Hail and Damaging Winds in Iowa, May 19, 2012

AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
644 PM CDT SAT MAY 19 2012

.DISCUSSION.../ISSUED AT 250 PM CDT/
PRETTY STRONG SHORTWAVE MOVING NORTHEAST INTO THE NORTHERN PLAINS
STATES THIS AFTERNOON AND INTO THE EVENING.  AS IT PULLS
NORTHEAST...SHOWERS AND STORMS WILL BECOME MORE NUMEROUS. SHEAR
PROFILE CONTINUES TO BE LESS THAN IMPRESSIVE...SO DONT EXPECT MORE
THAN AN ISOLATED SEVERE STORM THAT MAY PRODUCE QUARTER SIZE
HAIL...BUT THAT SHOULD EVEN BE A REACH.  DECREASED RAINFALL AMOUNTS
SOMEWHAT DUE TO LESS MOISTURE IN PLACE THAN WHAT WAS EXPECTED.  MOST
OF THE PRECIPITATION WILL BE PULLING OFF TO THE EAST-NORTHEAST AFTER
MIDNIGHT.  STILL MAY SEE A FEW RENEGADE SHOWERS AFTER THAT TIME BUT
HEAVIEST PRECIP SHOULD FALL BEFORE 08Z IN CWA.

A FEW SHOWERS MAY LINGER IN THE NORTHEAST CORNER OF THE FORECAST
AREA...EAST TO NORTH OF FSD...EARLY TUESDAY MORNING. OTHERWISE WITH
UPPER SYSTEM PULLING AWAY AND NO DECENT RESERVOIR OF COLD AIR ALOFT
OR CONTINUING INSTABILITY SUCH AS AN UPPER LOW BEHIND SYSTEM...
DRYING AND SUBSIDENCE SHOULD REIGN. THIS WILL BRING STEADILY
DECREASING CLOUDS. TEMPERATURES WILL BE COOL BUT SLIGHTLY LESS COOL
THAN WE HAD EARLIER FOR SUNDAY...IN FACT PRETTY CLOSE TO NORMAL. A
DRY REGIME SHOULD CONTINUE THROUGH TUESDAY AS WE TRANSFER FROM LIGHT
WINDS TO STRONG SOUTHERLY WINDS IN A WARM ADVECTION PATTERN. THE
LIGHT WINDS SUNDAY NIGHT WILL LEAD TO LOW READINGS GENERALLY 40 TO
45. PATCHY FOG ALSO SEEMS POSSIBLE UNDER THESE SEMI IDEAL COOLING
CONDITIONS...BUT WILL HOLD OFF FOR NOW GIVEN THE NON GENERAL NATURE
OF SUCH FOG AND THE SHORTENING NIGHTTIME PERIOD. THEN TOP THE
WARMING AND INCREASING WINDS...WHICH SHOULD BECOME QUITE STRONG FOR
TUESDAY...STRONG ENOUGH PERHAPS TO BRING A NEED FOR A WIND ADVISORY
WEST...AGAIN WILL HOLD OFF FOR NOW. AIR SHOULD BE CAPPED AND DRY
ENOUGH THROUGH TUESDAY DAYTIME TO PRECLUDE THUNDERSTORMS IN THIS
WARM ADVECTION PATTERN.

EXTENDED PERIOD WEDNESDAY THROUGH SATURDAY IS HIGHLY UNCERTAIN.
CURRENT MODELS SUGGEST A FRONTAL PASSAGE TUESDAY NIGHT WITH A
THUNDERSTORM THREAT...THEN A BREAK BEHIND FRONT UNTIL UPPER RIDGING
BRINGS BACK WARM AND MOISTURE ADVECTION AFTER A DAY OR SO. PREVIOUS
MODELS HAVE MADE THIS LESS OF A BREAK AND MODELS HAVE BEEN
OSCILLATING...SO WILL KEEP SOME MENTION OF THUNDERSTORMS EACH DAY.
MILD TEMPERATURES BEHIND COLD FRONT WEDNESDAY SHOULD TURN TO
INCREASING WARMTH AND HUMIDITY BY FRIDAY OR SATURDAY. THIS DOES SEEM
TO BE ONE CONSENSUS...THAT A REAL SUMMER MAY ARRIVE BY NEXT WEEKEND.
THE BIG QUESTION IS WILL IT BE WARM HUMID AND STORMY...OR WILL THE
RIDGING BE STRONG ENOUGH TO LEAD TO HOT HUMID AND CAPPED.

&&

.AVIATION.../FOR THE 00Z TAF ISSUANCE/
SHOWERS/THUNDERSTORMS FILLING IN ACROSS EASTERN NEBRASKA AS UPPER
WAVE LIFTS NORTHEAST THROUGH THE CENTRAL PLAINS. THIS PRECIPITATION
WILL LIFT NORTH-NORTHEAST ACROSS THIS FORECAST AREA THIS EVENING...
WITH MAINLY ELEVATED SHOWERS IN WESTERN AREAS...WHILE THUNDER MORE
LIKELY ALONG/EAST OF LAKE ANDES-DE SMET LINE THROUGH 04Z-06Z. MVFR
TO IFR VISIBILITY/CEILINGS LIKELY WITH THUNDERSTORMS...ESPECIALLY
EAST OF IA/MN STATE HIGHWAY 60 WHERE STRONGEST STORMS ARE MORE
LIKELY THROUGH THE EVENING. INSTABILITY AND ASSOCIATED TSRA COVERAGE
SHOULD DIMINISH AFTER 06Z. HOWEVER AREAS OF RAIN/MVFR CEILINGS COULD
LINGER EAST OF THAT LAKE ANDES-DE SMET LINE MUCH OF THE NIGHT. BY
14Z SUNDAY...IMPROVEMENT TO WIDESPREAD VFR CONDITIONS EXPECTED AS
HIGH PRESSURE BUILDS INTO THE AREA FROM THE WEST.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1043 AM CDT SAT MAY 19 2012

SDZ038>040-050-052>071-MNZ071-072-080-081-089-090-097-098-
IAZ001>003-012>014-020>022-031-032-NEZ013-014-201200-
AURORA-BEADLE-BON HOMME-BROOKINGS-BRULE-BUENA VISTA IA-
CHARLES MIX-CHEROKEE IA-CLAY-CLAY IA-COTTONWOOD MN-DAKOTA NE-
DAVISON-DICKINSON IA-DIXON NE-DOUGLAS-GREGORY-HANSON-HUTCHINSON-
IDA IA-JACKSON MN-JERAULD-KINGSBURY-LAKE-LINCOLN-LINCOLN MN-
LYON IA-LYON MN-MCCOOK-MINER-MINNEHAHA-MOODY-MURRAY MN-NOBLES MN-
OBRIEN IA-OSCEOLA IA-PIPESTONE MN-PLYMOUTH IA-ROCK MN-SANBORN-
SIOUX IA-TURNER-UNION-WOODBURY IA-YANKTON-
1043 AM CDT SAT MAY 19 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST SOUTH DAKOTA...
SOUTHWEST MINNESOTA...NORTHWEST IOWA...AND NORTHEAST NEBRASKA.

.DAY ONE...TODAY AND TONIGHT

THUNDERSTORMS...
SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP IN AREAS OF
NORTH CENTRAL NEBRASKA AND THEN MOVE NORTHEAST INTO CENTRAL AND
EASTERN SOUTH DAKOTA LATER THIS AFTERNOON.  THESE STORMS ARE
EXPECTED TO SLOWLY SPREAD EAST TONIGHT INTO SUNDAY MORNING.
SEVERE WEATHER IS NOT EXPECTED WITH THE STORMS THAT DEVELOP...BUT
CANT RULE OUT THE POSSIBILITY OF FEW STORMS PRODUCING HAIL.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

THERE IS A CHANCE FOR SEVERE WEATHER ACROSS THE REGION THE LATTER
HALF OF THE WEEK...BEGINNING WEDNESDAY EVENING. THERE IS STILL
SOME UNCERTAINTY ON HOW THE WEATHER PATTERN IS GOING TO EVOLVE AT
THIS POINT...BUT THE POTENTIAL EXISTS FOR PERIODS OF SEVERE
WEATHER.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY AND TONIGHT.

&&

FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE AT
WWW.WEATHER.GOV/SIOUXFALLS. THIS INCLUDES THE GRAPHICAL HAZARDOUS
WEATHER OUTLOOK.