A severe squall line moved south through eastern WI in conjunction with the passage of a trough of low pressure. Damaging straight line winds and large hail occurred.
Every event with a place to put it. Tap one for its entry below.
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 MKX wrote it up.
A severe squall line moved south through eastern WI in conjunction with the passage of a trough of low pressure. Damaging straight line winds and large hail occurred.
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 Milwaukee, WI wrote its last area forecast discussion before the first event at Aug 14, 1:13 PM CST, 3 hours 42 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI 213 PM CDT FRI AUG 14 2015 .SHORT TERM... .TONIGHT AND SATURDAY...FORECAST CONFIDENCE...MEDIUM STILL LOOKS LIKE THERE WILL BE A CHANCE FOR STORMS THIS AFTERNOON AS A WEAK WAVES MOVES THROUGH...THOUGH STRUGGLING TO GET MUCH IN THE WAY OF CUMULUS RIGHT NOW. HRRR HAS THE BEST HANDLE ON CONVECTION TO THE NORTH AND EAST OF THE FORECAST AREA THOUGH...AND STILL SHOWS CONVECTION DEVELOPING ACROSS THE FORECAST AREA MID TO LATE AFTERNOON. HAVE THUS MAINTAINED POPS FOR NOW. THOUGH A FEW STORMS COULD HANG ON INTO LATE EVENING...ANY STORMS THAT DO DEVELOP WILL LIKELY DIMINISH DURING THE EVENING AS DAYTIME HEATING IS LOST. SHOULD SEE MOSTLY CLEAR SKIES THEN LATER IN THE NIGHT. WITH LIGHT WINDS IN PLACE...MAY SEE SOME FOG DEVELOP...ESPECIALLY IN LOW LYING AREAS. UPPER RIDGING WILL CONTINUE TO BUILD INTO THE AREA SATURDAY. TEMPS ALOFT LOOK FAIRLY SIMILAR TO TODAY...SO WENT WITH SIMILAR HIGH TEMPS. ONLY BIG DIFFERENCE IS NEAR THE LAKE...WHERE WINDS WILL TURN ONSHORE BY AFTERNOON...KEEPING IT FROM GETTING AS HOT AS INLAND. MAY SEE A FEW STORMS FIRE WITHIN AREA OF LOW LEVEL CONVERGENCE IN THE AFTERNOON. MODELS ARE HIGHLIGHTING A CORRIDOR FROM THE SE TO NW FORECAST AS HAVING THE BEST CHANCE. OTHERWISE...NOT SEEING A TRIGGER FOR CONVECTIVE DEVELOPMENT UNDER THE RIDGE. .SATURDAY NIGHT AND SUNDAY...FORECAST CONFIDENCE...HIGH THE UPPER RIDGE EXTENDS FROM THE SOUTHWEST U.S. ACROSS SOUTHERN WISCONSIN. THE 700 MB WINDS INCREASE ACROSS THE UPPER GREAT LAKES AND SOUTHERN CANADA...BUT REMAIN WEAK OVER SOUTHERN WISCONSIN. THE 850 MB WINDS INCREASE A LITTLE MORE...BUT THE STRONGEST WINDS ARE TO THE NORTH. THE 850 MB TEMPERATURES REMAIN NEAR 20 CELSIUS AS THE 500 MB TEMPERATURES INCREASE. DESPITE STEEP LOW LEVEL LAPSE RATES...THE MID LEVEL LAPSE RATES ARE NEAR 6 CELSIUS/KM...WITH ONLY A SHALLOW LAYER OF MOISTURE NEAR 700 MB. THEREFORE SUNDAY SHOULD NOT HAVE ANY THUNDERSTORM DEVELOPMENT. 925 TEMPERATURES RISE TO AROUND 28 CELSIUS...SO ANOTHER HOT DAY IS EXPECTED. MOST PLACES SHOULD GET TO AT LEAST 90. APPEARS STEEP LAPSE RATES WILL MIX OUT DEW POINTS AGAIN DURING THE AFTERNOON THEREFORE HEAT INDEX VALUES SHOULD REMAIN BELOW ADVISORY CRITERIA. .SUNDAY NIGHT AND MONDAY...FORECAST CONFIDENCE...HIGH THE UPPER RIDGE SAGS SOUTH WITH AN UPPER LEVEL ZONAL FLOW ACROSS THE U.S. CANADIAN BORDER AREA DROPPING TOWARDS SOUTHERN WISCONSIN. AN 115 KNOT 250 MB UPPER JET WILL LIFT NORTH OF THE UPPER GREAT LAKES LATER MONDAY. THIS INCREASES THE UPPER DIVERGENCE ACROSS SOUTHERN WISCONSIN IN THE RIGHT ENTRANCE REGION OF THE JET. THE 850 MB THERMAL RIDGE MOVES ACROSS SOUTHERN WISCONSIN BUT COOLS A LITTLE AS IT DOES. 850 MB DEW POINTS INCREASE TO 10 TO 13 CELSIUS. THE 850 MB WINDS ARE RATHER WEAK AROUND 20 KNOTS. A WEAK COLD FRONT MOVES TOWARDS SOUTHERN WISCONSIN DURING THIS PERIOD BUT THE FRONTAL PASSAGE IS SLOWER AND DOES NOT MOVE ACROSS SOUTHERN WISCONSIN YET ON THE GFS. ZERO TO 1 KM CAPE IS WEAKER AT ONLY AROUND 500 TO 1000 JOULES/KG WITH MID LEVEL LAPSE RATES AROUND 5.7 CELSIUS/KM. THE GFS HAS SOME PRECIPITATION MONDAY...BUT IT IS FAIRLY LIGHT. .LONG TERM... .MONDAY NIGHT AND TUESDAY...FORECAST CONFIDENCE...MEDIUM THE UPPER LEVEL ZONAL FLOW BECOMES MORE WEST SOUTHWEST AS A SHORTWAVE MOVES ACROSS THE NORTHERN ROCKIES. THE GFS STALLS THE FRONT ACROSS SOUTHERN WISCONSIN AS HIGH PRESSURE MOVES ACROSS LAKE SUPERIOR AND SOUTHERN CANADA. THE 00Z ECMWF STALLS THE FRONT ACROSS NORTHERN OR CENTRAL ILLINOIS. AS A RESULT THE GFS BRINGS A MODERATE AMOUNT OF PRECIPITATION TUESDAY...WHILE THE 00Z ECMWF IS MAINLY DRY. .TUESDAY NIGHT AND WEDNESDAY...FORECAST CONFIDENCE...MEDIUM THE GFS AND ECMWF MOVES THE TROUGH ACROSS THE UPPER AND MID MISSISSIPPI VALLEY LATER WEDNESDAY AND WEDNESDAY NIGHT. PRECIPITATION CONTINUES TUESDAY NIGHT AND WEDNESDAY AS THE GFS TAKES A STRONG LOW INTO NORTHERN WISCONSIN. PREFER THE WEAKER AND SLOWER LOW ON THE ECMWF WHICH BRINGS MOST OF THE PRECIPITATION WEDNESDAY. .THURSDAY AND FRIDAY...FORECAST CONFIDENCE...MEDIUM A ZONAL FLOW AGAIN DEVELOPS IN THE MID/UPPER LEVELS ACROSS THE NORTHERN U.S. WITH THE ECMWF SHOWING MORE OF A TROUGH NEAR THE NORTHWEST U.S. FRIDAY. BOTH THE GFS AND ECMWF ARE DRY THURSDAY...WITH THE 12Z GFS BRINGING A QUICKER SOUTH FLOW AND WARM AIR ADVECTION. BOTH THE 12Z GFS AND 00Z ECMWF KEEP A LOW OVER THE HIGH PLAINS FRIDAY WITH SOME PRECIPITATION MAINLY JUST NORTHWEST OF THE FORECAST AREA. && .AVIATION/00Z TAFS/... STILL THINK A FEW STORMS MAY DEVELOP THIS AFTERNOON AS A WEAK WAVE MOVES THROUGH. ANY STORMS THAT TO FORM WILL PROBABLY DIMINISH IN THE EVENING AS DAYTIME HEATING IS LOST. COULD SEE SOME FOG IN A FEW SPOTS TONIGHT...ESPECIALLY IN LOW LYING AREAS. OTHERWISE...VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH SATURDAY. A COUPLE MODELS ARE FIRING OFF A FEW STORMS SATURDAY AFTERNOON WITHIN A ZONE OF LOW LEVEL CONVERGENCE. MODELS ARE HIGHLIGHTING A CORRIDOR FROM THE SE TO NW FORECAST AS HAVING THE BEST CHANCE. OTHERWISE...LOOKS MAINLY DRY AS STRONG UPPER RIDGING LEANS EASTWARD INTO THE AREA. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...NONE. && TONIGHT/SATURDAY AND AVIATION/MARINE...DDV SATURDAY NIGHT THROUGH FRIDAY...HENTZ
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI 320 PM CDT FRI AUG 14 2015 WIZ046-047-051-052-056>060-062>072-152030- MARQUETTE-GREEN LAKE-FOND DU LAC-SHEBOYGAN-SAUK-COLUMBIA-DODGE- WASHINGTON-OZAUKEE-IOWA-DANE-JEFFERSON-WAUKESHA-MILWAUKEE- LAFAYETTE-GREEN-ROCK-WALWORTH-RACINE-KENOSHA- 320 PM CDT FRI AUG 14 2015 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EAST CENTRAL WISCONSIN...SOUTH CENTRAL WISCONSIN AND SOUTHEAST WISCONSIN. .DAY ONE...TONIGHT HEAT INDEX VALUES WILL APPROACH 95 THROUGH LATE AFTERNOON. ISOLATED THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON AND EVENING WITH PASSAGE OF A WEAK TROUGH. THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS WITH STRONG WINDS AND HAIL MAINLY NORTH OF A SPRING GREEN TO BELOIT LINE. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH FRIDAY HEAT INDEX VALUES WILL BE AROUND 95 SATURDAY AFTERNOON AND EARLY EVENING...WITH SOME COOLING POSSIBLE ALONG THE LAKE MICHIGAN SHORE. HEAT INDEX VALUES WILL APPROACH 95 AGAIN SUNDAY AFTERNOON AND EARLY EVENING. CHANCES FOR THUNDERSTORMS RETURN LATE SUNDAY NIGHT THROUGH MONDAY NIGHT AS A COLD FRONT MOVES THROUGH THE REGION. LOW PRESSURE MOVING TOWARD WISCONSIN WEDNESDAY WILL BRING CHANCES FOR THUNDERSTORMS TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...WITH THE CHANCE FOR STORMS LINGERING THROUGH THURSDAY. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT ANTICIPATED AT THIS TIME. LMZ643>646-152030- SHEBOYGAN TO PORT WASHINGTON WI- PORT WASHINGTON TO NORTH POINT LIGHT WI- NORTH POINT LIGHT TO WIND POINT WI- WIND POINT WI TO WINTHROP HARBOR IL- 320 PM CDT FRI AUG 14 2015 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF LAKE MICHIGAN. .DAY ONE...TONIGHT THERE IS A CHANCE OF THUNDERSTORMS...INTO THE EVENING...WITH PASSAGE OF A WEAK TROUGH. THE STORMS COULD PRODUCE STRONG WINDS AND HAIL. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH FRIDAY CHANCES FOR THUNDERSTORMS RETURN MONDAY AND MONDAY NIGHT WITH A COLD FRONT. LOW PRESSURE MOVING TOWARD WISCONSIN WEDNESDAY WILL BRING CHANCES FOR THUNDERSTORMS TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...WITH THE CHANCE FOR STORMS LINGERING THROUGH THURSDAY. HENTZ WWW.WEATHER.GOV/MKX
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
500 PM CDT FRI AUG 14 2015
WIZ051-052-142245-
SHEBOYGAN-FOND DU LAC-
500 PM CDT FRI AUG 14 2015
...AN AREA OF STRONG THUNDERSTORMS WILL AFFECT NORTHERN SHEBOYGAN AND
NORTHEASTERN FOND DU LAC COUNTIES...
AT 459 PM CDT...AN AREA OF STRONG THUNDERSTORMS WAS NEAR
APPLETON...MOVING SOUTH AT 40 MPH.
WINDS IN EXCESS OF 40 MPH AND DIME SIZE HAIL ARE POSSIBLE WITH THIS
STORM.
THIS STORM WILL BE NEAR...
NORTH FOND DU LAC AROUND 535 PM CDT.
FOND DU LAC AROUND 540 PM CDT.
OTHER LOCATIONS IMPACTED BY THIS STORM INCLUDE JOHNSONVILLE...
JOHNSBURG...PIPE...LAMARTINE...MOUNT CALVARY...ST. CLOUD...
GREENBUSH...GLENBEULAH...MARYTOWN AND PEEBLES.
BOATERS ON LAKE WINNEBAGO SHOULD SEEK SAFE HARBOR.
FREQUENT CLOUD TO GROUND LIGHTNING IS OCCURRING WITH THIS STORM.
LIGHTNING CAN STRIKE 15 MILES AWAY FROM A THUNDERSTORM. SEEK A SAFE
SHELTER INSIDE A BUILDING OR VEHICLE.
LAT...LON 4372 8866 4389 8859 4389 8841 4394 8840
4394 8817 4389 8816 4389 8774 4381 8773
4376 8770
TIME...MOT...LOC 2159Z 005DEG 38KT 4420 8831
HENTZSPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
504 PM CDT FRI AUG 14 2015
WIZ052-142245-
SHEBOYGAN-
504 PM CDT FRI AUG 14 2015
...AN AREA OF STRONG THUNDERSTORMS WILL AFFECT NORTHERN SHEBOYGAN
COUNTY...
AT 502 PM CDT...AN AREA OF STRONG THUNDERSTORMS WAS 16 MILES
NORTHWEST OF MANITOWOC...MOVING SOUTH AT 40 MPH.
WINDS IN EXCESS OF 40 MPH AND DIME SIZE HAIL ARE POSSIBLE WITH THIS
STORM.
THIS STORM WILL BE NEAR...
ELKHART LAKE AROUND 540 PM CDT.
SHEBOYGAN...PLYMOUTH...SHEBOYGAN FALLS...HOWARDS GROVE AND KOHLER
AROUND 545 PM CDT.
OTHER LOCATIONS IMPACTED BY THIS STORM INCLUDE JOHNSONVILLE...HAVEN
AND GLENBEULAH.
FREQUENT CLOUD TO GROUND LIGHTNING IS OCCURRING WITH THIS STORM.
LIGHTNING CAN STRIKE 15 MILES AWAY FROM A THUNDERSTORM. SEEK A SAFE
SHELTER INSIDE A BUILDING OR VEHICLE.
LAT...LON 4374 8771 4372 8771 4368 8804 4369 8804
4389 8807 4389 8774 4386 8773 4381 8773
4376 8770
TIME...MOT...LOC 2202Z 348DEG 30KT 4417 8796
HENTZSPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
543 PM CDT FRI AUG 14 2015
WIZ059-060-066-142315-
MILWAUKEE-OZAUKEE-WASHINGTON-
543 PM CDT FRI AUG 14 2015
...A STRONG THUNDERSTORM WILL AFFECT EAST CENTRAL WASHINGTON AND
OZAUKEE COUNTIES...
AT 542 PM CDT...A STRONG THUNDERSTORM WAS OVER NEWBURG...OR NEAR
SAUKVILLE...MOVING SOUTHEAST AT 35 MPH.
WINDS IN EXCESS OF 30 MPH AND HALF INCH HAIL ARE POSSIBLE WITH THIS
STORM.
LOCATIONS IMPACTED INCLUDE...
WEST BEND...MEQUON...GRAFTON...CEDARBURG...PORT WASHINGTON...FOX
POINT...SAUKVILLE...BAYSIDE...THIENSVILLE...FREDONIA...NEWBURG AND
WAUBEKA.
THIS STORM MAY INTENSIFY...SO BE CERTAIN TO MONITOR LOCAL RADIO AND
TV STATIONS...AS WELL AS LOCAL CABLE TV OUTLETS...FOR ADDITIONAL
INFORMATION AND POSSIBLE WARNINGS FROM THE NATIONAL WEATHER SERVICE.
LAT...LON 4338 8787 4330 8789 4326 8791 4324 8791
4321 8790 4320 8790 4318 8788 4316 8789
4343 8816 4354 8796 4343 8783
TIME...MOT...LOC 2242Z 323DEG 29KT 4343 8800
HENTZThe Green Bay radar (KGRB), 72 km away, was scanning. The volume nearest the first event began at 22:56 UTC.
5 hail, 3 thunderstorm wind. Local standard time, as filed.
Numerous trees down and some powerlines down.
A flag pole fell on an individual, who suffered a broken arm, at the Whistling Straits golf course during the PGA Championship. The leaderboard was also blown over.
Numerous 8 inch to 2 foot diameter branches down. A branch landed on a garage.
Large hail with 30 to 35 mph wind gusts.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wisconsin in 2015Every state in 2015This day in weather historyWarnings in Wisconsin, August 2015
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: 599211, 599273, 599196, 599274, 599271, 599197, 599200, 599202.