Flooding and Heavy Rain in Iowa, July 15 to 17, 2015

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
400 AM CDT WED JUL 15 2015

.SHORT TERM /TODAY/...
ISSUED AT 400 AM CDT WED JUL 15 2015

CONVECTIVE TRENDS WILL BE THE MAIN FOCUS TODAY BUT UNFORTUNATELY
CONFIDENCE IS LOW.  KS/NE MCSS ARE REMNANTS OF PEAK HEATING
CONVECTION DRIVEN BY WEAK NE BOUNDARY AND SUBTLE SHORT WAVES LIFTING
THROUGH NM AND CO. WOULD HAVE EXPECTED MORE OF A DIMINISHING TREND
BY NOW WITH CONVECTION ENTERING HIGH MUCAPE AREA BUT ALSO HIGH
MUCINHS. DIFFICULT TO FIND MUCH SUPPORT IN SOUNDING PARCEL TRACES
DOWNSTREAM. THERE IS SOME WEAK WARM ADVECTION NOTED
H85/H7...ESPECIALLY LOWER TOWARD H85...BUT COMPLEXES SEEM QUITE
ELEVATED AND ARE LIKELY DRIVEN MORE BY WEAK SHORT WAVES EMBEDDED IN
MOIST FLOW ATOP THE SRN PLAINS RIDGE. THERE IS SOME 0-2KM MOISTURE
CONVERGENCE AHEAD OF THE CLUSTERS...BUT CONVECTION WOULD SEEM TO BE
ROOTED ABOVE THAT. THE POSITIVE TO NEGATIVE CG RATE ACROSS KS IS
QUITE HIGH SUGGESTION A VERY ELEVATED NATURE.

RAP DOES NOT APPEAR TO BE HANDLING CURRENT SITUATION WELL WITH
LITTLE IN THE WAY OF A PV COUPLET SHOWING UP ASSOCIATED WITH POTENT
KS MCS. THERE IS LITTLE SUPPORT THERMODYNAMICALLY INTO IA...BUT NERN
NE MCS IS SHOWING NO SIGNS UP DISSIPATING EITHER SO HAVE BROUGHT
CHANCE POPS INTO WRN IA THIS MORNING AND SLOWLY PUSHING EASTWARD
INTO THE AFTERNOON.  ECMWF AND GFS MID LEVEL FORCING...CURRENTLY
OVER KS/NE...TAKES ITS TIME GETTING EASTWARD ONLY REACHING FAR ERN
FORECAST AREA BY 00Z. ITS DIFFICULT TO HAVE TOO MUCH CONFIDENCE
HOWEVER AS RADAR TRENDS ARE BUCKING WHAT MODELS AND SUBJECTIVE
ANALYSIS WOULD SUGGEST.

HAVE KEPT TEMPS AT OR BELOW THE LOW END OF GUIDANCE WITH CONVECTIVE
DEBRIS AND EASTERLY WINDS GETTING NO BETTER THAN SELY INTO THE
AFTERNOON...AND OF COURSE THE POTENTIAL FOR PRECIP GETTING FARTHER
EAST THAN ANTICIPATED.

.LONG TERM /TONIGHT THROUGH MONDAY/...
ISSUED AT 400 AM CDT WED JUL 15 2015

MAIN FORECAST CHALLENGE FOR THE PERIOD CONTINUES TO BE THE
PLACEMENT OF RAINFALL FOR TONIGHT AND THURSDAY MORNING. WEAK
SURFACE CYCLONE IS STILL PROGGED TO EJECT FROM THE QUASI-
STATIONARY HIGH PLAINS TROUGH DURING THE DAY AS A SUBTLE 500 MB
SHORTWAVE/VORT MAX CRESTS THE SOUTHERN PLAINS HIGH. THESE FEATURES
WILL TRACK OVER THE REGION THROUGHOUT THE COURSE OF THE NIGHT AND
INTO THURSDAY. 00Z MODEL SOLUTIONS ARE STRUGGLING IN THIS WEAK
FLOW PATTERN TO LATCH ON TO A CONSENSUS SOLUTION WITH THE TRACK OF
THE CYCLONE AND ITS ASSOCIATED PRECIPITATION. GFS/NAM/GEM REMAIN
FOCUSED ON A NORTHERN TRACK THAT WOULD TAKE THE HEAVIEST
PRECIPITATION ACROSS NORTHERN IOWA AND SOUTHERN MINNESOTA.
MEANWHILE...THE EC AND RECENT RUNS OF THE NMM/ARW DEVELOP
ELEVATED CONVECTION FURTHER SOUTH ALONG THE LIFTING WARM FRONT AND
TAKE IT ACROSS MUCH OF IOWA.

IN EITHER CASE...THE SETUP REMAINS CONDUCIVE FOR A HEAVY RAIN
EVENT WITH SATURATED SOUNDING PROFILES/PWATS OVER 2
INCHES...STRONG MOISTURE TRANSPORT TIED TO A 40 TO 50 KT LLJ...AND
WARM CLOUD DEPTHS OVER 13 KFT. IN GENERAL USED A COMBINATION OF
WPC GUIDANCE AND THE GFS FOR PLACEMENT OF THE NORTHERN
POPS/QPF...WITH A SWATHS OF HIGHER POPS EXTENDING SOUTHWARD ALONG
THE 925-50MB THETA-E BOUNDARY TO ACCOUNT FOR THIS SOUTHERN
CONVECTION POSSIBILITY. ALSO CANNOT RULE OUT A STRONG STORM EARLY
ON IN THIS SOUTHERN BAND OWING TO HIGHER MUCAPE VALUES OF OVER
1000-1300 J/KG AT 06Z. RAINFALL AMOUNTS IN EXCESS OF 2 INCHES ARE
POSSIBLE IN THE HEAVIEST BANDS OF PRECIP.

THIS SYSTEM SHOULD PUSH EAST OF THE CWA SHORTLY AFTER 12Z
THURSDAY...IF NOT SOONER...AS AN 850 MB THERMAL RIDGE BUILDS IN.
AFTERNOON CONVECTION WILL STILL BE POSSIBLE ACROSS THE
NORTHEASTERN CWA CLOSER TO THE DEPARTING SURFACE LOW WERE THE WARM
NOSE WILL BE LESS PRONOUNCED AND GREATER LIFT WILL EXIST WITH THE
LOW. CLEAR SKIES ACROSS THE NORTH FRIDAY MORNING WILL PROMOTE FOG
DEVELOPMENT IN AREAS THAT SAW HEAVY RAINFALL...BUT DID NOT MENTION
FOG IN THE SOUTH WERE MID LEVEL CLOUDS AND STRONGER WINDS WILL
LIMIT FOG POTENTIAL.

THE STORY FOR THE REST OF FRIDAY AND THE WEEKEND WILL BE A RETURN
OF WARM AND MUGGY AIR WITH THE AFOREMENTIONED SURFACE HIGH PLAINS
TROUGH GRADUALLY MIGRATING OVER NEBRASKA THROUGH
SATURDAY...PROMOTING SOUTHERLY FLOW OFF THE GULF. MULTIPLE ROUNDS
OF SHOWERS AND STORMS ARE POSSIBLE FRIDAY NIGHT INTO SATURDAY AS A
SERIES OF UPPER LEVEL WAVES INTERACT WITH THE BOUNDARY. THE BETTER
THREAT FOR STORMS WILL COME SUNDAY AS AN AMPLIFYING PATTERN WILL
USHER THE BOUNDARY EASTWARD ACROSS IOWA. THIS WILL BRING COOLER AND
DRY WEATHER TO START NEXT WEEK.

&&

.AVIATION...15/06Z
ISSUED AT 1151 PM CDT TUE JUL 14 2015

VFR CONDITIONS WILL CONTINUE TO BE WIDESPREAD DURING THE OVERNIGHT
AND INTO WEDNESDAY. HIGH CLOUDS FROM CONVECTION TO THE WEST WILL
REMAIN OVER THE STATE DURING THIS TIME FRAME WITH LIGHT NORTHEAST
TO EAST SURFACE WINDS BECOMING SOUTHEAST ON WEDNESDAY. WITH
INCREASING WARM ADVECTION...MOISTURE TRANSPORT AND DECENT QG
FORCING ARRIVING LATER ON WEDNESDAY...ANTICIPATE CONVECTION
INCREASING IN WESTERN IOWA AND SPREADING EASTWARD INTO PORTIONS OF
THE AREA BY THE END OF THE PERIOD. THESE STORMS WILL BRING AN
INCREASING THREAT OF MVFR TO IFR CONDITIONS IN AND AROUND THE
STORMS.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

SHORT TERM...SMALL
LONG TERM...SKOW
AVIATION...COGIL

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
417 AM CDT WED JUL 15 2015

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-
081>086-092>097-160930-
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-
417 AM CDT WED JUL 15 2015

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA.

.DAY ONE...TODAY AND TONIGHT

THUNDERSTORMS WILL AFFECT PORTIONS OF CENTRAL IOWA WEST OF
INTERSTATE 35 THIS AFTERNOON...SPREADING EAST ACROSS THE REST OF
THE AREA THIS EVENING. HEAVY RAINFALL WILL BE THE MAIN THREAT
WITH THESE STORMS WHICH COULD LEAD TO LOCALIZED FLOODING.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

THUNDERSTORMS WILL BE POSSIBLE ACROSS EASTERN PORTIONS OF THE AREA
ON THURSDAY...WITH A SLIGHT CHANCE OF STORMS POSSIBLE SOUTH ON
FRIDAY MORNING. OCCASIONAL STORMS WILL THEN BE POSSIBLE THROUGHOUT
THE AREA FROM FRIDAY NIGHT THROUGH MONDAY MORNING. THE THREAT FOR
SEVERE WEATHER APPEARS LOW AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED AT THIS TIME.

KS