Flash Flood Warning 17, NWS Sioux Falls, SD

000 
WGUS73 KFSD 230358
FFSFSD

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1052 PM CDT TUE MAY 22 2007

SDC035-230600-
DAVISON SD-
1052 PM CDT TUE MAY 22 2007

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 100 AM CDT FOR
DAVISON COUNTY...

AT 1025 PM CDT...THE PUBLIC REPORTED LOCALIZED STREET FLOODING 
WITHIN THE CITY OF MITCHELL. AS OF 1055 PM CDT...THE STRONGER 
THUNDERSTORMS RESPONSIBLE FOR THE STREET FLOODING HAVE MOVED EAST OF 
DAVISON COUNTY. HOWEVER LIGHT TO MODERATE RAIN WILL CONTINUE ACROSS 
DAVISON COUNTY THROUGH AT LEAST 1 AM. 

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF URBAN 
AREAS...HIGHWAYS...STREETS AND UNDERPASSES AS WELL AS OTHER DRAINAGE 
AREAS AND LOW LYING SPOTS.

BE ESPECIALLY CAUTIOUS AT NIGHT WHEN IT IS HARDER TO RECOGNIZE THE
DANGERS OF FLOODING. IF FLASH FLOODING IS OBSERVED ACT QUICKLY. MOVE
UP TO HIGHER GROUND TO ESCAPE FLOOD WATERS. DO NOT STAY IN AREAS
SUBJECT TO FLOODING WHEN WATER BEGINS RISING.

TO REPORT FLOODING...HAVE THE NEAREST LAW ENFORCEMENT AGENCY RELAY
YOUR REPORT TO THE NATIONAL WEATHER SERVICE FORECAST OFFICE IN SIOUX
FALLS.

LAT...LON 4352 9830 4352 9799 4384 9797 4383 9830

$$
 JH

AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
920 PM CDT WED MAY 22 2007

.DISCUSSION...

HAS BEEN FAIRLY QUIET THROUGH MUCH OF THE EVENING OVER THE
AREA...BUT CONVECTION WHICH DEVELOPED ALONG COLD FRONT THROUGH
CENTRAL NEBRASKA IS NOW BEGINNING TO PUSH INTO OUR SOUTHWESTERN
ZONES...AIDED BY A SHORTWAVE TRACKING OUT OF WESTERN NEBRASKA. WHILE
THE SEVERE THREAT IS WANING...STILL COULD SEE AN ISOLATED SEVERE
STORM WITH CAPES STILL AROUND 1000 J/KG AND LI/S OF -5 OVER THE
WESTERN PORTIONS OF THE CWA...THOUGH STABILITY WILL BE INCREASING
THROUGH THE NEXT COUPLE OF HOURS. MORE LIKELY ISSUE WILL BE HEAVY
RAINFALL WITH ACTIVITY TRAINING OUT OF NEBRASKA INTO THE JAMES RIVER
VALLEY. SOME LOCALES CURRENTLY REPORTING RAINFALL RATES OF 3 TO 4
INCHES AN HOUR...SO FLASH FLOODING WILL BECOME AN ISSUE. COLD FRONT
HAS BEEN MOVING SLIGHTLY FASTER THAN WE HAD FORECASTED...SO HAD TO
MAKE SOME MINOR ADJUSTMENTS TO SHORT TERM GRIDS WITH REGARD TO
TEMPERATURE/DEW POINTS/WINDS/AND POPS FOR THE OVERNIGHT.  UPDATES
ALREADY SENT OUT.  /JM

&&

.AVIATION...

VFR CONDITIONS WILL BE PREVALENT THROUGHOUT THE AREA TONIGHT INTO
WEDNESDAY. THE ONLY EXCEPTION WILL BE NEAR TSRA...WHICH ARE EXPECTED
TO BECOME MORE NUMEROUS DURING THE 04Z-12Z TIMEFRAME AS LINE OF TSRA
IN CNTRL NEBRASKA MOVES NORTH-NORTHEAST INTO THE CWA. LOCALLY IFR
VSBYS AND MVFR CIGS LIKELY WITHIN THIS LINE OF TSRA...EXPECTED TO
MAINLY AFFECT KHON 04Z-06Z...AND KFSD 07Z-10Z.

&&

.PREV DISCUSSION...

TOTALLY AGREE WITH SPC PRODUCTS INCLUDING SWOMCD ABOUT DVLPG
CONVECTIVE POTENTIAL IN ERN HLF SD REST OF THE AFTN INTO THE EVE.
N/S TROF/CDFNT HUNG UP IN CNTRL SD ATTM...WITH GOOD CONVERGENCE
AND INSTABILITY DVLPG IN WRN CWA. DESPITE FAIRLY WEAK SHEAR...
INSTABILITY GOOD FOR HAILERS. BIQ QUESTION IS HOW FAR EAST
CONVECTION GETS BEFORE IT RUNS OUT OF GAS AND DYNAMICS...AND
WILL KEEP MAIN TSTMS AND QPF WEST OF I29...EVEN THOUGH IT WILL
PUSH EAST SOME WITH FNT. ALSO WIND SHIFT SHOULD MOVE EWD OVR CWA
SLOWER THAN PREV FCST. OTRW MINS IN THE BALLPARK.

ON WED FNT GETS THROUGH BUT THEN GETS HUNG UP E/SE OF FCST AREA
LATER ON. MDTLY STG SHRTWV APPCHG FROM THE SW SEEMS TO BE THE
CULPRIT AND THIS WILL PRBLY KEEP SHWR/TSTM THREAT IN WED ESPLY ERN
PART OF FCST AREA. SHRTWV THEN MOVE UP INTO FCST AREA WED NGT AND
MAY SOCK NWRN IA WITH SOME PRETTY GOOD RAIN/TSTMS. BIG QSTN IS HOW
FAR TO THE W/NW TO GO WITH THIS AND HAVE ALLOWED FOR A STEADILY DCRG
THREAT NWWD FROM NWRN IA TO NEAR JAMES VLY FOR LATE WED INTO THU
MRNG...UNTIL WE CAN GET MORE FINE TUNED.

THIS SHRTWV BY THE WAY THO IT WASNT THERE TO ANY CLOSE EXTENT ON
PAST RUNS...IS HANDLD ABOUT THE SAME BY ALL THE MODELS I HAVE LOOKED
AT...ALL THE WAT FROM THE GFS/NAM PACKAGES TO THE LOWLY NGM AND
NOGAPS...PLUS OUR FRIENDS FROM CANADA AND ECMWF LAND. IT MAY TURN
OUT TO GET JUST NWRN IA BUT THE WAY MODEL SOLNS HAVE BEEN BACKING UP
LATELY WE HAVE TO ALLOW FOR PCPN TO BACK UP AS WELL WITH THIS SYS.

THIS SYS SEEMS TO MOVE OUT PRETTY WELL DURG THU. WE ARE THEN FACED
WITH THE NEXT SYS FRI INTO SAT. THIS ONE WILL PRBLY BRING BEST PCPN
THREAT TO THE N AND W OF AREA INITIALLY BUT BY FRI NGT INTO ERY SAT
DECENT THREAT MOVES ACRS OUT FCST AREA FROM THE NW. WE WILL ALLOW
THIS ONE OUT BY SAT NGT AND SUN. THEN IT LOOKS LIKE ANOTHER ONE FOR
MON OR TUE. FOR NOW HAVE KEPT MON...THE HOLIDAY...DRY AS WE HAVE
CARRIED IT. AM BETTING THE GFS IS GUNG GO ON TIMING AS IT IS
SOMETIMES BUT WE WILL HAVE TO CONT TO CHECK IT OUT. MODEL VARIATIONS
FROM RUN TO RUN AND AMONG THEMSELVES WILL NO DOUBT CONTINUE. GFS FOR
EXAMPLE DOESNT HAVE THE RIDGING TO THE EXTENT OF THE ECMWF. TRUST
THE ECMWF A LITTLE MORE AND THIS IS ONE REASON WE ARE GOING FOR A
DECENT WARMUP BY MON AND TUE AFTER OSCILLATING FROM MILD TO MDTLY
COOL FROM NOW TILL THEN.

WIND ADVY NOW LONGER NEEDED FOR ERY THIS EVE AS WINDS HAVE SLIPPED
BLO ADVY LEVELS SO AM KILLING THIS.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.

&&

RYRHOLM/WILLIAMS

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1144 AM CDT TUE MAY 22 2007

SDZ038>040-050-052>071-MNZ071-072-080-081-089-090-097-098-
IAZ001>003-012>014-020>022-031-032-NEZ013-014-231200-
AURORA-BEADLE-BON HOMME-BROOKINGS-BRULE-BUENA VISTA IA-
CHARLES MIX-CHEROKEE IA-CLAY-CLAY IA-COTTONWOOD MN-DAKOTA NE-
DAVISON-DICKINSON IA-DIXON NE-DOUGLAS-GREGORY-HANSON-HUTCHINSON-
IDA IA-JACKSON MN-JERAULD-KINGSBURY-LAKE-LINCOLN-LINCOLN MN-
LYON IA-LYON MN-MCCOOK-MINER-MINNEHAHA-MOODY-MURRAY MN-NOBLES MN-
OBRIEN IA-OSCEOLA IA-PIPESTONE MN-PLYMOUTH IA-ROCK MN-SANBORN-
SIOUX IA-TURNER-UNION-WOODBURY IA-YANKTON-
1144 AM CDT TUE MAY 22 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST SOUTH DAKOTA...
SOUTHWEST MINNESOTA...NORTHWEST IOWA...AND NORTHEAST NEBRASKA.

.DAY ONE...TODAY AND TONIGHT

THUNDERSTORMS...
THUNDERSTORMS SHOULD DEVELOP WEST OF INTERSTATE 29 LATE THIS
AFTERNOON AND EVENING...AND THEN MOVE EAST TONIGHT. ISOLATED
STORMS COULD BE SEVERE WITH HAIL UP TO NICKEL SIZE AND WIND GUSTS
TO 60 MPH. OTHERWISE...THE THUNDERSTORMS MAY PRODUCE ONE TO TWO
INCHES OF RAINFALL...MAINLY ALONG THE JAMES AND BIG SIOUX RIVER
BASINS.

FLOODING...
THE JAMES RIVER IN SOUTH DAKOTA WILL CONTINUE TO EXPERIENCE
FLOODING DUE TO HEAVY RAINFALL EARLY THIS MONTH. MODERATE TO
MAJOR FLOODING ALONG THE JAMES RIVER WILL CONTINUE FOR AN
EXTENDED PERIOD OF TIME...WITH MANY LOCATIONS FROM MITCHELL TO
YANKTON NOT FALLING BELOW FLOOD STAGE UNTIL EARLY JUNE. THE RIVER
STAGES WILL BE WATCHED CLOSELY THE NEXT FEW DAYS DUE TO THE HEAVY
RAINFALL EXPECTED TONIGHT.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

THUNDERSTORMS ARE EXPECTED TO DEVELOP ALONG AND EAST OF
INTERSTATE 29 WEDNESDAY EVENING.  THESE THUNDERSTORMS ARE NOT
EXPECTED TO BE SEVERE.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL BE POSSIBLE AFTER 5 PM CDT WEST OF
INTERSTATE 29.

&&

FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE AT
WWW.CRH.NOAA.GOV/FSD. THIS INCLUDES THE GRAPHICAL HAZARDOUS
WEATHER OUTLOOK.

RSR