Severe Thunderstorm Warning 47, NWS Des Moines, IA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
230 PM CDT TUE APR 20 2004

.DISCUSSION...
MAIN CONCERN/FOCUS IS PCPN COVERAGE/TIMING OVER FORECAST PERIOD AS
MODELS IN LONGER TERM DIVERGE ON SOLUTIONS.  IN SHORT TERM MODELS IN
FAIR AGREEMENT WITH PCPN TONIGHT AND TRACK OF UPPER LEVEL LO INTO
THE GREAT LAKES REGION.  FAIR AGREEMENT ON TRACK OF SFC LO ACRS NWRN
IA AND INTO WI BY 06Z THOUGH ETA SLOWER.  ATTM WARM FNT MOVG NEWRD
ACRS IA WHILE WRN TROF AND SFC LO PROVIDE SOME CONVERGENCE SWRN IA
THOUGH BEST SVR WX POTENTIAL MAYBE FAR S CNTRL TO SERN IA AS
MOISTURE. FRZG LVL LO WONT TAKE MUCH FOR SMALL HAIL.  AS SFC LO
TRACKS INTO GREAT LAKES CHANCES FOR RAIN DIMINISH QUICKLY.  SOME
LINGERING RAIN IN NE.  MUCH OF WEDNESDAY DRY HWVR HINT OF NEXT
SYSTEM WITH CHANCE FOR RAIN AFTN INTO SMALL PORTION OF THE WEST WITH
BEST ACTIVITY SOUTH AND WEST AS STATE ON NRN EDGE OF SYSTEM/TRACK.
BY THURSDAY NIGHT GOOD BOUNDARY SETS UP TO OUR SOUTH WITH MODERATE
LIFT.  HAVE HIT POPS FAIRLY HARD IN LIKELY CATEGORY.  TEMPERATURES
WILL BE TRICKY THOUGH WILL REMAIN IN MAINLY 60S AND 40S THOUGH BY
THURSDAY NIGHT LOWS IN THE 30S NORTH POSSIBLE.

IN LONGER TERM SOLUTIONS MORE UNSETTLED.  MODELS JUST NOT IN LINE.
HAVE GENERALLY GONE WITH PERSISTENCE AND AVN.  PREVIOUS RUN AND
TODAYS VERY SIMILAR.  THURSDAY NIGHTS RAIN CARRIES OVER INTO
FRIDAY MRNG.  LINGERING PCPN FAR S FRIDAY NIGHT.,  SATURDAY SYSTEM
MOVES THROUGH THE STATE AND WILL GO WITH CHANCE.  THEN AS SYSTEM
PASSES MAINLY W OF STATE HAVE LEFT SLIGHT CHANCE IN PORTION OF WRN
IA SUNDAY.  HAVE LEFT REMAINDER OF FCST DRY ATTM WITH SOLUTION OUT
THAT FAR VERY UNCERTAIN.  TEMPERATURES OVER THIS FCST FRAME
DIFFICULT AS MODELS UNSETTLED AND HINTS ROLLER COASTER TYPE RIDE ON
TEMPS.  HAVE MADE ADJSTMNTS IN GUIDANCE FOR CLOUD COVER AND PCPN.
&&

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

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
250 PM CDT TUE APR 20 2004

...THREAT OF ISOLATED SEVERE WEATHER IS INCREASING IN SOUTHWEST AND
SOUTH CENTRAL IOWA...

IAZ033-034-044>046-057>059-070>072-081>083-092>094-211100-
ADAIR-ADAMS-AUDUBON-CALHOUN-CARROLL-CASS-CLARKE-CRAWFORD-DALLAS-
DECATUR-GREENE-GUTHRIE-MADISON-RINGGOLD-SAC-TAYLOR-UNION-
250 PM CDT TUE APR 20 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHWEST AND WEST CENTRAL
PORTIONS OF MID IOWA.

.DAY ONE...THIS AFTERNOON AND TONIGHT
ISOLATED THUNDERSTORMS HAVE DEVELOPED ALONG AND EAST OF THE MISSOURI
RIVER IN SOUTHWEST IOWA.  THESE WILL BE CAPABLE OF LARGE HAIL UP TO
QUARTER SIZED...STRONG WINDS AND POSSIBLY A BRIEF ISOLATED TORNADO.
THESE STORMS HAVE DEVELOPED EAST OF A LOW PRESSURE SYSTEM ALONG THE
INTERSECTION OF A WARM FRONT AND A TROUGH MOVING EAST INTO SOUTHWEST
IOWA.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

SHOWERS AND THUNDERSTORMS ARE POSSIBLE THURSDAY AFTERNOON AND
NIGHT.  THE THREAT OF SEVERE WEATHER IS LOW.

.SPOTTER ACTIVATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED BETWEEN 3 AND 8 PM.

IAZ004>007-015>017-023>028-035>039-047>050-060>062-073>075-084>086-
095>097-211100-
APPANOOSE-BLACK HAWK-BOONE-BREMER-BUTLER-CERRO GORDO-DAVIS-EMMET-
FRANKLIN-GRUNDY-HAMILTON-HANCOCK-HARDIN-HUMBOLDT-JASPER-KOSSUTH-
LUCAS-MAHASKA-MARION-MARSHALL-MONROE-PALO ALTO-POCAHONTAS-POLK-
POWESHIEK-STORY-TAMA-WAPELLO-WARREN-WAYNE-WEBSTER-WINNEBAGO-WORTH-
WRIGHT-
250 PM CDT TUE APR 20 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHERN AND EASTERN PORTIONS
OF MID IOWA.

.DAY ONE...THIS AFTERNOON AND TONIGHT
SCATTERED STRONG TO SEVERE THUNDERSTORMS ARE POSSIBLE IN FAR
SOUTHERN IOWA ALONG AND SOUTH OF A WARM FRONT IN SOUTHERN IOWA.  THE
MAIN SEVERE WEATHER THREATS ARE HAIL AND STRONG WINDS...ALTHOUGH AN
ISOLATED BRIEF TORNADO IS ALSO POSSIBLE WITH STORMS DEVELOPING NEAR
THE WARM FRONT.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

SHOWERS AND THUNDERSTORMS ARE POSSIBLE THURSDAY AFTERNOON AND
NIGHT.  THE THREAT OF SEVERE WEATHER IS LOW.

.SPOTTER ACTIVATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED BETWEEN 3 AND 8 PM.

KULA