Severe Thunderstorm Warning 125, NWS Des Moines, IA

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE DES MOINES IA
1249 PM CDT FRI JUN 29 2012

...UPDATED AVIATION DISCUSSION...

.SHORT TERM.../TODAY/
CLASSIC LOW-CONFIDENCE FORECAST FOR TODAY IN THE WEAK FORCING
DOLDRUMS OF WHAT FEELS LIKE LATE SUMMER. WIND SHIFT LINE OF THE
FRONT THAT CAME THROUGH YESTERDAY PENETRATED INTO NORTHERN MO...BUT
HAS SINCE BEGUN TO RETREAT NORTHWARD AND HAS RE-ENTERED OUR SOUTHERN
TIER OF COUNTIES. MEANWHILE BEHIND THE FRONT TEMPS/DEWS ACROSS OUR
NORTHERN AND NORTHEASTERN COUNTIES HAVE FALLEN OFF MORE THAN
ANTICIPATED AND THERE IS A PRETTY IMPRESSIVE GRADIENT WITH A 19
DEGREE DIFFERENCE BETWEEN DES MOINES AND MASON CITY AT THIS TIME.
MEANWHILE WATER VAPOR IMAGERY DEPICTS A SHORTWAVE APPROACHING FROM
THE WEST AND REGIONAL RADAR SHOWS SCATTERED SHOWERS AND
THUNDERSTORMS MOVING SLOWLY EASTWARD TOWARD THE MISSOURI RIVER IN
ASSOCIATION WITH THIS WAVE.

SHORT RANGE MODELS ONCE AGAIN PROVE OF LITTLE EFFECTIVE USE THIS
MORNING AS THEY ARE HAVING ISSUES WITH CONVECTIVE FEEDBACK SCHEMES
WHICH SHOVE THE SURFACE BOUNDARIES AND GRADIENTS AROUND ERRATICALLY.
AM NOT ENTHUSIASTIC ABOUT TRUSTING THE DETAILS OF ANY OF THESE
SOLUTIONS...AND HAVE INSTEAD OPTED FOR A BLEND OF PERSISTENCE AND
INTERPOLATION OF CURRENTLY IDENTIFIABLE FEATURES. THERE SEEMS A
REASONABLE CHANCE THAT THE CONVECTION ACROSS EASTERN NEBRASKA WILL
SPREAD INTO OUR WESTERN COUNTIES LATER THIS MORNING...WITH
ADDITIONAL DEVELOPMENT POSSIBLE THIS AFTERNOON MAINLY ACROSS OUR
NORTHERN HALF OR SO WHERE THE SHORTWAVE ENERGY WILL BE A BIT
STRONGER AND THE 925 MB FRONT IS HUNG UP. HAVE THUS MAINTAINED
DECENT CLOUD COVER THROUGH THE DAY AND SCATTERED THUNDER MENTION
ACROSS MUCH OF THE AREA...BUT AGAIN CONFIDENCE IS LOW IN THE DETAILS.

AS AN ADDED BONUS...WE ARE STILL LEFT DEALING WITH POTENTIALLY
HAZARDOUS HEAT LEVELS MAINLY ACROSS OUR SOUTHERN TIERS. WHILE THERE
IS A BIT MORE UNCERTAINTY TODAY WITH SLIGHTLY COOLER TEMPERATURES
AND THE LOOMING SPECTER OF THE STORMS ENTERING SOUTHWESTERN
IOWA...BELIEVE THERE IS SUFFICIENT JUSTIFICATION TO EXTEND THE HEAT
ADVISORY THROUGH THIS EVENING ESPECIALLY WITH 100-104 HEAT INDICES
IN THE FORECAST AND THIS BEING THE THIRD STRAIGHT DAY OF HEAT WITH
LITTLE OVERNIGHT RELIEF.

.LONG TERM.../TONIGHT THROUGH THURSDAY/
SCATTERED CONVECTION WILL LIKELY BE ONGOING AT THE BEGINNING OF THE
PERIOD TONIGHT WITH DECENT MOISTURE CONVERGENCE BETWEEN I80 AND THE
MINNESOTA BORDER.  THIS CONVECTION SHOULD PULL EAST OVERNIGHT AS A
SHORTWAVE PASSES JUST NORTH OF THE STATE.  MAIN THREAT WILL REMAIN
WITH DAMAGING WINDS AS VERY DEEP WARM LAYER WILL LIMIT OVERALL HAIL
THREAT.  HAVE CONTINUED THE THREAT IN THE SOUTHEAST ON SATURDAY
MORNING FOR ANY DEPARTING CONVECTION.  THE PASSING SHORTWAVE AND
OVERNIGHT CONVECTION WILL LIKELY PUSH THE FRONT BACK SOUTH TOWARD
THE IA/MO BORDER BY SATURDAY MORNING.  TEMPERATURES WILL LIKELY
REMAIN QUITE WARM INTO SATURDAY AS SOME SUNSHINE RETURNS BEHIND
DEPARTING CONVECTION AND THERMAL RIDGE REMAIN JUST TO THE SOUTHWEST
OF IA. HAVE MAINTAINED SOME ISOLD POPS IN THE SOUTH ON SATURDAY
AFTERNOON NEAR THE BOUNDARY ALTHOUGH CAP WILL LIKELY INHIBIT MUCH IN
THE WAY OF SUBSTANTIAL CONVECTION.  IT DOES APPEAR THERE WILL BE A
BETTER THREAT OF CONVECTION SOMETIME SATURDAY NIGHT INTO SUNDAY AS
THE MOISTURE GRADIENT PUSHES BACK NORTH ACRS THE STATE ALTHOUGH
SPECIFIC TIMING AND PLACEMENT REMAIN DIFFICULT TO DISCERN.  HAVE
GENERALLY LEFT ISOLD/SCT CONVECTION DURING THIS TIME WHICH MAY BE
THE LAST BEST CHANCE FOR DECENT QPF.

MEDIUM RANGE MODELS CONTINUE TO INDICATE A BUILDING RIDGE INTO THE
CENTRAL PORTION OF THE UNITED STATES DURING NEXT WEEK.  THIS IS
EXPECTED TO LIMIT THE THREAT OF PRECIPITATION ACROSS IOWA AS THE
ATMOSPHERE BECOMES CAPPED.  IN ADDITION...SOUTHWEST SURFACE
WINDS...GENERALLY SUNNY CONDITIONS AND 850MB TEMPS OF 24-28C WILL
LEAD TO HOT TEMPERATURES DURING THE WEEK.  HIGHS IN THE 90S SHOULD
BE COMMON WITH LOWER 100S CERTAINLY POSSIBLE AS THE RIDGING
STRENGTHENS.  AS MENTIONED THE PAST FEW DAYS...THIS WILL LIKELY
BECOME PROBLEMATIC FOR AGRICULTURE AS POLLINATION IS STARTING AND
RECENT RAINFALL HAS BEEN SPOTTY.  DROUGHT CONDITIONS ARE LIKELY
STRENGTHEN...ESPECIALLY IN ANY LOCATIONS THAT MISS OUT ON
PRECIPITATION THE NEXT COUPLE OF DAYS.

&&

.AVIATION...29/18Z
MOSTLY VFR THROUGH TAF PERIOD...WITH ONLY CHANCE FOR MVFR CONDITIONS
WITH TSRA OF VERY LIMITED COVERAGE. BEST CHANCE OF SHOWERS/TSRA WILL
BE WITH VORTICITY CENTER NEAR KSUX THAT WILL MOVE EAST ACROSS NORTH
CENTRAL IOWA. THIS SHOULD MOVE EAST OF KALO BY 30/03Z. SECOND WEAK
SHORT WAVE WILL MOVE ACROSS NORTHERN IOWA OVERNIGHT...BUT
ANTICIPATED COVERAGE WAS TOO LOW TO INCLUDE IN TAFS AT THIS TIME.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
HEAT ADVISORY UNTIL 8 PM CDT FRIDAY FOR ADAMS-APPANOOSE-CLARKE-
DAVIS-DECATUR-JASPER-LUCAS-MADISON-MAHASKA-MARION-MONROE-POLK-
POWESHIEK-RINGGOLD-TAYLOR-UNION-WAPELLO-WARREN-WAYNE.

&&

SHORT TERM...LEE
LONG TERM...COGIL
AVIATION...JUNGBLUTH

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
438 AM CDT FRI JUN 29 2012

IAZ004>007-015>017-023>028-033>039-044>050-057>059-070-071-301100-
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-CASS-ADAIR-
438 AM CDT FRI JUN 29 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA.

.DAY ONE...TODAY AND TONIGHT

ISOLATED TO SCATTERED THUNDERSTORMS ARE FORECAST THROUGH TONIGHT.
THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS WITH DAMAGING WIND
THE MAIN THREAT AND LARGE HAIL A SECONDARY THREAT.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

CHANCES FOR THUNDERSTORMS RETURN LATE SATURDAY INTO LATE SUNDAY.
A LIMITED THREAT FOR ADDITIONAL SEVERE WEATHER WILL PERSIST DURING
THIS PERIOD.

SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON AND EVENING.

IAZ060>062-072>075-081>086-092>097-301100-
POLK-JASPER-POWESHIEK-MADISON-WARREN-MARION-MAHASKA-ADAMS-UNION-
CLARKE-LUCAS-MONROE-WAPELLO-TAYLOR-RINGGOLD-DECATUR-WAYNE-APPANOOSE-
DAVIS-
438 AM CDT FRI JUN 29 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA.

.DAY ONE...TODAY AND TONIGHT

A HEAT ADVISORY IS IN EFFECT FOR THE AREA. PLEASE REFER TO THE
NATIONAL WEATHER SERVICE WEBSITE AT WEATHER.GOV/DESMOINES FOR
FURTHER DETAILS.

IN ADDITION...ISOLATED TO SCATTERED THUNDERSTORMS ARE POSSIBLE
THROUGH TONIGHT. THE THREAT FOR SEVERE WEATHER IS LOW.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

THERE ARE ADDITIONAL CHANCES OF THUNDERSTORMS ON SATURDAY AND
SUNDAY ALTHOUGH THE THREAT OF SEVERE WEATHER APPEARS LOW AT THIS
TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED AT THIS TIME.

CC

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
313 PM CDT FRI JUN 29 2012

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

0306 PM     HAIL             DE SOTO                 41.53N 94.01W
06/29/2012  E1.00 INCH       DALLAS             IA   TRAINED SPOTTER

            ESTIMATED QUARTER SIZE HAIL AND ESTIMATED 50 MPH WIND AT
            DE SOTO EXIT ON I-80.

&&

KJ