Showers and thunderstorms moved across the area August 20 as a trough of low pressure moved into western Iowa. Some of the storms were severe downing trees and power lines.
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 DVN wrote it up.
Showers and thunderstorms moved across the area August 20 as a trough of low pressure moved into western Iowa. Some of the storms were severe downing trees and power lines. Torrential downpours also accompanied the storms with rainfall totals of 1 to 2 inches in just an hour or two. Otherwise, warm and humid conditions prevailed across the region with high temperatures topping out in the middle 80s to lower 90s.
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 Quad Cities, IA wrote its last area forecast discussion before the first event at Aug 20, 2:32 AM CST, 9 hours 43 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE QUAD CITIES IA IL 332 AM CDT FRI AUG 20 2010 .SYNOPSIS... A WARM AND HUMID AIRMASS IS IN PLACE OVER THE REGION EARLY THIS MORNING. CLOUD COVER FROM UPSTREAM MCS ACTIVITY...ALONG WITH WEAK SURFACE WINDS AND LINGERING LOW LEVEL MOISTURE WAS HOLDING TEMPERATURES IN THE 70S AT 07Z. MSAS SURFACE ANALYSIS INDICATED LOW PRESSURE OVER CENTRAL SD WITH A COLD FRONT EXTENDING SOUTH TO ANOTHER LOW OVER FAR SW KS. A LARGE MCS WAS AHEAD OF THE NRN LOW COVERED MUCH OF MN AND WI...WHILE AN AXIS OF SHOWERS AND TSTSMS EXTENDED SW AHEAD OF THE COLD FRONT FROM EASTERN NE INTO CENTRAL KS. 00Z UPPER AIR ANALYSIS AND RECENT SATELLITE WV IMAGERY INDICATED A COUPLE SHORTWAVES EMERGING FROM THE ROCKIES. THE SOUTHERN IMPULSE...MOVING OUT OF NE CO...WILL BE THE ONE TO WATCH AS IT TRACKS THROUGH THE FORECAST AREA LATER TODAY...LIKELY RESULTING IN A LARGE...MODERATE TO HEAVY RAIN PRODUCING MCS. && .SHORT TERM...TODAY AND TONIGHT... POTENTIAL FOR THUNDERSTORMS AND HEAVY RAINFALL LATE TODAY AND TONIGHT IS THE PRIMARY FOCUS. SURFACE LOW OVER KS AND THE CO MID LEVEL SHORTWAVE DRIVE EAST TODAY...WITH MODELS GENERALLY TRACKING THE SURFACE LOW ACROSS NRN MO INTO CENTRAL IL BETWEEN 06Z AND 12Z SAT MORNING. LINGERING LOW LEVEL MOISTURE...STEEPENING MID LEVEL LAPSE RATES AND MID LEVEL QG FORCING AHEAD OF THE BROADER H5 TROUGH MOVING ACROSS IA AND MN...MAY PRODUCE SCATTERED THUNDERSTORMS DURING THE DAY AND HAVE MAINTAINED CHANCE POPS. WITH THE AMOUNT OF MUCAPE...WILL HAVE A THREAT OF DAMAGING WIND WITH THE DAYTIME STORMS AND SPC HAS A SLIGHT RISK IN DAY 1 OVER THE ENTIRE AREA. THE GREATER PRECIPITATION CHANCES WILL BE LATE THIS AFTERNOON AND EVENING...AS AXIS OF PW VALUES WELL OVER 2 INCHES AND SWRLY H8 25-30KT JET AHEAD OF THE FRONT WILL LIKELY TRIGGER A COMPLEX OF THUNDERSTORMS WITH MODERATE TO HEAVY RAINFALL...ESPECIALLY SOUTH OF HIGHWAY 34. HAVE RAISED POPS TO LIKELY TO CATEGORICAL AND QPF INTO THE RANGE OF .75 TO 1.25 RANGE OVER MUCH OF THE FORECAST AREA...WITH THE FAR SOUTH AS HIGH AS 1.75 FOR OVERNIGHT. THIS WILL BE APPROACHING FLASH FLOOD GUIDANCE AND HAVE KEPT HEAVY RAINFALL MENTION GOING. HOWEVER...WITH THIS AREA NOT HAVING SIGNIFICANT RAINFALL FOR SEVERAL DAYS...AND POTENTIAL FOR TRAINING OF STORMS LOW DUE TO THE PROGRESSIVE NATURE OF THE SYSTEM...WILL NOT ISSUE A FLASH FLOOD WATCH. TEMPERATURES TODAY WILL LIKELY BE SOMEWHAT LIMITED BY MID AND HIGH LEVEL CLOUDS FROM UPSTREAM THUNDERSTORMS AND HAVE KEPT VALUES IN THE MID 80S N TO AROUND 90 IN THE SOUTH...WHICH MAY BE TOO WARM IF THUNDERSTORMS ARE MORE WIDESPREAD OR DEVELOP SOONER IN THE DAY IN THE SOUTH. DEWPOINTS WELL INTO THE 70S WILL PUSH HEAT INDEX READINGS WELL INTO THE 90S AND APPROACHING 100 IN THE SOUTH. OVERNIGHT...MCS AND WEAK SURFACE LOW WILL LIKELY EXIT INTO CENTRAL IL BY SUNRISE WITH WINDS BECOMING LIGHT W TO NW. WITH LINGERING LOW LEVEL MOISTURE AND LACK OF COOL AIR BEHIND THE SYSTEM...HELD MINS IN UPPER 60S THE LOWER 70S. ..SHEETS.. .LONG TERM...SATURDAY THROUGH NEXT THURSDAY... CONTINUED WITH POPS S/E FOR LINGERING RAIN EARLY SAT AM. MOST MODELS HINT AT ADDITIONAL ENERGY DROPPING DOWN BACKSIDE OF DEPARTING SHORTWAVE TROUGH... WITH GEM AND GFS FURTHEST SW AND GENERATE SOME PCPN SAT AFTN WITH WEAK INVERTED SFC TROUGH OR CONVERGENCE ZONE MAINLY ACROSS THE NORTH. DPROG/DT OF MORE STABLE ECMWF PAST FEW RUNS HAS BEEN SHIFTING THIS FARTHER NORTHEAST INTO WI... WHICH IS IN AGREEMENT WITH UKMET... SO FOR NOW WITH INHERITING DRY FCST SAT AFTN HAVE NOT CHANGED GIVEN LOW CONFIDENCE AND LET LATER RUNS BETTER CLARIFY POTENTIAL... IF ANY. SAT NGT-MON... UPPER LEVEL RIDGE AMPLIFIES WITH HEAT BUILDING IN CENTRAL CONUS AHEAD OF WESTERN TROUGH. AT THE SFC... MODELS SHOW AREA UNDER THE INFLUENCE OF GREAT LAKES RIDGING WITH LIGHT ELY FLOW. THIS SHOULD HELP PREVENT AREA FROM SEEING FULL HEAT POTENTIAL KEEPING SOME OF THIS WARMING ALOFT. THEREFORE... EXPECT FAIRLY BENIGN PERIOD OF WX WITH MAINLY CLEAR SKIES AND TEMPS NEAR NORMAL WITH HUMIDITY QUITE MANAGEABLE FOR DECENT PRETTY TYPICAL LATE SUMMER CONDITIONS. MON NGT-TUE NGT... UPPER RIDGING IS SUPPRESSED TO THE SOUTH AS POTENT SHORTWAVE TROUGH SHIFTS EWD ACROSS THE NORTHERN PLAINS AND UPPER MIDWEST. ATTENDANT SFC COLD FRONT IS PROGGED TO SLIDE THROUGH ON TUE. MODELS HINT AT PRE-FRONTAL CAPPING AND SUPPORT PCPN POST FRONTAL NEAR H85 FRONT. UPPER DIFFLUENCE AND AMOUNT OF MOISTURE AND H85 CONVERGENCE SHOULD SUPPORT SOME ELEVATED PCPN TO SHIFT ACROSS CWA ON TUE AND LATER SHIFTS MAY NEED TO RAISE INTO CHC CAT IF TRENDS PERSIST. PCPN COULD LINGER INTO TUE NGT DEPENDING ON THE TIMING. WED-THU... PROGRESSIVE PATTERN BRINGS RETURN OF HIGH PRESSURE WITH TEMPS NEAR TO A LITTLE BELOW NORMAL. ECMWF HAS BEEN TRENDING STRONGER WITH INCOMING HIGH... AND WOULD SUPPORT LOWERING GOING TEMPS 2-4+ DEGS... ESPECIALLY LOWS. 2M TEMPS FROM BOTH ECMWF AND GFS SHOW U40S/L50S IN THE NORTH THU 12Z. ..MCCLURE.. && .AVIATION... LOW LEVEL MOISTURE WILL RESULT IN LINGERING FOG OR HAZE...KEEPING VISIBILITIES IN MVFR RANGE THROUGH MUCH OF TODAY. SCATTERED THUNDERSTORMS WILL BE POSSIBLE THROUGH THE DAY...AND MOST LIKELY FROM MID AFTERNOON INTO EVENING WITH AN APPROACHING COLD FRONT. FOR NOW...HAVE HANDLED THE THUNDERSTORM CHANCES WITH PROB30 GROUPS FROM MID AFTERNOON THROUGH EARLY EVENING. THESE WILL HAVE POTENTIAL FOR IFR VISIBILITIES...NOT INCLUDED IN TERMINALS AT THIS TIME. ..SHEETS.. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && SHEETS/MCCLURE
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE QUAD CITIES IA IL 450 AM CDT FRI AUG 20 2010 IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007- 009-015>018-024>026-034-035-MOZ009-010-211000- BUCHANAN-DELAWARE-DUBUQUE-BENTON-LINN-JONES-JACKSON-IOWA-JOHNSON- CEDAR-CLINTON-MUSCATINE-SCOTT-KEOKUK-WASHINGTON-LOUISA-JEFFERSON- HENRY IA-DES MOINES-VAN BUREN-LEE-JO DAVIESS-STEPHENSON-CARROLL- WHITESIDE-ROCK ISLAND-HENRY IL-BUREAU-PUTNAM-MERCER-HENDERSON- WARREN-HANCOCK-MCDONOUGH-SCOTLAND-CLARK- 450 AM CDT FRI AUG 20 2010 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH CENTRAL ILLINOIS...NORTHWEST ILLINOIS...WEST CENTRAL ILLINOIS...EAST CENTRAL IOWA...NORTHEAST IOWA...SOUTHEAST IOWA AND NORTHEAST MISSOURI. .DAY ONE...TODAY AND TONIGHT SCATTERED THUNDERSTORMS ARE POSSIBLE ACROSS THE ENTIRE AREA TODAY AND TONIGHT. SOME STORMS LATE THIS AFTERNOON AND EARLY EVENING MAY BE CAPABLE OF PRODUCING DAMAGING WIND GUSTS UP TO 60 MPH. THE STORM PREDICTION CENTER HAS A SLIGHT RISK FOR SEVERE STORMS OVER MOST OF THE OUTLOOK AREA. THUNDERSTORMS ARE EXPECTED TO BE MORE WIDESPREAD OVERNIGHT WITH HEAVY RAINFALL POSSIBLE. LOCAL RAINFALL AMOUNTS AS HIGH AS 2 TO 3 INCHES WILL BE POSSIBLE...ESPECIALLY ALONG AND SOUTH OF THE HIGHWAY 34 CORRIDOR. THIS MAY LEAD TO FLOODING ALONG SMALL STREAMS AND URBAN AREAS. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY THUNDERSTORMS WITH LOCALLY HEAVY RAIN WILL BE POSSIBLE EARLY SATURDAY MORNING SOUTHEAST OF THE QUAD CITIES. THERE IS ANOTHER CHANCE OF THUNDERSTORMS OVER THE ENTIRE OUTLOOK AREA ON TUESDAY. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON AND TONIGHT. SHEETS/MCCLURE
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE QUAD CITIES IA IL 1151 AM CDT FRI AUG 20 2010 IAZ067-068-078-089-ILZ015-016-024>026-201745- DES MOINES-HENDERSON-HENRY-LOUISA-MERCER-MUSCATINE-ROCK ISLAND-SCOTT-WARREN- 1151 AM CDT FRI AUG 20 2010 ...STRONG THUNDERSTORMS WITH GUSTY WINDS AND HEAVY RAIN... AT 1149 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A STRONG THUNDERSTORM NEAR GLADSTONE...OR 6 MILES EAST OF BURLINGTON... MOVING NORTHEAST AT 40 MPH. THIS THUNDERSTORM WILL BRING WIND GUSTS TO 50 MPH...AND TORRENTIAL RAINFALL FOR A BRIEF PERIOD. OTHER STORMS ARE DEVELOPING IN THE AREA...AND MAY BRING A SIMILAR THREAT. * THE THUNDERSTORM WILL BE NEAR... GLADSTONE AROUND 1155 AM CDT... OQUAWKA AND BIGGSVILLE AROUND NOON CDT... ROZETTA AROUND 1205 PM CDT... LITTLE YORK AND SEATON AROUND 1220 PM CDT... BURGESS AROUND 1235 PM CDT... VIOLA...WANLOCK AND SHALE CITY AROUND 1240 PM CDT... SEEK SHELTER IN A STURDY STRUCTURE UNTIL THIS STORM HAS PASSED. LAT...LON 4173 9084 4164 9021 4069 9094 4080 9116 TIME...MOT...LOC 1650Z 219DEG 35KT 4082 9099 ERVIN
The Lincoln radar (KILX), 119 km away, was scanning. The volume nearest the first event began at 18:14 UTC.
9 thunderstorm wind, 1 lightning. Local standard time, as filed.
Wind gusts estimated to be 60 mph blew down some branches in Macomb, IL at 115 pm CDT August 20.
A 12 year old boy was struck by lightning at Southside Elementary School in Morrison, IL just before 2 pm CDT August 20.
Wind gusts estimated to be 60 mph were observed about 2 miles west of Ustick, IL or about 6 miles north northwest of Morrison, IL at 205 pm CDT August 20.
Wind gusts estimated to be 70 mph were observed in Morrison, IL around 210 pm CDT August 20. Several trees and branches were blown down in the area as well as a utility pole along Prairie Center Road. Route 30 was closed for a while due to tree removal operations. The sources for this report were the spotter's police scanner and a newspaper.
Wind gusts estimated to be 60 mph were observed in Chadwick, IL at 222 pm CDT August 20.
Wind gusts estimated to be 65 mph blew a limb down in Freeport, IL around 255 pm CDT August 20. The limb, which was 6 to 8 inches in diameter, fell onto some power lines which in turn caused a house fire. This report was relayed by WREX.
Wind gusts estimated to be 65 mph blew down a 10 inch diameter tree limb about 7 miles northwest of Freeport, IL around 258 pm CDT August 20.
Wind gusts estimated to be 65 mph blew down some large tree limbs and power lines in Warsaw, IL around 520 pm CDT August 20.
Wind gusts estimated to be 65 mph blew down some large tree limbs and power lines in Hamilton, IL around 540 pm CDT August 20.
Wind gusts estimated to be 60 mph were observed in Augusta, IL around 550 pm CDT August 20. Some small tree limbs were blown down. The observer made the report the morning of August 21.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Illinois in 2010Every state in 2010This day in weather historyWarnings in Illinois, August 2010
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: 257135, 257138, 257139, 257142, 257144, 257147, 257150, 257160, 257163, 257194.