684
ACUS01 KWNS 170549
SWODY1
SPC AC 170547
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1247 AM CDT THU APR 17 2025
VALID 171200Z - 181200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM PORTIONS
OF EASTERN NEBRASKA INTO WESTERN IOWA...
..SUMMARY
ISOLATED TO SCATTERED SEVERE THUNDERSTORMS ARE EXPECTED, MAINLY FROM
LATE AFTERNOON INTO THE EVENING, ACROSS PARTS OF THE EASTERN CENTRAL
PLAINS TO THE UPPER MIDWEST. LARGE TO VERY LARGE HAIL AND LOCALIZED
DAMAGING WINDS ARE THE PRIMARY RISKS.
..CENTRAL PLAINS TO THE UPPER MIDWEST
MEAN UPPER RIDGE IS FORECAST TO SHIFT EAST DURING THE PERIOD AS A
BROAD CORRIDOR OF MID-LEVEL HEIGHT FALLS SPREAD ACROSS MUCH OF THE
ROCKIES INTO THE UPPER MS VALLEY REGION. AS THIS OCCURS,
SOUTHWESTERLY FLOW WILL STRENGTHEN ACROSS THE SOUTHERN
ROCKIES-CENTRAL PLAINS-UPPER MIDWEST. THIS EVOLUTION SUPPORTS
SURFACE PRESSURE RISES ACROSS THE NORTHERN PLAINS AND A PRONOUNCED
COLD FRONT WILL SURGE INTO SOUTHERN MN-NORTHWEST IA-EASTERN NE BY
18/00Z. STRONG BOUNDARY-LAYER HEATING IS FORECAST SOUTH OF THIS WIND
SHIFT FROM EASTERN CO INTO SOUTHEAST NE. AS TEMPERATURES RISE
THROUGH THE MID 80S, CONVECTIVE TEMPERATURES WILL BE BREACHED AND
FRONTAL CONVERGENCE SHOULD ENCOURAGE THUNDERSTORM DEVELOPMENT BY
22-23Z. WILE PW VALUES ARE A BIT MARGINAL, SURFACE DEW POINTS SHOULD
RISE INTO THE MID 50S, AND SBCAPE IS EXPECTED TO EXCEED 2500 J/KG BY
PEAK HEATING ALONG THE NORTHEASTERN EDGE OF THE STEEPER LAPSE RATE
PLUME. HRRR FORECAST SOUNDING FOR OMA AT 18/00Z EXHIBITS VERY STRONG
DEEP-LAYER SHEAR WITH SUBSTANTIAL 0-3KM SRH. IT APPEARS SCATTERED
SUPERCELLS MAY ULTIMATELY EVOLVE ALONG A CORRIDOR FROM SOUTHEAST NE
INTO SOUTHWEST IA, AND THIS ACTIVITY WILL LIKELY PROVE EFFICIENT IN
GENERATING HAIL. HAIL IN EXCESS OF 2 INCHES MAY BE NOTED IN THE MOST
ROBUST UPDRAFTS DUE TO FAVORABLE HODOGRAPHS. ALTHOUGH MOISTURE IS A
BIT SCANT, A NARROW WINDOW FOR TORNADOES DOES APPEAR TO EXIST IF DEW
POINTS CAN RISE INTO THE UPPER 50S, AND THIS IS MOST LIKELY ACROSS
PORTIONS OF EASTERN NE INTO WESTERN IA.
SUPERCELL THREAT WILL SPREAD NORTHEAST ALONG THE NOSE OF A
STRENGTHENING LLJ INTO THE UPPER MIDWEST DURING THE EVENING HOURS;
HOWEVER, CONDITIONS DOWNSTREAM WILL BE LESS FAVORABLE FOR
SURFACE-BASED CONVECTION BY MID EVENING, AND ELEVATED UPDRAFTS
SHOULD BE MORE COMMON.
..DARROW/WENDT.. 04/17/2025
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