Severe Thunderstorm Warning 82, NWS Des Moines, IA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
307 AM CDT WED MAY 14 2003

FORECAST WL FOCUS ON PCPN CHANCES THRU NEXT 24 HOURS AS UPPER LOW
DROPS INTO IA.  CURRENTLY...UPPER LOW NEAR ND/SD BORDER WITH AN
ARCHING BAND OF PCPN ACROSS THE MIDWEST.  THIS BAND HAS PROGRESSED
EAST OF THE CWA IN THE PAST HOUR WITH PARTIAL CLEARING FARTHER WEST
IN AN AREA OF SUBSIDENCE AND DRYING.

MODELS INDICATE THAT THE UPPER LOW WL GRADUALLY MOVE SOUTHEAST
THROUGH THE DAY WITH INCREASING LAPSE RATES ACRS THE STATE.  THIS WL
ALSO BE AIDED EARLY ON WITH SOME SUNSHINE HELPING TO WARM THE
BOUNDARY LAYER. SHWALTR AND LI/S BOTH DIVE BELOW ZERO BY MIDDAY WITH
CAPES FROM 500 TO 1500 ACRS MUCH OF THE CWA.  SHOULD SEE SHRA/TSRA
DEVELOP AROUND MIDDAY AND SPREAD ESE THROUGH THE CWA. WITH COLD POOL
APPROACHING AND THE LOWERING OF WBZ...THE THREAT FOR HAIL WL BE
INCREASING AND WL HIT HARD IN HWO AND MAY MENTION IN ZONES.  COULD
SEE SOME FUNNELS AS WELL IN RAPIDLY DEVELOPING CU THIS AFTERNOON...
HOWEVER HIGH LCL/LFCS SHOULD KEEP MUCH FROM NEARING THE GROUND.  AS
HEATING DIMINISHES THIS EVENING...TSRA WL WEAKEN INTO SHRA BEFORE
ENDING DURING THE OVERNIGHT.  BOUNDARY LAYER SHEAR AXIS REMAINS
THROUGH THE CWA INTO THURSDAY WITH MOIST CONDITIONS PREVAILING TO
THE EAST OF THIS FEATURE AND WL BE MORE PESSIMISTIC WITH CLEARING
DURING THE DAY.

REMAINDER OF THE FORECAST IS PROBLEMATIC WITH SYSTEM GRAZING THE
SOUTH ON FRIDAY INTO EARLY SATURDAY.  WL CONTINUE WITH DRY FORECAST
AS WEAK RIDGING ACRS THE STATE TO KEEP PCPN OUT OF MOST OF THE
CWA...HOWEVER A SHRA MAY PASS THROUGH THE FAR SOUTH.  MODELS ALL
OVER THE PLACE ON TIMING OF SUBSEQUENT SYSTEM RANGING FROM FAST
CANADIAN TO POKEY GFS.  AM GENERALLY AGAINST CHANGING A WHOLE LOT
WITH LARGE DISPARITY BETWEEN MODELS UNTIL SOMETHING A LITTLE MORE
CONSISTENT DEVELOPS.

.DSM...NONE

COGIL

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086-
092>097-16000-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
1253 PM CDT WED MAY 14 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL IOWA.

.DAY ONE...TODAY AND TONIGHT

AN UPPER LEVEL SYSTEM OVER THE DAKOTAS DRIFTING SOUTHEAST...COMBINED
WITH DAYTIME HEATING WILL INSTIGATE THUNDERSTORMS THIS AFTERNOON AND
EVENING. THUNDERSTORMS ARE LIKELY FROM WEST CENTRAL AND NORTH
CENTRAL IOWA...THEN SPREADING SOUTHEAST INTO THE EVENING. THE MAIN
THREAT WILL BE HAIL AND ISOLATED STRONG WIND GUSTS. IN ADDITION...A
FEW SHORT-LIVED FUNNEL CLOUDS MAY BE OBSERVED UNDERNEATH DEVELOPING
CUMULUS CLOUDS. THE STORMS WILL WEAKEN THROUGH THE EVENING AS
DAYTIME HEATING SUBSIDES.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

THUNDERSTORMS ARE FORECAST FOR NEXT TUESDAY AS A FRONTAL SYSTEM
APPROACHES IOWA.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED ACROSS CENTRAL IOWA THIS AFTERNOON.

&&

MORE INFORMATION CAN BE OBTAINED AT WWW.CRH.NOAA.GOV/DMX (ALL LOWER
CASE).

MYERS