A developing low pressure system moved through northeast Kansas into northern Missouri just south of the Iowa border during the evening of the 17th. A strong push of 50 degree dew points pushed north just ahead of the low.
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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 DMX wrote it up.
A developing low pressure system moved through northeast Kansas into northern Missouri just south of the Iowa border during the evening of the 17th. A strong push of 50 degree dew points pushed north just ahead of the low. The destabilization of the atmosphere resulted in rapid development of thunderstorms over southeast Iowa. One of the storms became severe northwest of the Ottumwa area in Wapello County and produced penny to nickel size hail.
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 Des Moines, IA wrote its last area forecast discussion before the first event at Feb 17, 9:22 PM CST, 2 hours 13 minutes earlier.
AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE DES MOINES IA 922 PM CST TUE FEB 17 2009 .DISCUSSION... MOISTURE AVAILABILITY WITH CURRENT SYSTEM CONTINUES TO BE LACKING AND LIKELY WILL NOT IMPROVE UNTIL THE SYSTEM PULLS EAST OF THE AREA. DRY SLOT HAS WORKED INTO SOUTHWEST IOWA WITH CLEAR SKIES OVER THE SW 6 COUNTIES AND SOME INCREASE IN CEILING HEIGHTS OVER CENTRAL IOWA TAKING PLACE. PRIMARY MOISTURE TRANSPORT FROM THE GULF OF MEXICO IS POINTED INTO THE LOWER OHIO VALLEY. TEMPERATURES THIS EVENING ARE HOLDING STEADY...ABOVE FREEZING AND IN THE 30S WHILE COLD FRONT JUST NOW ENTERING NW IA. EVEN LESS MOISTURE IS AVAILABLE POST FRONTAL THUS ONCE SNOW DOES DEVELOP...IT WILL BE QUITE LIGHT. STILL POSSIBLE THAT AN INCH...MAYBE TWO...COULD FALL OVER THE FAR NORTHEAST WITH LESSER AMOUNTS SOUTH AND WEST THOUGH THAT MAY BE STRETCHING IT. CHANCES FOR ANY ICE STILL LOW WITH WARM BUBBLE NEAR THE SFC IN PLACE UNTIL COOLING ALOFT TAKES PLACE AND ANY PRECIPITATION SWITCHES TO SNOW. && .PREVIOUS DISCUSSION... .SHORT TERM...TODAY PRECIPITATION TYPE AND TRENDS WILL BE A CHALLENGE TONIGHT. LATEST FORECAST SOUNDINGS SUGGEST AIR ALOFT QUICKLY SATURATING AND COOLING LATER THIS EVENING AND OVERNIGHT. FREEZING RAIN MAY BE LESS OF AN ISSUE...AS PROFILES JUST ABOVE ZERO CENTRAL AND NORTH INDICATE S/IP MIX...AND IN THE SOUTH RAIN WITH A QUICK TRANSITION TO SNOW OVERNIGHT. STAYED CONSERVATIVE WITH SNOWFALL AMOUNTS...WITH MAX AMOUNTS 1-1.5 INCHES IN THE NORTHEAST COUNTIES. LOCAL 18Z WRF RUN INDICATING DEF ZONE SNOW TRANSLATING FROM NW TO SE OVERNIGHT...SO DID NOT TRY TO NAIL A PARTICULAR SNOW AXIS PER THE GFS/NAM12. STAYED A COUPLE OF DEGREES ABOVE GUIDANCE WITH DENSE CLOUD COVER THROUGH THE OVERNIGHT. SOME ELEVATED INSTABILITY MAY CLIP SOUTHERN IOWA OVERNIGHT. INTRODUCED SHOWERS...BUT NOT THUNDER ATTM...SOMETHING FOR EVENING SHIFT TO MONITOR. && .LONG TERM...WEDNESDAY THROUGH TUESDAY CAA WILL INTENSIFY ON WEDNESDAY AS TROF CONTINUES TO DEEPEN TO THE EAST. FORCING WL END QUICKLY ON WEDNESDAY MORNING WITH PCPN ENDING BY MID MORNING IN MOST LOCATIONS. MAY CONTINUE TO SEE SOME FLURRIES EAST OF INTERSTATE 35 INTO THE AFTERNOON...BUT ANY SIGNIFICANT THREAT FOR PCPN WL BE OVER. PRESSURE GRADIENT WL ALSO BE INCREASING THROUGH THE MORNING AS LOW PRESSURE DEEPENS INTO THE GREAT LAKES. ANTICIPATE SFC WNDS TO BECOME RATHER STRONG FROM THE NORTHWEST BY MID TO LATE MORNING AND PERSIST THROUGH THE DAY. SUSTAINED WINDS OF 20 TO 30 MPH WITH GUSTS OF 40 MPH ARE EXPECTED AND WL HAVE TO WATCH FOR PSBL ADVISORY CRITERIA. TEMPERATURES ARE LIKELY TO REMAIN STEADY OR SLOWLY FALL...ESPECIALLY IN THE EAST DURING WEDNESDAY AS THERMAL TROF ENTERS THE STATE. THE COLD WEATHER WL PERSIST INTO THURSDAY AS SFC RIDGE SLOWLY ENTERS THE STATE. BOTH GFS/NAM ARE CONSISTENT WITH CLIPPER SYSTEM RACING THROUGH THE STATE ON FRIDAY. STRONG WAA AND FORCING WL HELP QUICKLY SATURATE THE ATMOSPHERE AND ANTICIPATE SOME ACCUMULATING SNOWFALL DURING THE DAY...ESPECIALLY FROM AFTERNOON INTO THE EVENING. RIGHT NOW...1 TO 3 INCHES SEEMS MOST LIKELY FOR MUCH OF THE CENTRAL AND NORTHERN PORTIONS OF THE CWA. WL SEE ANOTHER INVIGORATING SHOT OF COLD AIR INTO SATURDAY BEFORE WAA TAKES OVER ONCE AGAIN BY SUNDAY. THE MODERATION APPEARS TO CONTINUE INTO EARLY NEXT WEEK AS SOUTHERLY FLOW PERSISTS INTO THE MIDWEST. && .AVIATION...18/00Z CEILINGS BEGINNING TO LOWER QUICKLY OVER THE NORTHERN PORTION OF THE AREA ONCE THE SUN SET AND CEILINGS AND VISIBILITIES WILL CONTINUE TO DECREASE THIS EVENING. PRECIPITATION WILL MAINLY FALL IN THE FOR AS LIGHT RAIN OR DRIZZLE THIS EVENING THEN TRANSITION TO SNOW AFTER MIDNIGHT. WINDOW FOR FREEZING DRIZZLE LOOKS QUITE NARROW AT THIS TIME AND HAVE LEFT OUT OF THE TERMINALS. SOME UNCERTAINTY ABOUT HOW LONG THE DRY SLOT MOVING INTO SW IA WILL LAST AND IF IT WILL HAVE AN IMPACT AT KOTM. MODEL GUIDANCE WOULD SUGGEST CEILINGS LOWERING QUICKLY HERE BUT WITH UNCERTAINTY...HAVE NOT GONE LOWER THAN MVFR AT THIS TIME. COLD FRONT WILL PASS THROUGH LATE TONIGHT AND EARLY WED MORNING WITH GUSTY NW WINDS PERSISTING THE REMAINDER OF THE DAY. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && SHORT TERM/AVIATION...DONAVON PREVIOUS DISCUSSION...KINNEY/COGIL
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE DES MOINES IA 344 PM CST TUE FEB 17 2009 IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075- 081>086-092>097-181200- EMMET-KOSSUTH-WINNEBAGO-WORTH-PALO ALTO-HANCOCK-CERRO GORDO- POCAHONTAS-HUMBOLDT-WRIGHT-FRANKLIN-BUTLER-BREMER-SAC-CALHOUN- WEBSTER-HAMILTON-HARDIN-GRUNDY-BLACK HAWK-CRAWFORD-CARROLL-GREENE- BOONE-STORY-MARSHALL-TAMA-AUDUBON-GUTHRIE-DALLAS-POLK-JASPER- POWESHIEK-CASS-ADAIR-MADISON-WARREN-MARION-MAHASKA-ADAMS-UNION- CLARKE-LUCAS-MONROE-WAPELLO-TAYLOR-RINGGOLD-DECATUR-WAYNE- APPANOOSE-DAVIS- 344 PM CST TUE FEB 17 2009 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA. .DAY ONE...TONIGHT LIGHT RAIN AND DRIZZLE WILL CHANGE OVER TO SNOW AND SLEET THIS EVENING ALONG AND NORTH OF HIGHWAY 30...WITH ALL RAIN SOUTH OF HIGHWAY 30. AFTER MIDNIGHT...PRECIPITATION IN CENTRAL IOWA WILL TRANSITION TO ALL SNOW...WHILE SOUTHERN IOWA EXPERIENCES A MIX OF RAIN AND SNOW. TOTAL SNOWFALL AMOUNTS NORTH OF HIGHWAY 30 WILL RANGE FROM A HALF INCH...TO NEAR 1.5 INCHES NEAR MASON CITY AND WATERLOO. SOUTH OF HIGHWAY 30...SNOW AND SLEET ACCUMULATIONS SHOULD BE LIMITED TO A HALF INCH OR LESS. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY LIGHT SNOW WILL LINGER INTO WEDNESDAY MORNING...WITH MINOR ADDITIONAL ACCUMULATIONS OF A HALF INCH OR LESS POSSIBLE EAST OF INTERSTATE 35. NORTHWEST WINDS WILL INCREASE TO 20 TO 30 MPH WITH GUSTS AROUND 40 MPH WEDNESDAY...WHICH COMBINED WITH FALLING SNOW WOULD REDUCE VISIBILITY SIGNIFICANTLY. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED.
The Des Moines radar (KDMX), 126 km away, was scanning. The volume nearest the first event began at 05:34 UTC.
2 hail. Local standard time, as filed.
Hail lasted 5 to 10 minutes and was still on the ground late the following afternoon.
Hail covered the ground with some hail remaining on the ground the following afternoon.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2009Every state in 2009This day in weather historyWarnings in Iowa, February 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: 146306, 146307.