSTM WND DMG     2 N AITKIN              46.56N 93.71W
07/27/2010                   AITKIN             MN   TRAINED SPOTTER

            TREES DOWN NEAR AIKTIN WITH REPORTED WIND GUST OF 50 MPH.


0458 PM     TSTM WND DMG     MAPLE                   46.59N 91.72W
07/27/2010                   DOUGLAS            WI   LAW ENFORCEMENT

            SEVERAL POWER LINES DOWN.
0500 PM     LIGHTNING        9 SW DULUTH             46.69N 92.25W
07/27/2010                   ST. LOUIS          MN   NEWSPAPER

            *** 1 INJ *** A TEENAGE BOY WAS STRUCK BY LIGHTNING WHILE
            JOGGING ON SKYLINE PARKWAY NEAR SPIRIT MOUNTAIN.

0500 PM     HAIL             S PROCTOR               46.74N 92.23W
07/27/2010  M1.50 INCH       ST. LOUIS          MN   TRAINED SPOTTER

0500 PM     TSTM WND DMG     1 N BLUEBERRY           46.59N 91.67W
07/27/2010                   DOUGLAS            WI   TRAINED SPOTTER

            3 LARGE TREES DOWN

0520 PM     HAIL             2 SE IRON RIVER         46.54N 91.38W
07/27/2010  M1.00 INCH       BAYFIELD           WI   TRAINED SPOTTER

0520 PM     TSTM WND DMG     5 SE IRON RIVER         46.51N 91.33W
07/27/2010                   BAYFIELD           WI   TRAINED SPOTTER

            TREES DOWN ON RV TRAPPING CAMPER AT TWIN BEAR CAMPGROUND.

0530 PM     HAIL             8 SE IRON RIVER         46.48N 91.29W
07/27/2010  E1.75 INCH       BAYFIELD           WI   PUBLIC

            HAIL UP TO THE SIZE OF GOLF BALLS AT SCENIC DRIVE RESORT.
            ALSO...IN NEARBY AREAS ALONG HIGHWAY H...SOME TREES BLOWN
            DOWN AND A FEW SNAPPED OFF INCLUDING RED PINES AND OAKS.

0530 PM     HAIL             6 SW INO                46.47N 91.27W
07/27/2010  E1.75 INCH       BAYFIELD           WI   LAW ENFORCEMENT

            HAIL OF QUARTER TO GOLFBALL SIZE DENTED THREE VEHICLES
            AND CRACKED THE WINDSHIELD OF A POLICE CAR AS IT WAS
            DRIVEN BY EXTREMELY STRONG WINDS. TREE DAMAGE ALSO NOTED.

0535 PM     HAIL             3 S INO                 46.49N 91.18W
07/27/2010  E2.75 INCH       BAYFIELD           WI   EMERGENCY MNGR

            A COMBINATION OF SEVERE WIND AND HAIL CAUSING DAMAGE.
            WHEAT AND CORN FIELDS DESTROYED ALONG COUNTY HIGHWAY E.
            ALSO...SHINGLES BLOWN FROM A ROOF AND SIDING DAMAGE TO A
            HOUSE. BARN NEARLY COLLAPSED. REPORTS OF SPIKY GOLFBALL
            TO BASEBALL SIZE HAIL. HIGHWAY DEPT HAD TO SCRAPE ROADWAY
            CLEAR OF SEVERAL INCHES OF WET LEAVES THAT GOT STRIPPED
            FROM TREES BY WIND DRIVEN HAIL.

0545 PM     TSTM WND DMG     BENOIT                  46.50N 91.08W
07/27/2010                   BAYFIELD           WI   EMERGENCY MNGR

            ROOF BLOWN OFF OF A BARN.
0548 PM     HAIL             MASON                   46.44N 91.06W
07/27/2010  E1.00 INCH       BAYFIELD           WI   POST OFFICE

            ALSO A FEW TREES BLOWN DOWN IN THE AREA.

0600 PM     TSTM WND GST     11 WNW DRUMMOND         46.39N 91.47W
07/27/2010  E47.00 MPH       BAYFIELD           WI   MESONET

            41 MPH GUST MEASURED AT BARNES RAWS. THIS WOULD BE
            APPROXIMATELY 47 MPH WHEN ADJUSTED FOR A 10M WIND /RAWS
            MEASUREMENTS TAKEN AT 6M/.

0602 PM     HAIL             4 W MARENGO             46.42N 90.90W
07/27/2010  E1.75 INCH       ASHLAND            WI   PUBLIC

            LEAVES SHREDDED OFF TREES IN THE AREA. RELAYED BY A STORM
            SPOTTER.

0619 PM     HAIL             HIGH BRIDGE             46.39N 90.74W
07/27/2010  M1.75 INCH       ASHLAND            WI   AMATEUR RADIO

0622 PM     HAIL             2 N MELLEN              46.35N 90.66W
07/27/2010  M1.00 INCH       ASHLAND            WI   TRAINED SPOTTER

0624 PM     TORNADO          2 E MORSE               46.22N 90.59W
07/27/2010                   ASHLAND            WI   NWS STORM SURVEY

            DAMAGE ASSESSMENT CONFIRMED A TORNADO OCCURRED AROUND
            MORSE. THIS TORNADO WAS SIGHTED BY A CITIZEN AROUND
            MORSE. SIGNIFICANT TREE DAMAGE WAS NOTED ALONG DRY LAKE
            ROAD TO THE EAST OF MORSE.

0626 PM     HAIL             2 N MELLEN              46.35N 90.66W
07/27/2010  M1.50 INCH       ASHLAND            WI   TRAINED SPOTTER

0628 PM     TSTM WND DMG     1 N GLIDDEN             46.15N 90.58W
07/27/2010                   ASHLAND            WI   LAW ENFORCEMENT

            TREE DOWN

0634 PM     TSTM WND DMG     6 W TREGO               45.90N 91.95W
07/27/2010                   WASHBURN           WI   TRAINED SPOTTER

            SEVERAL TREES DOWN 6 INCHES IN DIAMETER

0650 PM     HAIL             10 NNE HAYWARD          46.14N 91.40W
07/27/2010  M1.75 INCH       SAWYER             WI   TRAINED SPOTTER

0653 PM     TSTM WND DMG     INO                     46.53N 91.18W
07/27/2010                   BAYFIELD           WI   AMATEUR RADIO

            2 FOOT DIAMETER TREE SNAPPED ABOVE GROUND.

0705 PM     HEAVY RAIN       ASKOV                   46.19N 92.78W
07/27/2010  M1.71 INCH       PINE               MN   TRAINED SPOTTER

            FELL IN THE LAST 2 HOURS

0710 PM     TSTM WND GST     MINONG                  46.10N 91.82W
07/27/2010  E49.00 MPH       WASHBURN           WI   MESONET

            43MPH GUST MEASURED AT MINONG RAWS. APPROX 49MPH WHEN
            ADJUSTED FROM 6M RAWS HEIGHT TO 10M STANDARD ANEMOMETER
            HEIGHT.

0711 PM     HEAVY RAIN       1 SW HINCKLEY           46.00N 92.95W
07/27/2010  M2.00 INCH       PINE               MN   TRAINED SPOTTER

            FELL IN THE LAST 50 MINUTES

0712 PM     TORNADO          8 NE BUTTERNUT          46.10N 90.38W
07/27/2010                   ASHLAND            WI   NWS STORM SURVEY

            THIS TORNADO OCCURRED NORTH OF HIGHWAY F ALONG RODDIS
            LINE ROAD. TREE DAMAGE WAS NOTED IN THIS AREA WITH TREES
            ON THE NORTH SIDE OF THE TRACK BLOWN DOWN FACING SOUTH
            AND TREES ON THE SOUTH SIDE OF THE TRACK BLOWN DOWN
            FACING NORTH.

0721 PM     TORNADO          TURTLE FLAMBEAU FLOWAGE 46.08N 90.18W
07/27/2010                   IRON               WI   NWS STORM SURVEY

            *** 6 INJ *** DAMAGE ASSESSMENT CONFIRMS A TORNADO. LSR
            ORIGINALLY SENT AS TSTM WIND DMG. EXTENSIVE DAMAGE TO
            TREES WAS NOTED...INCLUDING LARGE STANDS OF MIXED FOREST
            IN WHICH EVERY TREE WAS EITHER UPROOTED OR SNAPPED.
            FALLING TREES DAMAGED MANY STRUCTURES. 6 INJURIES - 3
            NEEDED ASSISTANCE AND HAD TO BE TRANSPORTED OUT AND 3
            WERE ABLE TO LEAVE THE AREA WITHOUT HELP.

0722 PM     HEAVY RAIN       MINONG                  46.10N 91.82W
07/27/2010  M2.13 INCH       WASHBURN           WI   MESONET

            FELL IN THE LAST HOUR. MINONG RAWS.

0727 PM     TSTM WND DMG     TURTLE FLAMBEAU FLOWAGE 46.08N 90.18W
07/27/2010                   IRON               MN   LAW ENFORCEMENT

            NUMEROUS TREES DOWN. REPORTED BY IRON COUNTY SHERRIF
            OFFICE.

0728 PM     TSTM WND DMG     2 N STONE LAKE          45.87N 91.54W
07/27/2010                   WASHBURN           WI   UTILITY COMPANY

            POWER LINES DOWN ON COUNTY HWY A

0730 PM     TSTM WND DMG     1 N MERCER              46.18N 90.06W
07/27/2010                   IRON               WI   AMATEUR RADIO

            NUMEROUS TREES DOWN

0730 PM     TSTM WND DMG     MERCER                  46.17N 90.06W
07/27/2010                   IRON               WI   AMATEUR RADIO

            NUMEROUS TREES DOWN ALONG MURRAY LANDING RD. POWER LINES
            ALSO DOWN. ROADS BLOCKED IN AREA.

0730 PM     TSTM WND DMG     STONE LAKE              45.85N 91.54W
07/27/2010                   SAWYER             WI   LAW ENFORCEMENT

            LARGE TREE DOWN ON BOUTEN ROAD

0730 PM     TSTM WND DMG     2 NE SPOONER            45.85N 91.86W
07/27/2010                   WASHBURN           WI   LAW ENFORCEMENT

            LARGE TREE LIMB ON CABIN

0747 PM     HEAVY RAIN       UPSON                   46.37N 90.41W
07/27/2010  M2.85 INCH       IRON               WI   TRAINED SPOTTER

            FELL THIS EVENING.

0748 PM     HEAVY RAIN       6 W TREGO               45.90N 91.95W
07/27/2010  M1.50 INCH       WASHBURN           WI   TRAINED SPOTTER

            FELL FROM 710 PM TO 740 PM

0749 PM     NON-TSTM WND GST 1 NW PORT WING          46.78N 91.40W
07/27/2010  E40.00 MPH       BAYFIELD           WI   OTHER FEDERAL

            35 KT WIND GUST MEASURED AT PORT WING MARINE OBSERVATION
            SITE...PNGW3.

0752 PM     TSTM WND DMG     BIRCHWOOD               45.66N 91.55W
07/27/2010                   WASHBURN           WI   LAW ENFORCEMENT

            LARGE PINE TREE FELL ON CABIN AND MADE A HHOLE IN THE
            ROOF.

0756 PM     HEAVY RAIN       HAYWARD                 46.01N 91.48W
07/27/2010  M2.60 INCH       SAWYER             WI   ASOS

            FELL FROM 656 PM TO 756 PM

0800 PM     TSTM WND DMG     PARK FALLS              45.93N 90.45W
07/27/2010                   PRICE              WI   LAW ENFORCEMENT

            TIME APPROXIMATE. SEVERAL TREES DOWN. REPORTED BY PRICE
            COUNTY DISPATCH

0806 PM     TSTM WND DMG     2 NNW RADISSON          45.80N 91.23W
07/27/2010                   SAWYER             WI   TRAINED SPOTTER

            LARGE TREE DOWN BLOCKING HIGHWAY 70 AND 27. BLINDING
            RAIN.

0823 PM     HEAVY RAIN       HAYWARD                 46.01N 91.48W
07/27/2010  M2.68 INCH       SAWYER             WI   MESONET

            2.00 INCHES FELL IN THE LAST HOUR.

0904 PM     HEAVY RAIN       GILE                    46.43N 90.23W
07/27/2010  M3.10 INCH       IRON               WI   TRAINED SPOTTER

            WITH THUNDERSTORMS

1000 PM     HEAVY RAIN       UPSON                   46.37N 90.41W
07/27/2010  M3.15 INCH       IRON               WI   CO-OP OBSERVER

            STORM TOTAL RAINFALL.

1000 PM     HEAVY RAIN       4 S BRUNO               46.22N 92.67W
07/27/2010  M2.60 INCH       PINE               MN   CO-OP OBSERVER

            STORM TOTAL RAINFALL.

1000 PM     HEAVY RAIN       11 WNW DRUMMOND         46.39N 91.47W
07/27/2010  M2.10 INCH       BAYFIELD           WI   MESONET

            1.36 INCHES BETWEEN 7PM AND 8PM AT BARNES RAWS.

1000 PM     HEAVY RAIN       BRUNO                   46.28N 92.67W
07/27/2010  M2.21 INCH       PINE               MN   CO-OP OBSERVER

            STORM TOTAL RAINFALL.

1100 PM     HEAVY RAIN       MINONG                  46.10N 91.82W
07/27/2010  M2.57 INCH       WASHBURN           WI   MESONET

            MEASURED AT THE MINONG RAWS. 2.13 INCHES BETWEEN 7PM AND
            8PM.

Environment

Event Regional Radar Loop	Event Regional Visible Satellite Loop

Here are some graphics from the SPC Mesoanalysis page, which is based on a RUC computer model analysis of the atmosphere at the indicated times. SBCAPE is surface based CAPE, a measure of instability in the atmosphere. Eff. Shear is effective wind shear which measures the amount of deep layer wind shear that a thunderstorm may experience. 30 to 40 knots or more is typically favorable for supercell thunderstorms - powerful rotating storms. Eff. SRH stands for effective storm relative helicity in which higher values tend to favor thunderstorms with rotating updrafts. STP stands for Significant Tornado Parameter which combines a number of different variables in the atmosphere to gauge the potential for strong tornadoes (EF2 or stronger); values of 1 or more are considered "favorable".

1PM CDT SBCAPE	1PM CDT Eff. Shear	1PM CDT Eff. SRH	1PM CDT STP
4PM CDT SBCAPE	4PM CDT Eff. Shear	4PM CDT Eff. SRH	4PM CDT STP
7PM CDT SBCAPE	7PM CDT Eff. Shear	7PM CDT Eff. SRH	7PM CDT STP
10PM CDT SBCAPE	10PM CDT Eff. Shear	10PM CDT Eff. SRH	10PM CDT STP