All of Iowa, Severe Weather

Severe Weather Possible Next Two Days

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There is a slight risk of severe weather Today and Saturday across the state. Today the risk covers almost the entire state, while Saturday’s risk area covers the areas along and north of Interstate 80. The main risks would be from large hail and damaging winds. There is an isolated tornado threat today across the northwestern counties today. There is a chance of an MCS developing and sweeping across the state both today and Saturday mainly in the evening into the overnight hours. This is very fluid and may change or may not develop at all (similar to what occurred last night).

Here is SPC’s statement, …N-CNTRL HIGH PLAINS TO THE UPPER MS VALLEY…
GIVEN VERY LITTLE CHANGE IS FORECAST TO OCCUR IN THE LARGE-SCALE
FLOW REGIME DURING MUCH OF THE DAY…GREATEST CONCENTRATION OF SVR
IS EXPECTED TO OCCUR INVOF A LOW-LEVEL BAROCLINIC ZONE ORIENTED
NE-SW FROM NERN SD INTO WRN NEB. UPPER 60S DEWPOINTS WILL RESIDE
ALONG THE FRONTAL ZONE OVER ERN SD/NEB…WHILE UPSLOPE ENELY FLOW
AIDS IN MAINTAINING 40S AND 50S DEWPOINTS OVER THE N-CNTRL HIGH
PLAINS. STEEP MIDLEVEL LAPSE RATES WILL ONCE AGAIN BE PRESENT ACROSS
THE REGION…WHICH WILL CONTRIBUTE TOWARD STRONG TO EXTREME
INSTABILITY FROM THE DAKOTAS SWD INTO NEB.

STORMS WILL BE ONGOING OVER THE UPPER MS VALLEY/UPPER MIDWEST AT THE
START OF THE PERIOD…AS WELL AS WRN/CNTRL SD INTO SERN MT. SOME OF
THIS ACTIVITY WILL POSE A THREAT FOR ISOLATED LARGE HAIL AND
DAMAGING WINDS DURING THE MORNING…BUT MAY WEAKEN TOWARD MIDDAY. BY
AFTERNOON…ADDITIONAL THUNDERSTORM DEVELOPMENT IS LIKELY OVER THE
HIGH PLAINS WITHIN THE UPSLOPE FLOW REGIME. STEEP MIDLEVEL LAPSE
RATES AND LONG/STRAIGHT HODOGRAPHS WILL FAVOR SUPERCELLS AND A LARGE
HAIL THREAT. FARTHER E FROM WRN NEB INTO CNTRL/ERN SD…A
COMBINATION OF LOW-LEVEL FRONTOGENESIS AND MINOR MIDLEVEL IMPULSES
MOVING ACROSS THE AREA WILL LEAD TO SCATTERED THUNDERSTORM
DEVELOPMENT BY LATE AFTERNOON INTO THE EVENING. MLCAPE VALUES
EXCEEDING 2500 J/KG…STEEP MIDLEVEL LAPSE RATES…AND WIND PROFILES
THAT VEER FROM ESELY IN THE LOW-LEVELS TO SWLY IN THE MIDLEVELS WILL
AID IN SUPERCELL DEVELOPMENT WITH A RISK FOR VERY LARGE HAIL.
UPSCALE GROWTH INTO AN MCS IS LIKELY DURING THE NIGHT OVER SD…NRN
NEB AND PORTIONS OF SRN MN/NRN IA…WITH A CONTINUED THREAT FOR
LARGE HAIL AND DAMAGING WIND GUSTS POSSIBLE.