An upper level disturbance initiated isolated to scattered showers and thunderstorms in a semi-dry to semi-moist atmosphere. One lone storm pulsed severe and produced a downburst that destroyed a metal shed just south of the village of Shannon.
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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.
An upper level disturbance initiated isolated to scattered showers and thunderstorms in a semi-dry to semi-moist atmosphere. One lone storm pulsed severe and produced a downburst that destroyed a metal shed just south of the village of Shannon. Rapid development of showers and thunderstorms during the late afternoon combined with cold air aloft lead to numerous reports of cold air funnels across northwest and west central Illinois.
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 May 1, 2:02 PM CST, 1 hour 45 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE QUAD CITIES IA IL 302 PM CDT SUN MAY 1 2006 .SYNOPSIS... SATELLITE AND RADAR IMAGERY INDICATE LINE OF TCU/SHRA DEVELOPING AT ABOUT 1830Z ROUGHLY ALONG THE MS RIVER IN AN AREA OF PRE-FRONTAL CONVERGENCE. SUBJECTIVE 12Z UPPER AIR ANALYSIS STILL DOMINATED BY STACKED LOW CENTERED OVER MN/DAKOTAS... WITH ONLY WEAK 500MB HEIGHT FALLS INDICATING LOW IS OPENING AS IT PULLS AWAY TO THE NORTHEAST. UPSTREAM 500MB SHORTWAVES WERE ANALYZED OVER CO/NM AND APPROACHING THE PACIFIC NORTHWEST. 250MB AND 300MB ANALYSIS SHOWS VERY WEAK UPPER-LEVEL JET STRUCTURE... WITH PEAK 250MB WINDS OF 75KT OVER THE FL PANHANDLE AND 50KT AT BEST OVER THE CENTRAL US. 700MB ANALYSIS INDICATED NEAR-SATURATED MID-LEVELS OVER THE CENTRAL US... WITH NORTHWESTERLY FLOW WORKING DRY AIR INTO THE MID-LEVEL IN WAKE OF THE STACKED LOW. && .SHORT TERM...TONIGHT AND TOMORROW... FORECAST ISSUE OF THE PERIOD IS CHANCE OF CONVECTION TODAY AND WALKING OUT CLOUDS/PRECIP THROUGH THE NIGHT AND INTO TOMORROW. SHOWERS ARE INITIATING ALONG THE PREFRONTAL CONVERGENT LINE WITHIN THE CLEAR SLOT WHERE BEST HEATING OCCURRED TODAY. PARTICULARLY WHERE SUN SHONE TODAY... LOW-LEVEL LAPSE RATES ARE STRONG AND LCL HEIGHTS ARE LOW ACROSS THE AREA. MANY FEATURES ARE LACKING FOR ORGANIZED CONVECTION TODAY... HOWEVER. BULK SHEAR IS WEAK /NO GREATER THAN 35KT/ NORTH OF THE IA/MO BORDER... SURFACE-BASED CAPE IS WEAK EVEN WHERE HEATING DID OCCUR... AND LIFTED INDICES ARE WEAK OR POSITIVE WEST OF THE MS RIVER WITH WEAK MID-LEVEL LAPSE RATES. EXPECT FACTORS TO BALANCE TO KEEP STORMS IN CWA BELOW SEVERE LIMITS... THOUGH STILL WOULD NOT RULE OUT AN ISOLATED STORM PULSING UP TO REACH MARGINAL SEVERE CRITERIA. STORMS WILL WEAKEN AFTER SUNSET... THUS HAVE WALKED OUT PRECIP AS SHOWERS AFTER 23Z IN ALL BUT THE SOUTHEASTERN CWA AND AS ALL SHOWERS AFTER 02Z. EXPECT CLOUDS TO LINGER THROUGH THE NIGHT... AND MAY SEE VISIBILITIES IN NORTHERN AREAS DROP SOME AS WINDS DIMINISH TONIGHT... THOUGH MORE AN AVIATION FOG THAN A DENSE FOG ISSUE. HAVE INCLUDED DROP IN KCID AND KDBQ TAFS BUT NOT IN GRIDS. KEPT MINS AT HIGH END OF GUIDANCE TONIGHT WITH EXPECTED LINGERING CLOUDS... THOUGH EXPECT BREAKS IN CLOUDS AND WILL HOLD OFF GOING ABOVE GUIDANCE. EXPECT QUICK CLEARING AROUND DAYBREAK TOMORROW AS LOW PULLS AWAY... ALLOWING A FULL DAY OF SUN TO HEAT THE AREA. WITH WINDS BACKING TO SOUTHWESTERLY AHEAD OF NEXT SFC LOW... WILL MIX FAIRLY EFFECTIVELY AND HAVE TINGED TOWARD HIGH END OF GUIDANCE FOR TOMORROW. .LONG TERM...TUESDAY NIGHT THROUGH MONDAY 100 KT H3 JET DIVING CURRENTLY DIVING INTO PACIFIC NW CARVES OUT NEW UPPER LOW THAT TRAVELS EAST JUST NORTH OF NORTHERN CONUS BORDER THROUGH MID WEEK. MODELS TRENDING A BIT SLOWER WITH THIS SYSTEM THAN PREVIOUS RUNS. RESULTING LOW LEVEL RETURN FLOW AND H8 MOISTURE ADVECTION REACHES INTO SW CWFA TOWARD 06Z WED. THERE ARE STILL SIGNIFICANT DIFFERENCES AMONG SHORT TERM MODELS IN DEVELOPMENT OF MID LEVEL SHORTWAVE IN ZONAL FLOW FURTHER SOUTH OVER SOUTHERN PLAINS...WHICH PRODUCES A SURFACE LOW AT AND QPF BULLSEYE WELL TO SOUTH. THE POTENTIAL FOR AN MCS THERE WOULD LIMIT CONVECTIVE POTENTIAL HERE...BUT STILL ENOUGH UNCERTAINTY TO KEEP LOW CHANCE POPS GOING LATE TUE NIGHT. SURFACE COLD FRONT AND MID LEVEL SUPPORT AT BASE OF ONTARIO H5 LOW PUSHES THROUGH WED AFTERNOON FOLLOWING SLIGHTLY SLOWER NAM SOLUTION. THIS WOULD BE FAVORABLE TIMING FOR SCATTERED SHOWERS AND THUNDERSTORMS WITH CHANCE POPS EXTENDED FROM AFTERNOON INTO EARLY EVENING. ANOTHER UPPER TROUGH ROTATES THROUGH UPPER MS VALLEY FRI AND SAT...BUT MOISTURE LOOKS LIMITED WITH GULF CLOSED OFF AND KEPT POPS IN SLIGHT CATEGORY FOR NOW. MID LEVEL FLOW RETURNS TO MORE ZONAL WITH MEDIUM RANGE GUIDANCE PLACING NEXT SHORTWAVE INTO AREA SUN NIGHT INTO MON AND INTRODUCED THESE PERIODS WITH LOW CHANCES FOR SHOWERS AND THUNDERSTORMS. WED LOOKS TO BE WARMEST DAY WITH POTENTIAL FOR PREFRONTAL WARMING BOOSTING HIGHS INTO 70S. OTHERWISE...TEMPERATURES THROUGH EXTENDED KEPT NEAR TO A BIT BELOW CLIMATOLOGICAL NORMALS WITH HIGHS IN MAINLY IN 60S AND LOWS IN 40S TO LOWER 50S. ..SHEETS.. .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && MAYES/SHEETS
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE QUAD CITIES IA IL 425 PM CDT MON MAY 1 2006 IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007- 009-015>018-024>026-034-035-MOZ009-010-022130- 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- 425 PM CDT MON MAY 1 2006 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...TONIGHT SHOWERS AND ISOLATED THUNDERSTORMS ARE POSSIBLE THIS EVENING AND IN THE EARLY OVERNIGHT HOURS... PARTICULARLY SOUTHEAST OF A LINE FROM GALENA TO THE QUAD CITIES TO KEOSAUQUA. SEVERE WEATHER IS NOT ANTICIPATED WITH THUNDERSTORMS THAT DEVELOP... ALTHOUGH SMALL HAIL AND GUSTY WINDS MAY ACCOMPANY THE SHOWERS AND THUNDERSTORMS. A COLD AIR FUNNEL WAS REPORTED THIS AFTERNOON IN NORTHWESTERN ILLINOIS. COLD AIR FUNNELS ARE NOT ASSOCIATED WITH THUNDERSTORMS AND DO NOT ROTATE AS STRONGLY AS A TORNADO. THEY USUALLY REMAIN ABOVE THE GROUND AND ARE NOT A THREAT. IF A COLD AIR FUNNEL DOES REACH THE GROUND... IT COULD PRODUCE BRIEFLY GUSTY WINDS. THE CHANCE OF COLD AIR FUNNELS WILL DIMINISH AFTER SUNSET. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY A STORM SYSTEM WILL BRING A CHANCE OF THUNDERSTORMS ON LATE TUESDAY NIGHT AND WEDNESDAY. AT THIS TIME... THE THREAT FOR ORGANIZED SEVERE WEATHER APPEARS LOW. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT ANTICIPATED THIS EVENING OR TONIGHT. MAYES
The Quad Cities radar (KDVN), 92 km away, was scanning. The volume nearest the first event began at 21:45 UTC.
6 funnel cloud, 1 thunderstorm wind. Local standard time, as filed.
Just south of Shannon on Stanton Street.
Numerous reports of cold air funnels
Numerous reports of cold air funnels
Numerous reports of cold air funnels
Numerous reports of cold air funnels
Numerous reports of cold air funnels
Several reports of cold air funnels
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Illinois in 2006Every state in 2006This day in weather historyWarnings in Illinois, May 2006
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: 5512457, 5512458, 5512459, 5512460, 5512461, 5512543, 5512544.