Heavy Rain in Iowa, August 15 to 16, 2014

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
650 AM CDT FRI AUG 15 2014

.SHORT TERM /TODAY/...
ISSUED AT 327 AM CDT FRI AUG 15 2014

SHOWERS AND THUNDERSTORMS BREAKING OUT ON LEADING EDGE OF WARM AIR
ADVECTION MOVING INTO WESTERN IOWA THIS MORNING. EURO 315K
SIMILAR TO GFS WITH FIRST AREA OF WARM AIR ADVECTION/BROAD AREA OF
WEAK ISENTROPIC LIFT BUILDING OVER THE WEST AS IT SLIDES ESE WITH
TIME IN PREVAILING H700 NORTHWEST FLOW. EXPECT THE AREA TO
GRADUALLY WEAKEN A BIT AS IT MOVES EAST SOUTHEAST INTO CENTRAL
IOWA TOWARD 18Z. CLOUDS AND WIDESPREAD SHOWERS TODAY WILL KEEP
TEMPERATURES DOWN FOR THE DAYTIME HOURS. HAVE LOWERED HIGHS TO THE
UPPER 70S/NEAR 80 MARK OVER MOST OF THE FORECAST AREA TODAY...AND
THAT MIGHT BE OPTIMISTIC AT A FEW SITES. DEW POINTS ARE FORECAST
TO GRADUALLY RISE BY DAYS END WITH SHOWERS. BY 18Z FORCING MOVES
OFF INTO CENTRAL/SOUTHEAST SECTIONS...WITH ANOTHER SURGE OF
MOISTURE TRANSPORT PUSHING NORTHEAST OUT OF KANSAS TOWARD 00Z.
THIS WILL RESULT IN A RENEWED THREAT FOR MORE ORGANIZED
THUNDERSTORMS BY LATE AFTERNOON/EARLY EVENING OVER THE SOUTHWEST.
UPPER LEVEL WIND FIELDS INCREASE MODESTLY AS UPPER LEVEL SYSTEM
OVER CENTRAL NEBRASKA THIS MORNING DRIFTS EAST TOWARD NORTHEAST
KANSAS BY LATE AFTERNOON. THERE MAY BE A FEW STRONG THUNDERSTORMS
OVER THE SOUTHWEST LATE THIS AFTERNOON OR EVENING. BUFKIT/BUFR
SOUNDINGS SHOW DRY LAYER NEAR THE SFC WHICH MAY LEAD TO A FEW
STORMS WITH THE POTENTIAL FOR A FEW SEVERE WIND GUSTS. ONCE AGAIN
TODAY...MODELS CONTINUE TO ADVERTISE PWATS INCREASING TO 2 INCHES
OVER THE WEST/SOUTHWEST BY 00Z WITH WARM CLOUD DEPTHS OF 13- 14KFT
OVER THE SOUTHWEST AND SOUTH BY 00Z AND THIS WILL LEAD TO
EFFICIENT RAINFALL FOR LATE AFTERNOON/EVENING/OVERNIGHT TONIGHT
OVER THE SOUTH.

.LONG TERM /TONIGHT THROUGH THURSDAY/...
ISSUED AT 327 AM CDT FRI AUG 15 2014

FORECAST REMAINED FOCUSED ON TIMING AND LOCATION OF PRECIPITATION
TONIGHT THROUGH EARLY NEXT WEEK. SEVERAL SHORTWAVES LOOK TO MOVE
ACROSS THE REGION AND MODELS ARE BEGINNING TO SHOW SOME CONTINUITY
WRT TO LOCATION THROUGH THE WEEKEND...BUT STILL SOME SIGNIFICANT
DIFFERENT WITH TIMING. USED AN ECMWF/SREF BLEND TONIGHT INTO
SUNDAY FOR POPS AND TEMPS AS GFS STILL TOO FAR NORTH WITH
SHORTWAVE TONIGHT AND NAM IS A BIT SLOWER.

TONIGHT INTO SUNDAY...A PAIR OF 500MB SHORTWAVE AND VORT MAX WILL
BRING SOME MUCH NEEDED RAINFALL TO CENTRAL IOWA THIS WEEKEND. THE
FIRST SHORTWAVE PUSHES INTO WESTERN IOWA BY 00Z SATURDAY AND EXITS
THE FORECAST AREA SATURDAY MORNING. MAINLY LOOKING AT WEST-CENTRAL
TO SOUTHEAST PORTIONS OF THE FORECAST AREA FOR THE MOST
SIGNIFICANT RAINFALL. SURFACE HIGH OVER THE OHIO VALLEY AND
GREAT LAKES WILL KEEP THE VORT MAX TO RIDE ALONG SOUTHERN IOWA AND
CONFIDENT TO GO DRY FOR MUCH OF THE PERIOD TONIGHT INTO SATURDAY.
FURTHER SOUTH...GOOD MOISTURE TRANSPORT AND THETA-E ADVECTION
INCREASES THIS EVENING IN SOUTHWEST IOWA AND NORTHWEST MISSOURI.
BEST OMEGA AND ISENTROPIC UPGLIDE WILL BE FOCUSED ALONG THE
IOWA/MISSOURI BORDER...WHICH MATCHES UP WELL WITH THE 4.0KM 15.00Z
SPC WRF PRECIPITATION. ECMWF HAS A NICE QPF BULLS-EYE IN THIS
LOCATION AS WELL THROUGH 18Z SATURDAY. PRECIPITABLE WATER VALUES
CREEP OVER 2.25 INCHES IN SOUTHERN IOWA BETWEEN 06Z TO 12Z
SATURDAY AND THE WARM LAYER CLOUD DEPTHS RISE OVER 14KFT. PLUS
WITH THE CORFIDI VECTORS LESS THAN 20 KNOTS...EXPECTING SOME
EFFICIENT RAIN PRODUCERS OVERNIGHT TONIGHT INTO SATURDAY MORNING
OVER SOUTHERN IOWA. HOWEVER...3-HOUR FLASH FLOOD GUIDANCE WELL
OVER 3 INCHES AND THIS AREA CAN HANDLE SOME RAINFALL TONIGHT. WILL
KEEP MENTION OF HEAVY RAIN IN THE HWO FOR NOW. COOLED DOWN MAX
TEMPERATURES OVER CENTRAL AND SOUTHERN IOWA WITH THE RAIN-COOLED
AIR AND CLOUD COVER ANTICIPATED DURING MUCH OF THE DAY.

500MB SHORTWAVE MOVES EAST OF THE FORECAST AREA WHILE SURFACE LOW
STALLS OVER EASTERN MISSOURI AND ILLINOIS ALLOWING FOR NEXT
SHORTWAVE TO PUSH INTO NORTHWEST IOWA BY SATURDAY NIGHT. SHOULD
SEE A BRIEF BREAK SATURDAY AFTERNOON BEFORE THIS NEXT SYSTEM MOVES
INTO THE AREA SATURDAY NIGHT. MUCH WEAKER AND QUICKER MOVING
SHORTWAVE SATURDAY NIGHT INTO SUNDAY...AND HENCE HAVE LESS
CONFIDENCE WITH WIDESPREAD RAINFALL AND EVEN LESSER FOR HEAVY
RAIN. LOWERED POPS SUNDAY NIGHT INTO MONDAY WITH WEAK SURFACE HIGH
MOVING INTO IOWA.

MONDAY THROUGH WEDNESDAY...ANOTHER SHORTWAVE AND COLD FRONT MOVE
ACROSS THE STATE MONDAY NIGHT INTO TUESDAY. ANTICIPATING TIMING OF
PRECIP TO SLOW WITH FUTURE MODEL RUNS AS SURFACE HIGH REMAINS
FAIRLY STABLE AND WITH SIGNIFICANT DRY AIR FOR SYSTEM TO
SATURATE. LOWERED POPS IN THE SOUTHEAST DURING THE DAY MONDAY AND
COULD EVEN CONSIDER GOING DRY IF ECMWF AND GFS CONTINUE THIS
SLOWER TREND. BEST FORCING AND MOISTURE MOVE ACROSS NORTHERN IOWA
LATE MONDAY NIGHT INTO TUESDAY BEFORE MOVING EAST OF THE FORECAST
AREA TUESDAY AND HAVE SOME LINGERING POPS GOING WITH THE UPPER LOW
STILL TO THE NORTHEAST OF IOWA IN WISCONSIN AND MAY SEE SOME WRAP-
AROUND MOISTURE DURING THE DAY TUESDAY. WENT DRY FOR MUCH OF THE
AREA TUESDAY NIGHT BEFORE ECMWF BRINGS YET ANOTHER SYSTEM THROUGH
ON WEDNESDAY.

&&

.AVIATION...15/12Z
ISSUED AT 650 AM CDT FRI AUG 15 2014

ELEVATED SHOWERS AND ISOLATED CONVECTION CONTINUES TO MOVE
SOUTHEAST ACROSS THE AREA THIS MORNING. CONVECTION SHOULD CONTINUE
TO SLOWLY WEAKEN THRU 18Z...WITH COVERAGE REMAINING ACROSS THE
AREA FOR MUCH OF THE DAY. VFR CIGS EXPECTED WITH SCT DECK FROM
030-050. BY LATE AFTERNOON SHORT WAVE OVER NEBRASKA TO DRIFT EAST.
THIS WILL INCREASE LIFT/THUNDERSTORM POTENTIAL SOUTH THIRD AFT 22Z
THROUGH SOUTHEAST 12Z SATURDAY. SOUTH SITES...KDSM AND KOTM MAY
SEE MVFR/IFR CIGS VSBY AFT 04-08Z IF EXPECTED MCS DEVELOPS ON NOSE
OF INCREASING LOW LEVEL JET AND H850 LOW...TONIGHT AND TRACKS
INTO SOUTHERN IOWA THROUGH SATURDAY 18Z. WILL LEAVE DETAILS FOR
NEXT PACKAGE TO CONFIRM PRESENT MODEL TRENDS./REV

&&

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

SHORT TERM...REV
LONG TERM...PODRAZIK
AVIATION...REV

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE DES MOINES IA
525 AM CDT FRI AUG 15 2014

IAZ057>062-070>075-081>086-092>097-161030-
AUDUBON-GUTHRIE-DALLAS-POLK-JASPER-POWESHIEK-CASS-ADAIR-MADISON-
WARREN-MARION-MAHASKA-ADAMS-UNION-CLARKE-LUCAS-MONROE-WAPELLO-
TAYLOR-RINGGOLD-DECATUR-WAYNE-APPANOOSE-DAVIS-
525 AM CDT FRI AUG 15 2014

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA.

.DAY ONE...TODAY AND TONIGHT

ISOLATED NON SEVERE THUNDERSTORMS ARE EXPECTED DURING THE DAY
TODAY. ANOTHER ROUND OF THUNDERSTORMS ARE FORECAST BY THIS EVENING
INTO SATURDAY MORNING. LOCALLY HEAVY RAINFALL IS LIKELY...BUT THE
SEVERE WEATHER POTENTIAL IS LOW.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

LINGERING THUNDERSTORMS WITH LOCALLY HEAVY RAIN ARE POSSIBLE
DURING THE MORNING HOURS ON SATURDAY.

SEVERAL ADDITIONAL ROUNDS OF THUNDERSTORM ARE FORECAST FROM
SATURDAY NIGHT THROUGH THE MIDDLE OF NEXT WEEK. HOWEVER...THE
PROBABILITY OF SEVERE WEATHER REMAINS LOW AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED.

IAZ004>007-015>017-023>028-033>039-044>050-161030-
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-
525 AM CDT FRI AUG 15 2014

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA.

.DAY ONE...TODAY AND TONIGHT

ISOLATED NON SEVERE THUNDERSTORMS ARE EXPECTED DURING THE DAY
TODAY. ADDITIONAL ISOLATED NON SEVERE THUNDERSTORMS ARE FORECAST
TONIGHT.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

SEVERAL ROUNDS OF THUNDERSTORM ARE FORECAST FROM SATURDAY NIGHT
THROUGH THE MIDDLE OF NEXT WEEK. HOWEVER...THE PROBABILITY OF
SEVERE WEATHER REMAINS LOW AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED.

PODRAZIK