CHASE PREDICTION CENTER
SIOUX FALLS, SD
CHASE OUTLOOK DAY 2
COD-047
0700Z MONDAY JUNE 17, 2002
VALID 12Z 06/18/02 THROUGH 12Z 06/19/02
THERE IS A SLIGHT RISK FOR CHASEABLE THUNDERSTORMS OVER PARTS OF THE NORTHERN AND CENTRAL PLAINS.
THUNDERSTORMS ARE LIKELY TO BE ONGOING AT THE BEGINNING OF THE PERIOD OVER PARTS OF THE MISSOURI RIVER VALLEY. SOME OF THESE STORMS MAY CONTAIN A MARGINAL THREAT FOR SEVERE HAIL BEFORE DIMINISHING BY MID MORNING. THIS SHOULD LEAVE A FAIRLY WELL DEFINED E-W OUTFLOW BOUNDARY FROM NEB EAST INTO IA.
SHORT WAVE ENERGY MOVING QUICKLY ACROSS SOUTHERN CANADA WILL ALLOW FOR A COLD FRONT TO SLOWLY PUSH INTO THE EASTERN DAKOTAS BY LATE AFTERNOON. OUTFLOW BOUNDARY WILL LIFT TO THE NORTH THROUGH THE AFTERNOON...AND WILL LIKELY BE SOMEWHERE ALONG THE SD/NEB BORDER BY 00Z (19TH). MOISTURE WILL CONTINUE TO RETURN TO THE REGION DURING THE DAY TWO PERIOD UNDER STEEP MID LEVEL LAPSE RATES OF 7-8C/KM. DEWPOINTS BY AFTERNOON ALONG AND AHEAD OF THE COLD FRONT WILL LIKELY RISE INTO THE LOWER 60S. THIS COMBINED WITH THE LAPSE RATES WILL CREASE A VERY UNSTABLE ATMOSPHERE WITH SBCAPE OF 2500-3500J/KT EXPECTED.
THUNDERSTORMS WILL LIKELY DEVELOP IN WEAKLY CAPPED ATMOSPHERE BY MID AFTERNOON ALONG THE COLD FRONT FROM ND SOUTH INTO CENTRAL SD. DEEP LAYER SHEAR WILL AGAIN BE ONLY MARGINALLY FAVORABLE FOR ORGANIZED SEVERE WEATHER AND MULTI-CELLED CLUSTER CONTAIN LARGE HAIL AND DAMAGING WINDS ARE EXPECTED THROUGH THE EVENING. FARTHER SOUTH ALONG THE NEB/SD BORDER (NEAR OUTFLOW BOUNDARY) DEEP LAYER SHEAR WILL BE A LITTLE MORE FAVORABLE FOR ORGANIZED SEVERE WEATHER...INCLUDING SUPERCELLS. THUS THUNDERSTORMS DEVELOPING IN THIS AREA WILL POSE A GREATER THREAT FOR LARGE HAIL AND DAMAGING WIND. OTHER THUNDERSTORM MAY AGAIN INITIATE ALONG LEE TROUGH...WHICH IS LIKELY TO BE A LITTLE FARTHER EAST INTO CENTRAL KS. INSTABILITY AND LOW LEVEL MOISTURE WILL BE LESS IN THIS REGION...BUT A DEEPLY MIXED BOUNDARY LAYER WILL LIKELY ALLOW FOR THUNDERSTORMS TO DEVELOP BY LATE AFTERNOON. THESE THUNDERSTORM WOULD POSE MAIN A MARGINAL SEVERE HAIL AND WIND THREAT. THUNDERSTORMS OVER THE NORTHERN PLAINS ARE LIKELY TO FORM AN MCS AT THE NOSE OF THE LLJ OVER NORTHERN NEB AND SOUTHERN SD.
CHASE TARGET...YANKTON, SD
BOUSTEAD
