A cluster of severe thunderstorms produced damaging winds across extreme northwest Missouri, during the afternoon hours of August 9, 2009.
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 EAX wrote it up.
A cluster of severe thunderstorms produced damaging winds across extreme northwest Missouri, during the afternoon hours of August 9, 2009.
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 Kansas City, MO wrote its last area forecast discussion before the first event at Aug 9, 3:30 PM CST, 35 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 430 PM CDT SUN AUG 9 2009 .DISCUSSION... SEVERE THUNDERSTORM WATCH NUMBER 686 IN EFFECT FOR PARTS OF NW MO AND EXTREME NE KS UNTIL 04Z. SCATTERED STRONG/SEVERE CONVECTION IS FORMING ALONG AND JUST BEHIND A SLOW MOVING COLD FRONT FROM NORTHEAST IA THROUGH THE OK PANHANDLE. RIGHT ENTRANCE REGION OF LARGE UPPER LEVEL JET SEGMENT IS ENHANCING LIFT WHERE CAP HAS BEEN BREACHED. AIRMASS AHEAD OF THE FRONT IS CAPPED BY VERY WARM ELEVATED MIXED LAYER. NAM/GFS/RUC/SREF ALL PROG THE LOW LEVEL JET WILL VEER/STRENGTHEN THIS EVENING ACROSS EASTERN KS INTO NORTHWEST MO. THIS TOO WILL AID IN MAINTAINING STRENGTH OF STORMS AND WITH MODERATELY STRONG 0-6KM SHEAR OF 35-50KTS WE COULD SEE A FEW SUPERCELLS OVER NORTHWEST MO THIS EVENING. WITH A VERY HIGH FREEZING LEVEL AROUND 15.5K FT AGL IT WILL TAKE SOME PRETTY STOUT STORMS TO PRODUCE LARGE HAIL. PROGGED SOUNDING PROFILES ALSO SUPPORT DAMAGING WIND POTENTIAL DUE TO PRECIPITATION LOADING FROM HIGH BASED STORMS. AND WILL ALSO NEED TO CONSIDER HEAVY RAIN THREAT THIS EVENING ACROSS NORTHWEST MO DUE TO STORMS TRAINING OVER THE SAME AREAS WHERE PRECIPITABLE WATER VALUES ARE RUNNING 150-175 PERCENT OF NORMAL. THIS INITIAL AREA OF STORMS ARE EXPECTED TO TRACK ACROSS FAR NORTHERN MO AS A LARGE COLD POOL FORMS BEHIND THE COMPLEX OF STORMS AND PULLS AWAY FROM THE COLD FRONT. MODELS ARE IN PRETTY GOOD AGREEMENT THAT A SECOND ROUND OF STORMS WILL FORM LATE THIS EVENING ALONG THE FRONT AS ANOTHER SPEED MAX EJECTS NORTHEAST FROM THE CENTRAL ROCKIES. THIS ACTIVITY WOULD MOST LIKELY AFFECT WEST CENTRAL TO CENTRAL MO NORTH OF THE MO RIVER WELL AFTER MIDNIGHT. MONDAY MORNING CONVECTION SHOULD BE EXITING THE SOUTHERN CWA. COULD SEE A RELATIVELY LONG BREAK BEFORE THE NEXT THREAT OF STORMS ARRIVES MONDAY EVENING. COLD FRONT MAY BE QUITE DIFFICULT TO LOCATE ON MONDAY DUE TO CONTAMINATION OF WIND FIELDS BY OVERNIGHT CONVECTION. HOWEVER...BEST ESTIMATE IS THE TRUE COLD FRONT WILL LIE OVER NORTHWEST MO IN THE MORNING. CANNOT RULE OUT WIDELY SCATTERED AFTERNOON CONVECTION AHEAD OF THE FRONT BUT BELIEVE BETTER THREAT OF ANOTHER ROUND OF CONVECTION WILL ARRIVE MONDAY EVENING AS AN IMPULSE EJECTS ENE FROM CO. NAM/GFS/ECMWF ARE VERY SIMILAR ON SUCH AN OCCURRENCE ALTHOUGH THE GFS IS OVERLY CONTAMINATED BY CONVECTIVE FEEDBACK. MONDAY TEMPERATURES COULD BE PROBLEMATIC DUE TO HOW EXTENSIVE CONVECTIVE DEBRIS ENDS UP. FOR NOW WILL GO THE CONSERVATIVE ROUTE AND STICK WITH NEAR NORMAL TEMPERATURES. CONVECTION SHOULD EXIT THE SOUTHERN PART OF THE CWA BY TUESDAY AFTERNOON WITH COOLER/DRIER HIGH PRESSURE BUILDING INTO THE REGION. WILL LOWER TEMPERATURES BY A FEW DEGREES. MJ MEDIUM RANGE (WEDNESDAY THROUGH SUNDAY)... LITTLE CHANGE IN CURRENT THINKING FOR MIDWEEK THROUGH THE COMING WEEKEND. MODELS IN FAIR AGREEMENT THAT UPPER RIDGE IN FOUR CORNERS WILL KEEP MIDDLE SECTION OF THE US IN WEAK FLOW ALOFT...AND FOR THE MOST PART DRY CONDITIONS. MEANWHILE...TEMPERATURES AT 850 MB WILL REMAIN NEARLY ISOTHERMAL AROUND 15 DEG C THROUGH THE MIDDLE STAGES OF THE WEEK WITH MAYBE A DEGREE OR TWO WARMER BY THE END OF THE WEEK. THEREFORE...WILL SLIGHTLY SCALE BACK THE WARMING TREND TO ALSO ACCOUNT FOR A POTENTIAL WEAK TROUGH THAT MAY BRING SOME SHOWERS AND THUNDERSTORMS AS EARLY AS WEDNESDAY. THE IMPULSE THAT MAY SPAWN THIS ACTIVITY IS VERY WEAK AND WELL AHEAD OF THE MAIN TROUGH THAT WILL JUST BE MAKING LANDFALL IN THE PACIFIC NORTHWEST. THEREFORE...IT IS NOT LIKELY THAT ANY SIGNIFICANT ACTIVITY WILL BE GENERATED FROM WHAT MAY JUST BE A SPURIOUS SHORTWAVE SHOWING IN MODEL HEIGHT FIELDS OVERTOPPING THE RIDGE. THE MAIN UPPER TROF PUSHES EASTWARD THROUGH SOUTHERN CANADA LATER IN THE WEEK...WE WILL SEE HEIGHTS LOWER FRIDAY AND USHER IN A SURFACE COLD FRONT FROM THE NORTHWEST. THE ECMWF IS STILL A BIT FASTER THAN THE GFS BUT BOTH ARE INDICATING THAT A FRONT WILL BE ACCOMPANYING THE UPPER TROF AS IT TRAVERSES THROUGH THE UPPER MIDWEST INTO THE GREAT LAKES. MAIN ENERGY FROM THIS FEATURE LOOKS TO STAY WELL NORTH INTO CANADA WHICH WOULD SLOW PROGRESSION SPEED INTO THIS AREA SO PROBABLY BEST CHANCES FOR PRECIPITATION ALONG THE FRONT WILL NOT BE UNTIL SUNDAY AFTERNOON. ADOLPHSON && .AVIATION... FOR THE 18Z TAF CONCERNS WILL NOW SHIFT TO CONVECTIVE POTENTIAL. SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED TO FORM BY MID AFTERNOON ALONG AND BEHIND A COLD FRONT CURRENTLY STRETCHING FROM SOUTHWEST IA THROUGH SOUTHWEST KS. THIS BOUNDARY WILL BE SLOW TO MOVE EASTWARD TODAY...SO UNTIL ITS ARRIVAL EXPECT NEARLY CLOUD FREE SKIES AND GUSTY SSW WINDS. COULD SEE TWO ROUNDS OF CONVECTION AT THE KSTJ TERMINAL WITH THE FIRST OCCURRING VERY EARLY THIS EVENING AS THE INITIAL ACTIVITY OVER KS LIFTS NORTHEAST THROUGH NORTHWEST MO. A SECOND ROUND OF CONVECTION MAY FORM OR MOVE INTO THE KSTJ TERMINAL AROUND OR SHORTLY AFTER MIDNIGHT WITH THE ACTIVITY EVENTUALLY SPREADING INTO THE KMCI/KMKC TERMINALS DURING THE PRE-DAWN HOURS. WITH A VERY HIGH FREEZING LEVEL AM EXPECTING HIGH BASED STORMS SO VFR CEILINGS MOST LIKELY WITH ANY ACTIVITY. SMALL HAIL AND STRONG WINDS ARE POSSIBLE WITH STRONGER STORMS BUT WILL ADDRESS THAT POSSIBILITY USING UPDATES AS CONFIDENCE LOW ON THIS OCCURRING AT A PARTICULAR POINT. SHOULD THE STORMS ORGANIZE INTO A MEANINGFUL CLUSTER THERE COULD BRIEF PERIODS OF MVFR CEILINGS AS THE CONVECTION PASSES THROUGH. AGAIN THAT IS BEST LEFT TO FUTURE UPDATED FORECASTS AFTER CONVECTION EVOLVES LATE THIS AFTERNOON. MJ && .EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE.
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 106 PM CDT SUN AUG 9 2009 KSZ025-057-060-102>105-MOZ001>008-011>017-020>025-028>033-037>040- 043>046-053-054-101815- ATCHISON KS-MIAMI-LINN KS-DONIPHAN-LEAVENWORTH-WYANDOTTE- JOHNSON KS-ATCHISON MO-NODAWAY-WORTH-GENTRY-HARRISON-MERCER- PUTNAM-SCHUYLER-HOLT-ANDREW-DE KALB-DAVIESS-GRUNDY-SULLIVAN-ADAIR- BUCHANAN-CLINTON-CALDWELL-LIVINGSTON-LINN MO-MACON-PLATTE-CLAY- RAY-CARROLL-CHARITON-RANDOLPH-JACKSON-LAFAYETTE-SALINE-HOWARD- CASS-JOHNSON MO-PETTIS-COOPER-BATES-HENRY- 106 PM CDT SUN AUG 9 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHWEST...NORTH CENTRAL AND WEST CENTRAL MISSOURI...AS WELL AS EXTREME EASTERN KANSAS. .DAY ONE...THIS AFTERNOON AND TONIGHT THERE IS A CHANCE FOR THUNDERSTORMS LATE SUNDAY AFTERNOON ACROSS FAR NORTHWEST AND NORTH CENTRAL MISSOURI...THEN ACROSS MUCH OF THE REGION NORTH OF THE MISSOURI TONIGHT. SCATTERED THUNDERSTORMS FORMING ALONG AND BEHIND A COLD FRONT FROM SOUTHWEST IOWA THROUGH SOUTHWEST KANSAS WILL SHIFT SLOWLY EAST AND INCREASE IN COVERAGE THIS AFTERNOON. ALTHOUGH THE AIRMASS AHEAD OF THE FRONT IS MODERATELY UNSTABLE THERE IS A VERY WARM LAYER ALOFT WHICH WILL INITIALLY PREVENT THUNDERSTORM DEVELOPMENT. SCATTERED THUNDERSTORMS ARE EXPECTED TO ENTER FAR NORTHWEST MISSOURI BY LATE AFTERNOON AND CONTINUE EAST ACROSS FAR NORTHERN MISSOURI. A SECOND ROUND OF THUNDERSTORMS WILL FORM BY LATE EVENING AND THESE WILL TRACK SOUTHEAST TO THE MISSOURI RIVER BY SUNRISE MONDAY. A FEW STORMS MAY BECOME SEVERE DURING THE LATE AFTERNOON AND EVENING HOURS IN NORTHWEST MISSOURI...GENERALLY NORTH OF AN OREGON TO BETHANY LINE. THE COMBINATION OF MODERATE SHEAR AND INSTABILITY WILL BE SUFFICIENT TO SUPPORT A FEW ROTATING THUNDERSTORMS WHICH COULD PRODUCE LARGE HAIL AND DAMAGING WINDS. IN ADDITION...ANOTHER HOT AND HUMID AFTERNOON IS EXPECTED ACROSS THE REGION WITH HEAT INDEX VALUES OF 99 TO 103 EXPECTED. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY AS THE COLD FRONT SAGS SOUTHEAST DURING THE DAY MONDAY IT MAY TRIGGER ADDITIONAL THUNDERSTORMS THROUGHOUT THE REGION WITH THESE STORMS SHIFTING GENERALLY SOUTH OF THE MISSOURI RIVER BY MONDAY NIGHT INTO TUESDAY MORNING. THERE CONTINUES CONSIDERABLE UNCERTAINTY REGARDING WHETHER ANY STORMS WILL BE SEVERE MONDAY AFTERNOON. HOWEVER...AT THIS TIME A FEW SEVERE STORMS CAN NOT BE RULED OUT. LARGE HAIL AND HIGH WINDS WOULD BE THE MAIN HAZARDS WITH THE STRONGEST STORMS. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED LATE SUNDAY AFTERNOON AND EVENING ACROSS NORTHWEST MISSOURI. MJ
The Omaha radar (KOAX), 122 km away, was scanning. The volume nearest the first event began at 22:07 UTC.
6 thunderstorm wind. Local standard time, as filed.
At the intersection of Highways 136 and 275, large signs were reported blown down.
Large tree limbs were reported down on their property.
A trained spotter estimated wind gusts to 70 mph.
Thunderstorm wind gusts were estimated to 60 mph, and lasted up to 10 minutes.
Trees and power lines were reported down.
Trees and power lines were reported down.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Missouri in 2009Every state in 2009This day in weather historyWarnings in Missouri, 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: 190570, 190569, 190571, 190572, 190573, 190574.