During the afternoon of August 19th, a large area of generally moderate to heavy showers occurred across most of south central, east central Minnesota, and into west central Wisconsin. The area had very few lightning strikes, and most of the shower activity was racing northward at 40 to 50 mph.
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 MPX wrote it up.
During the afternoon of August 19th, a large area of generally moderate to heavy showers occurred across most of south central, east central Minnesota, and into west central Wisconsin. The area had very few lightning strikes, and most of the shower activity was racing northward at 40 to 50 mph. An area of low pressure developed across east central Minnesota during the afternoon and began to intensify prior to the tornado development. Several weak areas of intense showers moved northward across the area. Low level humidity levels were very high, which provided a very low cloud base around 1000'. Although weak circulations were noted on radar, not until the surface low intensified and allowed for an overall increase in the surface inflow did tornadoes develop.
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 Twin Cities, MN wrote its last area forecast discussion before the first event at Aug 19, 11:35 AM CST, 2 hours 22 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 1235 PM CDT WED AUG 19 2009 .UPDATE... UPDATED TO INCLUDE 18Z AVIATION DISCUSSION BELOW. && .AVIATION.../18Z TAF ISSUANCE/ AVIATION FORECAST IS VERY COMPLICATED AND PREDOMINANTLY FULL OF POOR CONDITIONS THROUGH THE FORECAST PERIOD. OVERALL THINGS ARE DIVIDED INTO THREE TIME FRAMES... THE PRE-FRONTAL WIDESPREAD RAIN WITH EMBEDDED THUNDER ONGOING... A PERIOD OF MID-LEVEL DRYING LATE THIS AFTERNOON INTO THIS EVENING COINCIDENT WITH FROPA AND POTENTIAL FOR SOME SCT SHRA/TSRA... THEN THE ARRIVAL OF MORE WIDESPREAD CLOUD COVER TOWARD THE END OF THE FORECAST PERIOD AS CYCLONIC BOUNDARY LAYER FLOW AND THE LOW LEVEL THERMAL TROUGH WORK INTO THE AREA. CEILINGS ARE ALL OVER THE PLACE AT THE MOMENT... RANGING FROM IFR TO VFR IN VICINITY OF THE AXIS OF PCPN WHICH IS BEING FORCED BY WARM ADVECTION AND GOOD MOISTURE TRANSPORT AHEAD OF THE UPPER TROUGH AND SURFACE FRONT. THIS SHIFTS SLOWLY EAST THROUGH THE DAY... WITH SOME GENERAL IMPROVEMENT EXPECTED IN CEILINGS IN THE WAKE OF THIS ACTIVITY AS SOMEWHAT DRIER MID-LEVEL AIR WORKS IN. EXPECT SOME DEVELOPMENT OF SHRA/TSRA TO OUR WEST THIS AFTERNOON IN ASSOCIATION WITH THE MID LEVEL COLD POOL AND GOOD UPPER LEVEL PV ANOMALY. THIS ACTIVITY SHOULD WANE DURING THE EVENING DUE TO THE LOSS OF DIURNAL HEATING... SO UNSURE IF IT WILL MAKE IT TO THE EASTERN TAF SITES. LATER TONIGHT IS A TOUGH CALL AT THIS POINT... SINCE ANY SUBSTANTIAL CLEARING COULD LEAD TO QUICK DEVELOPMENT OF FOG/STRATUS... SO TRIED TO ACCOUNT FOR THAT POSSIBILITY WHILE NOT GOING OVERBOARD AT THIS POINT. MORE EXTENSIVE STRATOCU IS EXPECTED TO WORK INTO AND/OR DEVELOP OVER THE AREA TOMORROW... AND WILL LIKELY HAVE SOME SHRA DEVELOP LATER IN THE DAY WITH THE UPPER LOW IN THE VICINITY. && .PREV DISCUSSION... /ISSUED 701 AM CDT WED AUG 19 2009/ INCREASING LOW/MID LEVEL WINDS OVERNITE (MPX VAD WINDS AND WDL PROFILER) WORKED OVER A RATHER TIGHT THERMAL FIELD WITH NICE PUSH OF THETA E ADVECTION GENERATING WIDESPREAD SHOWERS AND THUNDERSTORMS. ALSO HAD A FEW HAIL REPORTS AROUND MIDNIGHT IN WC MN. PWATS HAVE NOT BEEN VERY IMPRESSIVE WITH 00Z VALUES AT MPX/ABV ONLY .75...BUT INCREASING SOUTH WINDS HAVE TAPPED MODERATE VALUES IN THE 1.25 RANGE TO OUR SOUTH. RADAR ESTIMATES HAVE YIELDED SOME 2 TO 3 INCH RANGE RAINS ACROSS PORTIONS OF WC MN ROUGHLY FROM APPLETON TO WILLMAR. EXPECT THAT IN THE NEXT FEW HOURS SHOULD SEE A BROAD BAND OF 1 INCH PLUS RAINS ACROSS MUCH OF THE NORTHERN FEW TIERS OF COUNTIES IN MN PORTION OF CWA AS PUSH OF THETA E ADVECTION MOVES THRU. SHARPENING UPPER LEVEL TROUGH IN THE DAKOTAS WILL GENERATE BROAD LIFT ACROSS AREA TODAY AS SURFACE FRONT MOVES INTO WESTERN MN. EXTENSIVE CLOUDS WILL INHIBIT SURFACE BASED INSTABILITY...BUT MAY SEE A FEW STRONG STORMS AGAIN MAINLY IN WC INTO SC MN THIS AFTERNOON. CLOUDS AND PRECIPITATION WILL KEEP TEMPERATURES MAINLY IN THE LOWER AND MID 70S. CONTINUED LIFT AS CLOSED UPPER LOW CRAWLS ACROSS AREA WILL CONTINUE TO WRING OUT SHOWERS AND A FEW THUNDERSTORMS AT LEAST INTO THURSDAY EVENING. STRONG PUSH OF COLD ADVECTION AS DEEPENING FALL-LIKE SURFACE LOW MOVES THRU WILL MAKE FOR GUSTY NORTHWEST WINDS BEGINNING IN WESTERN MINNESOTA TONIGHT AND ACROSS AREA THURSDAY INTO FRIDAY. HARD TO SEE TEMPERATURES GETTING OUT OF THE MID 60S THURSDAY...AND NOT A LOT WARMER ON FRIDAY. HIGH PRESSURE MOVES INTO W MN LATE FRIDAY AND ARRIVES IN WI BY SATURDAY EVENING. TEMPERATURES WILL MODERATE OVER THE WEEKEND TOWARD MORE SEASONAL LEVELS AS UPPER RIDGE FLATTENS DEVELOPING MORE ZONAL FLOW. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. &&
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 1051 AM CDT WED AUG 19 2009 MNZ041>045-047>070-073>078-082>085-091>093-WIZ014>016-023>028- 201600- DOUGLAS-TODD-MORRISON-MILLE LACS-KANABEC-STEVENS-POPE-STEARNS- BENTON-SHERBURNE-ISANTI-CHISAGO-LAC QUI PARLE-SWIFT-CHIPPEWA- KANDIYOHI-MEEKER-WRIGHT-HENNEPIN-ANOKA-RAMSEY-WASHINGTON- YELLOW MEDICINE-RENVILLE-MCLEOD-SIBLEY-CARVER-SCOTT-DAKOTA- REDWOOD-BROWN-NICOLLET-LE SUEUR-RICE-GOODHUE-WATONWAN-BLUE EARTH- WASECA-STEELE-MARTIN-FARIBAULT-FREEBORN-POLK-BARRON-RUSK- ST. CROIX-PIERCE-DUNN-PEPIN-EAU CLAIRE- 1051 AM CDT WED AUG 19 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL AND SOUTHERN MINNESOTA...AND WEST CENTRAL WISCONSIN. .DAY ONE...TODAY AND TONIGHT A COLD FRONT WILL PUSH INTO WESTERN MINNESOTA THIS AFTERNOON AND THEN ARRIVE IN CENTRAL MINNESOTA THIS EVENING. SCATTERED THUNDERSTORMS WILL PERSIST AHEAD OF THE FRONT. A FEW COULD BECOME SEVERE IN SOUTH CENTRAL MINNESOTA AND PORTIONS OF WEST CENTRAL WISCONSIN THIS AFTERNOON AND EVENING. LARGE HAIL WOULD BE THE PRIMARY SEVERE WEATHER THREAT. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY SHOWERS WITH A FEW EMBEDDED THUNDERSTORMS WILL CONTINUE INTO THURSDAY MAINLY IN EASTERN MINNESOTA INTO WISCONSIN. THESE STORMS ARE NOT EXPECTED TO BE SEVERE. .SPOTTER INFORMATION STATEMENT... SKYWARN SPOTTER ACTIVATION IS POSSIBLE IN SOUTH CENTRAL MINNESOTA AND PORTIONS OF WEST CENTRAL WISCONSIN THIS AFTERNOON AND EVENING.
PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
1053 AM CDT WED AUG 19 2009
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1145 PM HAIL LOUISBURG 45.17N 96.17W
08/18/2009 M1.00 INCH LAC QUI PARLE MN LAW ENFORCEMENT
HAIL COVERED THE GROUND WITH LARGEST STONES BETWEEN DIME
AND QUARTER SIZE.
&&
KMEPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
245 PM CDT WED AUG 19 2009
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0220 PM TSTM WND DMG MINNEAPOLIS 44.96N 93.27W
08/19/2009 HENNEPIN MN EMERGENCY MNGR
ROOF OFF HOUSE, LARGE TREE BLOCKING ROAD AND POWER POLES
DOWN AT PORTLAND AND 35TH AVE SOUTH.
&&
KMEPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
254 PM CDT WED AUG 19 2009
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0243 PM TORNADO COTTAGE GROVE 44.82N 92.93W
08/19/2009 WASHINGTON MN EMERGENCY MNGR
TORNADO ON GROUND AT HIGHWAY 61 HIGHWAY 95 REPORTED BY
DAKOTA COUNTY EOC.
&&
KMEThe Minneapolis radar (KMPX), 93 km away, was scanning. The volume nearest the first event began at 19:58 UTC.
4 tornado. Local standard time, as filed.
A tornado touched down briefly and tore a narrow path through two fields of corn. A tree was partially broken.
A National Weather Service Storm Survey determined that an EF-0 tornado tracked northward across a small portion of Hudson, Wisconsin, near County Road UU, and Larson Lane. Damage was mainly associated with large trees blown down, along with minor damage to several roofs. Based on the extent of the tree and roof damage, winds were estimated between 80 and 85 mph.
A tornado briefly touched down several times as it tracked northward along 250th Street. Vegetation was occasionally torn up and tossed in the air.
A trained spotter observed a tornado that tracked from the Highway 64, and 63 intersection, northeast to the intersection of 270th and 200th Street, west and northwest of Forest, Wisconsin.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wisconsin in 2009Every state in 2009This day in weather historyThe tornado archive for Wisconsin, 2009Warnings in Wisconsin, August 2009
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: 186082, 182814, 186088, 182816.