Hail and Damaging Winds in Iowa, May 6, 2008

AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
857 PM CDT MON MAY 5 2008

.DISCUSSION...
RED FLAG WARNING ALLOWED TO EXPIRE AS WINDS HAVE DROPPED OFF AND
HUMIDITIES ARE ON THE RISE. OTHER THAN A FEW MID CLOUDS IN THE
NORTH...SKIES HAVE CLEARED WITH THE LOSS OF SOLAR HEATING. CLOUDS
WILL AGAIN INCREASE THROUGH THE OVERNIGHT HOURS AS MID LEVEL
MOISTURE RETURNS. A SMALL CHANCE FOR SHOWER/THUNDERSTORM DEVELOPMENT
AFTER MIDNIGHT...HOWEVER OVERALL MOISTURE RETURN IS LIMITED AND
THUNDERSTORMS OVER KS MAY DELAY MOISTURE...WHICH WOULD DECREASE
COVECTION POTENTIAL TONIGHT. BETTER MOISTURE RETURN BEGINS TOMORROW
MORNING...WITH AN INCREASING THUNDERSTORM CHANCES THROUGH THE
MORNING AND INTO THE AFTERNOON.

&&

.AVIATION...
VFR CONDITIONS EXPECTED THROUGH 18Z MONDAY. ISOLD ACCAS CONVECTION
POSSIBLE ACROSS THE AREA 06Z-14Z WITH BASES GENERALLY AOA 8KFT.
ACTIVITY WILL BE SPOTTY THOUGH...AND HAVE OPTED NOT TO INCLUDE IN
POINT TAF FORECASTS AS PROBABILITY AT ANY ONE LOCATION IS VERY
SMALL. AFT 15Z INCREASING LOW LEVEL MOISTURE WILL RESULT IN CUMULUS
DEVELOPMENT DURING THE LATE MORNING/AFTERNOON. AT THIS TIME...CIGS
EXPECTED TO REMAIN IN LOWER END OF VFR RANGE...ALTHOUGH SCATTERED
TSRA BECOME INCREASINGLY LIKELY AFTER 20Z...AND LOCALLY MVFR CIGS
AND MVFR-IFR VSBYS POSSIBLE WITH STRONGER CONVECTION.

&&

.PREV DISCUSSION...
MIXG REGIME AND FIRE WX FCST INCLUDG RED FLAG HAS TURNED OUT WELL.
VERY HI BASED CU WHICH FORMD WITH 35-40F SPRD SHUD GNLY DSIPT THIS
EVE AND LEAVE US AGN WITH MOCLR. THEN OVERNIGHT INFLUX OF INCRGLY
UNSTBL AND MOIST AIR FCST WILL SPREAD TWRDS THE FCST AREA FROM THE
S. LO LVL MOISTR WILL LAG OF COURSE...BUT STILL LOOKS LIKE SOME
SPOTTY TSTMS DVLPG OVER SRN PART OF FCST AREA LATE TNGT AND TRYING
TO SPRD NE. LIMTD MOISTR AND LACK OF CLEAR FOCUS WILL KEEP MENTN IN
SLGT CHC CATEGORY...THO IN THIS CASE IT SEEMS THERE IS A FAIRLY GOOD
PSBLTY OF THIS SPOTTY CONVECTN...SO IT IS MORE OF A CVRG ISSUE LATE
TNGT AND THAT IS WHERE THE MINIMAL POP COMES IN.

CONT TO PREFER WARMER MAV GUIDNCE LOWS OVER FWC DESPITE A DECENT EVE
COOLING PERIOD. WITH AIR GETTING SO WELL HEATED  THIS AFTN AND SOME
WEAK SRLY LO LVL FLO DVLPG...DONT FEEL WE WILL DROP INTO THE 40S
TNGT XCP MAYBE BARELY AND MAINLY N. CLDS WILL OF COURSE INCRS FROM
THE S SOME LATE TNGT.

CONVECTIVE CHANCES WILL CONTINUE INTO THE DAY ON TUESDAY AS A COLD
FRONT APPROACHES FROM THE WEST. LOOKS LIKE THE FRONT SHOULD REMAIN
WEST OF THE JAMES RIVER THROUGH LATE AFTERNOON AND WILL SEE IF ANY
CONVECTION CAN FIRE ALONG OR JUST AHEAD OF THIS BOUNDARY. COULD BE
AN ADDITIONAL BOUNDARY OR TWO AROUND AS WELL AS MORNING CONVECTIVE
THREAT MAY LEAVE SOME BEHIND. WILL ALSO NEED TO WATCH HOW MUCH WINDS
IN THE LOW LEVELS CAN BACK AS MAIN UPPER LEVEL WAVE EXPECTED TO BE
OVER WESTERN ND BY LATE TUESDAY AFTERNOON AND ANY ADDITIONAL BACKING
COULD AID IN SOME CONVERGENCE ON INCOMING FRONT. THERE WILL BE A
THREAT FOR SEVERE AS THE CAPE AND SHEAR ARE SUPPORTIVE OF SUSTAINING
UPDRAFTS. OTHERWISE...SHOULD SEE A WARM DAY WITH MOST LOCATIONS FROM
THE MID 70S TO LOWER 80S.

THE THREAT SHOULD TRANSITION FROM WEST TO EAST THROUGH THE EVENING
AND CHANCES FOR MEASURABLE PRECIPTATION LOOK BEST OVER THE EASTERN
HALF OF THE CWA. WILL HAVE A CONTINUED THREAT FOR SEVERE INTO THE
EVENING BUT THIS SHOULD WANE AROUND SUNSET. LOWS WILL BE MILD
RANGING FROM THE MID 40S IN CENTRAL SD TO THE MID 50S IN NW IA.

WEDNESDAY WILL BE COOLER AND SEE A LINGERING THREAT FOR SHOWERS OVER
NW IA. WILL SEE HIGHS MAINLY IN THE 60S WITH LOWS BACK INTO THE 30S
AND LOWER 40S WEDNESDAY NIGHT.

HIGH PRESSURE WORKS ACROSS THE AREA ON THURSDAY AND OTHER THAN COOL
TEMPERATURES...WINDS SHOULD BE FAIRLY LIGHT SO EXPECT A VERY NICE
DAY.

IN THE LATTER PERIODS(FRI-MON)...ENERGY EJECTING ONTO THE PLAINS
FRIDAY AND SATURDAY AND WILL NEED TO INCREASE POPS THURSDAY NIGHT
INTO FRIDAY MORNING AS UPPER LEVEL SUPPORT BECOMES FAVORABLE ENOUGH
FOR PRECIPITATION. BETTER UPPER LEVEL SUPPORT DIGS IN ON SOUTHWETS
SIDE OF HUDSON BAY LOW SATURDAY AND GETS MORE WRAPPED UP LATE IN THE
WEEKEND AND EARLY NEXT WEEK. THIS SHOULD LEAVE OUR AREA IN A COOL
BUT NOT EXCESSIVELY WINDY PATTERN FOR SUNDAY AND MONDAY. AS FOR
TEMPERATURES...ONE THING TO WATCH WILL BE HOW COOL TO GO FOR HIGHS
ON ESPECIALLY FRIDAY AND SATURDAY. STATISTICAL GUIDANCE FROM THE GFS
SHOWING HIGHS ABOUT 6 TO 10 DEGREES BELOW NORMAL AND GFS ENSEMBLE
HIGHS A COUPLE OF DEGREES COLDER. IN THE PAST WHEN THIS HAS
OCCURRED...WHERE GUIDANCE IS BELOW CLIMATOLOGY AND THE ENSEMBLE IS
EVEN COLDER...THERE IS A HIGH PROBABILITY THAT GOING COLDER THAN
GUIDANCE IS THE BEST ROUTE. SO...WITH PROJECTED 850MB TEMPS OF ABOUT
+2 TO +6 AND WHAT SHOULD BE AN ABUNDANCE OF CLOUD COVER AS WELL AS
OFF AND ON PRECIPITATION CHANCES...GOING COOLER SEEMS LIKE A GOOD
BET.

&&

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

&&

UPDATE...LIEBL/JH
WILLIAMS/08

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1057 AM CDT MON MAY 05 2008

SDZ038>040-050-052>071-MNZ071-072-080-081-089-090-097-098-
IAZ001>003-012>014-020>022-031-032-NEZ013-014-061200-
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-
1057 AM CDT MON MAY 05 2008

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

.DAY ONE...TODAY AND TONIGHT

THUNDERSTORMS...
ISOLATED THUNDERSTORMS MAY DEVELOP LATE TONIGHT ALONG AND EAST OF
A YANKTON SOUTH DAKOTA TO FLANDREAU SOUTH DAKOTA LINE. THIS
INCLUDES MOST OF SOUTHWEST MINNESOTA...NORTHWEST IOWA...EXTREME
NORTHEAST NEBRASKA...AND EXTREME SOUTHEAST SOUTH DAKOTA. STORMS
ARE NOT EXPECTED TO BE SEVERE.

FLOODING...
MINOR FLOODING WILL CONTINUE ON THE LITTLE SIOUX RIVER FROM NORTH
OF SPENCER TO NEAR LINN GROVE IN NORTHWEST IOWA. THE RIVER SHOULD
FALL BELOW FLOOD STAGE BY WEDNESDAY...UNLESS SIGNIFICANT RAIN
FALLS TUESDAY OR TUESDAY NIGHT.

FIRE DANGER...
THE GRASSLAND FIRE DANGER INDEX WILL REACH THE VERY HIGH CATEGORY
THIS AFTERNOON IN THE MISSOURI RIVER AREA AND IMMEDIATE ADJACENT
AREAS. ELSEWHERE...THE GRASSLAND FIRE DANGER INDEX WILL REACH THE
EXTREME CATEGORY DUE TO STRONGER WINDS...WITH A RED FLAG WARNING
THROUGH 800 PM CDT FOR MUCH OF THIS EXTREME AREA. ALL AREAS THIS
AFTERNOON WILL SEE RELATIVE HUMIDITY VALUES FALLING TO LESS THAN
30 PERCENT.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

A SLIGHT RISK OF SEVERE THUNDERSTORMS EXISTS ALONG AND EAST OF A
LINE FROM TYNDALL AND YANKTON SOUTH DAKOTA...NORTHEASTWARD TO
SIOUX FALLS AND MARSHALL MINNESOTA TUESDAY AFTERNOON OR EVENING.
ELSEWHERE... GENERAL THUNDERSTORMS ARE EXPECTED ALTHOUGH AN
ISOLATED SEVERE STORM CANNOT BE RULED OUT.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY AND TONIGHT.

&&

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

WILLIAMS