Hail and Damaging Winds in Iowa, April 12 to 14, 2014

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
637 AM CDT SAT APR 12 2014

.SHORT TERM /TODAY/...
ISSUED AT 339 AM CDT SAT APR 12 2014

SURFACE LOW PASSING THROUGH SOUTH DAKOTA EARLY THIS MORNING WITH
STRONG WARM ADVECTION ACROSS IOWA.  STRONG LOW LEVEL THERMAL
GRADIENT EXISTS NEAR THE IA/MN BORDER AND HIGH BASED SHOWERS AND A
FEW THUNDERSTORMS HAVE DEVELOPED ALONG THIS BOUNDARY.  LACK OF
DEEPER MOISTURE HAS LIMITED COVERAGE AND INTENSITY AND ANTICIPATE
THIS ACTIVITY TO PROGRESS EASTWARD ACROSS THE NORTHERN HALF OF THE
STATE THIS MORNING.  MEANWHILE...LOW LEVEL MOISTURE HAS BEEN SURGING
NORTHWARD ACROSS KANSAS AND INTO FAR SOUTHERN NEBRASKA EARLY THIS
MORNING.  THIS MOISTURE WILL CONTINUE TO PUSH RAPIDLY NORTHWARD
TODAY AHEAD OF AN APPROACHING BOUNDARY.  INSTABILITY WILL RAPIDLY
INCREASE DURING THE DAY AS THE MOISTURE ADVECTS INTO THE STATE AND
DEWPOINTS CLIMB INTO THE MID TO UPPER 50S BY AFTERNOON.  MLCAPES
WILL BE ON THE ORDER OF 1000-2000 J/KG BY LATE AFTERNOON AS BOUNDARY
SETTLES INTO NORTHERN IOWA.  WILL THERE IS SUFFICIENT BULK SHEAR FOR
ORGANIZATION OF STORMS WHEN DEVELOPMENT OCCURS BY LATE AFTERNOON
WHEN CAP SHOULD BREAK NEAR THE BOUNDARY.  SOME SUPERCELLS WILL BE
POSSIBLE WITH LARGE HAIL AND SOME DAMAGING WINDS AS THE PRIMARY
THREAT.  THESE STORMS WILL INITIALLY HAVE HIGHER BASES AND 0-1KM
HELICITY IS NOT OVERLY IMPRESSIVE...THEREFORE THE TORNADO
THREAT...WHILE NOT NON-EXISTENT...APPEARS TO BE LIMITED.  WITH PWATS
CLIMBING TO ABOVE ONE TO ONE AND A QUARTER INCHES BY LATE IN THE
PERIOD...MAY BEGIN TO SEE SOME LOCALIZED HEAVY RAINFALL AS WELL.
HAVE STAYED ON THE WARM SIDE OF GUIDANCE TODAY WITH THERMAL RIDGE
PASSING OVER THE STATE.

.LONG TERM /TONIGHT THROUGH FRIDAY/...
ISSUED AT 339 AM CDT SAT APR 12 2014

FOR TONIGHT THE FRONTAL BOUNDARY STALLS ACROSS THE SOUTHERN
PORTION OF THE CWA AS A PRETTY IMPRESSIVE SHORTWAVE RIDES EAST
ALONG THE BOUNDARY. THIS WILL PUSH EAST INTO THE OVERNIGHT HOURS.
WE REMAIN UNSTABLE AND STORMS SHOULD INCREASE THIS EVENING. WITH
CAPES AT 1500-2500 J/KG AND SHEAR REMAINING DECENT EXPECT STORMS
TO REMAIN THIS EVENING. SOME WILL ALSO BE SEVERE WITH HAIL AND
DAMAGING WIND REMAINING THE MAIN THREATS.

THE FRONT FINALLY PASSES TO THE EAST ON SUNDAY BY MID AFTERNOON
THE COLDER AIR LAGS BEHIND THE FRONT HOWEVER AND BY THE TIME IT
WORKS INTO THE CWA PRECIP WILL BE WINDING DOWN. THERE WILL BE A
CHANGE OVER TO SNOW FROM NORTHWEST TO SOUTHEAST...PROBABLY NOT
MAKING IT COMPLETELY OVER TO SNOW IN THE FAR SOUTHEAST. GIVEN THE
PRECIP WILL BE ENDING BY THIS TIME I AM NOT LOOKING FOR MUCH IN
THE WAY OF SNOWFALL...MAINLY A TENTH OR TWO ON GRASSY AREAS.

THE COLDEST TEMPS WILL ARRIVE MONDAY AND MONDAY NIGHT AND A
SHORTWAVE PASSES AND BRINGS DOWN EVEN COLDER AIR. BY LATE TUESDAY
NIGHT AND WEDNESDAY THE FLOW BECOMES WESTERLY THEN BACK AROUND TO
THE SOUTH. AFTER HIGHS IN THE 40S FOR MONDAY AND TUESDAY AND LOWS
IN MANY SPOTS BACK BELOW FREEZING...HIGHS ON WEDNESDAY WILL BE
BACK IN THE 50S WITH LOWS IN THE MID 30S TO LOWER 40S.

FOR THE REST OF THE EXTENDED THERE ARE SUBSTANTIAL DIFFERENCES IN
THE MODELS WITH THE GFS DIGGING A DEEP TROUGH OVER THE
INTERMOUNTAIN WEST WHILE THE EURO HAS MORE OF A WEAKER WAVE
PUSHING ACROSS THE NORTHERN PLAINS. THE GFS IS OBVIOUSLY SLOWER
WITH THE DIGGING SYSTEM BUT NEITHER SOLUTION GIVE US MUCH PRECIP
THROUGH EARLY THURSDAY. BY THURSDAY NIGHT/FRIDAY...IF YOU BELIEVE
THE GFS...THE SYSTEM WILL PULL GULF MOISTURE OVER THE REGION AND
BRING US A CHANCE FOR PRECIP AGAIN. GIVEN THE SLOWER MOVEMENT IT
WOULD BE ANOTHER PRECIP EVENT THAT WILL EXTEND OVER SEVERAL
PERIODS...FROM LATE THURSDAY NIGHT THROUGH FRIDAY NIGHT. BOTH
MODELS THEN AGAIN BRING A SHORTWAVE ACROSS THE NORTHERN PLAINS
AGAIN FOR NEXT WEEKEND BUT AGAIN DIFFERENCES ARE SUBSTANTIAL AS TO
SPEED AND STRENGTH OF THE SHORTWAVE. BROAD-BRUSHED CHANCE POPS
ACROSS THE AREA MAINLY THURSDAY THROUGH FRIDAY NIGHT.

&&

.AVIATION...12/12Z
ISSUED AT 637 AM CDT SAT APR 12 2014

BOUNDARY WILL SAG INTO NORTHERN IOWA TODAY WITH WARM ADVECTION
CONTINUING THROUGH THE DAY. SCATTERED SHOWER AND ISOLATED
THUNDERSTORMS WILL PERSIST IN THE NORTH THIS MORNING. ADDITIONAL
STRONGER CONVECTION IS EXPECTED LATE THIS AFTERNOON INTO THE
EVENING ACROSS CENTRAL IOWA EVENTUALLY DROPPING INTO THE SOUTH
TONIGHT. WINDS WILL BE FROM THE SOUTH TO SOUTHWEST TONIGHT BUT
WILL BECOME NORTHEAST BEHIND THE FRONT TONIGHT. CEILING WILL
PRIMARILY REMAIN VFR TODAY BUT DROP TO MVFR AND IFR BEHIND THE
FRONT TONIGHT.

&&

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

&&

SHORT TERM...COGIL
LONG TERM...FAB
AVIATION...COGIL

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
424 AM CDT SAT APR 12 2014

IAZ004>007-015>017-023>025-130930-
EMMET-KOSSUTH-WINNEBAGO-WORTH-PALO ALTO-HANCOCK-CERRO GORDO-
POCAHONTAS-HUMBOLDT-WRIGHT-
424 AM CDT SAT APR 12 2014

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA.

.DAY ONE...TODAY AND TONIGHT

SCATTERED NON SEVERE THUNDERSTORMS ARE POSSIBLE THIS MORNING.
ISOLATED TO SCATTERED THUNDERSTORMS ARE POSSIBLE AGAIN THIS
AFTERNOON INTO EARLY EVENING. A FEW STRONG STORMS ARE POSSIBLE
WITH SMALL HAIL AND STRONG WIND GUSTS POSSIBLE. HEAVY RAINFALL IS
POSSIBLE WITH A FEW OF THE STORMS AS WELL.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

A WINTERY MIX OF PRECIPITATION IS POSSIBLE SUNDAY AFTERNOON INTO
SUNDAY EVENING BEFORE CHANGING TO ALL SNOW BY LATER SUNDAY
EVENING. VERY LIGHT SNOWFALL AMOUNTS ARE POSSIBLE...MAINLY ON
GRASSY AREAS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON FOR A BRIEF
PERIOD.

IAZ026>028-033>039-044>050-057>062-070>075-081>086-092>097-130930-
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-
424 AM CDT SAT APR 12 2014

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA.

.DAY ONE...TODAY AND TONIGHT

PERIODS OF SHOWERS AND THUNDERSTORMS WILL DEVELOP BY MID TO LATE
AFTERNOON AND PERSIST TONIGHT. THERE IS A SLIGHT RISK FOR SEVERE
THUNDERSTORM INTO THIS EVENING WITH LARGE HAIL AND DAMAGING WIND
THE MAIN THREATS. AN ISOLATED TORNADO IS POSSIBLE FOR A BRIEF
PERIOD LATE THIS AFTERNOON. HEAVY RAINFALL IS ALSO POSSIBLE WITH
SOME STORMS.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

SHOWERS AND ISOLATED THUNDERSTORMS ARE POSSIBLE AGAIN SUNDAY.
SEVERE STORMS ARE NOT EXPECTED AT THIS POINT. RAIN WILL MIX WITH
OR CHANGE TO SNOW SUNDAY NIGHT BUT ONLY VERY LIGHT ACCUMULATIONS
ARE EXPECTED AT THIS POINT AND MAINLY ON GRASSY AREAS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED SATURDAY AFTERNOON AND EVENING
SOUTH OF U.S. HIGHWAY 20.

FAB