Wisconsin Record Tornado Outbreak - Looking Back

Aug 19, 2010
On August 18, 2005 Wisconsin experienced its largest tornado outbreak ever for the state. While conditions were favorable for severe thunderstorms, here is a look back at what forecasters were starting to see unfold during the afternoon of the 18th.

The Storm Prediction Center (SPC) issues daily convective outlooks pin-pointing what areas of the country may experience severe weather. Usually if such an area may face the threat of imminent severe weather, SPC issues mesoscale discussions explaining the atmospheric environment and if a weather watch is needed. Around 2:00 p.m. on the 18th, the first mesoscale discussion was issued signaling a possible severe weather event unfolding across Southern Wisconsin.

209 PM CDT THU AUG 18 2005

SFC MESOANALYSIS SHOWS WELL-DEFINED LOW OVER SERN MN -- N RST AS OF 19Z -- FCST TO MOVE EWD INTO SWRN/S-CENTRAL WI THROUGH REMAINDER AFTERNOON. WARM FRONT EXTENDS SEWD FROM LOW ACROSS SWRN WI INTO OUTFLOW POOL LEFT BY MORNING MCS. WARM FRONT WILL CONTINUE LIFTING NWD AND WRN PORTION OF OLD OUTFLOW POOL WILL FAVORABLY MODIFY. 80S SFC TEMPS AND 70S DEW POINTS -- EVIDENT IN WARM SECTOR ALONG AND S OF WARM FRONT AND OUTFLOW BOUNDARY -- SHOULD SUPPORT MLCAPES AROUND 2000 J/KG BASED ON MODIFIED RUC SOUNDINGS. LOW LEVEL VERTICAL SHEAR PROFILES SHOULD REMAIN MAXIMIZED INVOF WARM FRONT...WHERE BACKED SFC WINDS CONTRIBUTE TO ENLARGED LOW LEVEL HODOGRAPHS AND 0-1 KM SRH OF 150-250 J/KG SRH IN 0-1 KM AGL LAYER. THOSE VALUES -- DERIVED FROM OBSERVED REGIONAL VWP DATA...ARE SUBSTANTIALLY HIGHER THAN INDICATED BY SHORT TERM RUC ANALYSES AND FCSTS...AND SUPPORT SUPERCELL/TORNADO THREAT PARTICULARLY NEAR WARM FRONT.

Link to August 18, 2005 Mesoscale Discussion

Soon after, SPC issued a Tornado Watch for most of Southern Wisconsin, severe storms developed and produced tornadoes across the southwestern part of the state. Another mesoscale discussion was issued highlighting the ongoing situation and the possibility of a new Tornado watch further east across Eastern Wisconsin.

0547 PM CDT THU AUG 18 2005

SEVERE STORM/TORNADO POTENTIAL PERSISTS ACROSS SWRN AND S CENTRAL WI/WITHIN WW 730...AND SHOULD SHIFT EWD ACROSS THE REMAINDER OF SERN WI OVER THE NEXT FEW HOURS. NEW TORNADO WATCH WILL BE ISSUED SHORTLY.

LATEST SURFACE ANALYSIS SHOWS LOW SE OF LSE...WITH WARM FRONT EXTENDING EWD/ESEWD TO THE LK MI LAKESHORE N OF MKE. AIRMASS REMAINS MODERATELY UNSTABLE NEAR AND S OF FRONT...WHERE 1500 J/KG MEAN-LAYER CAPE IS INDICATED. SCATTERED SEVERE STORMS CONTINUE ACROSS S CENTRAL WI ATTM -- WITH STRONGEST STORM NOW MOVING ESEWD ACROSS ERN SAUK COUNTY TOWARD SWRN COLUMBIA/NRN DANE COUNTIES. THIS STORM IN PARTICULAR HAS A HISTORY OF PRODUCING TORNADOES AND ASSOCIATED DAMAGE. WITH FAVORABLE LOW-LEVEL VEERING/DEEP-LAYER SHEAR INDICATED ACROSS THIS REGION ALONG WITH VERY MOIST BOUNDARY
LAYER/LOW LCLS...EXPECT SEVERE STORMS CAPABLE OF PRODUCING TORNADOES TO CONTINUE MOVING ACROSS SERN WI.

Link to August 18, 2005 Mesoscale Discussion # 2

After this was issued, a F3 tornado struck the village of Stoughton, Wisconsin which caused major damage along with a fatality and numerous injuries. While watches and warnings are beneficial, you can even take a step further and monitor what areas SPC are discussing potential areas of severe weather.

Storm Prediction Center Mesoscale Discussion Page

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