Alert archive / Wisconsin / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 30, NWS Milwaukee, WI

August 7, 2021Jefferson County, Wisconsin

NWS Milwaukee, WI issued this severe thunderstorm warning at Aug 7, 2021, 12:32 PM CDT for Jefferson County, Wisconsin. It was in force for 43 min. 2 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
Aug 7, 2021, 12:32 PM CDT (17:32 UTC)
Expired
Aug 7, 2021, 1:15 PM CDT
In force
43 min
Issued by
NWS Milwaukee, WI
Area
Storm-based polygon
Hail
0.75 in
Wind
60.0 mph

County Jefferson County, WI

The radar

The Milwaukee radar (KMKX), 21 km from the middle of the area, began a volume at 17:35 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

What was reported inside it

TimeReportWhereRemark
Aug 7, 12:35 PM CDTTSTM WND DMG1 S Watertown, WITREE DOWN ALONG BOOMER ST.
Aug 7, 12:35 PM CDTTSTM WND GST 601 S Watertown, WIMEASURED AT WATERTOWN AIRPORT.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Green Bay/Straub, WI (KGRB), launched 12:00Z, 5.5 hours before the alert went out and 159 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Green Bay/Straub, WI at 12:00Z on 2021-08-07Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 20 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Green Bay/Straub, WI at 12:00Z on 2021-08-07The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 72 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
20 J/kg
Mixed-layer CIN
-32 J/kg
Mixed-layer LCL
656 m above ground
0-6 km bulk shear
17 kt
0-1 km storm-relative helicity
72 m²/s²
0-3 km storm-relative helicity
103 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

043 
WUUS53 KMKX 071732
SVRMKX
WIC055-071815-
/O.NEW.KMKX.SV.W.0030.210807T1732Z-210807T1815Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Milwaukee/Sullivan WI
1232 PM CDT Sat Aug 7 2021

The National Weather Service in Milwaukee/Sullivan has issued a

* Severe Thunderstorm Warning for...
  Northeastern Jefferson County in southeastern Wisconsin...

* Until 115 PM CDT.

* At 1232 PM CDT, a severe thunderstorm was located near Watertown,
  moving southeast at 25 mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

  IMPACT...Expect damage to roofs, siding, and trees.

* Locations impacted include...
  Watertown, Johnson Creek, Lac La Belle, Ixonia, Rome, Milford,
  Sullivan, Pipersville, Helenville, Nws Milwaukee/sullivan and Lake
  Lac La Belle.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4311 8888 4320 8880 4320 8858 4318 8853
      4291 8854
TIME...MOT...LOC 1732Z 303DEG 21KT 4315 8873 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

HANSEN
2 follow-up statements
641 
WWUS53 KMKX 071739
SVSMKX

Severe Weather Statement
National Weather Service Milwaukee/Sullivan WI
1239 PM CDT Sat Aug 7 2021

WIC055-071815-
/O.CON.KMKX.SV.W.0030.000000T0000Z-210807T1815Z/
Jefferson WI-
1239 PM CDT Sat Aug 7 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 115 PM CDT
FOR NORTHEASTERN JEFFERSON COUNTY...

At 1238 PM CDT, a severe thunderstorm was located near Watertown,
moving southeast at 25 mph.

HAZARD...60 mph wind gusts.

SOURCE...Trained weather spotter reports 60 mph winds in Watertown.

IMPACT...Expect damage to roofs, siding, and trees.

Locations impacted include...
Watertown, Johnson Creek, Lac La Belle, Ixonia, Rome, Milford,
Sullivan, Pipersville, Helenville, Nws Milwaukee/sullivan and Lake
Lac La Belle.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4311 8888 4320 8880 4320 8858 4318 8853
      4291 8854
TIME...MOT...LOC 1738Z 303DEG 21KT 4313 8869 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

HANSEN
833 
WWUS53 KMKX 071802
SVSMKX

Severe Weather Statement
National Weather Service Milwaukee/Sullivan WI
102 PM CDT Sat Aug 7 2021

WIC055-071815-
/O.CON.KMKX.SV.W.0030.000000T0000Z-210807T1815Z/
Jefferson WI-
102 PM CDT Sat Aug 7 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 115 PM CDT
FOR NORTHEASTERN JEFFERSON COUNTY...

At 101 PM CDT, a severe thunderstorm was located near Oconomowoc, or
near Okauchee Lake, moving southeast at 25 mph.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

IMPACT...Expect damage to roofs, siding, and trees.

Locations impacted include...
Lac La Belle, Ixonia, Rome, Sullivan, Helenville, Nws
Milwaukee/sullivan and Lake Lac La Belle.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4301 8871 4320 8857 4318 8853 4291 8854
TIME...MOT...LOC 1801Z 303DEG 21KT 4305 8853 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

HANSEN

The office that day

Everything else NWS Milwaukee, WI issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 6, 7:34 PM CDTAreal Flood AdvisoryMKXMilwaukee, Waukesha119 min
Aug 6, 7:38 PM CDTSevere Thunderstorm WarningMKXJefferson37 min
Aug 6, 7:55 PM CDTSpecial Marine WarningMKX50 min
Aug 6, 7:57 PM CDTSpecial Weather StatementMKXKenosha, Racine, Walworth63 min
Aug 6, 8:00 PM CDTAreal Flood AdvisoryMKXJefferson, Rock, Walworth2 hr
Aug 6, 8:14 PM CDTSevere Thunderstorm WarningMKXRock, Walworth31 min
Aug 6, 8:51 PM CDTSpecial Weather StatementMKXRock, Walworth54 min
Aug 6, 9:45 PM CDTSevere Thunderstorm WarningMKXDane30 min
Aug 6, 10:15 PM CDTSpecial Weather StatementMKXDane30 min
Aug 7, 10:06 AM CDTSpecial Weather StatementMKXColumbia, Marquette54 min
Aug 7, 11:01 AM CDTSpecial Weather StatementMKXColumbia, Green Lake59 min
Aug 7, 11:47 AM CDTSpecial Weather StatementMKXDodge, Jefferson58 min
Aug 7, 12:54 PM CDTSevere Thunderstorm WarningMKXJefferson, Waukesha45 min
Aug 7, 1:48 PM CDTSevere Thunderstorm WarningMKXSauk42 min
Aug 7, 3:53 PM CDTSevere Thunderstorm Warning Considerable damage threatMKXSauk52 min
Aug 7, 4:33 PM CDTSevere Thunderstorm Warning Considerable damage threatMKXColumbia, Dane, Iowa, Sauk57 min
Aug 7, 4:38 PM CDTTornado Warning Tornado observedMKXIowa67 min
Aug 7, 5:17 PM CDTSevere Thunderstorm WarningMKXColumbia, Green Lake, Marquette, Sauk58 min
Aug 7, 5:26 PM CDTTornado WarningMKXColumbia39 min
Aug 7, 5:31 PM CDTSevere Thunderstorm WarningMKXColumbia, Dane59 min
Aug 7, 5:33 PM CDTTornado WarningMKXIowa57 min
Aug 7, 6:03 PM CDTSpecial Weather StatementMKXDodge, Fond du Lac, Green Lake42 min
Aug 7, 6:09 PM CDTSevere Thunderstorm WarningMKXDane66 min
Aug 7, 6:25 PM CDTSevere Thunderstorm WarningMKXDane50 min
Aug 7, 6:40 PM CDTSpecial Weather StatementMKXJefferson50 min

Nearby

Severe Thunderstorm Warnings in Wisconsin, 2021Every severe thunderstorm warning in 2021

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.