Unusually warm weather over the previous four weeks allowed heavier rain than normal to fall in early December with many locations receiving precipitation that was 200 to 300% above normal. This caused many rivers to flood during December.
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.
Unusually warm weather over the previous four weeks allowed heavier rain than normal to fall in early December with many locations receiving precipitation that was 200 to 300% above normal. This caused many rivers to flood during December.
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 Dec 20, 11:44 PM CST, 3 hours 16 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE QUAD CITIES IA IL 1144 PM CST SUN DEC 20 2015 ...AVIATION UPDATE... .UPDATE... ISSUED AT 722 PM CST SUN DEC 20 2015 EVENING UPDATE MAINLY FOR MINOR ADJUSTMENTS TO POP TRENDS OVERNIGHT INTO MONDAY MORNING. AREAS SOUTH OF INTERSTATE 80 STILL FAVORED FOR ISOLATED THUNDERSTORMS OVERNIGHT. && .SYNOPSIS... ISSUED AT 330 PM CST SUN DEC 20 2015 STRATUS CREEPING NORTHWARD IN THE MOISTURE RETURN HAD REACHED NW MO AND SW AND CENTRAL PORTIONS OF IA AS OF MID AFTERNOON BASED ON SURFACE OBSERVATIONS. SURFACE ANALYSIS DEPICTED LOW PRESSURE DEVELOPING LEE OF CENTRAL ROCKIES WITH A COLD FRONT IN THE PLAINS FROM WESTERN KS NW TO CENTRAL MN. A VIGOROUS SHORTWAVE WAS EVIDENT ON WV IMAGERY OVER THE CO/NM BORDER REGION WITH A FEED OF PACIFIC MOISTURE AND WEAK GULF RETURN OUT IN ADVANCE ACROSS THE PLAINS AND MID MS VALLEY REGION. OVER THE LOCAL AREA...INITIALLY DRY AIR AT THE SURFACE HAS BEEN SLOW TO SATURATE AND THIN AREAS IN THE HIGH CLOUD COVER HAS ALLOWED TEMPERATURES TO REACH INTO THE MID 40S TO MID 50S. AREA RADARS SHOW VERY HIGH BASED WEAK SHOWERS OR SPRINKLES OVER PORTIONS OF CENTRAL AND EASTERN IA WEST OF A LINE FROM OTTUMWA TO INDEPENDENCE...WHICH HAS SPREAD TOWARD THE DBQ AREA AS OF 3 PM WITH VERY STEEP MID LEVEL LAPSE RATES RESULTING IN ISOLATED THUNDERSTORMS. && .SHORT TERM...(THIS EVENING THROUGH MONDAY) ISSUED AT 330 PM CST SUN DEC 20 2015 UPPER LEVEL SHORTWAVE AND SURFACE CYCLONE OVER THE CENTRAL ROCKIES LIFTS NORTHEAST THROUGH THE FORECAST AREA LATE TONIGHT INTO MONDAY MORNING. THIS INTERACTS WITH INCREASING LOW LEVEL MOISTURE TO SPREAD WIDESPREAD LIGHT RAIN OR DRIZZLE TONIGHT...THEN PRECIPITATION OF MORE OF A SHOWERY NATURE AS THE MAIN FORCING PUSHES THROUGH EARLY MONDAY. MODELS ARE IN DECENT AGREEMENT WITH THE TRACK OF THE UPPER LEVEL FORCING IN THE FORM OF STRONG PVA WITH THE SLIGHTLY NEGATIVE TILTED SHORTWAVE PASSING THROUGH NE MO...SE IA AND W CENTRAL IL AROUND 12Z. AT THE SURFACE...THE LOW TRACKS NORTHEAST ACROSS E CENTRAL IA DURING THIS TIMEFRAME. THE WRF/NAM HAS HAD A SLIGHT EDGE SO FAR WITH ITS SLOWER ADVANCEMENT OF MOISTURE AND QPF AND IS FAVORED IN THE SHORT TERM. HOWEVER...WHILE LESS THAN THE GFS...EVEN THE DRIER WRF/NAM APPEARED TO BE TOO BE TOO MOIST OR AGGRESSIVE WITH HIGHER PW VALUES INTO THE PLAINS COMPARED TO WHAT WAS OBSERVED AT 12Z THIS MORNING. TONIGHT...STEEP MID LEVEL LAPSE RATES AND CONVERGENCE ALONG THE EDGE OF 40 TO 50 KT LOW LEVEL JET WILL CONTINUE THE WIDELY SCATTERED SHOWERS IN THE EVENING. WIDESPREAD ADVANCEMENT OF THE STRATUS AND A DEEPER MOISTURE COLUMN SHOULD THEN SUPPORT WIDESPREAD LIGHT RAIN OVERNIGHT IN THE DEEPER THETAE ADVECTION AND DEVELOPING UPPER LEVEL LIFT TOWARD MORNING AND HAVE LIKELY TO CATEGORICAL POPS. WITH MODEST LIFT DURING THIS TIME...AND MOISTURE NOT LIKELY AS HIGH AS DEPICTED BY MODELS...HAVE KEPT QPF GENERALLY LESS THAN A QUARTER INCH OVERNIGHT. TEMPERATURES WILL BE NEARLY STEADY IN THE 40S TO LOW 50S THROUGH THE NIGHT...THEN BEGIN TO DROP WITH FRONTAL PASSAGE REACHING INTO THE NW EARLIEST...WHERE LOWS MAY REACH THE UPPER 30S AFTER SUNRISE. STRONG FORCING...ANOTHER ROUND OF STEEP MID LEVEL LAPSE RATES... AND THE LOCATION OF A DRY SLOT MAY LEAD TO AT LEAST ISOLATED THUNDERSTORMS ACROSS THE SOUTH AND CONFIDENCE IS NOW HIGH ENOUGH TO PLACE IN THE FORECAST FOR THE EARLY MORNING HOURS. OTHERWISE...THE CONVECTIVE NATURE OF THE PRECIPITATION AROUND SUNRISE THROUGH MID MORNING WILL SUPPORT HEAVIER RAINFALL RATES OVER ESPECIALLY NW IL WHERE A QUARTER TO HALF INCH AMOUNTS WILL BE POSSIBLE. WRAP AROUND DEFORMATION LIGHT RAIN WILL LIKELY PERSIST THROUGH THE MORNING... ENDING OVER MOST OF THE AREA BY EARLY AFTERNOON. WILL KEEP THE REST OF THE DAY CLOUDY AND COOLER THAN TODAY WITH TEMPERATURES HOLDING IN THE 30S NW AND 40S SW IN THE MOIST CYCLONIC FLOW LINGERING BEHIND THE EXITING SYSTEM. .LONG TERM...(MONDAY NIGHT THROUGH NEXT SUNDAY) ISSUED AT 330 PM CST SUN DEC 20 2015 MONDAY NIGHT AND TUESDAY...12Z RUN NAM/GFS AND ECMWF ALL IN DECENT AGREEMENT OF SUGGESTING PASSING UPPER SHORT WAVE TROF AXIS MAY INDUCE SOME LIGHT ISENTROPIC LIFT PRECIP IN THE NORTHEASTERN QUARTER TO THIRD OF THE DVN CWA MON EVENING. FCST SOUNDINGS IN THOSE AREAS WITH TOP-DOWN DRYING OCCURRING IN THE MID LAYERS SUGGEST MAINLY A DRIZZLE SOUNDING...BUT POSSIBLY SOME VERY LIGHT RAIN AS WELL BEFORE THE REAL DRYING OCCURS AND WILL GO WITH A SLIGHT CHC FOR LIGHT RAIN BUT MENTION THE DRIZZLE TOO. IF DRIZZLE HANGS ON LONG ENOUGH IN NORTHWESTERN IL WHILE SFC TEMPS DROP TO FREEZING OR COLDER...THERE MAY BE SOME SPOTTY FREEZING DRIZZLE ISSUES AFTER MIDNIGHT. IF SFC WINDS CAN DROP OFF ENOUGH...THERE MAY BE SOME FOG DEVELOPMENT AS WELL MAINLY ALONG AND NORTH OF HWY 30 MON EVENING. BACKING FLOW IN ALL LEVELS WARM ADVECTS ON TUE WITH ANOTHER LOW TO MID LEVEL INVERSION LIKELY DEVELOPING. THIS MAY TRAP CLOUD COVER IN FOR MUCH OF THE DAY AND LIMIT MIXING...BUT LLVL FLOW INCREASING UNDER THIS FEATURE STILL TO WARM TEMPS SFC LAYER UP IN THE 40S AS THE DAY PROGRESSES. TUESDAY NIGHT...MOST SOLUTIONS SUGGEST STRONG DEEP SOUTHWESTERLY FLOW TO REALLY TAKE HOLD ACRS THE REGION AS UPSTREAM L/W TROF SHIFTS ACRS THE WESTERN PLAINS. THE WARM MOIST CONVEYOR ACCELERATES OVERNIGHT INTO EARLY WED MORNING...WITH 40-50+ KT SOUTH- SOUTHWESTERLY LOW-LEVEL JET/LLJ FORECAST TO TAKE AIM AT THE AREA. ANOTHER ROUND OF UNSEASONABLY PWAT/S ALSO IS BEING SUGGESTED BY INCOMING VERTICAL PROFILES...WITH VALUES INCREASING FROM 0.80 TO AROUND AN INCH BY WED MORNING ACRS MUCH OF THE DVN CWA. WHILE MUCH OF TUE EVENING MAY BE DRY..WILL INCREASE POPS FROM MIDNIGHT ON THRU 12Z WED FOR AREAS OF RAIN OR SHOWERS DEVELOPING AND QUICKLY MOVING UP ACRS THE AREA IN PROGRESSIVE FLOW. 12 HR LOWS TO OCCUR EARLY IN THE EVENING...WITH TEMPS STEADY TO RISING OVERNIGHT. WEDNESDAY AND THURSDAY...THE 12Z RUN MEDIUM RANGE MODELS IN GENERAL AGREEMENT OF SUGGESTING A DEEPENING SFC LOW/POSSIBLY SUB 990 MB/ WILL LOOK TO ROLL NORTH-NORTHEASTWARD ACRS THE WESTERN CWA AND MAKE IT INTO WI BY AFTERNOON. WITH THE CURRENTLY PROGGED FORCING AND SATURATION...THERE IS THE POTENTIAL FOR UP TO AN INCH OF RAIN ACRS THE EASTERN HALF OF THE CWA BY WED EVENING...AND 0.40 TO 0.80 ACRS THE WESTERN HALF TAKING INTO ACCOUNT LATEST LOW TRACK. THIS AMOUNT OF RAIN AND RUN-OFF COULD AGGRAVATE ONGOING RIVER FLOODING SITUATIONS... AS WELL AS PRODUCE PONDING OF WATER AGAIN ON STREETS AND DRAINAGE DITCHES...ELEVATED CREEK/STREAM LEVELS. THE PRECIP SHOULD BE ON THE WAY OUT WED EVENING...ALTHOUGH THE 12Z GFS WRAPS IN POST-SYSTEM COLD CONVEYOR FOR A PRECIP SWITCH TO WET SNOW WITH SOME LIGHT ACCUMULATIONS POSSIBLE IN THE NORTHWEST. THE 12Z EURO AND NAM SUGGEST MOST OF THE PRECIP TO BE EAST OF THE AREA BY THE TIME THE COLUMN COOLS TO SNOW PRODUCING PARAMETERS...FOR NOW PREFER THIS IDEA WITH PROGRESSIVE NATURE OF THE SYSTEM. WILL GO DRY AND COOLER FOR THU AS THE MEDIUM RANGE MODELS SUGGEST LLVL BAROCLINICITY RE-ALIGNS UNDER BROAD WEST-SOUTHWESTERLIES TO THE SOUTH OF THE REGION. FRIDAY THROUGH NEXT SUNDAY...LARGE MEDIUM RANGE MODEL AND RUN-TO-RUN DISCREPANCIES CONTINUE THIS PERIOD FOR ONGOING LOW CONFIDENCE IN HANDLING A POTENTIAL WEEKEND STORM SYSTEM. THE 12Z GFS NOW EJECTS A LOW PRESSURE OUT OF THE SOUTHERN PLAINS AND TOWARD THE SOUTHERN CWA LATE FRI NIGHT AND SAT...WITH THIS MODEL SUGGESTING MAINLY RAIN SPREADING UP ACRS THE AREA WITH APPROACHING WARM FRONT LATE FRI NIGHT AND SAT...WITH THE PRECIP TURNING INTO A WINTRY MIX OR TO ALL SNOW SAT NIGHT INTO EARLY SUNDAY MORNING. THE REAL HEAVY RAIN AXIS OF THE GFS LAYS OUT MAINLY TO THE SOUTH AND EAST OF THE DVN FCST AREA ON SAT AND SAT NIGHT. THE 12Z ECMWF IS WEAKER WITH AN INITIAL LOW AN MAKES FOR AN ACTIVE STALLED BOUNDARY TO THE SOUTH OF THE CWA SAT INTO SUNDAY...BUT STILL PRODUCES SOME DECENT OVERRUNNING RAINS ACRS THE SOUTHERN 2/3S OF THE DVN CWA SAT NIGHT...WITH THE ACTIVE FRONT SETTLING SOUTHWARD ON SUNDAY TAKING THE RAIN WITH IT. BUT IT THEN EJECTS OUT THE MAIN LOW MON NIGHT INTO NEXT TUE BUT IS WARM ENOUGH FOR ANOTHER DEF ZONE RAIN EVENT. NEEDLESS TO SAY THE MODELS ARE HAVING TROUBLE WITH THE WEEKEND WAVE ENERGY/PHASING IN THAT TYPE OF FLOW AND WILL HAMMER OUT A GENERAL SOLUTION FOR THE WEEKEND WITH LOW TO MODERATE CHC POPS UNTIL MORE CONFIDENCE/MODEL AGREEMENT OCCURS. ..12.. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1138 PM CST SUN DEC 20 2015 CIGS WILL CONTINUE TO DROP OVERNIGHT...EVENTUALLY BECOMING IFR THEN LIFR INTO MONDAY MORNING. EXPECT A SECONDARY SURGE OF SHOWERS/ISOLD THUNDER AFTER 09Z...EXITING AREA BY 18Z. BEST CHANCE OF THUNDER AT KBRL...BUT HAVE NOT INCLUDED IN TAF DUE TO THE ISOLATED COVERAGE EXPECTED. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && UPDATE...RP KINNEY SYNOPSIS...SHEETS SHORT TERM...SHEETS LONG TERM...12 AVIATION...RP KINNEY
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE QUAD CITIES IA IL 343 PM CST SUN DEC 20 2015 IAZ040>042-051>054-063>068-076>078-087>089-098-099-ILZ001-002-007- 009-015>018-024>026-034-035-MOZ009-010-212145- 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- 343 PM CST SUN DEC 20 2015 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...THIS AFTERNOON AND TONIGHT ISOLATED THUNDERSTORMS ARE POSSIBLE LATE TONIGHT INTO EARLY MONDAY MORNING...MAINLY SOUTH OF INTERSTATE 80. SEVERE WEATHER IS NOT EXPECTED. AREA RIVERS ARE EXPERIENCING FLOODING. PLEASE SEE THE LATEST FLOOD STATEMENTS AND FLOOD WARNINGS FOR DETAILS. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED TONIGHT. SHEETS
The national radar mosaic for the moment the first event began.
2 flood. Local standard time, as filed.
The Wapsipinicon River near DeWitt rose above the major flood stage of 12.5 feet at midnight on December 21 and fell below 12.5 feet around noon on December 24. The river crested at 12.97 feet at 9:15AM on December 22.
The Wapsipinicon River near DeWitt rose above the major flood stage of 12.5 feet at midnight on December 21 and fell below 12.5 feet around noon on December 24. The river crested at 12.97 feet at 9:15AM on December 22.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2015Every state in 2015This day in weather historyWarnings in Iowa, December 2015
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: 610059, 610061.