Severe Thunderstorm Warning 194, NWS Des Moines, IA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
323 PM CDT WED JUN 21 2006

.SYNOPSIS...

JET SEGMENT UNDER ONTARIO SHRT WV CURRENTLY MOVING ACROSS MN/NRN
GREAT LAKES WITH RIGHT ENTRANCE REGION DIVERGENCE AIDING IA/WI/IL
TSTMS.  SEVERAL EMBEDDED CENTRAL PLAINS SHRT WVS ALSO HELPING
UVM...SOME LEFT OVER MCVS FROM LAST NIGHT.  LOW LEVEL TSTM FOCUS WAS
CONVERGENCE WITH CDFNT CURRENTLY NOTED ALONG KOTM-KDBQ LINE.  THIS
WILL SOON EXIT FORECAST AREA WITH WATCH DROPPED BY ZONE ISSUANCE.

.SHORT TERM...TONIGHT THROUGH FRI

POTENTIAL FOR REDEVELOPMENT WILL BE PRIMARY FOCUS OF NEAR TERM
FORECAST.  HAVE LOW CHANCES FOR LINGERING WEAK CONVECTION THIS EVE
FOLLOWED BY RETURN THROUGH CHANCE CATEGORY OVERNIGHT.  305/310K UVM
AND MOISTURE CONVERGENCE INCREASES OVERNIGHT AS LOW LEVEL JET
MATURES BUT THIS QUICKLY VEERS AND PUSHES S AND E BY THURSDAY
MORNING.  GFS MUCH MORE OPTIMISTIC REGARDING ELEVATED INSTABILITY
WITH BETTER MOISTURE IN H85/H8 LAYER.  LESSER NAM MUCAPES DIMINISH
OVERNIGHT BUT STILL 1-2K J/KG AND ADEQUATE FOR ANOTHER FEW SVR
TSTMS. THIS COULD LINGER INTO EARLY THU BEFORE DIMINISHING LATER IN
THE DAY.  COULD JUST BRUSH FAR SRN ZNS WITH ANOTHER ROUND OF ISENT
LIFT PCPN THU NIGHT AS WELL WITH LOW CHANCES IN PLACE.  ALTHOUGH
CONVERGENCE IS WEAK...NERN IA FORECAST SOUNDINGS DURING PEAK HEATING
FRI SUGGEST SOME POTENTIAL FOR HIGH BASED SFC DEVELOPMENT SO HAVE
ADDED SLIGHT CHANCES LATE AFTERNOON/EARLY EVE.

TEMP WISE...STAYED CLOSE TO BLEND FOR MINS AND TOWARD WARMER END OF
GUIDANCE FOR MAXES WITH GOOD MIXING TO NEAR CLIMATOLOGY ANTICIPATED.

.LONG TERM...FRI NIGHT THROUGH WED

INITIAL AND PRIMARY CONCERNS WILL BE PCPN TRENDS OVER THE WEEKEND.
DETAILS WITH FRONTAL POSITION AND TIMING DIFFICULT TO PINDOWN IN
THIS TIME FRAME BUT MODELS IN DECENT AGREEMENT BRINGING NW FLOW SHRT
WV THROUGH NRN PLAINS.  GENERAL SCENARIO IS POTENTIAL FOR WRM
ADVECTION PCPN FRI NIGHT INTO SATURDAY MAINLY W...FOLLOWED BY MORE
SFC BASED THREAT SAT AND SAT NIGHT.  CURTAILED POPS SOMEWHAT FRI
NIGHT WITH THETA-E ADVECTION AND INSTABILITY NOT AS IMPRESSIVE.
HOWEVER TRIPLE POINT AND CONVERGENCE ALONG ATTENDANT COLD AND WARM
FRONTS SHOULD BE NEAR OR IN WRN IA DURING PEAK HEATING SAT WITH
LITTLE CIN NOTED AND INITIATION REFLECTED IN GEM/GFS QPF.  THUS HAVE
RAISED POPS FURTHER THROUGH CHANCE CATEGORY NW SAT EVE.

UPR LEVEL TROUGH PASSES THROUGH CANADIAN PROVINCES EARLY NEXT
WEEK...BUT IA SHOULD REMAIN FAR ENOUGH S AND W TO NOT BE INFLUENCED
WITH ELONGATED HIGH PLAINS SFC RIDGE IN PLACE.  BY TUE/WED THERE IS
SOME CONCERN REGARDING STRENGTH OF ROCKIES UPR LEVEL RIDGE.
ECMWF/GEM MORE AGGRESSIVE LOWERING HEIGHTS THAN GFS AND ENSEMBLES
WITH BOUNDARY APPROACHING WRN IA BUT LEFT REMAINDER OF PD DRY FOR
THE MOMENT.  EVEN GEM/ECMWF SCENARIO WOULD PROBABLY LEAVE
CONVERGENCE...AND WEAK AT THAT...JUST TO OUR W.

LITTLE CHANGES TO MINS/MAXES WITH NEW GUIDANCE...MODEL FORECAST
SOUNDINGS AND H85 TEMPS SIMILAR AND SUPPORTIVE OF PREVIOUS FORECAST.

&&

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

&&

BOKSA/SMALL

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
1110 PM CDT WED JUN 21 2006

IAZ004>007-015>017-023>028-033>039-044>050-057>062-221100-
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-
1110 PM CDT WED JUN 21 2006

THIS HAZARDOUS WEATHER OUTLOOK IS FOR A PORTION OF CENTRAL IOWA
GENERALLY NORTH OF INTERSTATE 80.

.DAY ONE...TONIGHT

NO HAZARDOUS WEATHER IS EXPECTED.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

ISOLATED NON SEVERE THUNDERSTORMS ARE EXPECTED ON THURSDAY. ANOTHER
ROUND OF THUNDERSTORMS IS EXPECTED SATURDAY AND SATURDAY
NIGHT...WHICH IS TOO FAR INTO THE FUTURE TO ASSESS SEVERE POTENTIAL.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED.

IAZ070>075-081>086-092>097-221100-
CASS-ADAIR-MADISON-WARREN-MARION-MAHASKA-ADAMS-UNION-CLARKE-LUCAS-
MONROE-WAPELLO-TAYLOR-RINGGOLD-DECATUR-WAYNE-APPANOOSE-DAVIS-
1110 PM CDT WED JUN 21 2006

THIS HAZARDOUS WEATHER OUTLOOK IS FOR A PORTION OF CENTRAL IOWA
GENERALLY SOUTH OF INTERSTATE 80.

.DAY ONE...TONIGHT

A FEW STORMS MAYBE SEVERE OVERNIGHT...ESPECIALLY NEAR THE MISSOURI
BORDER. THE MAIN THREAT WILL BE LARGE HAIL WITH A SECONDARY THREAT
OF DAMAGING WIND.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

ISOLATED NON SEVERE THUNDERSTORMS ARE EXPECTED ON THURSDAY.
ANOTHER ROUND OF THUNDERSTORMS IS EXPECTED SATURDAY AND SATURDAY
NIGHT...WHICH IS TOO FAR INTO THE FUTURE TO ASSESS SEVERE POTENTIAL.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED.

MYERS