Severe Thunderstorm Warning 42, NWS Des Moines, IA

989 
WWUS53 KDMX 031934
SVSDMX

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE DES MOINES IA
234 PM CDT THU MAY 3 2012

IAC109-031945-
/O.CON.KDMX.SV.W.0042.000000T0000Z-120503T1945Z/
KOSSUTH IA-
234 PM CDT THU MAY 3 2012

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT FOR CENTRAL
KOSSUTH COUNTY UNTIL 245 PM CDT...

AT 230 PM CDT...TRAINED WEATHER SPOTTERS REPORTED A SEVERE
THUNDERSTORM PRODUCING QUARTER SIZE HAIL.  THIS STORM WAS LOCATED
NEAR BANCROFT...OR 15 MILES NORTH OF ALGONA...MOVING SOUTH AT 10 MPH.

AT 230 PM CDT...STORM SPOTTERS REPORTED QUARTER SIZED HAIL IN 
BANCROFT. 

LOCATIONS IMPACTED INCLUDE...
  MAINLY RURAL AREAS OF CENTRAL KOSSUTH COUNTY.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

PREPARE FOR LARGE HAIL AND DEADLY CLOUD TO GROUND LIGHTNING. PEOPLE
OUTSIDE SHOULD MOVE TO A REINFORCED BUILDING AND AWAY FROM WINDOWS.

TORRENTIAL RAINFALL IS ALSO OCCURRING WITH THIS STORM...AND MAY LEAD
TO FLASH FLOODING. DO NOT DRIVE YOUR VEHICLE THROUGH FLOODED
ROADWAYS. TURN AROUND DON/T DROWN.

&&

LAT...LON 4324 9408 4320 9429 4334 9429 4337 9414
TIME...MOT...LOC 1933Z 343DEG 9KT 4328 9421
WIND...HAIL <50MPH 1.00IN

$$

COGIL

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE DES MOINES IA
1247 PM CDT THU MAY 3 2012

...UPDATED AVIATION DISCUSSION...

.SHORT TERM /TODAY/...
FORECAST CONCERN INVOLVES THE ONGOING CONVECTION ASSOCIATED WITH A
DYING MCS MOVING ACROSS THE SOUTHERN TWO-THIRDS OF THE FORECAST AREA
THIS MORNING. LATEST HRRR (05Z RUN) HAS CONVECTION DISSIPATING AND
MOVING EAST THROUGH 15Z AND THE 00Z 4KM WRF HAS CONVECTION
DISSIPATING BY AROUND 18Z IN EASTERN PORTIONS OF THE FORECAST AREA.
Q2 CURRENTLY DEPICTING RAINFALL RATES AROUND 2 IN/HR OR LESS WITHIN
THE STRONGER CORES...BUT LINE IS MOVING FAIRLY PROGRESSIVE AT
30-35KTS. SO NOT ANTICIPATING MUCH FLOODING ISSUES...ESPECIALLY
FURTHER EAST WITHIN THE FLASH FLOOD WATCH AREA IN NORTHEAST IOWA.
CONVECTION SHOULD BE MUCH WEAKER BY THE TIME IT REACHES IT AND
THUS...WENT AHEAD AND CANCELLED FLASH FLOOD WATCH.

OTHER CONCERN IS WITH POTENTIAL FOR AFTERNOON CONVECTION ALONG AND
SOUTH OF THE BOUNDARY IN NORTHERN IOWA.  RUC/NAM/GFS ALL KEEP THE
SURFACE FRONT LAID UP ALONG THE MN/IA BORDER KEEPING THE FORECAST
AREA WITHIN THE WARM SECTOR.  BEST INSTABILITY WILL BE LOCATED SOUTH
OF HIGHWAY 30 WHERE LOW LEVEL CAPE INCREASES TO AROUND 2000-3000
J/KG BUT LOW LEVEL SHEAR VALUES NOT IMPRESSIVE. CLOUDS LEFTOVER FROM
DYING MCS SHOULD LIMIT SOME OF THE DAYTIME HEATING...BUT THINKING
THE WAA WILL BE STRONG ENOUGH TO BUMPED TEMPS BACK INTO THE LOWER
80S BY THIS AFTERNOON. TIMING OF AFTERNOON CONVECTION LOOKS TO BE
AFTER 21Z WITH MID-LEVEL SHORTWAVE MOVING INTO WESTERN IOWA BY 00Z
FRIDAY. SURFACE DEW POINTS REMAIN WELL INTO THE 60S...SO PLENTY OF
MOISTURE AVAILABLE.

.LONG TERM /TONIGHT THROUGH WEDNESDAY/...
CURRENT LONG WAVE PATTERN...WRN CONUS TROUGH/ERN RIDGE...WILL REMAIN
INTACT THROUGH MUCH OF THE PERIOD BUT WITH SLOW PROGRESS.  THIS
SHOULD HAVE TROUGH ONLY REACH CENTRAL CONUS BY EARLY NEXT WEEK.
EXPECT CONVERGENCE FROM CURRENT NE TO MN FRONTAL BOUNDARY AND/OR
OUTFLOW FROM WEAKENING WRN IA MCS TO EVENTUALLY POSITION ITSELF INTO
CENTRAL/SRN IA BY EARLY THIS EVENING AND TRIGGER ANOTHER ROUND OF
CONVECTION...TIMED MUCH LIKE PAST FEW EVENTS MAINLY AT NIGHT.  MCS
SHOULD THEN PUSH TO THE SOUTH AND EAST DIMINISHING POPS OVERNIGHT.
CONFIDENCE IN THIS SCENARIO IS SOMEWHAT LOW HOWEVER AS CURRENT MCS
CONTINUES TO BACK BUILD ACROSS SRN NE.  FORECASTING EVENTUAL
POSITION OF SYNOPTIC AND/OR MESOSCALE BOUNDARIES WILL BE DIFFICULT.

BY FRI MODEL CONSENSUS SUGGESTS A RELATIVE LULL WITH IA IN FAIRLY
WEAK SELY SURFACE FLOW.  STILL UNSTABLE BUT LITTLE FOCUS.  ATTENTION
TURNS TO THE WEST AGAIN EYING RESPONSE TO GRADUALLY APPROACHING
WRN TROUGH.  THIS WILL LEAD TO INCREASING WARM ADVECTION AND
BAROCLINICITY THROUGH SIOUXLAND MO VALLEY REGION.  305K FLOW IS
FAIRLY WEAK SO DO NOT EXPECT SIGNIFICANT MCS BUT INCREASING POPS.
CONVECTION MAY BE MORE SIGNIFICANT BY SAT NIGHT AND SUNDAY HOWEVER
AS FLOW AND ASSOCIATED THETA-E ADVECTION INCREASE.  KINEMATIC
FORCING WILL INCREASE AS WELL AS LOBE OF UVM PUSHES ACROSS NRN
PLAINS INTO EARLY SUN WHICH IS ALSO FOCUSED BY PASSAGE OF INVERTED
SURFACE TROUGH.  THIS ALL LEADS TO POPS BACK UP INTO LIKELIES DURING
THIS PERIOD.

BY EARLY NEXT WEEK PATTERN WILL SHIFT SUFFICIENTLY TO LOWER OUR
PRECIP CHANCES AND COOL TEMPS SOMEWHAT AS IA ENDS UP IN NWLY SURFACE
FLOW.  THIS RESULTS IN EXTENDED FORECAST EITHER DRY OR WITH ONLY
SLIGHT CHANCES AND MAXES ONLY IN THE 60S OR POSSIBLY LOWER 70S.

&&

.AVIATION...03/18Z
IN WAKE OF MORNING SHRA/TSRA A SMALL AREA OF HIGH PRESSURE HAS
DEVELOPED...CREATING SMALL-SCALE WIND FIELD EFFECTS THAT ARE PROVING
DIFFICULT TO PREDICT WITH WINDS ANYWHERE FROM 170-270 AND FROM
NEARLY CALM TO ABOUT 15G25KT. HAVE TAKEN A BEST GUESS IN THE TAFS
BUT WINDS WILL BE TRICKY UNTIL THE HIGH DISSIPATES. MEANWHILE...MORE
STORMS ANTICIPATED LATE TODAY HAVE A HIGH DEGREE OF UNCERTAINTY.
BEST CHANCES APPEAR TO BE IN OUR FAR NORTH AND FAR SOUTH THIS EVE
WHERE PRONOUNCED BOUNDARIES ARE PRESENT...HOWEVER HAVE SO LITTLE
CONFIDENCE IN TIMING/EXTENT THAT VCTS IS ALL THAT CAN BE JUSTIFIED
IN 18Z TAFS. IN ANY EVENT STORMS SHOULD END BY MIDNIGHT...WITH MVFR
OR LOWER CIGS/VSBYS IN FOG AND STRATUS POSSIBLE DURING THE EARLY
MORNING HOURS FRI WITH LIGHT/VRBL WINDS AND AMPLE LOW-LEVEL MOISTURE.

&&

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

&&

SHORT TERM...KLP
LONG TERM...BSS
AVIATION...LEE

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
621 AM CDT THU MAY 3 2012

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086-
092>097-041100-
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-
621 AM CDT THU MAY 3 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR MUCH OF CENTRAL IOWA.

.DAY ONE...TODAY AND TONIGHT

SCATTERED THUNDERSTORMS BELOW SEVERE LIMITS WILL AFFECT CENTRAL
AND EASTERN IOWA EARLY THIS MORNING. ADDITIONAL THUNDERSTORMS MAY
DEVELOP LATER THIS AFTERNOON AND TONIGHT AS WELL WITH THE BEST
POTENTIAL FOR STRONG TO SEVERE THUNDERSTORMS OVER CENTRAL AND
SOUTHERN IOWA INTO THE EVENING. LOCALLY HEAVY RAINS AND FLASH
FLOODING ARE ALSO POSSIBLE.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

OUR RECENT ACTIVE WEATHER PATTERN WILL CHANGE LITTLE THROUGH THE
WEEKEND WITH OFF AND ON CHANCES FOR THUNDERSTORMS. A FEW OF THESE
STORMS MAY STILL BE SEVERE WITH LARGE HAIL AND DAMAGING WINDS THE
PRIMARY THREATS. LOCALLY HEAVY RAINS AND FLASH FLOODING REMAIN
POSSIBLE AS WELL.

OTHER LESSER THUNDERSTORM CHANCES ARE IN THE FORECAST EARLY NEXT
WEEK...BUT THE POTENTIAL FOR SEVERE WEATHER APPEARS LOW AT THIS
TIME.

.SPOTTER INFORMATION STATEMENT...

A FEW EPISODES OF SPOTTER ACTIVATION MAY BE NEEDED THROUGH THE WEEKEND.

SMALL

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
828 AM CDT THU MAY 03 2012

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0811 AM     NON-TSTM WND GST 4 ESE PELLA AIRPORT     41.38N 92.87W
05/03/2012  M76.00 MPH       MAHASKA            IA   MESONET

            HEAT BURST. MEASURED BY THE PELLA RWIS SITE.

0812 AM     NON-TSTM WND GST 3 WNW BUSSEY            41.22N 92.94W
05/03/2012  M60.00 MPH       MARION             IA   TRAINED SPOTTER

            HEAT BURST.

&&

SKOW