Alert archive / Wisconsin / Severe Thunderstorm Watches in 2011

Severe Thunderstorm Watch 656

July 18, 2011Allamakee County, Clayton County, Iowa; Houston County, Winona County, Minnesota; 38 counties in Wisconsin

The Storm Prediction Center issued this severe thunderstorm watch at Jul 18, 2011, 8:05 AM CDT for Allamakee County, Clayton County, Iowa; Houston County, Winona County, Minnesota; 38 counties in Wisconsin. It was in force for 4 hr.

The area

The outline as issued.

The facts

Issued
Jul 18, 2011, 8:05 AM CDT (13:05 UTC)
Expired
Jul 18, 2011, 11:48 AM CDT
In force
4 hr
Issued by
the Storm Prediction Center
Largest hail expected
2 in
Strongest gust expected
60 kt
All 42 counties

Allamakee County, IA, Clayton County, IA, Houston County, MN, Winona County, MN, Adams County, WI, Brown County, WI, Buffalo County, WI, Calumet County, WI, Clark County, WI, Columbia County, WI, Crawford County, WI, Dane County, WI, Dodge County, WI, Fond du Lac County, WI, Grant County, WI, Green Lake County, WI, Iowa County, WI, Jackson County, WI, Jefferson County, WI, Juneau County, WI, Kewaunee County, WI, La Crosse County, WI, Manitowoc County, WI, Marathon County, WI, Marquette County, WI, Milwaukee County, WI, Monroe County, WI, Outagamie County, WI, Ozaukee County, WI, Portage County, WI, Richland County, WI, Sauk County, WI, Shawano County, WI, Sheboygan County, WI, Trempealeau County, WI, Vernon County, WI, Washington County, WI, Waukesha County, WI, Waupaca County, WI, Waushara County, WI, Winnebago County, WI, Wood County, WI

The radar

The La Crosse radar (KARX), 96 km from the middle of the area, began a volume at 13:05 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 SPC expected

The probabilities SPC published with the watch, for the watch area over its life.

Two or more tornadoes
20%
One or more EF2 to EF5 tornadoes
5%
Ten or more severe wind reports
30%
One or more gusts of 65 knots or more
30%
Ten or more severe hail reports
30%
One or more hailstones of 2 inches or more
20%
Six or more combined severe hail and wind reports
70%

Warnings issued inside it

10 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

IssuedProductOfficeCountiesLasted
Jul 18, 8:14 AM CDTSevere Thunderstorm WarningGRBPortage, Waupaca46 min
Jul 18, 8:19 AM CDTSevere Thunderstorm WarningGRBWaushara41 min
Jul 18, 8:46 AM CDTFlash Flood WarningARXJackson, Trempealeau4 hr
Jul 18, 8:46 AM CDTSevere Thunderstorm WarningGRBOutagamie, Winnebago59 min
Jul 18, 9:01 AM CDTSevere Thunderstorm WarningARXJackson, Trempealeau44 min
Jul 18, 9:03 AM CDTSevere Thunderstorm WarningGRBShawano, Waupaca39 min
Jul 18, 9:15 AM CDTSevere Thunderstorm WarningGRBBrown, Calumet45 min
Jul 18, 9:32 AM CDTFlash Flood WarningARXJackson, Monroe3 hr
Jul 18, 9:38 AM CDTSevere Thunderstorm WarningARXJackson, La Crosse, Monroe, Trempealeau37 min
Jul 18, 9:40 AM CDTSevere Thunderstorm WarningGRBKewaunee, Manitowoc38 min

Discussions around it

SPC mesoscale discussions over the same counties from four hours before the watch to its end.

The nearest sounding before it

Green Bay/Straub, WI (KGRB), launched 12:00Z, 1.1 hours before the alert went out and 167 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 2011-07-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 3928 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 2011-07-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 106 square meters per square second.19395878Sfc1 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
3928 J/kg
Mixed-layer CIN
-31 J/kg
Mixed-layer LCL
613 m above ground
0-6 km bulk shear
47 kt
0-1 km storm-relative helicity
106 m²/s²
0-3 km storm-relative helicity
111 m²/s²
Significant tornado parameter
0.0
Supercell composite
9.7

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

961 
WWUS20 KWNS 181304
SEL6
SPC WW 181304
IAZ000-MNZ000-WIZ000-LMZ000-182000-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 656
NWS STORM PREDICTION CENTER NORMAN OK
805 AM CDT MON JUL 18 2011

THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

       FAR NORTHEAST IOWA
       FAR SOUTHEAST MINNESOTA
       CENTRAL AND SOUTHERN WISCONSIN
       LAKE MICHIGAN

EFFECTIVE THIS MONDAY MORNING AND AFTERNOON FROM 805 AM UNTIL 300
PM CDT.

HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 65
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 20 MILES SOUTHWEST
OF LA CROSSE WISCONSIN TO 35 MILES SOUTH OF MANITOWOC WISCONSIN.
FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU6).

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY
DO PRODUCE TORNADOES.

DISCUSSION...ELEVATED TSTMS HAVE RECENTLY INTENSIFIED ACROSS WATCH
AREA IN RESPONSE TO WEAK LOW-LEVEL WAA AND POTENTIAL INFLUENCE OF
MCV MOVING ACROSS THE REGION.  12Z OBSERVED SOUNDING SHOW THE
PRESENCE OF AN ALREADY VERY UNSTABLE ENVIRONMENT WITH MUCAPE VALUES
OF 5000-6000 J/KG.  WITH TIME...STORMS SHOULD BECOME ROOTED IN A
VERY MOIST BOUNDARY LAYER WITH THE POTENTIAL FOR UPSCALE GROWTH INTO
AN MCS.  DAMAGING WINDS AND HAIL WILL BE THE PRIMARY HAZARDS WITH
THESE STORMS.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM
MOTION VECTOR 30030.


...MEAD

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 17, 7:22 PM CDTSevere Thunderstorm WatchSPCBrown, Calumet, Door, Florence, Forest, Kewaunee and 17 more4 hr
Jul 17, 9:24 PM CDTMesoscale DiscussionSPCDoor, Florence, Forest, Kewaunee, Langlade, Lincoln and 9 more66 min
Jul 17, 11:06 PM CDTMesoscale DiscussionSPCCalumet, Fond du Lac, Kewaunee, Manitowoc, Sheboygan54 min
Jul 18, 6:30 AM CDTMesoscale DiscussionSPCAdams, Clark, Columbia, Crawford, Dane, Dodge and 25 more2 hr
Jul 18, 9:54 AM CDTMesoscale DiscussionSPCManitowoc, Sheboygan96 min
Jul 18, 2:06 PM CDTMesoscale DiscussionSPCBarron, Brown, Chippewa, Clark, Dunn, Eau Claire and 17 more84 min
Jul 18, 2:26 PM CDTSevere Thunderstorm WatchSPCAdams, Brown, Calumet, Chippewa, Clark, Door and 28 more7 hr
Jul 18, 5:42 PM CDTMesoscale DiscussionSPCAdams, Brown, Calumet, Chippewa, Clark, Eau Claire and 21 more63 min
Jul 18, 6:18 PM CDTSevere Thunderstorm WatchSPCColumbia, Dane, Dodge, Fond du Lac, Green, Green Lake and 14 more3 hr

Nearby

Severe Thunderstorm Watches in Wisconsin, 2011Severe Thunderstorm Watches in Iowa, 2011Severe Thunderstorm Watches in Minnesota, 2011Every severe thunderstorm watch in 2011

Sources

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