Tuesday Sep 4, 2012 Afternoon/Night Storms & Rainfall (updated 9/7)

Updated to include a cloud picture from Mineral Point in Iowa County

A weakening low pressure trough pushing through the region triggered numerous thunderstorms over western Wisconsin later Tuesday afternoon and evening hours.

One of the storms generated an EF2 tornado in Grant County (preliminary rating, subject to change).

Otherwise, those storms that became severe produced large hail and damaging straight-line winds.  Some of these thunderstorms produced large hail and damaging winds in southwest Wisconsin.

The La Crosse NWS office has a nice storm summary for their area of responsibility (includes radar loops).

The thunderstorms moved across south-central and southeast Wisconsin between 7 pm and 11 pm CDT.  The large hail threat diminished as the thunderstorms coalesced into mostly a single line that "bowed out" as it moved east.

Scattered damaging wind events were the most common type of severe weather over the south-central and southeast parts of Wisconsin, with wind gusts in the 60 to 65 mph range. Large trees were pushed over or uprooted, and downed power-lines left at least 13,000 customers out of power.  The storms and wind gusts weakened as they reached the Lake Michigan shoreline.

As the storms moved southeast through the Mineral Point area of southern Iowa County about 730 pm, the picture below was taken (click on image for larger version).  You are looking at mammatus clouds - which are found in the upper portionsn of a storm on the underside of the anvil top.  They can be scary looking and indicate high-level turbulence - not tornadoes or funnel clouds.  For examples of scary-looking clouds click here.  

159-TrickelMammatus 

Below is a picture taken by Andrew Shoaf of some tree damage in the Okauchee area - typical of what happened in other areas.

 

  OkaucheeDamageAndrewShoaf

A local storm report graphic is available below.  Click on image for larger version.

Sep 4 2012 LSR graphic

To view details about individual reports, go to the end of this story. 


Below are two images.  The single image on the left shows the 9 pm radar display. The one on the right consists of a 6-pack and shows the storms at 7 pm, 8 pm, 9 pm, 10 pm, 11 pm, and midnight Tuesday evening and night, starting in top row and going left to right.   Click on images for larger version.

 

  Sep 4 2012 9 pm radar image  Sep 4 2012 radar 6-pack

 


The thunderstorms also resulted in widespread rainfall across southern Wisconsin.  Many locations received between one quarter and three quarters inch of precipitation Tuesday night from the Thunderstorms as illustrated by the below 24-hour rainfall graphic.  Click on image for larger version.

 

Southern Wisconsin Rainfall

Several locations received between one and one and one quarter inches of rainfall including Benton (1.24"), 2 NE Darlington (1.12"), Stoughton (1.03"), and 1 NW Whitewater (1.10"). 

Thunderstorms also rolled across central Wisconsin during the night.  The below graphic illustrates rainfall across the entire state Tuesday afternoon and night.  Click on imamge for larger version.

Wisconsin Rainfall from Tuesday afternoon and night

A cold front moving across southern Wisconsin is expected to trigger more scattered to numerous showers and thunderstorms this afternoon (9/5/12).  Some of the thunderstorms may produce large hail, damaging winds and brief heavy rainfall.  Drier and cooler conditions will settle into southern Wisconsin tonight.

NWUS53 KMKX 051541
LSRMKX

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
1041 AM CDT WED SEP 05 2012

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

0741 PM     TSTM WND GST     LONE ROCK AIRPORT       43.21N 90.19W
09/04/2012  M55.00 MPH       SAUK               WI   ASOS

0742 PM     TSTM WND DMG     BARABOO                 43.47N 89.74W
09/04/2012                   SAUK               WI   911 CALL CENTER

            LARGE TREE LIMB DOWN IN TOWN. EXACT LOCATION NOT
            AVAILABLE.

0746 PM     TSTM WND DMG     5 SE BARABOO            43.42N 89.67W
09/04/2012                   SAUK               WI   911 CALL CENTER

            MULTIPLE POWERLINES AND LARGE TREES DOWN ACROSS THE AREA.
            TIME ESTIMATED.

0749 PM     TSTM WND DMG     MERRIMAC                43.37N 89.63W
09/04/2012                   SAUK               WI   911 CALL CENTER

            MULTIPLE POWERLINES AND LARGE TREES DOWN ACROSS THE AREA.
            TIME ESTIMATED.

0756 PM     TSTM WND DMG     DODGEVILLE              42.96N 90.13W
09/04/2012                   IOWA               WI   LAW ENFORCEMENT

            TREES AND POWERLINES DOWN ACROSS THE COUNTY...MAINLY IN
            DODGEVILLE...EDMUND...AND LINDEN. TIME ESTIMATED.

0801 PM     TSTM WND GST     1 S WATERTOWN           43.18N 88.72W
09/04/2012  M52.00 MPH       JEFFERSON          WI   AWOS

0801 PM     TSTM WND GST     1 N JUNEAU              43.42N 88.70W
09/04/2012  M51.00 MPH       DODGE              WI   AWOS

            JUNEAU AIRPORT REPORTED A 51 MPH THUNDERSTORM WIND GUST
            AT 755 PM CDT.

0810 PM     TSTM WND DMG     PORTAGE                 43.55N 89.47W
09/04/2012                   COLUMBIA           WI   911 CALL CENTER

            TREES AND POWERLINES DOWN ACROSS THE ENTIRE COUNTY. TIME
            ESTIMATED.

0811 PM     TSTM WND GST     MINERAL POINT AIRPORT   42.89N 90.23W
09/04/2012  M59.00 MPH       IOWA               WI   AWOS

0812 PM     TSTM WND GST     1 NE CAMP RANDALL STADI 43.08N 89.40W
09/04/2012  E60.00 MPH       DANE               WI   TRAINED SPOTTER

0814 PM     TSTM WND GST     MADISON TRUAX AIRPORT   43.14N 89.33W
09/04/2012  M58.00 MPH       DANE               WI   ASOS

0821 PM     TSTM WND DMG     7 NE DARLINGTON         42.75N 90.02W
09/04/2012                   LAFAYETTE          WI   LAW ENFORCEMENT

            TREE DOWN IN FAYETTE TOWNSHIP. TIME ESTIMATED.

0824 PM     TSTM WND DMG     2 SSW STOUGHTON         42.89N 89.24W
09/04/2012                   DANE               WI   AMATEUR RADIO

            ESTIMATED 2 FOOT TREE LIMB DOWN. BLOCKING SOUTH BOUND
            LANE OF CTY HWY A. TIME ESTIMATED.

0824 PM     TSTM WND DMG     NEW GLARUS              42.81N 89.63W
09/04/2012                   GREEN              WI   LAW ENFORCEMENT

            NINE TREES DOWN ACROSS THE COUNTY...MAINLY IN NORTH. TIME
            ESTIMATED.

0831 PM     TSTM WND DMG     JEFFERSON               43.01N 88.81W
09/04/2012                   JEFFERSON          WI   911 CALL CENTER

            TREES DOWN ACROSS THE COUNTY...PARTICULARLY IN LAKE
            MILLS. TIME ESTIMATED.

0835 PM     TSTM WND GST     LOWELL                  43.34N 88.82W
09/04/2012  E65.00 MPH       DODGE              WI   AMATEUR RADIO

            LOSS OF POWER.

0835 PM     TSTM WND DMG     EDGERTON                42.84N 89.07W
09/04/2012                   ROCK               WI   TRAINED SPOTTER

            LARGE TREE BLOCKING WASHINGTON STREET IN EDGERTON. TIME
            IS ESTIMATED.

0839 PM     TSTM WND GST     1 NE STOUGHTON          42.93N 89.21W
09/04/2012  E60.00 MPH       DANE               WI   TRAINED SPOTTER

0848 PM     TSTM WND DMG     JANESVILLE              42.68N 89.02W
09/04/2012                   ROCK               WI   911 CALL CENTER

            TREES DOWN ACROSS THE COUNTY...MAINLY IN THE NORTHERN
            HALF. TIME ESTIMATED.

0853 PM     TSTM WND GST     1 E FORT ATKINSON       42.93N 88.82W
09/04/2012  E60.00 MPH       JEFFERSON          WI   TRAINED SPOTTER

0855 PM     HAIL             2 NNE WATERTOWN         43.22N 88.71W
09/04/2012  E0.25 INCH       DODGE              WI   AMATEUR RADIO

0905 PM     TSTM WND DMG     EAGLE                   42.88N 88.47W
09/04/2012                   WAUKESHA           WI   911 CALL CENTER

            TREES DOWN IN SOUTHWEST WAUKESHA COUNTY. NEAR EAGLE AND
            OTTAWA. TIME ESTIMATED.

0910 PM     TSTM WND DMG     NEW DIGGINGS            42.54N 90.34W
09/04/2012                   LAFAYETTE          WI   LAW ENFORCEMENT

            TREE DOWN IN NEW DIGGINGS TOWNSHIP. TIME ESTIMATED.

0914 PM     TSTM WND DMG     ELKHORN                 42.67N 88.54W
09/04/2012                   WALWORTH           WI   LAW ENFORCEMENT

            TREES DOWN ACROSS THE COUNTY...MAINLY IN THE WESTERN
            HALF. TIME ESTIMATED.

0925 PM     TSTM WND GST     EAST TROY               42.79N 88.40W
09/04/2012  M36.00 MPH       WALWORTH           WI   TRAINED SPOTTER

0929 PM     TSTM WND DMG     WATERFORD               42.76N 88.22W
09/04/2012                   RACINE             WI   911 CALL CENTER

            TREES AND POWERLINES DOWN IN WATERFORD...TICHIGAN...AND
            BURLINGTON. TIME ESTIMATED.

0935 PM     TSTM WND GST     MUKWONAGO               42.87N 88.33W
09/04/2012  E45.00 MPH       WAUKESHA           WI   TRAINED SPOTTER

            ESTIMATED 40 TO 45 MPH GUSTS BETWEEN 930 AND 935 PM.

0935 PM     TSTM WND GST     WAUKESHA AIRPORT        43.04N 88.23W
09/04/2012  M41.00 MPH       WAUKESHA           WI   AWOS

0935 PM     TSTM WND GST     BURLINGTON AIRPORT      42.69N 88.30W
09/04/2012  M46.00 MPH       WALWORTH           WI   AWOS

0939 PM     TSTM WND DMG     4 WNW PADDOCK LAKE      42.59N 88.18W
09/04/2012                   KENOSHA            WI   911 CALL CENTER

            TREE DOWN IN WHEATLAND. TIME ESTIMATED.

0942 PM     TSTM WND DMG     2 E WAUBEKA             43.47N 87.95W
09/04/2012                   OZAUKEE            WI   LAW ENFORCEMENT

            TREE AND SEVERAL BRANCHES DOWN IN FREDONIA. TIME
            ESTIMATED.

0943 PM     TSTM WND GST     1 S WAUKESHA            43.00N 88.24W
09/04/2012  E40.00 MPH       WAUKESHA           WI   TRAINED SPOTTER

            ESTIMATED 35 TO 40 MPH WIND GUSTS AND ABOUT 1 BLOCK
            VISIBILITY.

0948 PM     TSTM WND DMG     6 WNW KENOSHA AIRPORT   42.63N 88.04W
09/04/2012                   KENOSHA            WI   911 CALL CENTER

            TREE DOWN IN PARIS AT 156TH BLOCK OF HWY N. TIME
            ESTIMATED.

0952 PM     TSTM WND DMG     BRISTOL                 42.56N 88.05W
09/04/2012                   KENOSHA            WI   LAW ENFORCEMENT

            LARGE TREE DOWN ON 209 AND HIGHWAY V. TIME ESTIMATED.

1001 PM     TSTM WND GST     MILWAUKEE               43.03N 87.92W
09/04/2012  E45.00 MPH       MILWAUKEE          WI   TRAINED SPOTTER

            ESTIMATED 45 MPH GUST AT UW MILWAUKEE CAMPUS.

1002 PM     TSTM WND GST     KENOSHA AIRPORT         42.60N 87.93W
09/04/2012  M44.00 MPH       KENOSHA            WI   ASOS

1020 PM     MARINE TSTM WIND 1 NE KENOSHA            42.59N 87.81W
09/04/2012  M45.00 MPH       LMZ646             WI   C-MAN STATION

            45 MPH GUST...39 KNOTS...AT THE KENOSHA C-MAN STATION.

0255 AM     HAIL             BELMONT                 42.74N 90.33W
09/05/2012  E0.75 INCH       LAFAYETTE          WI   TRAINED SPOTTER

            TRAINED SPOTTER REPORTED DIME TO PENNY SIZED HAIL.

 


Kavinsky/AFK
NWS - Milwaukee/Sullivan

 



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