Alert archive / Wisconsin / Severe Thunderstorm Watches in 2012
Severe Thunderstorm Watch 556
The Storm Prediction Center issued this severe thunderstorm watch at Aug 3, 2012, 10:57 PM CDT for 7 counties in Minnesota; 14 counties in Wisconsin. It was in force for 4 hr.
The area
The outline as issued.
The facts
- Issued
- Aug 3, 2012, 10:57 PM CDT (03:57 UTC)
- Expired
- Aug 4, 2012, 2:50 AM CDT
- In force
- 4 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
All 21 counties
Dodge County, MN, Freeborn County, MN, Goodhue County, MN, Olmsted County, MN, Steele County, MN, Wabasha County, MN, Winona County, MN, Barron County, WI, Buffalo County, WI, Chippewa County, WI, Clark County, WI, Dunn County, WI, Eau Claire County, WI, Jackson County, WI, Pepin County, WI, Pierce County, WI, Polk County, WI, Rusk County, WI, Saint Croix County, WI, Taylor County, WI, Trempealeau County, WI
The radar
The Minneapolis radar (KMPX), 96 km from the middle of the area, began a volume at 03:58 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
- 50%
- One or more gusts of 65 knots or more
- 30%
- Ten or more severe hail reports
- 40%
- One or more hailstones of 2 inches or more
- 20%
- Six or more combined severe hail and wind reports
- 70%
Warnings issued inside it
5 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 3, 11:12 PM CDT | Severe Thunderstorm Warning | MPX | Polk | 33 min |
| Aug 3, 11:18 PM CDT | Severe Thunderstorm Warning | MPX | Dakota, Goodhue, Rice, Scott, Washington | 42 min |
| Aug 3, 11:38 PM CDT | Severe Thunderstorm Warning | MPX | Barron, Dunn, Polk, Saint Croix | 67 min |
| Aug 3, 11:43 PM CDT | Severe Thunderstorm Warning | ARX | Dodge, Olmsted, Wabasha | 62 min |
| Aug 3, 11:44 PM CDT | Severe Thunderstorm Warning | MPX | Dakota, Goodhue, Washington | 61 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
Minneapolis, MN (KMPX), launched 00:00Z, 4.0 hours before the alert went out and 99 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.
- Mixed-layer CAPE
- 576 J/kg
- Mixed-layer CIN
- -95 J/kg
- Mixed-layer LCL
- 1840 m above ground
- 0-6 km bulk shear
- 48 kt
- 0-1 km storm-relative helicity
- 100 m²/s²
- 0-3 km storm-relative helicity
- 257 m²/s²
- Significant tornado parameter
- 0.1
- Supercell composite
- 7.5
The text
As transmitted, in the capitals the NWS used until 2016.
852
WWUS20 KWNS 040356
SEL6
SPC WW 040356
MNZ000-WIZ000-040900-
URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 556
NWS STORM PREDICTION CENTER NORMAN OK
1100 PM CDT FRI AUG 3 2012
THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
SOUTHEAST MINNESOTA
WESTERN WISCONSIN
EFFECTIVE THIS FRIDAY NIGHT AND SATURDAY MORNING FROM 1100 PM
UNTIL 400 AM 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 75
STATUTE MILES EAST AND WEST OF A LINE FROM 55 MILES NORTH
NORTHWEST OF EAU CLAIRE WISCONSIN TO 15 MILES EAST SOUTHEAST OF
ROCHESTER MINNESOTA. 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.
OTHER WATCH INFORMATION...CONTINUE...WW 554...WW 555...
DISCUSSION...A RELATIVELY FAST MOVING SQUALL LINE WILL TRACK
EASTWARD INTO WESTERN WI DURING THE NEXT FEW HOURS. THIS LINE HAS
PRODUCE LOCALIZED DAMAGING WINDS DURING THE PAST FEW HOURS...AND MAY
CONTINUE TO DO SO GIVEN BOWING LINE SEGMENTS AND SUFFICIENT
INSTABILITY.
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 27040.
...HARTSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 3, 7:33 PM CDT | Severe Thunderstorm Watch | SPC | Aitkin, Anoka, Beltrami, Benton, Blue Earth, Brown and 53 more | 6 hr |
| Aug 3, 10:33 PM CDT | Mesoscale Discussion | SPC | Aitkin, Anoka, Benton, Blue Earth, Brown, Carlton and 33 more | 87 min |
| Aug 4, 1:41 AM CDT | Mesoscale Discussion | SPC | Clark, Iron, Jackson, La Crosse, Lincoln, Marathon and 6 more | 64 min |
| Aug 4, 10:26 AM CDT | Mesoscale Discussion | SPC | Grant, Green, Lafayette, Rock, Walworth | 49 min |
| Aug 4, 1:09 PM CDT | Mesoscale Discussion | SPC | Green, Lafayette | 66 min |
| Aug 4, 1:46 PM CDT | Severe Thunderstorm Watch | SPC | Dane, Dodge, Green, Jefferson, Kenosha, Lafayette and 7 more | 4 hr |
Nearby
Severe Thunderstorm Watches in Wisconsin, 2012Severe Thunderstorm Watches in Minnesota, 2012Every severe thunderstorm watch in 2012
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.