Severe Thunderstorm Warning 180, NWS Des Moines, IA

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE DES MOINES IA
952 PM CDT SUN JUN 18 2006

.SHORT TERM /REST OF TONIGHT/...
LATEST REGIONAL RADAR INDICATING AN INCREASE IN SHRA/TSRA COVERAGE
ACROSS THE MID MO VALLEY - INTO WCENT IA AS THE UPR LVL
TROUGH/ASSOD VORTICITY MAXIMUM ACROSS THE NRN PLAINS/UPR MIDWEST
CONTINUES TO SAG SWD INTO THE MID MO VALLEY. INC IN MID/UPR LVL
CLOUD COVER ACROSS THE AFOREMENTIONED AREAS COINCIDENT WITH EXIT
REGION OF AN 85KT JET MAX FOCUSED INTO MID MO VALLEY...AIDING IN
DIV ALOFT. WITH RELATIVELY DRY AIR IN PLACE NEAR THE SFC...SHORT
RANGE MODELS DEPICTING STRONG WARM AIR/THETA-E ADV ON THE NOSE OF
SSW LLVL JET...COMBINED WITH MODEST MID LVL LAPSE RATES AND
LOCALIZED CONVERGENCE IN VCNTY OF THE STNRY FRONT SHOULD BE
SUFFICIENT TO CONT/INC ELV SHRA/TSRA DVPMNT OVR MUCH OF CENT IA
/MAINLY S OF HWY 20/ OVRNGHT. HAVE TIGHTENED GRIDDED FIELDS TO
REFLECT CURRENT 88-D COVERAGE AND HOURLY TRENDS. GFS/RUC/NAM-P ALL
IN AGREEMENT IN REGARDS TO ONGOING AND EVENTUAL EVOLUTION OF PCPN
THRU EARLY MON.

&&

.PREV DISCUSSION... (ISSUED 400 PM CDT SUN JUN 18 2006)

DISCUSSION...
THE MAIN FORECAST CONCERNS IN THE NEAR TERM ARE CONVECTIVE TRENDS
AND SVR WX POTENTIAL TONIGHT...AND AGAIN LATE MON INTO TUES. LATEST
INDICATIONS ARE THAT STORMS WILL FIRE NEAR SFC LOW/BOUNDARY IN
CNTRL/ERN NEBRASKA LATE THIS AFTERNOON THEN PROGRESS ESE INTO
SOUTHERN IA THIS EVENING. UNIDIRECTIONAL SHEAR AND STEEP LOWER LEVEL
LAPSE RATES INDICATE SOME WIND THREAT WITH POTENTIAL FOR A FORWARD
PROPAGATING COMPLEX. CORFIDI VECTORS INDICATE STORM MOTION AOA 40
KTS. THE PARALLEL NAM SUGGESTS STORM COVERAGE WILL BE MORE LIMITED
THAN THE 12KM NAM...AND HAVE KEPT POPS RATHER LOW FOR TONIGHT.
COOLER AIR WILL MOVE INTO NRN IA TEMPORARILY MONDAY BUT THE ACTIVE
WEATHER PATTERN WILL RESUME LATE MONDAY NIGHT INTO TUESDAY. FORECAST
CONFIDENCE IS INCREASING AS SHORT RANGE MODELS HAVE MAINTAINED
DECENT CONTINUITY FOR THE PAST COUPLE OF DAYS. A WARM FRONT WILL
PUSH INTO SW IA LATE MONDAY WITH THE MOST LIKELY SCENARIO A FEW
ELEVATED HAILERS. TUESDAY COULD BE QUITE ACTIVE WITH THE TRIPLE
POINT ACRS CENTRAL IA. THE MAIN CHANGES TO PREVIOUS FORECAST WERE TO
BUMP POPS UP A CATEGORY OR TWO. TUESDAY NIGHT INTO WEDNESDAY...THE
MAIN THREAT AREA WILL SHIFT ALONG THE BOUNDARY INTO SOUTHERN IOWA.
IN THE EXTENDED PERIOD...PRECIP CHCS WILL CONTINUE THURS INTO
FRIDAY. OTHERWISE...NEAR ZONAL FLOW WILL BUCKLE LATER IN THE PERIOD
ALLOW FOR A MODEST COOL DOWN.

&&

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

.SHORT TERM...STEINBUGL

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
352 PM CDT SUN JUN 18 2006

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-
081>086-092>097-190800-
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-
352 PM CDT SUN JUN 18 2006

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA.

.DAY ONE...TONIGHT

SCATTERED THUNDERSTORMS ARE POSSIBLE THIS EVENING THROUGH THE
OVERNIGHT HOURS...MAINLY OVER CENTRAL AND SOUTHERN SECTIONS OF THE
OUTLOOK AREA. A FEW OF THE STORMS THIS EVENING SOUTH OF HIGHWAY 30 MAY
BE SEVERE WITH DAMAGING THUNDERSTORM WINDS OF 60 TO 70 MPH THE
MAIN THREAT.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

SCATTERED THUNDERSTORMS ARE EXPECTED LATE MONDAY THROUGH TUESDAY
ACROSS THE OUTLOOK AREA...A FEW OF WHICH COULD BE SEVERE. PERIODS
OF THUNDERSTORMS WILL CONTINUE ACROSS THE STATE WEDNESDAY THROUGH
FRIDAY...AND THE PROSPECTS FOR SEVERE WEATHER WILL BECOME CLEARER
IN THE COMING DAYS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED THIS EVENING...MAINLY SOUTH OF
STATE HIGHWAY 30. SPOTTER ACTIVATION MAY AGAIN BE NEEDED LATE MONDAY
EVENING AND AGAIN TUESDAY INTO TUESDAY EVENING.

REV/KINNEY