SPC AC 091718 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1218 PM CDT Sat Oct 09 2021 Valid 101200Z - 111200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF OKLAHOMA AND FAR NORTH TEXAS... ...SUMMARY... Strong/severe storms are forecast from Sunday afternoon into Sunday night across portions of the southern Plains and vicinity, with large hail, damaging winds, and a few tornadoes possible. ...Southern Plains... Overall forecast remains similar to the initial Day 2 Outlook. As a potent upper trough ejects into the southern Plains by late Sunday afternoon, moderate/strong vertical shear and large-scale ascent will overspread the region. Capping will limit convection much of the day, but low-level warm advection coupled with strong forcing should sufficiently erode the cap by late afternoon/early evening. A surface low is forecast to deepen across western North Texas and develop northeast across OK during the evening, and into MO overnight. Backed/south-southeasterly low level winds beneath southwesterly mid/upper level flow will result in effective shear magnitudes greater than 45 kt and favorably curved low-level hodographs. Mid 60s to near 70 F surface dewpoints beneath steep midlevel lapse rates will foster moderate instability across the warm sector, with 1000-2000 J/kg MLCAPE expected. A 10% SIG tornado area has been added for portions of southwest OK near the surface low where at least a brief window of opportunity will exist for a few discrete supercells early in convective evolution (22z-02z). Initial convection near the surface low and cold front across north/central OK, as well as along a dryline extending southward into central TX, also will pose a threat for large hail given favorable shear and steep midlevel lapse rates. As the sharp cold front shifts south/southeast in conjunction with a strengthening low-level jet during the evening, convection is expected to quickly expand in coverage across OK/TX and grow upscale into a severe QLCS. Damaging wind gusts will become the primary hazard with linear convection. However, low-level shear will remain strong, with forecast soundings maintaining favorable hodographs for rotation, and a few QLCS tornadoes may accompany the line of convection as it spreads eastward across OK and North Texas. ...Upper Midwest... An upper low and attendant trough will lift northeast across the Upper Midwest on Sunday. Elevated convection will likely be ongoing Sunday morning, and pose a threat for marginally severe hail. A surface low near the ND/MN border will lift northeast through the day, bringing a warm front north of the international border. If enough heating can occur, another round of convection may develop during the afternoon. Steep lapse rates and moderate vertical shear amid weak instability will support a threat for marginally severe hail and strong gusts. ...NC Outer Banks... A surface low is forecast to be located near/just offshore the Outer Banks vicinity early Sunday. Most forecast guidance keeps the low offshore, but strong low-level north/northeasterly flow will impinge on the coast. Weak instability amid 20-30 kt effective shear magnitudes could result in a few strong cells capable of gusty winds. A very moist, tropical airmass will be in place, but 0-3 km MLCAPE is forecast to remain weak. While curved low-level hodographs are forecast, overall tornado potential appears too low/uncertain to include probabilities at this time. ..Leitman.. 10/09/2021 CLICK TO GET WUUS02 PTSDY2 PRODUCT NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0600Z CURRENT UTC TIME: 0418Z (12:18AM), RELOAD THIS PAGE TO UPDATE THE TIME
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