Flash Flood Warning 98, NWS Des Moines, IA

330 
WGUS73 KDMX 211645
FFSDMX

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE DES MOINES IA
1145 AM CDT TUE SEP 21 2010

IAC009-015-049-073-077-153-169-212130-
/O.CON.KDMX.FF.W.0098.000000T0000Z-100921T2130Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
GREENE IA-BOONE IA-STORY IA-POLK IA-GUTHRIE IA-AUDUBON IA-DALLAS IA-
1145 AM CDT TUE SEP 21 2010

...FLASH FLOOD WARNING REMAINS IN EFFECT FOR NORTHERN DALLAS...
AUDUBON...NORTHERN GUTHRIE...NORTHERN POLK...STORY...SOUTHERN BOONE
AND SOUTHERN GREENE COUNTIES UNTIL 430 PM CDT...

AT 1143 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED 
THUNDERSTORMS WITH VERY HEAVY RAINFALL HAD DRIFTED SOUTH OF THE 
WARNED AREA. ALTHOUGH THE HEAVY RAINFALL HAS EXITED THE WARNED 
AREA...THE RISK OF FLASH FLOODING STILL EXISTS. RADAR ESTIMATES THAT 
AS MUCH AS 2 TO 4 INCHES OF RAIN FELL ACROSS THE WARNED AREA. THE 
HEAVIEST RAINFALL GENERALLY OCCURRED OUTSIDE THE LARGER TOWNS AND 
CITIES...AND FELL FROM NORTHERN GUTHRIE INTO SOUTHERN STORY COUNTIES.

RUNOFF FROM THIS EXCESSIVE RAINFALL WILL CAUSE FLASH FLOODING TO
OCCUR. SOME LOCATIONS THAT WILL EXPERIENCE FLASH  FLOODING INCLUDE...
AMES...AUDUBON...GUTHRIE CENTER...HUXLEY...MADRID...NEVADA...
PANORA...PERRY...POLK CITY AND WOODWARD.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF SMALL
CREEKS AND STREAMS...HIGHWAYS AND UNDERPASSES. ADDITIONALLY...COUNTRY
ROADS AND FARMLANDS ALONG THE BANKS OF CREEKS...STREAMS AND OTHER LOW
LYING AREAS ARE ALSO SUBJECT TO FLOODING.

DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE
ROADWAY. FLOOD WATERS ARE USUALLY DEEPER THAN THEY APPEAR AND THE
WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS SAFELY. TURN
AROUND...DONT DROWN.

&&

LAT...LON 4181 9510 4186 9479 4186 9464 4189 9463
      4195 9420 4217 9324 4186 9324 4187 9334
      4184 9335 4168 9419 4159 9506 4160 9511

$$

ZOGG

165 
WGUS73 KDMX 211754
FFSDMX

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE DES MOINES IA
1254 PM CDT TUE SEP 21 2010

IAC009-015-049-073-077-211806-
/O.CAN.KDMX.FF.W.0098.000000T0000Z-100921T2130Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
GREENE IA-BOONE IA-GUTHRIE IA-AUDUBON IA-DALLAS IA-
1254 PM CDT TUE SEP 21 2010

...THE FLASH FLOOD WARNING THAT WAS IN EFFECT FOR NORTHERN DALLAS...
AUDUBON...NORTHERN GUTHRIE...SOUTHERN BOONE AND SOUTHERN GREENE
COUNTIES IS CANCELLED...

EXCESS RUNOFF FROM HEAVY RAIN HAS ENDED OVER THE WARNED AREA. STREAMS
AND CREEKS IN THE WARNED AREA HAVE RECEDED OR WERE BEGINNING TO
RECEDE...ENDING THE FLOOD THREAT. IF FLOODING HAS BEEN OBSERVED...
PLEASE REPORT IT TO YOUR LOCAL LAW ENFORCEMENT AGENCY.

LAT...LON 4187 9324 4187 9334 4184 9335 4183 9340
      4178 9370 4193 9370 4204 9324

$$

IAC153-169-212130-
/O.CON.KDMX.FF.W.0098.000000T0000Z-100921T2130Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
STORY IA-POLK IA-
1254 PM CDT TUE SEP 21 2010

...FLASH FLOOD WARNING REMAINS IN EFFECT FOR NORTHEASTERN POLK AND
SOUTHERN STORY COUNTIES UNTIL 430 PM CDT...

AT 1251 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED 
THUNDERSTORMS WITH VERY HEAVY RAINFALL REMAINED SOUTH OF THE WARNED 
AREA. RAINFALL ESTIMATES FROM THE EARLIER RAINFALL WERE AS HIGH AS 2 
TO 4 INCHES.

RUNOFF FROM THIS EXCESSIVE RAINFALL WILL CAUSE FLASH FLOODING TO
OCCUR. SOME LOCATIONS THAT WILL EXPERIENCE FLASH  FLOODING INCLUDE...
HUXLEY.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF SMALL
CREEKS AND STREAMS...HIGHWAYS AND UNDERPASSES. ADDITIONALLY...COUNTRY
ROADS AND FARMLANDS ALONG THE BANKS OF CREEKS...STREAMS AND OTHER LOW
LYING AREAS ARE ALSO SUBJECT TO FLOODING.

DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE
ROADWAY. FLOOD WATERS ARE USUALLY DEEPER THAN THEY APPEAR AND THE
WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS SAFELY. TURN
AROUND...DONT DROWN.

&&

LAT...LON 4187 9324 4187 9334 4184 9335 4183 9340
      4178 9370 4193 9370 4204 9324

$$

ZOGG

503 
WGUS73 KDMX 211849
FFSDMX

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE DES MOINES IA
149 PM CDT TUE SEP 21 2010

IAC153-169-211904-
/O.CAN.KDMX.FF.W.0098.000000T0000Z-100921T2130Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
STORY IA-POLK IA-
149 PM CDT TUE SEP 21 2010

...THE FLASH FLOOD WARNING THAT WAS IN EFFECT FOR NORTHEASTERN POLK
AND SOUTHERN STORY COUNTIES IS CANCELLED...

EXCESS RUNOFF FROM HEAVY RAIN HAS ENDED OVER THE WARNED AREA. STREAMS
AND CREEKS IN THE WARNED AREA HAVE RECEDED OR WERE BEGINNING TO
RECEDE...ENDING THE FLOOD THREAT. IF FLOODING HAS BEEN OBSERVED...
PLEASE REPORT IT TO YOUR LOCAL LAW ENFORCEMENT AGENCY.

LAT...LON 4187 9324 4187 9334 4184 9335 4183 9340
      4178 9370 4193 9370 4204 9324

$$

ZOGG

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE DES MOINES IA
623 AM CDT TUE SEP 21 2010

...UPDATED AVIATION DISCUSSION...

.SHORT TERM /TODAY/...
COMPLEX AND ACTIVE FORECAST FOR TODAY AS COLD FRONT MOVES SOUTHEAST
ACROSS THE CWA COINCIDENT WITH ONE OR MORE SHORTWAVES PASSING
OVERHEAD. WIDE SWATH OF SHOWERS AND THUNDERSTORMS HAS MOVED IN FROM
THE NORTHWEST OVERNIGHT AND IS CURRENTLY AFFECTING OUR NORTHERN AND
WESTERN COUNTIES. AS THE LEADING SHORTWAVE THAT HAS PROVIDED SOME OF
THE FORCING FOR THIS FEATURE BEGINS TO MOVE OFF THIS MORNING WE
SHOULD SEE A DECREASE IN CONVECTIVE COVERAGE...HOWEVER ENOUGH LIFT
WILL REMAIN ESPECIALLY NEAR THE FRONTAL ZONE TO SUPPORT A BAND OF
CATEGORICAL POPS MOVING ACROSS THE AREA THIS MORNING. WILL ALSO
INCLUDE A PRE-FIRST PERIOD IN THE ZONES TO ACCOUNT FOR CONVECTIVE
TRENDS.

THE FRONT WILL HANG UP SOMEWHERE ACROSS OUR SOUTHEASTERN HALF
THIS AFTERNOON AFTER BEING ABANDONED BY THE RAPIDLY DEPARTING WAVE
ALOFT. SOUTHERLY FLOW AHEAD OF THE FRONT WILL PUMP WARM AIR AND
INCREASING MOISTURE INTO THE BOUNDARY WHICH WILL THEN ACTIVATE IN
THE MID AFTERNOON TO EVENING HOURS PRODUCING MORE THUNDERSTORMS IN
OUR SOUTH AND SOUTHEAST. STRENGTHENING SOUTHERLY LOW LEVEL WINDS
BENEATH SOUTHWESTERLY FLOW ALOFT SHOULD PROVIDE SUFFICIENT SHEAR
PROFILES FOR THE DEVELOPMENT OF SOME SEVERE STORMS...HOWEVER
UNCERTAINTY REGARDING THE LOCATION OF THE FRONT AND TIMING OF LATE
DAY ACTIVATION PRECLUDED SEVERE WORDING IN THE GRIDS/FORECAST ATTM.
HEAVY RAIN WILL ALSO BE POSSIBLE WITH THE STORMS IN THE AFTERNOON
GIVEN GOOD MOISTURE TRANSPORT INTO THE BOUNDARY AND HIGH PWATS FOR
THIS LATE IN THE SUMMER...HOWEVER THE STORMS SHOULD HAVE A DECENT
FORWARD MOTION AND BE SPOTTY ENOUGH THAT FLASH FLOOD THREAT WILL BE
TOO LOCALIZED TO JUSTIFY A FFA OR HVY RAIN WORDING THIS MORNING.

OTHER THAN POP/WX TIMING TRANSITIONS ACROSS THE CWA OTHER FORECAST
CHALLENGE IS TEMPERATURES. DECENT CAA BEHIND THE FRONT SHOULD BE
MITIGATED SOMEWHAT BY DIURNAL HEATING AS THE FRONT STALLS LATER IN
THE DAY...AND SOME CLEARING IN OUR NW MAY ACTUALLY CAUSE DECENT
TEMPERATURE RISES IN THAT AREA. CONCURRENTLY TEMPS WILL BE HELD DOWN
BY SHOWERS AND STORMS BUT THE AREA OF SAID STORMS WILL BE
MOVING...SO HAVE MADE BEST ATTEMPT AT HOURLY TEMP TRENDS TODAY BUT
THERE IS A LARGE DEGREE OF VARIABILITY IN THAT FORECAST.

.LONG TERM /TONIGHT THROUGH MONDAY/...
MADE NO LARGE CHANCES TO THE LONG TERM FORECAST. MODELS REMAIN IN
GOOD AGREEMENT THROUGH THE WEEK...WITH A FEW CHANGES IN HOW MODELS
HANDLE THE WEEKEND SYSTEM.

THROUGH THE WEEK...MAIN FORECAST CONCERN WILL BE THE PLACEMENT OF
BOUNDARY WHICH HANGS ACROSS THE SOUTH...AND HOW FAR NORTH IT WILL
MAKE IT BEFORE LOW PUSHES NORTHEAST FROM COLORADO. BELIEVE
BOUNDARY WILL STALL ACROSS NORTHERN MO...WITH GREATEST CHANCES FOR
HEAVIEST RAIN BEING SOUTH OF THE CWA OVERNIGHT TUESDAY. FRONT WILL
PUSH BACK NORTH THROUGHOUT THE DAY WEDNESDAY...WITH CO LOW BEGINNING
TO INFLUENCE THE CHANCE FOR RAIN LATE WEDNESDAY. THIS LOW WILL TRACK
ACROSS NEBRASKA AND THE DAKOTAS. ALONG WITH RAIN CHANCES...LOW WILL
BRING QUITE BREEZY CONDITIONS ON THURSDAY WITH STRONG PRESSURE
GRADIENT. LOW WILL PUSH OUT OF AREA BY FRIDAY...AND DRY WEATHER WILL
RETURN...WITH WEAK SURFACE HIGH PRESSURE BUILDING IN.

FOR THE WEEKEND...MODELS HAVE BEGUN TO COME INTO AGREEMENT WITH
LOW PRESSURE SWEEPING SE FROM CANADA. GFS PREVIOUSLY DID NOT HAVE
THIS FEATURE...BUT NEW RUN HAS BROUGHT LOW PRESSURE SE ACROSS
WISCONSIN. ECMWF...WHICH HAS BEEN DEVELOPING THE LOW THE PAST FEW
RUNS...HAS PUSHED IT FURTHER EAST AS WELL THIS RUN. HAVE OPTED TO
LEAVE THE FORECAST DRY FOR THE WEEKEND. WITH THIS EASTWARD PUSH OF
THE MODELS...IF THE LOW DOES DEVELOP...IT IS UNLIKELY TO PROVIDE
MUCH FORCING FOR PRECIP ACROSS THE CWA. HOWEVER...IT IS A SYSTEM
TO WATCH CLOSELY...AS UNCERTAINTY STILL EXISTS SO FAR OUT.

&&

.AVIATION...
21/12Z...COLD FRONT OVER NW IA ATTM WILL SLOWLY ADVANCE SEWARD AND
STALL OVER SRN IA BY THIS AFTERNOON. SWATH OF SHRA/TSRA EVIDENT ON
RADAR WILL DIMINISH DURING MORNING HRS BUT STILL AFFECT
KMCW/KFOD/KALO AT TIMES...THEN REDEVELOP FURTHER SOUTH THIS
AFTERNOON WITH PEAK HEATING. HAVE INCLUDED TEMPO GROUPS AT NRTHRN
TERMINALS FOR THE MORN CONVECTION BUT STUCK WITH VCTS IN THE AFTN AS
DETAILS OF CONVECTIVE TIMING/LOCATION ARE UNCLEAR. WINDS WILL BECOME
LGT AND VBL FOR MUCH OF THE DAY WITH THE FRONT WASHING OUT
OVHD...AND COMBINED WITH MOISTURE POOLING ALONG THE STALLED BOUNDARY
WILL SUPPORT DVLPMNT OF STRATUS AND FOG AFTER SUNSET TONIGHT...ESP
AT KDSM/KOTM. HAVE ADVERTISED MVFR CONDS IN 12Z TAFS BUT THIS MAY
NEED TO BE TAKEN DOWN ON SUBSEQUENT ISSUANCES.

&&

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

SHORT TERM...LEE
LONG TERM...WILKINS
AVIATION...LEE

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
507 AM CDT TUE SEP 21 2010

IAZ004>007-015>017-023>028-033>035-044-045-221015-
EMMET-KOSSUTH-WINNEBAGO-WORTH-PALO ALTO-HANCOCK-CERRO GORDO-
POCAHONTAS-HUMBOLDT-WRIGHT-FRANKLIN-BUTLER-BREMER-SAC-CALHOUN-
WEBSTER-CRAWFORD-CARROLL-
507 AM CDT TUE SEP 21 2010

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA.

.DAY ONE...TODAY AND TONIGHT

SHOWERS AND THUNDERSTORMS WILL SPREAD NORTHWEST TO SOUTHEAST
ACROSS THE AREA THROUGHOUT THE MORNING AND AFTERNOON HOURS. THE
THREAT FOR SEVERE WEATHER IS LOW.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

INTERMITTENT THUNDERSTORM CHANCES WILL PERSIST THROUGH FRIDAY MORNING. A
FEW SEVERE THUNDERSTORMS AND LOCALLY HEAVY RAINFALL WILL BE
POSSIBLE AT TIMES.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED.

IAZ036>039-046>050-057>062-070>075-081>086-092>097-221015-
HAMILTON-HARDIN-GRUNDY-BLACK HAWK-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-
507 AM CDT TUE SEP 21 2010

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA.

.DAY ONE...TODAY AND TONIGHT

SHOWERS AND THUNDERSTORMS WILL SPREAD IN FROM THE NORTHWEST LATE
THIS MORNING...PERSISTING INTO TONIGHT. SOME OF THE STORMS IN THE
AFTERNOON COULD BE SEVERE...WITH LARGE HAIL AND DAMAGING WINDS THE
MAIN THREATS. LOCALLY HEAVY RAINFALL IS ALSO POSSIBLE WITH THESE
STORMS.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

INTERMITTENT THUNDERSTORM CHANCES WILL PERSIST THROUGH FRIDAY
MORNING. A FEW SEVERE THUNDERSTORMS AND LOCALLY HEAVY RAINFALL
WILL BE POSSIBLE AT TIMES.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS POSSIBLE THIS AFTERNOON.

AW

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE DES MOINES IA
514 AM CDT TUE SEP 21 2010

IAZ007-016-017-211045-
CERRO GORDO-HANCOCK-WORTH-
514 AM CDT TUE SEP 21 2010

...THUNDERSTORM PRODUCING HAIL...

AT 509 AM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 25 MILES SOUTHWEST OF MASON CITY...MOVING
NORTHEAST AT 60 MPH.

NICKEL SIZE HAIL IS POSSIBLE WITH THIS STORM.

* THE THUNDERSTORM WILL BE NEAR...
  VENTURA BY 520 AM CDT...
  CLEAR LAKE BY 525 AM CDT...
  MASON CITY AIRPORT BY 530 AM CDT...
  MASON CITY BY 535 AM CDT...
  PLYMOUTH AND ROCK FALLS BY 540 AM CDT...
  GRAFTON BY 545 AM CDT...

SEEK SHELTER IN A STURDY STRUCTURE UNTIL THIS STORM HAS PASSED.

LEE