Severe Thunderstorm Warning 297, NWS Des Moines, IA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
400 PM CDT TUE OCT 4 2005

.DISCUSSION...
FORECAST ISSUES TODAY WILL CENTER AROUND THE COLD FRONTAL PASSAGE
AND ASSOCIATED PRECIP ACTIVITY ALONG AND BEHIND THE FRONT.  AT 08Z
THE FRONT HAS PUSHED TO JUST WEST OF THE IOWA BORDER.  AS THE
SURFACE LOW RIDES UP THE FRONT AND INTO SOUTHERN MINNESOTA THE FRONT
WILL PICK UP SPEED.  BY 15Z THE FRONT IS FORECAST TO BE THROUGH HALF
THE STATE.  THE MODELS ARE IN DECENT AGREEMENT ON TIMING ISSUES
ALTHOUGH THE NAM HAS NOW BECOME THE SLOWER MODEL.  THE GFS STILL HAD
THE BEST CONSISTENCY AND INITIALIZED BETTER THAN THE NAM SO I WENT
WITH THE GFS ON TIMING AND TEMPS.  THE SLIGHTLY FASTER ONSET OF THE
COLD FRONT SHOULD MAKE FOR COOLER TEMPS.  AT OUR CURRENT TEMP OF 73
AT DMX...THIS WILL LIKELY BE THE HIGH FOR TODAY.  STRONG CAA WL KEEP
TEMPS STEADY THIS MORNING WITH FALLING TEMPS ALL AFTERNOON.

I AM NOT PARTICULARLY IMPRESSED WITH CONVECTIVE TRENDS WITH THE
FROPA.  THE BEST CAPES WL BE IN MN AND THEY LOOK TO RANGE BETWEEN
1200 TO 1500 J/KG.  IN IA CAPES OF 900-1100 IS ALL THE MODELS ARE
FORECASTING. AS FOR SHEAR...THE BEST SHEAR IS POST FRONTAL AND THE
SHEAR IS IMPRESSIVE BEHIND THE FRONT BUT IT IS OUT OF PHASE.  GIVEN
THE MARGINAL CAPES AND BEST SHEAR POST FRONTAL I THINK THE SEVERE
THREAT WILL BE MINIMAL OVER OUR CWA.  FURTHER EAST WHERE THERE WILL
BE MORE DAYTIME HEATING THE CHANCES WILL BE A LITTLE BETTER...AS
WILL CHANCES BE CLOSER TO THE LOW IN MN.  GIVEN THE EXPECTED
ACCELERATION OF THE FRONT THROUGH THE CWA FLASH FLOOD CONCERNS ARE
ALSO MINIMAL.

HIGH PRESSURE BUILDS IN BEHIND THE FRONT TONIGHT AND TEMPERATURES
WILL COOL INTO THE MID TO UPPER 30S.  THE MODELS WANT TO CLEAR US
OUT FAIRLY QUICKLY AND BASED ON THE EXPANSIVE CLOUD COVER TO THE
NORTH AND WEST I THINK THAT MAY BE A BIT OVERDONE.  IF THE CLOUDS
HANG IN THEN TEMPS WILL NOT DROP AS MUCH AS WE THINK.  WE WILL
ADVISE THE DAY SHIFT OF THIS CAVEAT.  FOR THURSDAY THROUGH SATURDAY
HIGH PRESSURE REMAINS FIRMLY IN PLACE AND TEMPS WILL BE QUITE COOL.
THERE WILL BE ABOUT A 30 DEGREE DIFFERENCE IN HIGHS FROM EARLIER
THIS WEEK AND THURSDAY.  BY LATE IN THE WEEKEND AND THE START OF
NEXT WEEK RETURN FLOW AROUND THE HIGH WILL ACT TO MODERATE TEMPS AND
WE SHOULD SEE A RETURN TO 70 DEGREE READINGS.  THIS WILL PROBABLY BE
SHORT LIVED THOUGH AS EXTENDED MODELS WANT TO CARVE A BIG TROUGH
ACROSS THE WESTERN PLAINS ON TUESDAY AND MOVE IT OVER THE UPPER
MIDWEST TUESDAY NIGHT AND WEDNESDAY.  I HAVE TWEAKED THE EXTENDED
FOR TIMING OF THE TROUGH.  TEMPS SHOULD DIP ONCE AGAIN TO BELOW
NORMALS ON WEDNESDAY WITH THE PASSAGE OF THE TROUGH.

&&

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

&&

FAB

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
356 PM CDT TUE OCT 4 2005

IAZ004>007-015>017-023>026-033>035-044-045-051100-
EMMET-KOSSUTH-WINNEBAGO-WORTH-PALO ALTO-HANCOCK-CERRO GORDO-
POCAHONTAS-HUMBOLDT-WRIGHT-FRANKLIN-SAC-CALHOUN-WEBSTER-CRAWFORD-
CARROLL-
356 PM CDT TUE OCT 4 2005

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHERN
IOWA...ALONG AND NORTHWEST OF A LINE FROM HAMPTON...TO GOWRIE...TO CARROLL.

.DAY ONE...REST OF THIS AFTERNOON AND TONIGHT

SCATTERED THUNDERSTORMS WILL CONTINUE LATE THIS AFTERNOON AND
EARLY THIS EVENING. A FEW STORMS COULD PRODUCE HAIL UP TO QUARTER
SIZE AND 60 MPH WIND GUSTS. AN ISOLATED TORNADO CANNOT BE RULED OUT
BEFORE SUNSET. ADDITIONAL NON-SEVERE THUNDERSTORMS ARE POSSIBLE AFTER 4 AM
WEDNESDAY ACROSS AREAS FROM ESTHERVILLE TO DENISON.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

SCATTERED THUNDERSTORMS ARE EXPECTED THROUGH EARLY AFTERNOON
WEDNESDAY. ISOLATED SEVERE STORMS ARE POSSIBLE...WITH 60 MPH WINDS
AND PENNY SIZE HAIL THE MAIN THREATS. THE MOST FAVORED AREA FOR
SEVERE WEATHER IS ALONG AND EAST OF THE INTERSTATE 35 CORRIDOR.

PATCHY FROST IS EXPECT LATE THURSDAY NIGHT AS TEMPERATURES DIP
INTO THE LOW TO MID 30S.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NECESSARY THROUGH 7 OR 8 PM THIS
EVENING. ACTIVATION IS ALSO POSSIBLE WEDNESDAY THROUGH EARLY AFTERNOON.

IAZ027-028-036>039-046>050-057>062-070>075-081>086-092>097-051100-
BUTLER-BREMER-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-
356 PM CDT TUE OCT 4 2005

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL AND
SOUTHERN IOWA...SOUTHEAST OF A LINE FROM HAMPTON...TO GOWRIE...TO CARROLL.

.DAY ONE...TONIGHT

NON-SEVERE THUNDERSTORMS ARE POSSIBLE AFTER 4 AM WEDNESDAY ACROSS
AREAS FROM AUDUBON TO TAYLOR.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

SCATTERED THUNDERSTORMS ARE EXPECTED WEDNESDAY FROM WEST TO EAST
ACROSS CENTRAL AND SOUTHERN IOWA. ISOLATED SEVERE STORMS ARE
POSSIBLE...WITH 60 MPH WINDS AND PENNY SIZE HAIL THE MAIN THREATS.
THE MOST FAVORED AREA FOR SEVERE WEATHER IS ALONG AND EAST OF THE
INTERSTATE 35 CORRIDOR.

PATCHY FROST IS EXPECT LATE THURSDAY NIGHT AS TEMPERATURES DIP
INTO THE LOW TO MID 30S.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS POSSIBLE WEDNESDAY...MAINLY FROM LATE
MORNING THROUGH THE AFTERNOON HOURS.

KINNEY

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
342 PM CDT TUE OCT 04 2005

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

0335 PM     HAIL             2 E CYLINDER            43.09N 94.51W
10/04/2005  0.88 INCH        PALO ALTO          IA   PUBLIC

&&

RDONAVON

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
405 PM CDT TUE OCT 04 2005

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

0345 PM     HAIL             4 N WHITTEMORE          43.12N 94.42W
10/04/2005  0.88 INCH        KOSSUTH            IA   PUBLIC

            MOSTLY PEA SIZED HAIL WITH A FEW UP TO NICKEL SIZED

&&

RDONAVON