DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1152 PM CDT WED SEP 18 2013 VALID 191200Z - 201200Z ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE UPPER GREAT LAKES TO THE CENTRAL PLAINS... ...UPPER GREAT LAKES TO CENTRAL PLAINS... EARLY MORNING WV IMAGERY DEPICTS A WELL DEFINED SHORT-WAVE TROUGH OVER THE NRN ROCKIES. THIS FEATURE IS FORECAST BY LATEST SHORT-RANGE MODEL GUIDANCE TO SHIFT INTO THE PLAINS BY 20/00Z WITH WEAK HEIGHT FALLS EXPECTED TO THE LATITUDE OF I-70 OVER KS. WHILE SIGNIFICANT MID LEVEL FLOW SHOULD NOT SPREAD APPRECIABLY INTO THE WARM SECTOR...FORECAST SOUNDINGS SUGGEST 500MB WIND SPEEDS COULD EXCEED 30KT ACROSS THE UPPER MS VALLEY...SWWD ALONG A SFC FRONT INTO SCNTRL KS. EARLY IN THE PERIOD VEERED LLJ WILL BE FOCUSED ACROSS IA AND ELEVATED CONVECTION MAY BE NOTED ACROSS WI/NRN IL DUE TO WARM ADVECTION ATOP STABLE BOUNDARY LAYER. A FEW ROBUST UPDRAFTS MAY BE NOTED WITHIN THIS ACTIVITY BUT LITTLE MORE THAN MARGINALLY SEVERE HAIL OR GUSTY WINDS CAN BE EXPECTED WITH NEAR-DAWN CONVECTION. BY LATE MORNING STRONG FORCING SHOULD SPREAD ACROSS THE DAKOTAS AND FRONTAL UPLIFT SHOULD ENCOURAGE ELEVATED POST-WIND SHIFT TSTM ACTIVITY ACROSS THE UPPER MS VALLEY. ELEVATED NATURE SUGGESTS MARGINALLY SEVERE HAIL IS THE PRIMARY THREAT HERE AS WELL. HOWEVER...STRONG SFC HEATING ACROSS NRN IA INTO SRN WI FAVORS DEEPENING BOUNDARY LAYER AND CONVECTIVE TEMPERATURES MAY BE BREACHED BY 21Z. TSTMS WILL DEVELOP BY MID AFTERNOON ACROSS SRN MN/WRN WI...ESPECIALLY WITH FRONTAL CONVERGENCE...AHEAD OF WEAK SFC LOW. FORECAST SHEAR PROFILES FAVOR LINEAR STORM MODE THROUGH WEAK ROTATION IS POSSIBLE NEAR THE ADVANCING WARM FRONT ACROSS THE UPPER GREAT LAKES REGION. THUNDERSTORMS ARE EXPECTED TO READILY DEVELOP ALONG THE WIND SHIFT ACROSS IA/MO/KS BY LATE AFTERNOON AS AMPLE MOISTURE AND SUFFICIENT INSTABILITY SHOULD BE WEAKLY CAPPED AND AVAILABLE FOR CONVECTIVE DEVELOPMENT. HAIL/GUSTY WINDS ARE THE PRIMARY THREATS WITH FRONTAL CONVECTION.
Posted on: Thu, 19 Sep 2013 11:17:19 +0000
Trending Topics
Recently Viewed Topics
© 2015